This document covers the configuration language as implemented in the version
specified above. It does not provide any hints, examples, or advice. For such
documentation, please refer to the Reference Manual or the Architecture Manual.
The summary below is meant to help you find sections by name and navigate
through the document.
Note to documentation contributors :
This document is formatted with 80 columns per line, with even number of
spaces for indentation and without tabs. Please follow these rules strictly
so that it remains easily printable everywhere. If a line needs to be
printed verbatim and does not fit, please end each line with a backslash
('\') and continue on next line, indented by two characters. It is also
sometimes useful to prefix all output lines (logs, console outputs) with 3
closing angle brackets ('>>>') in order to emphasize the difference between
inputs and outputs when they may be ambiguous. If you add sections,
please update the summary below for easier searching.
Summary
| 1. | Quick reminder about HTTP | |
| 1.1. | ||
| 1.2. | ||
| 1.2.1. | ||
| 1.2.2. | ||
| 1.3. | ||
| 1.3.1. | ||
| 1.3.2. | ||
2. |
Configuring HAProxy | |
| 2.1. | ||
| 2.2. | ||
| 2.3. | ||
| 2.4. | ||
| 2.5. | ||
| 2.6. | ||
| 2.7. | ||
3. |
Global parameters | |
| 3.1. | ||
| 3.2. | ||
| 3.3. | ||
| 3.4. | ||
| 3.5. | ||
| 3.6. | ||
| 3.7. | ||
| 3.8. | ||
| 3.9. | ||
| 3.10. | ||
| 3.11. | ||
| 3.12. | ||
4. |
Proxies | |
| 4.1. | ||
| 4.2. | ||
5. |
Bind and server options | |
| 5.1. | ||
| 5.2. | ||
| 5.3. | ||
| 5.3.1. | ||
| 5.3.2. | ||
6. |
Cache | |
| 6.1. | ||
| 6.2. | ||
| 6.2.1. | ||
| 6.2.2. | ||
7. |
Using ACLs and fetching samples | |
| 7.1. | ||
| 7.1.1. | ||
| 7.1.2. | ||
| 7.1.3. | ||
| 7.1.4. | ||
| 7.1.5. | ||
| 7.1.6. | ||
| 7.2. | ||
| 7.3. | ||
| 7.3.1. | ||
| 7.3.2. | ||
| 7.3.3. | ||
| 7.3.4. | ||
| 7.3.5. | ||
| 7.3.6. | ||
| 7.3.7. | ||
| 7.4. | ||
8. |
Logging | |
| 8.1. | ||
| 8.2. | ||
| 8.2.1. | ||
| 8.2.2. | ||
| 8.2.3. | ||
| 8.2.4. | ||
| 8.2.5. | ||
| 8.3. | ||
| 8.3.1. | ||
| 8.3.2. | ||
| 8.3.3. | ||
| 8.3.4. | ||
| 8.4. | ||
| 8.5. | ||
| 8.6. | ||
| 8.7. | ||
| 8.8. | ||
| 8.9. | ||
9. |
Supported filters | |
| 9.1. | ||
| 9.2. | ||
| 9.3. | ||
| 9.4. | ||
| 9.5. | ||
| 9.6. | ||
10. |
FastCGI applications | |
| 10.1. | ||
| 10.1.1. | ||
| 10.1.2. | ||
| 10.1.3. | ||
| 10.2. | ||
| 10.3. | ||
11. |
Address formats | |
| 11.1. | ||
| 11.2. | ||
| 11.3. |
1. Quick reminder about HTTP
When HAProxy is running in HTTP mode, both the request and the response are
fully analyzed and indexed, thus it becomes possible to build matching criteria
on almost anything found in the contents.
However, it is important to understand how HTTP requests and responses are
formed, and how HAProxy decomposes them. It will then become easier to write
correct rules and to debug existing configurations.
1.1. The HTTP transaction model
The HTTP protocol is transaction-driven. This means that each request will lead
to one and only one response. Traditionally, a TCP connection is established
from the client to the server, a request is sent by the client through the
connection, the server responds, and the connection is closed. A new request
will involve a new connection :
[CON1] [REQ1] ... [RESP1] [CLO1] [CON2] [REQ2] ... [RESP2] [CLO2] ...
In this mode, called the "HTTP close" mode, there are as many connection
establishments as there are HTTP transactions. Since the connection is closed
by the server after the response, the client does not need to know the content
length.
Due to the transactional nature of the protocol, it was possible to improve it
to avoid closing a connection between two subsequent transactions. In this mode
however, it is mandatory that the server indicates the content length for each
response so that the client does not wait indefinitely. For this, a special
header is used: "Content-length". This mode is called the "keep-alive" mode :
[CON] [REQ1] ... [RESP1] [REQ2] ... [RESP2] [CLO] ...
Its advantages are a reduced latency between transactions, and less processing
power required on the server side. It is generally better than the close mode,
but not always because the clients often limit their concurrent connections to
a smaller value.
Another improvement in the communications is the pipelining mode. It still uses
keep-alive, but the client does not wait for the first response to send the
second request. This is useful for fetching large number of images composing a
page :
[CON] [REQ1] [REQ2] ... [RESP1] [RESP2] [CLO] ...
This can obviously have a tremendous benefit on performance because the network
latency is eliminated between subsequent requests. Many HTTP agents do not
correctly support pipelining since there is no way to associate a response with
the corresponding request in HTTP. For this reason, it is mandatory for the
server to reply in the exact same order as the requests were received.
The next improvement is the multiplexed mode, as implemented in HTTP/2. This
time, each transaction is assigned a single stream identifier, and all streams
are multiplexed over an existing connection. Many requests can be sent in
parallel by the client, and responses can arrive in any order since they also
carry the stream identifier.
By default HAProxy operates in keep-alive mode with regards to persistent
connections: for each connection it processes each request and response, and
leaves the connection idle on both sides between the end of a response and the
start of a new request. When it receives HTTP/2 connections from a client, it
processes all the requests in parallel and leaves the connection idling,
waiting for new requests, just as if it was a keep-alive HTTP connection.
HAProxy supports 4 connection modes :
- keep alive : all requests and responses are processed (default)
- tunnel : only the first request and response are processed,
everything else is forwarded with no analysis (deprecated).
- server close : the server-facing connection is closed after the response.
- close : the connection is actively closed after end of response.
1.2. HTTP request
First, let's consider this HTTP request :
Line Contents
number
1 GET /serv/login.php?lang=en&profile=2 HTTP/1.1
2 Host: www.mydomain.com
3 User-agent: my small browser
4 Accept: image/jpeg, image/gif
5 Accept: image/png
1.2.1. The Request line
Line 1 is the "request line". It is always composed of 3 fields :
- a METHOD : GET
- a URI : /serv/login.php?lang=en&profile=2
- a version tag : HTTP/1.1
All of them are delimited by what the standard calls LWS (linear white spaces),
which are commonly spaces, but can also be tabs or line feeds/carriage returns
followed by spaces/tabs. The method itself cannot contain any colon (':') and
is limited to alphabetic letters. All those various combinations make it
desirable that HAProxy performs the splitting itself rather than leaving it to
the user to write a complex or inaccurate regular expression.
The URI itself can have several forms :
- A "relative URI" :
/serv/login.php?lang=en&profile=2
It is a complete URL without the host part. This is generally what is
received by servers, reverse proxies and transparent proxies.
- An "absolute URI", also called a "URL" :
http://192.168.0.12:8080/serv/login.php?lang=en&profile=2
It is composed of a "scheme" (the protocol name followed by '://'), a host
name or address, optionally a colon (':') followed by a port number, then
a relative URI beginning at the first slash ('/') after the address part.
This is generally what proxies receive, but a server supporting HTTP/1.1
must accept this form too.
- a star ('*') : this form is only accepted in association with the OPTIONS
method and is not relayable. It is used to inquiry a next hop's
capabilities.
- an address:port combination : 192.168.0.12:80
This is used with the CONNECT method, which is used to establish TCP
tunnels through HTTP proxies, generally for HTTPS, but sometimes for
other protocols too.
In a relative URI, two sub-parts are identified. The part before the question
mark is called the "path". It is typically the relative path to static objects
on the server. The part after the question mark is called the "query string".
It is mostly used with GET requests sent to dynamic scripts and is very
specific to the language, framework or application in use.
HTTP/2 doesn't convey a version information with the request, so the version is
assumed to be the same as the one of the underlying protocol (i.e. "HTTP/2").
1.2.2. The request headers
The headers start at the second line. They are composed of a name at the
beginning of the line, immediately followed by a colon (':'). Traditionally,
an LWS is added after the colon but that's not required. Then come the values.
Multiple identical headers may be folded into one single line, delimiting the
values with commas, provided that their order is respected. This is commonly
encountered in the "Cookie:" field. A header may span over multiple lines if
the subsequent lines begin with an LWS. In the example in 1.2, lines 4 and 5
define a total of 3 values for the "Accept:" header.
Contrary to a common misconception, header names are not case-sensitive, and
their values are not either if they refer to other header names (such as the
"Connection:" header). In HTTP/2, header names are always sent in lower case,
as can be seen when running in debug mode. Internally, all header names are
normalized to lower case so that HTTP/1.x and HTTP/2 use the exact same
representation, and they are sent as-is on the other side. This explains why an
HTTP/1.x request typed with camel case is delivered in lower case.
The end of the headers is indicated by the first empty line. People often say
that it's a double line feed, which is not exact, even if a double line feed
is one valid form of empty line.
Fortunately, HAProxy takes care of all these complex combinations when indexing
headers, checking values and counting them, so there is no reason to worry
about the way they could be written, but it is important not to accuse an
application of being buggy if it does unusual, valid things.
Important note:
As suggested by RFC7231, HAProxy normalizes headers by replacing line breaks
in the middle of headers by LWS in order to join multi-line headers. This
is necessary for proper analysis and helps less capable HTTP parsers to work
correctly and not to be fooled by such complex constructs.
1.3. HTTP response
An HTTP response looks very much like an HTTP request. Both are called HTTP
messages. Let's consider this HTTP response :
Line Contents
number
1 HTTP/1.1 200 OK
2 Content-length: 350
3 Content-Type: text/html
As a special case, HTTP supports so called "Informational responses" as status
codes 1xx. These messages are special in that they don't convey any part of the
response, they're just used as sort of a signaling message to ask a client to
continue to post its request for instance. In the case of a status 100 response
the requested information will be carried by the next non-100 response message
following the informational one. This implies that multiple responses may be
sent to a single request, and that this only works when keep-alive is enabled
(1xx messages are HTTP/1.1 only). HAProxy handles these messages and is able to
correctly forward and skip them, and only process the next non-100 response. As
such, these messages are neither logged nor transformed, unless explicitly
state otherwise. Status 101 messages indicate that the protocol is changing
over the same connection and that HAProxy must switch to tunnel mode, just as
if a CONNECT had occurred. Then the Upgrade header would contain additional
information about the type of protocol the connection is switching to.
1.3.1. The response line
Line 1 is the "response line". It is always composed of 3 fields :
- a version tag : HTTP/1.1
- a status code : 200
- a reason : OK
The status code is always 3-digit. The first digit indicates a general status :
- 1xx = informational message to be skipped (e.g. 100, 101)
- 2xx = OK, content is following (e.g. 200, 206)
- 3xx = OK, no content following (e.g. 302, 304)
- 4xx = error caused by the client (e.g. 401, 403, 404)
- 5xx = error caused by the server (e.g. 500, 502, 503)
Please refer to RFC7231 for the detailed meaning of all such codes. The
"reason" field is just a hint, but is not parsed by clients. Anything can be
found there, but it's a common practice to respect the well-established
messages. It can be composed of one or multiple words, such as "OK", "Found",
or "Authentication Required".
HAProxy may emit the following status codes by itself :
Code When / reason
200 access to stats page, and when replying to monitoring requests
301 when performing a redirection, depending on the configured code
302 when performing a redirection, depending on the configured code
303 when performing a redirection, depending on the configured code
307 when performing a redirection, depending on the configured code
308 when performing a redirection, depending on the configured code
400 for an invalid or too large request
401 when an authentication is required to perform the action (when
accessing the stats page)
403 when a request is forbidden by a "http-request deny" rule
404 when the requested resource could not be found
408 when the request timeout strikes before the request is complete
410 when the requested resource is no longer available and will not
be available again
500 when HAProxy encounters an unrecoverable internal error, such as a
memory allocation failure, which should never happen
501 when HAProxy is unable to satisfy a client request because of an
unsupported feature
502 when the server returns an empty, invalid or incomplete response, or
when an "http-response deny" rule blocks the response.
503 when no server was available to handle the request, or in response to
monitoring requests which match the "monitor fail" condition
504 when the response timeout strikes before the server responds
The error 4xx and 5xx codes above may be customized (see "errorloc" in section
4.2).
1.3.2. The response headers
Response headers work exactly like request headers, and as such, HAProxy uses
the same parsing function for both. Please refer to paragraph 1.2.2 for more
details.
2. Configuring HAProxy
2.1. Configuration file format
HAProxy's configuration process involves 3 major sources of parameters :
- the arguments from the command-line, which always take precedence
- the configuration file(s), whose format is described here
- the running process's environment, in case some environment variables are
explicitly referenced
The configuration file follows a fairly simple hierarchical format which obey
a few basic rules:
1. a configuration file is an ordered sequence of statements
2. a statement is a single non-empty line before any unprotected "#" (hash)
3. a line is a series of tokens or "words" delimited by unprotected spaces or
tab characters
4. the first word or sequence of words of a line is one of the keywords or
keyword sequences listed in this document
5. all other words are all arguments of the first one, some being well-known
keywords listed in this document, others being values, references to other
parts of the configuration, or expressions
6. certain keywords delimit a section inside which only a subset of keywords
are supported
7. a section ends at the end of a file or on a special keyword starting a new
section
This is all that is needed to know to write a simple but reliable configuration
generator, but this is not enough to reliably parse any configuration nor to
figure how to deal with certain corner cases.
First, there are a few consequences of the rules above. Rule 6 and 7 imply that
the keywords used to define a new section are valid everywhere and cannot have
a different meaning in a specific section. These keywords are always a single
word (as opposed to a sequence of words), and traditionally the section that
follows them is designated using the same name. For example when speaking about
the "global section", it designates the section of configuration that follows
the "global" keyword. This usage is used a lot in error messages to help locate
the parts that need to be addressed.
A number of sections create an internal object or configuration space, which
requires to be distinguished from other ones. In this case they will take an
extra word which will set the name of this particular section. For some of them
the section name is mandatory. For example "frontend foo" will create a new
section of type "frontend" named "foo". Usually a name is specific to its
section and two sections of different types may use the same name, but this is
not recommended as it tends to complexify configuration management.
A direct consequence of rule 7 is that when multiple files are read at once,
each of them must start with a new section, and the end of each file will end
a section. A file cannot contain sub-sections nor end an existing section and
start a new one.
Rule 1 mentioned that ordering matters. Indeed, some keywords create directives
that can be repeated multiple times to create ordered sequences of rules to be
applied in a certain order. For example "tcp-request" can be used to alternate
"accept" and "reject" rules on varying criteria. As such, a configuration file
processor must always preserve a section's ordering when editing a file. The
ordering of sections usually does not matter except for the global section
which must be placed before other sections, but it may be repeated if needed.
In addition, some automatic identifiers may automatically be assigned to some
of the created objects (e.g. proxies), and by reordering sections, their
identifiers will change. These ones appear in the statistics for example. As
such, the configuration below will assign "foo" ID number 1 and "bar" ID number
2, which will be swapped if the two sections are reversed:
listen foo
bind :80
listen bar
bind :81
Another important point is that according to rules 2 and 3 above, empty lines,
spaces, tabs, and comments following and unprotected "#" character are not part
of the configuration as they are just used as delimiters. This implies that the
following configurations are strictly equivalent:
global#this is the global section
daemon#daemonize
frontend foo
mode http # or tcp
and:
global
daemon
# this is the public web frontend
frontend foo
mode http
The common practice is to align to the left only the keyword that initiates a
new section, and indent (i.e. prepend a tab character or a few spaces) all
other keywords so that it's instantly visible that they belong to the same
section (as done in the second example above). Placing comments before a new
section helps the reader decide if it's the desired one. Leaving a blank line
at the end of a section also visually helps spotting the end when editing it.
Tabs are very convenient for indent but they do not copy-paste well. If spaces
are used instead, it is recommended to avoid placing too many (2 to 4) so that
editing in field doesn't become a burden with limited editors that do not
support automatic indent.
In the early days it used to be common to see arguments split at fixed tab
positions because most keywords would not take more than two arguments. With
modern versions featuring complex expressions this practice does not stand
anymore, and is not recommended.
2.2. Quoting and escaping
In modern configurations, some arguments require the use of some characters
that were previously considered as pure delimiters. In order to make this
possible, HAProxy supports character escaping by prepending a backslash ('\')
in front of the character to be escaped, weak quoting within double quotes
('"') and strong quoting within single quotes ("'").
This is pretty similar to what is done in a number of programming languages and
very close to what is commonly encountered in Bourne shell. The principle is
the following: while the configuration parser cuts the lines into words, it
also takes care of quotes and backslashes to decide whether a character is a
delimiter or is the raw representation of this character within the current
word. The escape character is then removed, the quotes are removed, and the
remaining word is used as-is as a keyword or argument for example.
If a backslash is needed in a word, it must either be escaped using itself
(i.e. double backslash) or be strongly quoted.
Escaping outside quotes is achieved by preceding a special character by a
backslash ('\'):
\ to mark a space and differentiate it from a delimiter
\# to mark a hash and differentiate it from a comment
\\ to use a backslash
\' to use a single quote and differentiate it from strong quoting
\" to use a double quote and differentiate it from weak quoting
In addition, a few non-printable characters may be emitted using their usual
C-language representation:
\n to insert a line feed (LF, character \x0a or ASCII 10 decimal)
\r to insert a carriage return (CR, character \x0d or ASCII 13 decimal)
\t to insert a tab (character \x09 or ASCII 9 decimal)
\xNN to insert character having ASCII code hex NN (e.g \x0a for LF).
Weak quoting is achieved by surrounding double quotes ("") around the character
or sequence of characters to protect. Weak quoting prevents the interpretation
of:
space or tab as a word separator
' single quote as a strong quoting delimiter
# hash as a comment start
Weak quoting permits the interpretation of environment variables (which are not
evaluated outside of quotes) by preceding them with a dollar sign ('$'). If a
dollar character is needed inside double quotes, it must be escaped using a
backslash.
Strong quoting is achieved by surrounding single quotes ('') around the
character or sequence of characters to protect. Inside single quotes, nothing
is interpreted, it's the efficient way to quote regular expressions.
As a result, here is the matrix indicating how special characters can be
entered in different contexts (unprintable characters are replaced with their
name within angle brackets). Note that some characters that may only be
represented escaped have no possible representation inside single quotes,
hence the '-' there:
| Character | Unquoted | Weakly quoted | Strongly quoted |
|---|
2.3. Environment variables
HAProxy's configuration supports environment variables. Those variables are
interpreted only within double quotes. Variables are expanded during the
configuration parsing. Variable names must be preceded by a dollar ("$") and
optionally enclosed with braces ("{}") similarly to what is done in Bourne
shell. Variable names can contain alphanumerical characters or the character
underscore ("_") but should not start with a digit. If the variable contains a
list of several values separated by spaces, it can be expanded as individual
arguments by enclosing the variable with braces and appending the suffix '[*]'
before the closing brace.
Example:
bind "fd@${FD_APP1}"
log "${LOCAL_SYSLOG}:514" local0 notice # send to local server
user "$HAPROXY_USER"
Some variables are defined by HAProxy, they can be used in the configuration
file, or could be inherited by a program (See 3.7. Programs):
* HAPROXY_LOCALPEER: defined at the startup of the process which contains the
name of the local peer. (See "-L" in the management guide.)
* HAPROXY_CFGFILES: list of the configuration files loaded by HAProxy,
separated by semicolons. Can be useful in the case you specified a
directory.
* HAPROXY_MWORKER: In master-worker mode, this variable is set to 1.
* HAPROXY_CLI: configured listeners addresses of the stats socket for every
processes, separated by semicolons.
* HAPROXY_MASTER_CLI: In master-worker mode, listeners addresses of the master
CLI, separated by semicolons.
* HAPROXY_STARTUP_VERSION: contains the version used to start, in master-worker
mode this is the version which was used to start the master, even after
updating the binary and reloading.
In addition, some pseudo-variables are internally resolved and may be used as
regular variables. Pseudo-variables always start with a dot ('.'), and are the
only ones where the dot is permitted. The current list of pseudo-variables is:
* .FILE: the name of the configuration file currently being parsed.
* .LINE: the line number of the configuration file currently being parsed,
starting at one.
* .SECTION: the name of the section currently being parsed, or its type if the
section doesn't have a name (e.g. "global"), or an empty string before the
first section.
These variables are resolved at the location where they are parsed. For example
if a ".LINE" variable is used in a "log-format" directive located in a defaults
section, its line number will be resolved before parsing and compiling the
"log-format" directive, so this same line number will be reused by subsequent
proxies.
This way it is possible to emit information to help locate a rule in variables,
logs, error statuses, health checks, header values, or even to use line numbers
to name some config objects like servers for example.
See also "external-check command" for other variables.
2.4. Conditional blocks
It may sometimes be convenient to be able to conditionally enable or disable
some arbitrary parts of the configuration, for example to enable/disable SSL or
ciphers, enable or disable some pre-production listeners without modifying the
configuration, or adjust the configuration's syntax to support two distinct
versions of HAProxy during a migration.. HAProxy brings a set of nestable
preprocessor-like directives which allow to integrate or ignore some blocks of
text. These directives must be placed on their own line and they act on the
lines that follow them. Two of them support an expression, the other ones only
switch to an alternate block or end a current level. The 4 following directives
are defined to form conditional blocks:
- .if <condition>
- .elif <condition>
- .else
- .endif
The ".if" directive nests a new level, ".elif" stays at the same level, ".else"
as well, and ".endif" closes a level. Each ".if" must be terminated by a
matching ".endif". The ".elif" may only be placed after ".if" or ".elif", and
there is no limit to the number of ".elif" that may be chained. There may be
only one ".else" per ".if" and it must always be after the ".if" or the last
".elif" of a block.
Comments may be placed on the same line if needed after a '#', they will be
ignored. The directives are tokenized like other configuration directives, and
as such it is possible to use environment variables in conditions.
The conditions are currently limited to:
- an empty string, always returns "false"
- the integer zero ('0'), always returns "false"
- a non-nul integer (e.g. '1'), always returns "true".
- a predicate optionally followed by argument(s) in parenthesis.
The list of currently supported predicates is the following:
- defined(<name>) : returns true if an environment variable <name>
exists, regardless of its contents
- feature(<name>) : returns true if feature <name> is listed as present
in the features list reported by "haproxy -vv"
(which means a <name> appears after a '+')
- streq(<str1>,<str2>) : returns true only if the two strings are equal
- strneq(<str1>,<str2>) : returns true only if the two strings differ
- version_atleast(<ver>): returns true if the current haproxy version is
at least as recent as <ver> otherwise false. The
version syntax is the same as shown by "haproxy -v"
and missing components are assumed as being zero.
- version_before(<ver>) : returns true if the current haproxy version is
strictly older than <ver> otherwise false. The
version syntax is the same as shown by "haproxy -v"
and missing components are assumed as being zero.
Example:
.if defined(HAPROXY_MWORKER)
listen mwcli_px
bind :1111
...
.endif
.if strneq("$SSL_ONLY",yes)
bind :80
.endif
.if streq("$WITH_SSL",yes)
.if feature(OPENSSL)
bind :443 ssl crt ...
.endif
.endif
.if version_atleast(2.4-dev19)
profiling.memory on
.endif
Four other directives are provided to report some status:
- .diag "message" : emit this message only when in diagnostic mode (-dD)
- .notice "message" : emit this message at level NOTICE
- .warning "message" : emit this message at level WARNING
- .alert "message" : emit this message at level ALERT
Messages emitted at level WARNING may cause the process to fail to start if the
"strict-mode" is enabled. Messages emitted at level ALERT will always cause a
fatal error. These can be used to detect some inappropriate conditions and
provide advice to the user.
Example:
.if "${A}"
.if "${B}"
.notice "A=1, B=1"
.elif "${C}"
.notice "A=1, B=0, C=1"
.elif "${D}"
.warning "A=1, B=0, C=0, D=1"
.else
.alert "A=1, B=0, C=0, D=0"
.endif
.else
.notice "A=0"
.endif
.diag "WTA/2021-05-07: replace 'redirect' with 'return' after switch to 2.4"
http-request redirect location /goaway if ABUSE
2.5. Time format
Some parameters involve values representing time, such as timeouts. These
values are generally expressed in milliseconds (unless explicitly stated
otherwise) but may be expressed in any other unit by suffixing the unit to the
numeric value. It is important to consider this because it will not be repeated
for every keyword. Supported units are :
- us : microseconds. 1 microsecond = 1/1000000 second
- ms : milliseconds. 1 millisecond = 1/1000 second. This is the default.
- s : seconds. 1s = 1000ms
- m : minutes. 1m = 60s = 60000ms
- h : hours. 1h = 60m = 3600s = 3600000ms
- d : days. 1d = 24h = 1440m = 86400s = 86400000ms
2.6. Size format
Some parameters involve values representing size, such as bandwidth limits.
These values are generally expressed in bytes (unless explicitly stated
otherwise) but may be expressed in any other unit by suffixing the unit to the
numeric value. It is important to consider this because it will not be repeated
for every keyword. Supported units are case insensitive :
- k : kilobytes. 1 kilobyte = 1024 bytes
- m : megabytes. 1 megabyte = 1048576 bytes
- g : gigabytes. 1 gigabyte = 1073741824 bytes
Both time and size formats require integers, decimal notation is not allowed.
2.7. Examples
# Simple configuration for an HTTP proxy listening on port 80 on all
# interfaces and forwarding requests to a single backend "servers" with a
# single server "server1" listening on 127.0.0.1:8000
global
daemon
maxconn 256
defaults
mode http
timeout connect 5000ms
timeout client 50000ms
timeout server 50000ms
frontend http-in
bind *:80
default_backend servers
backend servers
server server1 127.0.0.1:8000 maxconn 32
# The same configuration defined with a single listen block. Shorter but
# less expressive, especially in HTTP mode.
global
daemon
maxconn 256
defaults
mode http
timeout connect 5000ms
timeout client 50000ms
timeout server 50000ms
listen http-in
bind *:80
server server1 127.0.0.1:8000 maxconn 32
Assuming haproxy is in $PATH, test these configurations in a shell with:
$ sudo haproxy -f configuration.conf -c
3. Global parameters
Parameters in the "global" section are process-wide and often OS-specific. They
are generally set once for all and do not need being changed once correct. Some
of them have command-line equivalents.
The following keywords are supported in the "global" section :
* Process management and security
- 51degrees-cache-size
- 51degrees-data-file
- 51degrees-property-name-list
- 51degrees-property-separator
- ca-base
- chroot
- cpu-map
- crt-base
- daemon
- default-path
- description
- deviceatlas-json-file
- deviceatlas-log-level
- deviceatlas-properties-cookie
- deviceatlas-separator
- expose-experimental-directives
- external-check
- gid
- group
- h1-case-adjust
- h1-case-adjust-file
- h2-workaround-bogus-websocket-clients
- hard-stop-after
- insecure-fork-wanted
- insecure-setuid-wanted
- issuers-chain-path
- localpeer
- log
- log-send-hostname
- log-tag
- lua-load
- lua-load-per-thread
- lua-prepend-path
- mworker-max-reloads
- nbproc
- nbthread
- node
- numa-cpu-mapping
- pidfile
- pp2-never-send-local
- presetenv
- resetenv
- set-dumpable
- set-var
- setenv
- ssl-default-bind-ciphers
- ssl-default-bind-ciphersuites
- ssl-default-bind-curves
- ssl-default-bind-options
- ssl-default-server-ciphers
- ssl-default-server-ciphersuites
- ssl-default-server-options
- ssl-dh-param-file
- ssl-server-verify
- ssl-skip-self-issued-ca
- stats
- strict-limits
- uid
- ulimit-n
- unix-bind
- unsetenv
- user
- wurfl-cache-size
- wurfl-data-file
- wurfl-information-list
- wurfl-information-list-separator
* Performance tuning
- busy-polling
- max-spread-checks
- maxcompcpuusage
- maxcomprate
- maxconn
- maxconnrate
- maxpipes
- maxsessrate
- maxsslconn
- maxsslrate
- maxzlibmem
- no-memory-trimming
- noepoll
- noevports
- nogetaddrinfo
- nokqueue
- nopoll
- noreuseport
- nosplice
- profiling.tasks
- server-state-base
- server-state-file
- spread-checks
- ssl-engine
- ssl-mode-async
- tune.buffers.limit
- tune.buffers.reserve
- tune.bufsize
- tune.chksize
- tune.comp.maxlevel
- tune.fail-alloc
- tune.fd.edge-triggered
- tune.h2.header-table-size
- tune.h2.initial-window-size
- tune.h2.max-concurrent-streams
- tune.h2.max-frame-size
- tune.http.cookielen
- tune.http.logurilen
- tune.http.maxhdr
- tune.idle-pool.shared
- tune.idletimer
- tune.lua.forced-yield
- tune.lua.maxmem
- tune.lua.service-timeout
- tune.lua.session-timeout
- tune.lua.task-timeout
- tune.maxaccept
- tune.maxpollevents
- tune.maxrewrite
- tune.pattern.cache-size
- tune.pipesize
- tune.pool-high-fd-ratio
- tune.pool-low-fd-ratio
- tune.rcvbuf.client
- tune.rcvbuf.server
- tune.recv_enough
- tune.runqueue-depth
- tune.sched.low-latency
- tune.sndbuf.client
- tune.sndbuf.server
- tune.ssl.cachesize
- tune.ssl.capture-cipherlist-size
- tune.ssl.default-dh-param
- tune.ssl.force-private-cache
- tune.ssl.keylog
- tune.ssl.lifetime
- tune.ssl.maxrecord
- tune.ssl.ssl-ctx-cache-size
- tune.vars.global-max-size
- tune.vars.proc-max-size
- tune.vars.reqres-max-size
- tune.vars.sess-max-size
- tune.vars.txn-max-size
- tune.zlib.memlevel
- tune.zlib.windowsize
* Debugging
- quiet
- zero-warning
* HTTPClient
- httpclient.resolvers.id
- httpclient.resolvers.prefer
- httpclient.ssl.ca-file
- httpclient.ssl.verify
3.1. Process management and security
The path of the 51Degrees data file to provide device detection services. The
file should be unzipped and accessible by HAProxy with relevant permissions.
Please note that this option is only available when HAProxy has been
compiled with USE_51DEGREES.
A list of 51Degrees property names to be load from the dataset. A full list
of names is available on the 51Degrees website:
https://51degrees.com/resources/property-dictionary
Please note that this option is only available when HAProxy has been
compiled with USE_51DEGREES.
A char that will be appended to every property value in a response header
containing 51Degrees results. If not set that will be set as ','.
Please note that this option is only available when HAProxy has been
compiled with USE_51DEGREES.
Sets the size of the 51Degrees converter cache to <number> entries. This
is an LRU cache which reminds previous device detections and their results.
By default, this cache is disabled.
Please note that this option is only available when HAProxy has been
compiled with USE_51DEGREES.
Assigns a default directory to fetch SSL CA certificates and CRLs from when a
relative path is used with "ca-file", "ca-verify-file" or "crl-file"
directives. Absolute locations specified in "ca-file", "ca-verify-file" and
"crl-file" prevail and ignore "ca-base".
Changes current directory to <jail dir> and performs a chroot() there before
dropping privileges. This increases the security level in case an unknown
vulnerability would be exploited, since it would make it very hard for the
attacker to exploit the system. This only works when the process is started
with superuser privileges. It is important to ensure that <jail_dir> is both
empty and non-writable to anyone.
Define a time window during which idle connections and active connections
closing is spread in case of soft-stop. After a SIGUSR1 is received and the
grace period is over (if any), the idle connections will all be closed at
once if this option is not set, and active HTTP or HTTP2 connections will be
ended after the next request is received, either by appending a "Connection:
close" line to the HTTP response, or by sending a GOAWAY frame in case of
HTTP2. When this option is set, connection closing will be spread over this
set <time>.
If the close-spread-time is set to "infinite", active connection closing
during a soft-stop will be disabled. The "Connection: close" header will not
be added to HTTP responses (or GOAWAY for HTTP2) anymore and idle connections
will only be closed once their timeout is reached (based on the various
timeouts set in the configuration).
Arguments :
<time> is a time window (by default in milliseconds) during which
connection closing will be spread during a soft-stop operation, or
"infinite" if active connection closing should be disabled.
It is recommended to set this setting to a value lower than the one used in
the "hard-stop-after" option if this one is used, so that all connections
have a chance to gracefully close before the process stops.
See also: grace, hard-stop-after, idle-close-on-response
On Linux 2.6 and above, it is possible to bind a process or a thread to a
specific CPU set. This means that the process or the thread will never run on
other CPUs. The "cpu-map" directive specifies CPU sets for process or thread
sets. The first argument is a process set, eventually followed by a thread
set. These sets have the format
all | odd | even | number[-[number]]
<number>> must be a number between 1 and 32 or 64, depending on the machine's
word size. Any process IDs above nbproc and any thread IDs above nbthread are
ignored. It is possible to specify a range with two such number delimited by
a dash ('-'). It also is possible to specify all processes at once using
"all", only odd numbers using "odd" or even numbers using "even", just like
with the "bind-process" directive. The second and forthcoming arguments are
CPU sets. Each CPU set is either a unique number starting at 0 for the first
CPU or a range with two such numbers delimited by a dash ('-'). Outside of
Linux and BSDs, there may be a limitation on the maximum CPU index to either
31 or 63. Multiple CPU numbers or ranges may be specified, and the processes
or threads will be allowed to bind to all of them. Obviously, multiple
"cpu-map" directives may be specified. Each "cpu-map" directive will replace
the previous ones when they overlap. A thread will be bound on the
intersection of its mapping and the one of the process on which it is
attached. If the intersection is null, no specific binding will be set for
the thread.
Ranges can be partially defined. The higher bound can be omitted. In such
case, it is replaced by the corresponding maximum value, 32 or 64 depending
on the machine's word size.
The prefix "auto:" can be added before the process set to let HAProxy
automatically bind a process or a thread to a CPU by incrementing
process/thread and CPU sets. To be valid, both sets must have the same
size. No matter the declaration order of the CPU sets, it will be bound from
the lowest to the highest bound. Having a process and a thread range with the
"auto:" prefix is not supported. Only one range is supported, the other one
must be a fixed number.
Examples:
cpu-map 1-4 0-3 # bind processes 1 to 4 on the first 4 CPUs
cpu-map 1/all 0-3 # bind all threads of the first process on the
# first 4 CPUs
cpu-map 1- 0- # will be replaced by "cpu-map 1-64 0-63"
# or "cpu-map 1-32 0-31" depending on the machine's
# word size.
# all these lines bind the process 1 to the cpu 0, the process 2 to cpu 1
# and so on.
cpu-map auto:1-4 0-3
cpu-map auto:1-4 0-1 2-3
cpu-map auto:1-4 3 2 1 0
# all these lines bind the thread 1 to the cpu 0, the thread 2 to cpu 1
# and so on.
cpu-map auto:1/1-4 0-3
cpu-map auto:1/1-4 0-1 2-3
cpu-map auto:1/1-4 3 2 1 0
# bind each process to exactly one CPU using all/odd/even keyword
cpu-map auto:all 0-63
cpu-map auto:even 0-31
cpu-map auto:odd 32-63
# invalid cpu-map because process and CPU sets have different sizes.
cpu-map auto:1-4 0 # invalid
cpu-map auto:1 0-3 # invalid
# invalid cpu-map because automatic binding is used with a process range
# and a thread range.
cpu-map auto:all/all 0 # invalid
cpu-map auto:all/1-4 0 # invalid
cpu-map auto:1-4/all 0 # invalid
Assigns a default directory to fetch SSL certificates from when a relative
path is used with "crtfile" or "crt" directives. Absolute locations specified
prevail and ignore "crt-base".
Makes the process fork into background. This is the recommended mode of
operation. It is equivalent to the command line "-D" argument. It can be
disabled by the command line "-db" argument. This option is ignored in
systemd mode.
By default HAProxy loads all files designated by a relative path from the
location the process is started in. In some circumstances it might be
desirable to force all relative paths to start from a different location
just as if the process was started from such locations. This is what this
directive is made for. Technically it will perform a temporary chdir() to
the designated location while processing each configuration file, and will
return to the original directory after processing each file. It takes an
argument indicating the policy to use when loading files whose path does
not start with a slash ('/'):
- "current" indicates that all relative files are to be loaded from the
directory the process is started in ; this is the default.
- "config" indicates that all relative files should be loaded from the
directory containing the configuration file. More specifically, if the
configuration file contains a slash ('/'), the longest part up to the
last slash is used as the directory to change to, otherwise the current
directory is used. This mode is convenient to bundle maps, errorfiles,
certificates and Lua scripts together as relocatable packages. When
multiple configuration files are loaded, the directory is updated for
each of them.
- "parent" indicates that all relative files should be loaded from the
parent of the directory containing the configuration file. More
specifically, if the configuration file contains a slash ('/'), ".."
is appended to the longest part up to the last slash is used as the
directory to change to, otherwise the directory is "..". This mode is
convenient to bundle maps, errorfiles, certificates and Lua scripts
together as relocatable packages, but where each part is located in a
different subdirectory (e.g. "config/", "certs/", "maps/", ...).
- "origin" indicates that all relative files should be loaded from the
designated (mandatory) path. This may be used to ease management of
different HAProxy instances running in parallel on a system, where each
instance uses a different prefix but where the rest of the sections are
made easily relocatable.
Each "default-path" directive instantly replaces any previous one and will
possibly result in switching to a different directory. While this should
always result in the desired behavior, it is really not a good practice to
use multiple default-path directives, and if used, the policy ought to remain
consistent across all configuration files.
Warning: some configuration elements such as maps or certificates are
uniquely identified by their configured path. By using a relocatable layout,
it becomes possible for several of them to end up with the same unique name,
making it difficult to update them at run time, especially when multiple
configuration files are loaded from different directories. It is essential to
observe a strict collision-free file naming scheme before adopting relative
paths. A robust approach could consist in prefixing all files names with
their respective site name, or in doing so at the directory level.
Add a text that describes the instance.
Please note that it is required to escape certain characters (# for example)
and this text is inserted into a html page so you should avoid using
"<" and ">" characters.
Sets the path of the DeviceAtlas JSON data file to be loaded by the API.
The path must be a valid JSON data file and accessible by HAProxy process.
Sets the level of information returned by the API. This directive is
optional and set to 0 by default if not set.
Sets the client cookie's name used for the detection if the DeviceAtlas
Client-side component was used during the request. This directive is optional
and set to DAPROPS by default if not set.
Sets the character separator for the API properties results. This directive
is optional and set to | by default if not set.
This statement must appear before using directives tagged as experimental or
the config file will be rejected.
Allows the use of an external agent to perform health checks. This is
disabled by default as a security precaution, and even when enabled, checks
may still fail unless "insecure-fork-wanted" is enabled as well. If the
program launched makes use of a setuid executable (it should really not),
you may also need to set "insecure-setuid-wanted" in the global section.
See "option external-check", and "insecure-fork-wanted", and
"insecure-setuid-wanted".
Changes the process's group ID to <number>. It is recommended that the group
ID is dedicated to HAProxy or to a small set of similar daemons. HAProxy must
be started with a user belonging to this group, or with superuser privileges.
Note that if HAProxy is started from a user having supplementary groups, it
will only be able to drop these groups if started with superuser privileges.
See also "group" and "uid".
Similar to "gid" but uses the GID of group name <group name> from /etc/group.
See also "gid" and "user".
Defines the case adjustment to apply, when enabled, to the header name
<from>, to change it to <to> before sending it to HTTP/1 clients or
servers. <from> must be in lower case, and <from> and <to> must not differ
except for their case. It may be repeated if several header names need to be
adjusted. Duplicate entries are not allowed. If a lot of header names have to
be adjusted, it might be more convenient to use "h1-case-adjust-file".
Please note that no transformation will be applied unless "option
h1-case-adjust-bogus-client" or "option h1-case-adjust-bogus-server" is
specified in a proxy.
There is no standard case for header names because, as stated in RFC7230,
they are case-insensitive. So applications must handle them in a case-
insensitive manner. But some bogus applications violate the standards and
erroneously rely on the cases most commonly used by browsers. This problem
becomes critical with HTTP/2 because all header names must be exchanged in
lower case, and HAProxy follows the same convention. All header names are
sent in lower case to clients and servers, regardless of the HTTP version.
Applications which fail to properly process requests or responses may require
to temporarily use such workarounds to adjust header names sent to them for
the time it takes the application to be fixed. Please note that an
application which requires such workarounds might be vulnerable to content
smuggling attacks and must absolutely be fixed.
Example:
global
h1-case-adjust content-length Content-Length
See "h1-case-adjust-file", "option h1-case-adjust-bogus-client" and
"option h1-case-adjust-bogus-server".
Defines a file containing a list of key/value pairs used to adjust the case
of some header names before sending them to HTTP/1 clients or servers. The
file <hdrs-file> must contain 2 header names per line. The first one must be
in lower case and both must not differ except for their case. Lines which
start with '#' are ignored, just like empty lines. Leading and trailing tabs
and spaces are stripped. Duplicate entries are not allowed. Please note that
no transformation will be applied unless "option h1-case-adjust-bogus-client"
or "option h1-case-adjust-bogus-server" is specified in a proxy.
If this directive is repeated, only the last one will be processed. It is an
alternative to the directive "h1-case-adjust" if a lot of header names need
to be adjusted. Please read the risks associated with using this.
See "h1-case-adjust", "option h1-case-adjust-bogus-client" and
"option h1-case-adjust-bogus-server".
This disables the announcement of the support for h2 websockets to clients.
This can be use to overcome clients which have issues when implementing the
relatively fresh RFC8441, such as Firefox 88. To allow clients to
automatically downgrade to http/1.1 for the websocket tunnel, specify h2
support on the bind line using "alpn" without an explicit "proto" keyword. If
this statement was previously activated, this can be disabled by prefixing
the keyword with "no'.
Defines the maximum time allowed to perform a clean soft-stop.
Arguments :
<time> is the maximum time (by default in milliseconds) for which the
instance will remain alive when a soft-stop is received via the
SIGUSR1 signal.
This may be used to ensure that the instance will quit even if connections
remain opened during a soft-stop (for example with long timeouts for a proxy
in tcp mode). It applies both in TCP and HTTP mode.
Example:
global
hard-stop-after 30s
See also: grace
By default HAProxy tries hard to prevent any thread and process creation
after it starts. Doing so is particularly important when using Lua files of
uncertain origin, and when experimenting with development versions which may
still contain bugs whose exploitability is uncertain. And generally speaking
it's good hygiene to make sure that no unexpected background activity can be
triggered by traffic. But this prevents external checks from working, and may
break some very specific Lua scripts which actively rely on the ability to
fork. This option is there to disable this protection. Note that it is a bad
idea to disable it, as a vulnerability in a library or within HAProxy itself
will be easier to exploit once disabled. In addition, forking from Lua or
anywhere else is not reliable as the forked process may randomly embed a lock
set by another thread and never manage to finish an operation. As such it is
highly recommended that this option is never used and that any workload
requiring such a fork be reconsidered and moved to a safer solution (such as
agents instead of external checks). This option supports the "no" prefix to
disable it.
HAProxy doesn't need to call executables at run time (except when using
external checks which are strongly recommended against), and is even expected
to isolate itself into an empty chroot. As such, there basically is no valid
reason to allow a setuid executable to be called without the user being fully
aware of the risks. In a situation where HAProxy would need to call external
checks and/or disable chroot, exploiting a vulnerability in a library or in
HAProxy itself could lead to the execution of an external program. On Linux
it is possible to lock the process so that any setuid bit present on such an
executable is ignored. This significantly reduces the risk of privilege
escalation in such a situation. This is what HAProxy does by default. In case
this causes a problem to an external check (for example one which would need
the "ping" command), then it is possible to disable this protection by
explicitly adding this directive in the global section. If enabled, it is
possible to turn it back off by prefixing it with the "no" keyword.
Assigns a directory to load certificate chain for issuer completion. All
files must be in PEM format. For certificates loaded with "crt" or "crt-list",
if certificate chain is not included in PEM (also commonly known as
intermediate certificate), HAProxy will complete chain if the issuer of the
certificate corresponds to the first certificate of the chain loaded with
"issuers-chain-path".
A "crt" file with PrivateKey+Certificate+IntermediateCA2+IntermediateCA1
could be replaced with PrivateKey+Certificate. HAProxy will complete the
chain if a file with IntermediateCA2+IntermediateCA1 is present in
"issuers-chain-path" directory. All other certificates with the same issuer
will share the chain in memory.
The OCSP features are not able to use the completed chain from
'issuers-chain-path', please use an additionnal .issuer file if you want to
achieve OCSP stapling.
Sets the local instance's peer name. It will be ignored if the "-L"
command line argument is specified or if used after "peers" section
definitions. In such cases, a warning message will be emitted during
the configuration parsing.
This option will also set the HAPROXY_LOCALPEER environment variable.
See also "-L" in the management guide and "peers" section below.
log <address> [len <length>] [format <format>] [sample <ranges>:<sample_size>]
<facility> [max level [min level]]
Adds a global syslog server. Several global servers can be defined. They
will receive logs for starts and exits, as well as all logs from proxies
configured with "log global".
<address> can be one of:
- An IPv4 address optionally followed by a colon and a UDP port. If
no port is specified, 514 is used by default (the standard syslog
port).
- An IPv6 address followed by a colon and optionally a UDP port. If
no port is specified, 514 is used by default (the standard syslog
port).
- A filesystem path to a datagram UNIX domain socket, keeping in mind
considerations for chroot (be sure the path is accessible inside
the chroot) and uid/gid (be sure the path is appropriately
writable).
- A file descriptor number in the form "fd@<number>", which may point
to a pipe, terminal, or socket. In this case unbuffered logs are used
and one writev() call per log is performed. This is a bit expensive
but acceptable for most workloads. Messages sent this way will not be
truncated but may be dropped, in which case the DroppedLogs counter
will be incremented. The writev() call is atomic even on pipes for
messages up to PIPE_BUF size, which POSIX recommends to be at least
512 and which is 4096 bytes on most modern operating systems. Any
larger message may be interleaved with messages from other processes.
Exceptionally for debugging purposes the file descriptor may also be
directed to a file, but doing so will significantly slow HAProxy down
as non-blocking calls will be ignored. Also there will be no way to
purge nor rotate this file without restarting the process. Note that
the configured syslog format is preserved, so the output is suitable
for use with a TCP syslog server. See also the "short" and "raw"
format below.
- "stdout" / "stderr", which are respectively aliases for "fd@1" and
"fd@2", see above.
- A ring buffer in the form "ring@<name>", which will correspond to an
in-memory ring buffer accessible over the CLI using the "show events"
command, which will also list existing rings and their sizes. Such
buffers are lost on reload or restart but when used as a complement
this can help troubleshooting by having the logs instantly available.
You may want to reference some environment variables in the address
parameter, see section 2.3 about environment variables.
<length> is an optional maximum line length. Log lines larger than this value
will be truncated before being sent. The reason is that syslog
servers act differently on log line length. All servers support the
default value of 1024, but some servers simply drop larger lines
while others do log them. If a server supports long lines, it may
make sense to set this value here in order to avoid truncating long
lines. Similarly, if a server drops long lines, it is preferable to
truncate them before sending them. Accepted values are 80 to 65535
inclusive. The default value of 1024 is generally fine for all
standard usages. Some specific cases of long captures or
JSON-formatted logs may require larger values. You may also need to
increase "tune.http.logurilen" if your request URIs are truncated.
<format> is the log format used when generating syslog messages. It may be
one of the following :
local Analog to rfc3164 syslog message format except that hostname
field is stripped. This is the default.
Note: option "log-send-hostname" switches the default to
rfc3164.
rfc3164 The RFC3164 syslog message format.
(https://tools.ietf.org/html/rfc3164)
rfc5424 The RFC5424 syslog message format.
(https://tools.ietf.org/html/rfc5424)
priority A message containing only a level plus syslog facility between
angle brackets such as '<63>', followed by the text. The PID,
date, time, process name and system name are omitted. This is
designed to be used with a local log server.
short A message containing only a level between angle brackets such as
'<3>', followed by the text. The PID, date, time, process name
and system name are omitted. This is designed to be used with a
local log server. This format is compatible with what the systemd
logger consumes.
timed A message containing only a level between angle brackets such as
'<3>', followed by ISO date and by the text. The PID, process
name and system name are omitted. This is designed to be
used with a local log server.
iso A message containing only the ISO date, followed by the text.
The PID, process name and system name are omitted. This is
designed to be used with a local log server.
raw A message containing only the text. The level, PID, date, time,
process name and system name are omitted. This is designed to be
used in containers or during development, where the severity only
depends on the file descriptor used (stdout/stderr).
<ranges> A list of comma-separated ranges to identify the logs to sample.
This is used to balance the load of the logs to send to the log
server. The limits of the ranges cannot be null. They are numbered
from 1. The size or period (in number of logs) of the sample must be
set with <sample_size> parameter.
<sample_size>
The size of the sample in number of logs to consider when balancing
their logging loads. It is used to balance the load of the logs to
send to the syslog server. This size must be greater or equal to the
maximum of the high limits of the ranges.
(see also <ranges> parameter).
<facility> must be one of the 24 standard syslog facilities :
kern user mail daemon auth syslog lpr news
uucp cron auth2 ftp ntp audit alert cron2
local0 local1 local2 local3 local4 local5 local6 local7
Note that the facility is ignored for the "short" and "raw"
formats, but still required as a positional field. It is
recommended to use "daemon" in this case to make it clear that
it's only supposed to be used locally.
An optional level can be specified to filter outgoing messages. By default,
all messages are sent. If a maximum level is specified, only messages with a
severity at least as important as this level will be sent. An optional minimum
level can be specified. If it is set, logs emitted with a more severe level
than this one will be capped to this level. This is used to avoid sending
"emerg" messages on all terminals on some default syslog configurations.
Eight levels are known :
emerg alert crit err warning notice info debug
Sets the hostname field in the syslog header. If optional "string" parameter
is set the header is set to the string contents, otherwise uses the hostname
of the system. Generally used if one is not relaying logs through an
intermediate syslog server or for simply customizing the hostname printed in
the logs.
Sets the tag field in the syslog header to this string. It defaults to the
program name as launched from the command line, which usually is "haproxy".
Sometimes it can be useful to differentiate between multiple processes
running on the same host. See also the per-proxy "log-tag" directive.
This global directive loads and executes a Lua file in the shared context
that is visible to all threads. Any variable set in such a context is visible
from any thread. This is the easiest and recommended way to load Lua programs
but it will not scale well if a lot of Lua calls are performed, as only one
thread may be running on the global state at a time. A program loaded this
way will always see 0 in the "core.thread" variable. This directive can be
used multiple times.
This global directive loads and executes a Lua file into each started thread.
Any global variable has a thread-local visibility so that each thread could
see a different value. As such it is strongly recommended not to use global
variables in programs loaded this way. An independent copy is loaded and
initialized for each thread, everything is done sequentially and in the
thread's numeric order from 1 to nbthread. If some operations need to be
performed only once, the program should check the "core.thread" variable to
figure what thread is being initialized. Programs loaded this way will run
concurrently on all threads and will be highly scalable. This is the
recommended way to load simple functions that register sample-fetches,
converters, actions or services once it is certain the program doesn't depend
on global variables. For the sake of simplicity, the directive is available
even if only one thread is used and even if threads are disabled (in which
case it will be equivalent to lua-load). This directive can be used multiple
times.
Prepends the given string followed by a semicolon to Lua's package.<type>
variable.
<type> must either be "path" or "cpath". If <type> is not given it defaults
to "path".
Lua's paths are semicolon delimited lists of patterns that specify how the
`require` function attempts to find the source file of a library. Question
marks (?) within a pattern will be replaced by module name. The path is
evaluated left to right. This implies that paths that are prepended later
will be checked earlier.
As an example by specifying the following path:
lua-prepend-path /usr/share/haproxy-lua/?/init.lua
lua-prepend-path /usr/share/haproxy-lua/?.lua
When `require "example"` is being called Lua will first attempt to load the
/usr/share/haproxy-lua/example.lua script, if that does not exist the
/usr/share/haproxy-lua/example/init.lua will be attempted and the default
paths if that does not exist either.
See https://www.lua.org/pil/8.1.html for the details within the Lua
documentation.
Master-worker mode. It is equivalent to the command line "-W" argument.
This mode will launch a "master" which will monitor the "workers". Using
this mode, you can reload HAProxy directly by sending a SIGUSR2 signal to
the master. The master-worker mode is compatible either with the foreground
or daemon mode. It is recommended to use this mode with multiprocess and
systemd.
By default, if a worker exits with a bad return code, in the case of a
segfault for example, all workers will be killed, and the master will leave.
It is convenient to combine this behavior with Restart=on-failure in a
systemd unit file in order to relaunch the whole process. If you don't want
this behavior, you must use the keyword "no-exit-on-failure".
See also "-W" in the management guide.
In master-worker mode, this option limits the number of time a worker can
survive to a reload. If the worker did not leave after a reload, once its
number of reloads is greater than this number, the worker will receive a
SIGTERM. This option helps to keep under control the number of workers.
See also "show proc" in the Management Guide.
Creates <number> processes when going daemon. This requires the "daemon"
mode. By default, only one process is created, which is the recommended mode
of operation. For systems limited to small sets of file descriptors per
process, it may be needed to fork multiple daemons. When set to a value
larger than 1, threads are automatically disabled. USING MULTIPLE PROCESSES
IS HARDER TO DEBUG AND IS REALLY DISCOURAGED. This directive is deprecated
and scheduled for removal in 2.5. Please use "nbthread" instead. See also
"daemon" and "nbthread".
This setting is only available when support for threads was built in. It
makes HAProxy run on <number> threads. This is exclusive with "nbproc". While
"nbproc" historically used to be the only way to use multiple processors, it
also involved a number of shortcomings related to the lack of synchronization
between processes (health-checks, peers, stick-tables, stats, ...) which do
not affect threads. As such, any modern configuration is strongly encouraged
to migrate away from "nbproc" to "nbthread". "nbthread" also works when
HAProxy is started in foreground. On some platforms supporting CPU affinity,
when nbproc is not used, the default "nbthread" value is automatically set to
the number of CPUs the process is bound to upon startup. This means that the
thread count can easily be adjusted from the calling process using commands
like "taskset" or "cpuset". Otherwise, this value defaults to 1. The default
value is reported in the output of "haproxy -vv". See also "nbproc".
By default, if running on Linux, HAProxy inspects on startup the CPU topology
of the machine. If a multi-socket machine is detected, the affinity is
automatically calculated to run on the CPUs of a single node. This is done in
order to not suffer from the performance penalties caused by the inter-socket
bus latency. However, if the applied binding is non optimal on a particular
architecture, it can be disabled with the statement 'no numa-cpu-mapping'.
This automatic binding is also not applied if a nbthread statement is present
in the configuration, or the affinity of the process is already specified,
for example via the 'cpu-map' directive or the taskset utility.
Writes PIDs of all daemons into file <pidfile> when daemon mode or writes PID
of master process into file <pidfile> when master-worker mode. This option is
equivalent to the "-p" command line argument. The file must be accessible to
the user starting the process. See also "daemon" and "master-worker".
A bug in the PROXY protocol v2 implementation was present in HAProxy up to
version 2.1, causing it to emit a PROXY command instead of a LOCAL command
for health checks. This is particularly minor but confuses some servers'
logs. Sadly, the bug was discovered very late and revealed that some servers
which possibly only tested their PROXY protocol implementation against
HAProxy fail to properly handle the LOCAL command, and permanently remain in
the "down" state when HAProxy checks them. When this happens, it is possible
to enable this global option to revert to the older (bogus) behavior for the
time it takes to contact the affected components' vendors and get them fixed.
This option is disabled by default and acts on all servers having the
"send-proxy-v2" statement.
Sets environment variable <name> to value <value>. If the variable exists, it
is NOT overwritten. The changes immediately take effect so that the next line
in the configuration file sees the new value. See also "setenv", "resetenv",
and "unsetenv".
Removes all environment variables except the ones specified in argument. It
allows to use a clean controlled environment before setting new values with
setenv or unsetenv. Please note that some internal functions may make use of
some environment variables, such as time manipulation functions, but also
OpenSSL or even external checks. This must be used with extreme care and only
after complete validation. The changes immediately take effect so that the
next line in the configuration file sees the new environment. See also
"setenv", "presetenv", and "unsetenv".
Limits the stats socket to a certain set of processes numbers. By default the
stats socket is bound to all processes, causing a warning to be emitted when
nbproc is greater than 1 because there is no way to select the target process
when connecting. However, by using this setting, it becomes possible to pin
the stats socket to a specific set of processes, typically the first one. The
warning will automatically be disabled when this setting is used, whatever
the number of processes used. The maximum process ID depends on the machine's
word size (32 or 64). Ranges can be partially defined. The higher bound can
be omitted. In such case, it is replaced by the corresponding maximum
value. A better option consists in using the "process" setting of the "stats
socket" line to force the process on each line.
Specifies the directory prefix to be prepended in front of all servers state
file names which do not start with a '/'. See also "server-state-file",
"load-server-state-from-file" and "server-state-file-name".
Specifies the path to the file containing state of servers. If the path starts
with a slash ('/'), it is considered absolute, otherwise it is considered
relative to the directory specified using "server-state-base" (if set) or to
the current directory. Before reloading HAProxy, it is possible to save the
servers' current state using the stats command "show servers state". The
output of this command must be written in the file pointed by <file>. When
starting up, before handling traffic, HAProxy will read, load and apply state
for each server found in the file and available in its current running
configuration. See also "server-state-base" and "show servers state",
"load-server-state-from-file" and "server-state-file-name"
This option is better left disabled by default and enabled only upon a
developer's request. If it has been enabled, it may still be forcibly
disabled by prefixing it with the "no" keyword. It has no impact on
performance nor stability but will try hard to re-enable core dumps that were
possibly disabled by file size limitations (ulimit -f), core size limitations
(ulimit -c), or "dumpability" of a process after changing its UID/GID (such
as /proc/sys/fs/suid_dumpable on Linux). Core dumps might still be limited by
the current directory's permissions (check what directory the file is started
from), the chroot directory's permission (it may be needed to temporarily
disable the chroot directive or to move it to a dedicated writable location),
or any other system-specific constraint. For example, some Linux flavours are
notorious for replacing the default core file with a path to an executable
not even installed on the system (check /proc/sys/kernel/core_pattern). Often,
simply writing "core", "core.%p" or "/var/log/core/core.%p" addresses the
issue. When trying to enable this option waiting for a rare issue to
re-appear, it's often a good idea to first try to obtain such a dump by
issuing, for example, "kill -11" to the "haproxy" process and verify that it
leaves a core where expected when dying.
Sets the process-wide variable '<var-name>' to the result of the evaluation
of the sample expression <expr>. The variable '<var-name>' may only be a
process-wide variable (using the 'proc.' prefix). It works exactly like the
'set-var' action in TCP or HTTP rules except that the expression is evaluated
at configuration parsing time and that the variable is instantly set. The
sample fetch functions and converters permitted in the expression are only
those using internal data, typically 'int(value)' or 'str(value)'. It is
possible to reference previously allocated variables as well. These variables
will then be readable (and modifiable) from the regular rule sets.
Example:
global
set-var proc.current_state str(primary)
set-var proc.prio int(100)
set-var proc.threshold int(200),sub(proc.prio)
Sets the process-wide variable '<var-name>' to the string resulting from the
evaluation of the log-format <fmt>. The variable '<var-name>' may only be a
process-wide variable (using the 'proc.' prefix). It works exactly like the
'set-var-fmt' action in TCP or HTTP rules except that the expression is
evaluated at configuration parsing time and that the variable is instantly
set. The sample fetch functions and converters permitted in the expression
are only those using internal data, typically 'int(value)' or 'str(value)'.
It is possible to reference previously allocated variables as well. These
variables will then be readable (and modifiable) from the regular rule sets.
Please see section 8.2.4 for details on the log-format syntax.
Example:
global
set-var-fmt proc.current_state "primary"
set-var-fmt proc.bootid "%pid|%t"
Sets environment variable <name> to value <value>. If the variable exists, it
is overwritten. The changes immediately take effect so that the next line in
the configuration file sees the new value. See also "presetenv", "resetenv",
and "unsetenv".
This setting is only available when support for OpenSSL was built in. It sets
the default string describing the list of cipher algorithms ("cipher suite")
that are negotiated during the SSL/TLS handshake up to TLSv1.2 for all
"bind" lines which do not explicitly define theirs. The format of the string
is defined in "man 1 ciphers" from OpenSSL man pages. For background
information and recommendations see e.g.
(https://wiki.mozilla.org/Security/Server_Side_TLS) and
(https://mozilla.github.io/server-side-tls/ssl-config-generator/). For TLSv1.3
cipher configuration, please check the "ssl-default-bind-ciphersuites" keyword.
Please check the "bind" keyword for more information.
This setting is only available when support for OpenSSL was built in and
OpenSSL 1.1.1 or later was used to build HAProxy. It sets the default string
describing the list of cipher algorithms ("cipher suite") that are negotiated
during the TLSv1.3 handshake for all "bind" lines which do not explicitly define
theirs. The format of the string is defined in
"man 1 ciphers" from OpenSSL man pages under the section "ciphersuites". For
cipher configuration for TLSv1.2 and earlier, please check the
"ssl-default-bind-ciphers" keyword. This setting might accept TLSv1.2
ciphersuites however this is an undocumented behavior and not recommended as
it could be inconsistent or buggy.
The default TLSv1.3 ciphersuites of OpenSSL are:
"TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256"
TLSv1.3 only supports 5 ciphersuites:
- TLS_AES_128_GCM_SHA256
- TLS_AES_256_GCM_SHA384
- TLS_CHACHA20_POLY1305_SHA256
- TLS_AES_128_CCM_SHA256
- TLS_AES_128_CCM_8_SHA256
Please check the "bind" keyword for more information.
Example:
global
ssl-default-bind-ciphers ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-RSA-AES128-GCM-SHA256
ssl-default-bind-ciphersuites TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
This setting is only available when support for OpenSSL was built in. It sets
the default string describing the list of elliptic curves algorithms ("curve
suite") that are negotiated during the SSL/TLS handshake with ECDHE. The format
of the string is a colon-delimited list of curve name.
Please check the "bind" keyword for more information.
This setting is only available when support for OpenSSL was built in. It sets
default ssl-options to force on all "bind" lines. Please check the "bind"
keyword to see available options.
Example:
global
ssl-default-bind-options ssl-min-ver TLSv1.0 no-tls-tickets
This setting is only available when support for OpenSSL was built in. It
sets the default string describing the list of cipher algorithms that are
negotiated during the SSL/TLS handshake up to TLSv1.2 with the server,
for all "server" lines which do not explicitly define theirs. The format of
the string is defined in "man 1 ciphers" from OpenSSL man pages. For background
information and recommendations see e.g.
(https://wiki.mozilla.org/Security/Server_Side_TLS) and
(https://mozilla.github.io/server-side-tls/ssl-config-generator/).
For TLSv1.3 cipher configuration, please check the
"ssl-default-server-ciphersuites" keyword. Please check the "server" keyword
for more information.
This setting is only available when support for OpenSSL was built in and
OpenSSL 1.1.1 or later was used to build HAProxy. It sets the default
string describing the list of cipher algorithms that are negotiated during
the TLSv1.3 handshake with the server, for all "server" lines which do not
explicitly define theirs. The format of the string is defined in
"man 1 ciphers" from OpenSSL man pages under the section "ciphersuites". For
cipher configuration for TLSv1.2 and earlier, please check the
"ssl-default-server-ciphers" keyword. Please check the "server" keyword for
more information.
This setting is only available when support for OpenSSL was built in. It sets
default ssl-options to force on all "server" lines. Please check the "server"
keyword to see available options.
This setting is only available when support for OpenSSL was built in. It sets
the default DH parameters that are used during the SSL/TLS handshake when
ephemeral Diffie-Hellman (DHE) key exchange is used, for all "bind" lines
which do not explicitly define theirs. It will be overridden by custom DH
parameters found in a bind certificate file if any. If custom DH parameters
are not specified either by using ssl-dh-param-file or by setting them
directly in the certificate file, pre-generated DH parameters of the size
specified by tune.ssl.default-dh-param will be used. Custom parameters are
known to be more secure and therefore their use is recommended.
Custom DH parameters may be generated by using the OpenSSL command
"openssl dhparam <size>", where size should be at least 2048, as 1024-bit DH
parameters should not be considered secure anymore.
This setting allows to configure the way HAProxy does the lookup for the
extra SSL files. By default HAProxy adds a new extension to the filename.
(ex: with "foobar.crt" load "foobar.crt.key"). With this option enabled,
HAProxy removes the extension before adding the new one (ex: with
"foobar.crt" load "foobar.key").
Your crt file must have a ".crt" extension for this option to work.
This option is not compatible with bundle extensions (.ecdsa, .rsa. .dsa)
and won't try to remove them.
This option is disabled by default. See also "ssl-load-extra-files".
This setting alters the way HAProxy will look for unspecified files during
the loading of the SSL certificates. This option applies to certificates
associated to "bind" lines as well as "server" lines but some of the extra
files will not have any functional impact for "server" line certificates.
By default, HAProxy discovers automatically a lot of files not specified in
the configuration, and you may want to disable this behavior if you want to
optimize the startup time.
"none": Only load the files specified in the configuration. Don't try to load
a certificate bundle if the file does not exist. In the case of a directory,
it won't try to bundle the certificates if they have the same basename.
"all": This is the default behavior, it will try to load everything,
bundles, sctl, ocsp, issuer, key.
"bundle": When a file specified in the configuration does not exist, HAProxy
will try to load a "cert bundle". Certificate bundles are only managed on the
frontend side and will not work for backend certificates.
Starting from HAProxy 2.3, the bundles are not loaded in the same OpenSSL
certificate store, instead it will loads each certificate in a separate
store which is equivalent to declaring multiple "crt". OpenSSL 1.1.1 is
required to achieve this. Which means that bundles are now used only for
backward compatibility and are not mandatory anymore to do an hybrid RSA/ECC
bind configuration.
To associate these PEM files into a "cert bundle" that is recognized by
HAProxy, they must be named in the following way: All PEM files that are to
be bundled must have the same base name, with a suffix indicating the key
type. Currently, three suffixes are supported: rsa, dsa and ecdsa. For
example, if www.example.com has two PEM files, an RSA file and an ECDSA
file, they must be named: "example.pem.rsa" and "example.pem.ecdsa". The
first part of the filename is arbitrary; only the suffix matters. To load
this bundle into HAProxy, specify the base name only:
Example :
bind :8443 ssl crt example.pem
Note that the suffix is not given to HAProxy; this tells HAProxy to look for
a cert bundle.
HAProxy will load all PEM files in the bundle as if they were configured
separately in several "crt".
The bundle loading does not have an impact anymore on the directory loading
since files are loading separately.
On the CLI, bundles are seen as separate files, and the bundle extension is
required to commit them.
OCSP files (.ocsp), issuer files (.issuer), Certificate Transparency (.sctl)
as well as private keys (.key) are supported with multi-cert bundling.
"sctl": Try to load "<basename>.sctl" for each crt keyword. If provided for
a backend certificate, it will be loaded but will not have any functional
impact.
"ocsp": Try to load "<basename>.ocsp" for each crt keyword. If provided for
a backend certificate, it will be loaded but will not have any functional
impact.
"issuer": Try to load "<basename>.issuer" if the issuer of the OCSP file is
not provided in the PEM file. If provided for a backend certificate, it will
be loaded but will not have any functional impact.
"key": If the private key was not provided by the PEM file, try to load a
file "<basename>.key" containing a private key.
The default behavior is "all".
Example:
ssl-load-extra-files bundle sctl
ssl-load-extra-files sctl ocsp issuer
ssl-load-extra-files none
The default behavior for SSL verify on servers side. If specified to 'none',
servers certificates are not verified. The default is 'required' except if
forced using cmdline option '-dV'.
Self issued CA, aka x509 root CA, is the anchor for chain validation: as a
server is useless to send it, client must have it. Standard configuration
need to not include such CA in PEM file. This option allows you to keep such
CA in PEM file without sending it to the client. Use case is to provide
issuer for ocsp without the need for '.issuer' file and be able to share it
with 'issuers-chain-path'. This concerns all certificates without intermediate
certificates. It's useless for BoringSSL, .issuer is ignored because ocsp
bits does not need it. Requires at least OpenSSL 1.0.2.
By default, the stats socket is limited to 10 concurrent connections. It is
possible to change this value with "stats maxconn".
Binds a UNIX socket to <path> or a TCPv4/v6 address to <address:port>.
Connections to this socket will return various statistics outputs and even
allow some commands to be issued to change some runtime settings. Please
consult section 9.3 "Unix Socket commands" of Management Guide for more
details.
All parameters supported by "bind" lines are supported, for instance to
restrict access to some users or their access rights. Please consult
section 5.1 for more information.
The default timeout on the stats socket is set to 10 seconds. It is possible
to change this value with "stats timeout". The value must be passed in
milliseconds, or be suffixed by a time unit among { us, ms, s, m, h, d }.
Makes process fail at startup when a setrlimit fails. HAProxy tries to set the
best setrlimit according to what has been calculated. If it fails, it will
emit a warning. This option is here to guarantee an explicit failure of
HAProxy when those limits fail. It is enabled by default. It may still be
forcibly disabled by prefixing it with the "no" keyword.
Changes the process's user ID to <number>. It is recommended that the user ID
is dedicated to HAProxy or to a small set of similar daemons. HAProxy must
be started with superuser privileges in order to be able to switch to another
one. See also "gid" and "user".
Sets the maximum number of per-process file-descriptors to <number>. By
default, it is automatically computed, so it is recommended not to use this
option.
unix-bind [ prefix <prefix> ] [ mode <mode> ] [ user <user> ] [ uid <uid> ]
[ group <group> ] [ gid <gid> ]
Fixes common settings to UNIX listening sockets declared in "bind" statements.
This is mainly used to simplify declaration of those UNIX sockets and reduce
the risk of errors, since those settings are most commonly required but are
also process-specific. The <prefix> setting can be used to force all socket
path to be relative to that directory. This might be needed to access another
component's chroot. Note that those paths are resolved before HAProxy chroots
itself, so they are absolute. The <mode>, <user>, <uid>, <group> and <gid>
all have the same meaning as their homonyms used by the "bind" statement. If
both are specified, the "bind" statement has priority, meaning that the
"unix-bind" settings may be seen as process-wide default settings.
Removes environment variables specified in arguments. This can be useful to
hide some sensitive information that are occasionally inherited from the
user's environment during some operations. Variables which did not exist are
silently ignored so that after the operation, it is certain that none of
these variables remain. The changes immediately take effect so that the next
line in the configuration file will not see these variables. See also
"setenv", "presetenv", and "resetenv".
Similar to "uid" but uses the UID of user name <user name> from /etc/passwd.
See also "uid" and "group".
Only letters, digits, hyphen and underscore are allowed, like in DNS names.
This statement is useful in HA configurations where two or more processes or
servers share the same IP address. By setting a different node-name on all
nodes, it becomes easy to immediately spot what server is handling the
traffic.
Sets the WURFL Useragent cache size. For faster lookups, already processed user
agents are kept in a LRU cache :
- "0" : no cache is used.
- <size> : size of lru cache in elements.
Please note that this option is only available when HAProxy has been compiled
with USE_WURFL=1.
The path of the WURFL data file to provide device detection services. The
file should be accessible by HAProxy with relevant permissions.
Please note that this option is only available when HAProxy has been compiled
with USE_WURFL=1.
A space-delimited list of WURFL capabilities, virtual capabilities, property
names we plan to use in injected headers. A full list of capability and
virtual capability names is available on the Scientiamobile website :
https://www.scientiamobile.com/wurflCapability
Valid WURFL properties are:
- wurfl_id Contains the device ID of the matched device.
- wurfl_root_id Contains the device root ID of the matched
device.
- wurfl_isdevroot Tells if the matched device is a root device.
Possible values are "TRUE" or "FALSE".
- wurfl_useragent The original useragent coming with this
particular web request.
- wurfl_api_version Contains a string representing the currently
used Libwurfl API version.
- wurfl_info A string containing information on the parsed
wurfl.xml and its full path.
- wurfl_last_load_time Contains the UNIX timestamp of the last time
WURFL has been loaded successfully.
- wurfl_normalized_useragent The normalized useragent.
Please note that this option is only available when HAProxy has been compiled
with USE_WURFL=1.
A char that will be used to separate values in a response header containing
WURFL results. If not set that a comma (',') will be used by default.
Please note that this option is only available when HAProxy has been compiled
with USE_WURFL=1.
A list of WURFL patch file paths. Note that patches are loaded during startup
thus before the chroot.
Please note that this option is only available when HAProxy has been compiled
with USE_WURFL=1.
3.2. Performance tuning
In some situations, especially when dealing with low latency on processors
supporting a variable frequency or when running inside virtual machines, each
time the process waits for an I/O using the poller, the processor goes back
to sleep or is offered to another VM for a long time, and it causes
excessively high latencies. This option provides a solution preventing the
processor from sleeping by always using a null timeout on the pollers. This
results in a significant latency reduction (30 to 100 microseconds observed)
at the expense of a risk to overheat the processor. It may even be used with
threads, in which case improperly bound threads may heavily conflict,
resulting in a worse performance and high values for the CPU stolen fields
in "show info" output, indicating which threads are misconfigured. It is
important not to let the process run on the same processor as the network
interrupts when this option is used. It is also better to avoid using it on
multiple CPU threads sharing the same core. This option is disabled by
default. If it has been enabled, it may still be forcibly disabled by
prefixing it with the "no" keyword. It is ignored by the "select" and
"poll" pollers.
This option is automatically disabled on old processes in the context of
seamless reload; it avoids too much cpu conflicts when multiple processes
stay around for some time waiting for the end of their current connections.
By default, HAProxy tries to spread the start of health checks across the
smallest health check interval of all the servers in a farm. The principle is
to avoid hammering services running on the same server. But when using large
check intervals (10 seconds or more), the last servers in the farm take some
time before starting to be tested, which can be a problem. This parameter is
used to enforce an upper bound on delay between the first and the last check,
even if the servers' check intervals are larger. When servers run with
shorter intervals, their intervals will be respected though.
Sets the maximum CPU usage HAProxy can reach before stopping the compression
for new requests or decreasing the compression level of current requests.
It works like 'maxcomprate' but measures CPU usage instead of incoming data
bandwidth. The value is expressed in percent of the CPU used by HAProxy. A
value of 100 disable the limit. The default value is 100. Setting a lower
value will prevent the compression work from slowing the whole process down
and from introducing high latencies.
Sets the maximum per-process input compression rate to <number> kilobytes
per second. For each session, if the maximum is reached, the compression
level will be decreased during the session. If the maximum is reached at the
beginning of a session, the session will not compress at all. If the maximum
is not reached, the compression level will be increased up to
tune.comp.maxlevel. A value of zero means there is no limit, this is the
default value.
Sets the maximum per-process number of concurrent connections to <number>. It
is equivalent to the command-line argument "-n". Proxies will stop accepting
connections when this limit is reached. The "ulimit-n" parameter is
automatically adjusted according to this value. See also "ulimit-n". Note:
the "select" poller cannot reliably use more than 1024 file descriptors on
some platforms. If your platform only supports select and reports "select
FAILED" on startup, you need to reduce maxconn until it works (slightly
below 500 in general). If this value is not set, it will automatically be
calculated based on the current file descriptors limit reported by the
"ulimit -n" command, possibly reduced to a lower value if a memory limit
is enforced, based on the buffer size, memory allocated to compression, SSL
cache size, and use or not of SSL and the associated maxsslconn (which can
also be automatic).
Sets the maximum per-process number of connections per second to <number>.
Proxies will stop accepting connections when this limit is reached. It can be
used to limit the global capacity regardless of each frontend capacity. It is
important to note that this can only be used as a service protection measure,
as there will not necessarily be a fair share between frontends when the
limit is reached, so it's a good idea to also limit each frontend to some
value close to its expected share. Also, lowering tune.maxaccept can improve
fairness.
Sets the maximum per-process number of pipes to <number>. Currently, pipes
are only used by kernel-based tcp splicing. Since a pipe contains two file
descriptors, the "ulimit-n" value will be increased accordingly. The default
value is maxconn/4, which seems to be more than enough for most heavy usages.
The splice code dynamically allocates and releases pipes, and can fall back
to standard copy, so setting this value too low may only impact performance.
Sets the maximum per-process number of sessions per second to <number>.
Proxies will stop accepting connections when this limit is reached. It can be
used to limit the global capacity regardless of each frontend capacity. It is
important to note that this can only be used as a service protection measure,
as there will not necessarily be a fair share between frontends when the
limit is reached, so it's a good idea to also limit each frontend to some
value close to its expected share. Also, lowering tune.maxaccept can improve
fairness.
Sets the maximum per-process number of concurrent SSL connections to
<number>. By default there is no SSL-specific limit, which means that the
global maxconn setting will apply to all connections. Setting this limit
avoids having openssl use too much memory and crash when malloc returns NULL
(since it unfortunately does not reliably check for such conditions). Note
that the limit applies both to incoming and outgoing connections, so one
connection which is deciphered then ciphered accounts for 2 SSL connections.
If this value is not set, but a memory limit is enforced, this value will be
automatically computed based on the memory limit, maxconn, the buffer size,
memory allocated to compression, SSL cache size, and use of SSL in either
frontends, backends or both. If neither maxconn nor maxsslconn are specified
when there is a memory limit, HAProxy will automatically adjust these values
so that 100% of the connections can be made over SSL with no risk, and will
consider the sides where it is enabled (frontend, backend, both).
Sets the maximum per-process number of SSL sessions per second to <number>.
SSL listeners will stop accepting connections when this limit is reached. It
can be used to limit the global SSL CPU usage regardless of each frontend
capacity. It is important to note that this can only be used as a service
protection measure, as there will not necessarily be a fair share between
frontends when the limit is reached, so it's a good idea to also limit each
frontend to some value close to its expected share. It is also important to
note that the sessions are accounted before they enter the SSL stack and not
after, which also protects the stack against bad handshakes. Also, lowering
tune.maxaccept can improve fairness.
Sets the maximum amount of RAM in megabytes per process usable by the zlib.
When the maximum amount is reached, future sessions will not compress as long
as RAM is unavailable. When sets to 0, there is no limit.
The default value is 0. The value is available in bytes on the UNIX socket
with "show info" on the line "MaxZlibMemUsage", the memory used by zlib is
"ZlibMemUsage" in bytes.
Disables memory trimming ("malloc_trim") at a few moments where attempts are
made to reclaim lots of memory (on memory shortage or on reload). Trimming
memory forces the system's allocator to scan all unused areas and to release
them. This is generally seen as nice action to leave more available memory to
a new process while the old one is unlikely to make significant use of it.
But some systems dealing with tens to hundreds of thousands of concurrent
connections may experience a lot of memory fragmentation, that may render
this release operation extremely long. During this time, no more traffic
passes through the process, new connections are not accepted anymore, some
health checks may even fail, and the watchdog may even trigger and kill the
unresponsive process, leaving a huge core dump. If this ever happens, then it
is suggested to use this option to disable trimming and stop trying to be
nice with the new process. Note that advanced memory allocators usually do
not suffer from such a problem.
Disables the use of the "epoll" event polling system on Linux. It is
equivalent to the command-line argument "-de". The next polling system
used will generally be "poll". See also "nopoll".
Disables the use of the event ports event polling system on SunOS systems
derived from Solaris 10 and later. It is equivalent to the command-line
argument "-dv". The next polling system used will generally be "poll". See
also "nopoll".
Disables the use of getaddrinfo(3) for name resolving. It is equivalent to
the command line argument "-dG". Deprecated gethostbyname(3) will be used.
Disables the use of the "kqueue" event polling system on BSD. It is
equivalent to the command-line argument "-dk". The next polling system
used will generally be "poll". See also "nopoll".
Disables the use of the "poll" event polling system. It is equivalent to the
command-line argument "-dp". The next polling system used will be "select".
It should never be needed to disable "poll" since it's available on all
platforms supported by HAProxy. See also "nokqueue", "noepoll" and
"noevports".
Disables the use of SO_REUSEPORT - see socket(7). It is equivalent to the
command line argument "-dR".
Disables the use of kernel tcp splicing between sockets on Linux. It is
equivalent to the command line argument "-dS". Data will then be copied
using conventional and more portable recv/send calls. Kernel tcp splicing is
limited to some very recent instances of kernel 2.6. Most versions between
2.6.25 and 2.6.28 are buggy and will forward corrupted data, so they must not
be used. This option makes it easier to globally disable kernel splicing in
case of doubt. See also "option splice-auto", "option splice-request" and
"option splice-response".
Enables ('on') or disables ('off') per-function memory profiling. This will
keep usage statistics of malloc/calloc/realloc/free calls anywhere in the
process (including libraries) which will be reported on the CLI using the
"show profiling" command. This is essentially meant to be used when an
abnormal memory usage is observed that cannot be explained by the pools and
other info are required. The performance hit will typically be around 1%,
maybe a bit more on highly threaded machines, so it is normally suitable for
use in production. The same may be achieved at run time on the CLI using the
"set profiling memory" command, please consult the management manual.
Enables ('on') or disables ('off') per-task CPU profiling. When set to 'auto'
the profiling automatically turns on a thread when it starts to suffer from
an average latency of 1000 microseconds or higher as reported in the
"avg_loop_us" activity field, and automatically turns off when the latency
returns below 990 microseconds (this value is an average over the last 1024
loops so it does not vary quickly and tends to significantly smooth short
spikes). It may also spontaneously trigger from time to time on overloaded
systems, containers, or virtual machines, or when the system swaps (which
must absolutely never happen on a load balancer).
CPU profiling per task can be very convenient to report where the time is
spent and which requests have what effect on which other request. Enabling
it will typically affect the overall's performance by less than 1%, thus it
is recommended to leave it to the default 'auto' value so that it only
operates when a problem is identified. This feature requires a system
supporting the clock_gettime(2) syscall with clock identifiers
CLOCK_MONOTONIC and CLOCK_THREAD_CPUTIME_ID, otherwise the reported time will
be zero. This option may be changed at run time using "set profiling" on the
CLI.
Sometimes it is desirable to avoid sending agent and health checks to
servers at exact intervals, for instance when many logical servers are
located on the same physical server. With the help of this parameter, it
becomes possible to add some randomness in the check interval between 0
and +/- 50%. A value between 2 and 5 seems to show good results. The
default value remains at 0.
Sets the OpenSSL engine to <name>. List of valid values for <name> may be
obtained using the command "openssl engine". This statement may be used
multiple times, it will simply enable multiple crypto engines. Referencing an
unsupported engine will prevent HAProxy from starting. Note that many engines
will lead to lower HTTPS performance than pure software with recent
processors. The optional command "algo" sets the default algorithms an ENGINE
will supply using the OPENSSL function ENGINE_set_default_string(). A value
of "ALL" uses the engine for all cryptographic operations. If no list of
algo is specified then the value of "ALL" is used. A comma-separated list
of different algorithms may be specified, including: RSA, DSA, DH, EC, RAND,
CIPHERS, DIGESTS, PKEY, PKEY_CRYPTO, PKEY_ASN1. This is the same format that
openssl configuration file uses:
https://www.openssl.org/docs/man1.0.2/apps/config.html
Adds SSL_MODE_ASYNC mode to the SSL context. This enables asynchronous TLS
I/O operations if asynchronous capable SSL engines are used. The current
implementation supports a maximum of 32 engines. The Openssl ASYNC API
doesn't support moving read/write buffers and is not compliant with
HAProxy's buffer management. So the asynchronous mode is disabled on
read/write operations (it is only enabled during initial and renegotiation
handshakes).
Sets a hard limit on the number of buffers which may be allocated per process.
The default value is zero which means unlimited. The minimum non-zero value
will always be greater than "tune.buffers.reserve" and should ideally always
be about twice as large. Forcing this value can be particularly useful to
limit the amount of memory a process may take, while retaining a sane
behavior. When this limit is reached, sessions which need a buffer wait for
another one to be released by another session. Since buffers are dynamically
allocated and released, the waiting time is very short and not perceptible
provided that limits remain reasonable. In fact sometimes reducing the limit
may even increase performance by increasing the CPU cache's efficiency. Tests
have shown good results on average HTTP traffic with a limit to 1/10 of the
expected global maxconn setting, which also significantly reduces memory
usage. The memory savings come from the fact that a number of connections
will not allocate 2*tune.bufsize. It is best not to touch this value unless
advised to do so by an HAProxy core developer.
Sets the number of buffers which are pre-allocated and reserved for use only
during memory shortage conditions resulting in failed memory allocations. The
minimum value is 2 and is also the default. There is no reason a user would
want to change this value, it's mostly aimed at HAProxy core developers.
Sets the buffer size to this size (in bytes). Lower values allow more
sessions to coexist in the same amount of RAM, and higher values allow some
applications with very large cookies to work. The default value is 16384 and
can be changed at build time. It is strongly recommended not to change this
from the default value, as very low values will break some services such as
statistics, and values larger than default size will increase memory usage,
possibly causing the system to run out of memory. At least the global maxconn
parameter should be decreased by the same factor as this one is increased. In
addition, use of HTTP/2 mandates that this value must be 16384 or more. If an
HTTP request is larger than (tune.bufsize - tune.maxrewrite), HAProxy will
return HTTP 400 (Bad Request) error. Similarly if an HTTP response is larger
than this size, HAProxy will return HTTP 502 (Bad Gateway). Note that the
value set using this parameter will automatically be rounded up to the next
multiple of 8 on 32-bit machines and 16 on 64-bit machines.
This option is deprecated and ignored.
Sets the maximum compression level. The compression level affects CPU
usage during compression. This value affects CPU usage during compression.
Each session using compression initializes the compression algorithm with
this value. The default value is 1.
If compiled with DEBUG_FAIL_ALLOC, gives the percentage of chances an
allocation attempt fails. Must be between 0 (no failure) and 100 (no
success). This is useful to debug and make sure memory failures are handled
gracefully.
Enables ('on') or disables ('off') the edge-triggered polling mode for FDs
that support it. This is currently only support with epoll. It may noticeably
reduce the number of epoll_ctl() calls and slightly improve performance in
certain scenarios. This is still experimental, it may result in frozen
connections if bugs are still present, and is disabled by default.
Sets the HTTP/2 dynamic header table size. It defaults to 4096 bytes and
cannot be larger than 65536 bytes. A larger value may help certain clients
send more compact requests, depending on their capabilities. This amount of
memory is consumed for each HTTP/2 connection. It is recommended not to
change it.
Sets the HTTP/2 initial window size, which is the number of bytes the client
can upload before waiting for an acknowledgment from HAProxy. This setting
only affects payload contents (i.e. the body of POST requests), not headers.
The default value is 65535, which roughly allows up to 5 Mbps of upload
bandwidth per client over a network showing a 100 ms ping time, or 500 Mbps
over a 1-ms local network. It can make sense to increase this value to allow
faster uploads, or to reduce it to increase fairness when dealing with many
clients. It doesn't affect resource usage.
Sets the HTTP/2 maximum number of concurrent streams per connection (ie the
number of outstanding requests on a single connection). The default value is
100. A larger one may slightly improve page load time for complex sites when
visited over high latency networks, but increases the amount of resources a
single client may allocate. A value of zero disables the limit so a single
client may create as many streams as allocatable by HAProxy. It is highly
recommended not to change this value.
Sets the HTTP/2 maximum frame size that HAProxy announces it is willing to
receive to its peers. The default value is the largest between 16384 and the
buffer size (tune.bufsize). In any case, HAProxy will not announce support
for frame sizes larger than buffers. The main purpose of this setting is to
allow to limit the maximum frame size setting when using large buffers. Too
large frame sizes might have performance impact or cause some peers to
misbehave. It is highly recommended not to change this value.
Sets the maximum length of captured cookies. This is the maximum value that
the "capture cookie xxx len yyy" will be allowed to take, and any upper value
will automatically be truncated to this one. It is important not to set too
high a value because all cookie captures still allocate this size whatever
their configured value (they share a same pool). This value is per request
per response, so the memory allocated is twice this value per connection.
When not specified, the limit is set to 63 characters. It is recommended not
to change this value.
Sets the maximum length of request URI in logs. This prevents truncating long
request URIs with valuable query strings in log lines. This is not related
to syslog limits. If you increase this limit, you may also increase the
'log ... len yyy' parameter. Your syslog daemon may also need specific
configuration directives too.
The default value is 1024.
Sets the maximum number of headers in a request. When a request comes with a
number of headers greater than this value (including the first line), it is
rejected with a "400 Bad Request" status code. Similarly, too large responses
are blocked with "502 Bad Gateway". The default value is 101, which is enough
for all usages, considering that the widely deployed Apache server uses the
same limit. It can be useful to push this limit further to temporarily allow
a buggy application to work by the time it gets fixed. The accepted range is
1..32767. Keep in mind that each new header consumes 32bits of memory for
each session, so don't push this limit too high.
Enables ('on') or disables ('off') sharing of idle connection pools between
threads for a same server. The default is to share them between threads in
order to minimize the number of persistent connections to a server, and to
optimize the connection reuse rate. But to help with debugging or when
suspecting a bug in HAProxy around connection reuse, it can be convenient to
forcefully disable this idle pool sharing between multiple threads, and force
this option to "off". The default is on. It is strongly recommended against
disabling this option without setting a conservative value on "pool-low-conn"
for all servers relying on connection reuse to achieve a high performance
level, otherwise connections might be closed very often as the thread count
increases.
Sets the duration after which HAProxy will consider that an empty buffer is
probably associated with an idle stream. This is used to optimally adjust
some packet sizes while forwarding large and small data alternatively. The
decision to use splice() or to send large buffers in SSL is modulated by this
parameter. The value is in milliseconds between 0 and 65535. A value of zero
means that HAProxy will not try to detect idle streams. The default is 1000,
which seems to correctly detect end user pauses (e.g. read a page before
clicking). There should be no reason for changing this value. Please check
tune.ssl.maxrecord below.
Enables ('on') or disables ('off') the listener's multi-queue accept which
spreads the incoming traffic to all threads a "bind" line is allowed to run
on instead of taking them for itself. This provides a smoother traffic
distribution and scales much better, especially in environments where threads
may be unevenly loaded due to external activity (network interrupts colliding
with one thread for example). This option is enabled by default, but it may
be forcefully disabled for troubleshooting or for situations where it is
estimated that the operating system already provides a good enough
distribution and connections are extremely short-lived.
This directive forces the Lua engine to execute a yield each <number> of
instructions executed. This permits interrupting a long script and allows the
HAProxy scheduler to process other tasks like accepting connections or
forwarding traffic. The default value is 10000 instructions. If HAProxy often
executes some Lua code but more responsiveness is required, this value can be
lowered. If the Lua code is quite long and its result is absolutely required
to process the data, the <number> can be increased.
Sets the maximum amount of RAM in megabytes per process usable by Lua. By
default it is zero which means unlimited. It is important to set a limit to
ensure that a bug in a script will not result in the system running out of
memory.
This is the execution timeout for the Lua sessions. This is useful for
preventing infinite loops or spending too much time in Lua. This timeout
counts only the pure Lua runtime. If the Lua does a sleep, the sleep is
not taken in account. The default timeout is 4s.
This is the execution timeout for the Lua services. This is useful for
preventing infinite loops or spending too much time in Lua. This timeout
counts only the pure Lua runtime. If the Lua does a sleep, the sleep is
not taken in account. The default timeout is 4s.
Purpose is the same as "tune.lua.session-timeout", but this timeout is
dedicated to the tasks. By default, this timeout isn't set because a task may
remain alive during of the lifetime of HAProxy. For example, a task used to
check servers.
Sets the maximum number of consecutive connections a process may accept in a
row before switching to other work. In single process mode, higher numbers
used to give better performance at high connection rates, though this is not
the case anymore with the multi-queue. This value applies individually to
each listener, so that the number of processes a listener is bound to is
taken into account. This value defaults to 4 which showed best results. If a
significantly higher value was inherited from an ancient config, it might be
worth removing it as it will both increase performance and lower response
time. In multi-process mode, it is divided by twice the number of processes
the listener is bound to. Setting this value to -1 completely disables the
limitation. It should normally not be needed to tweak this value.
Sets the maximum amount of events that can be processed at once in a call to
the polling system. The default value is adapted to the operating system. It
has been noticed that reducing it below 200 tends to slightly decrease
latency at the expense of network bandwidth, and increasing it above 200
tends to trade latency for slightly increased bandwidth.
Sets the reserved buffer space to this size in bytes. The reserved space is
used for header rewriting or appending. The first reads on sockets will never
fill more than bufsize-maxrewrite. Historically it has defaulted to half of
bufsize, though that does not make much sense since there are rarely large
numbers of headers to add. Setting it too high prevents processing of large
requests or responses. Setting it too low prevents addition of new headers
to already large requests or to POST requests. It is generally wise to set it
to about 1024. It is automatically readjusted to half of bufsize if it is
larger than that. This means you don't have to worry about it when changing
bufsize.
Sets the size of the pattern lookup cache to <number> entries. This is an LRU
cache which reminds previous lookups and their results. It is used by ACLs
and maps on slow pattern lookups, namely the ones using the "sub", "reg",
"dir", "dom", "end", "bin" match methods as well as the case-insensitive
strings. It applies to pattern expressions which means that it will be able
to memorize the result of a lookup among all the patterns specified on a
configuration line (including all those loaded from files). It automatically
invalidates entries which are updated using HTTP actions or on the CLI. The
default cache size is set to 10000 entries, which limits its footprint to
about 5 MB per process/thread on 32-bit systems and 8 MB per process/thread
on 64-bit systems, as caches are thread/process local. There is a very low
risk of collision in this cache, which is in the order of the size of the
cache divided by 2^64. Typically, at 10000 requests per second with the
default cache size of 10000 entries, there's 1% chance that a brute force
attack could cause a single collision after 60 years, or 0.1% after 6 years.
This is considered much lower than the risk of a memory corruption caused by
aging components. If this is not acceptable, the cache can be disabled by
setting this parameter to 0.
Sets the kernel pipe buffer size to this size (in bytes). By default, pipes
are the default size for the system. But sometimes when using TCP splicing,
it can improve performance to increase pipe sizes, especially if it is
suspected that pipes are not filled and that many calls to splice() are
performed. This has an impact on the kernel's memory footprint, so this must
not be changed if impacts are not understood.
This setting sets the max number of file descriptors (in percentage) used by
HAProxy globally against the maximum number of file descriptors HAProxy can
use before we start killing idle connections when we can't reuse a connection
and we have to create a new one. The default is 25 (one quarter of the file
descriptor will mean that roughly half of the maximum front connections can
keep an idle connection behind, anything beyond this probably doesn't make
much sense in the general case when targeting connection reuse).
This setting sets the max number of file descriptors (in percentage) used by
HAProxy globally against the maximum number of file descriptors HAProxy can
use before we stop putting connection into the idle pool for reuse. The
default is 20.
Forces the kernel socket receive buffer size on the client or the server side
to the specified value in bytes. This value applies to all TCP/HTTP frontends
and backends. It should normally never be set, and the default size (0) lets
the kernel auto-tune this value depending on the amount of available memory.
However it can sometimes help to set it to very low values (e.g. 4096) in
order to save kernel memory by preventing it from buffering too large amounts
of received data. Lower values will significantly increase CPU usage though.
HAProxy uses some hints to detect that a short read indicates the end of the
socket buffers. One of them is that a read returns more than <recv_enough>
bytes, which defaults to 10136 (7 segments of 1448 each). This default value
may be changed by this setting to better deal with workloads involving lots
of short messages such as telnet or SSH sessions.
Sets the maximum amount of task that can be processed at once when running
tasks. The default value depends on the number of threads but sits between 35
and 280, which tend to show the highest request rates and lowest latencies.
Increasing it may incur latency when dealing with I/Os, making it too small
can incur extra overhead. Higher thread counts benefit from lower values.
When experimenting with much larger values, it may be useful to also enable
tune.sched.low-latency and possibly tune.fd.edge-triggered to limit the
maximum latency to the lowest possible.
Enables ('on') or disables ('off') the low-latency task scheduler. By default
HAProxy processes tasks from several classes one class at a time as this is
the most efficient. But when running with large values of tune.runqueue-depth
this can have a measurable effect on request or connection latency. When this
low-latency setting is enabled, tasks of lower priority classes will always
be executed before other ones if they exist. This will permit to lower the
maximum latency experienced by new requests or connections in the middle of
massive traffic, at the expense of a higher impact on this large traffic.
For regular usage it is better to leave this off. The default value is off.
Forces the kernel socket send buffer size on the client or the server side to
the specified value in bytes. This value applies to all TCP/HTTP frontends
and backends. It should normally never be set, and the default size (0) lets
the kernel auto-tune this value depending on the amount of available memory.
However it can sometimes help to set it to very low values (e.g. 4096) in
order to save kernel memory by preventing it from buffering too large amounts
of received data. Lower values will significantly increase CPU usage though.
Another use case is to prevent write timeouts with extremely slow clients due
to the kernel waiting for a large part of the buffer to be read before
notifying HAProxy again.
Sets the size of the global SSL session cache, in a number of blocks. A block
is large enough to contain an encoded session without peer certificate. An
encoded session with peer certificate is stored in multiple blocks depending
on the size of the peer certificate. A block uses approximately 200 bytes of
memory (based on `sizeof(struct sh_ssl_sess_hdr) + SHSESS_BLOCK_MIN_SIZE`
calculation used for `shctx_init` function). The default value may be forced
at build time, otherwise defaults to 20000. When the cache is full, the most
idle entries are purged and reassigned. Higher values reduce the occurrence
of such a purge, hence the number of CPU-intensive SSL handshakes by ensuring
that all users keep their session as long as possible. All entries are
pre-allocated upon startup and are shared between all processes if "nbproc"
is greater than 1. Setting this value to 0 disables the SSL session cache.
Sets the maximum size of the buffer used for capturing client hello cipher
list, extensions list, elliptic curves list and elliptic curve point
formats. If the value is 0 (default value) the capture is disabled,
otherwise a buffer is allocated for each SSL/TLS connection.
Sets the maximum size of the Diffie-Hellman parameters used for generating
the ephemeral/temporary Diffie-Hellman key in case of DHE key exchange. The
final size will try to match the size of the server's RSA (or DSA) key (e.g,
a 2048 bits temporary DH key for a 2048 bits RSA key), but will not exceed
this maximum value. Only 1024 or higher values are allowed. Higher values
will increase the CPU load, and values greater than 1024 bits are not
supported by Java 7 and earlier clients. This value is not used if static
Diffie-Hellman parameters are supplied either directly in the certificate
file or by using the ssl-dh-param-file parameter.
If there is neither a default-dh-param nor a ssl-dh-param-file defined, and
if the server's PEM file of a given frontend does not specify its own DH
parameters, then DHE ciphers will be unavailable for this frontend.
This option disables SSL session cache sharing between all processes. It
should normally not be used since it will force many renegotiations due to
clients hitting a random process. But it may be required on some operating
systems where none of the SSL cache synchronization method may be used. In
this case, adding a first layer of hash-based load balancing before the SSL
layer might limit the impact of the lack of session sharing.
This option activates the logging of the TLS keys. It should be used with
care as it will consume more memory per SSL session and could decrease
performances. This is disabled by default.
These sample fetches should be used to generate the SSLKEYLOGFILE that is
required to decipher traffic with wireshark.
https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/Key_Log_Format
The SSLKEYLOG is a series of lines which are formatted this way:
<Label> <space> <ClientRandom> <space> <Secret>
The ClientRandom is provided by the %[ssl_fc_client_random,hex] sample
fetch, the secret and the Label could be find in the array below. You need
to generate a SSLKEYLOGFILE with all the labels in this array.
The following sample fetches are hexadecimal strings and does not need to be
converted.
SSLKEYLOGFILE Label | Sample fetches for the Secrets
--------------------------------|-----------------------------------------
CLIENT_EARLY_TRAFFIC_SECRET | %[ssl_fc_client_early_traffic_secret]
CLIENT_HANDSHAKE_TRAFFIC_SECRET | %[ssl_fc_client_handshake_traffic_secret]
SERVER_HANDSHAKE_TRAFFIC_SECRET | %[ssl_fc_server_handshake_traffic_secret]
CLIENT_TRAFFIC_SECRET_0 | %[ssl_fc_client_traffic_secret_0]
SERVER_TRAFFIC_SECRET_0 | %[ssl_fc_server_traffic_secret_0]
EXPORTER_SECRET | %[ssl_fc_exporter_secret]
EARLY_EXPORTER_SECRET | %[ssl_fc_early_exporter_secret]
This is only available with OpenSSL 1.1.1, and useful with TLS1.3 session.
If you want to generate the content of a SSLKEYLOGFILE with TLS < 1.3, you
only need this line:
"CLIENT_RANDOM %[ssl_fc_client_random,hex] %[ssl_fc_session_key,hex]"
Sets how long a cached SSL session may remain valid. This time is expressed
in seconds and defaults to 300 (5 min). It is important to understand that it
does not guarantee that sessions will last that long, because if the cache is
full, the longest idle sessions will be purged despite their configured
lifetime. The real usefulness of this setting is to prevent sessions from
being used for too long.
Sets the maximum amount of bytes passed to SSL_write() at a time. Default
value 0 means there is no limit. Over SSL/TLS, the client can decipher the
data only once it has received a full record. With large records, it means
that clients might have to download up to 16kB of data before starting to
process them. Limiting the value can improve page load times on browsers
located over high latency or low bandwidth networks. It is suggested to find
optimal values which fit into 1 or 2 TCP segments (generally 1448 bytes over
Ethernet with TCP timestamps enabled, or 1460 when timestamps are disabled),
keeping in mind that SSL/TLS add some overhead. Typical values of 1419 and
2859 gave good results during tests. Use "strace -e trace=write" to find the
best value. HAProxy will automatically switch to this setting after an idle
stream has been detected (see tune.idletimer above).
Sets the size of the cache used to store generated certificates to <number>
entries. This is a LRU cache. Because generating a SSL certificate
dynamically is expensive, they are cached. The default cache size is set to
1000 entries.
These five tunes help to manage the maximum amount of memory used by the
variables system. "global" limits the overall amount of memory available for
all scopes. "proc" limits the memory for the process scope, "sess" limits the
memory for the session scope, "txn" for the transaction scope, and "reqres"
limits the memory for each request or response processing.
Memory accounting is hierarchical, meaning more coarse grained limits include
the finer grained ones: "proc" includes "sess", "sess" includes "txn", and
"txn" includes "reqres".
For example, when "tune.vars.sess-max-size" is limited to 100,
"tune.vars.txn-max-size" and "tune.vars.reqres-max-size" cannot exceed
100 either. If we create a variable "txn.var" that contains 100 bytes,
all available space is consumed.
Notice that exceeding the limits at runtime will not result in an error
message, but values might be cut off or corrupted. So make sure to accurately
plan for the amount of space needed to store all your variables.
Sets the memLevel parameter in zlib initialization for each session. It
defines how much memory should be allocated for the internal compression
state. A value of 1 uses minimum memory but is slow and reduces compression
ratio, a value of 9 uses maximum memory for optimal speed. Can be a value
between 1 and 9. The default value is 8.
Sets the window size (the size of the history buffer) as a parameter of the
zlib initialization for each session. Larger values of this parameter result
in better compression at the expense of memory usage. Can be a value between
8 and 15. The default value is 15.
3.3. Debugging
Do not display any message during startup. It is equivalent to the command-
line argument "-q".
When this option is set, HAProxy will refuse to start if any warning was
emitted while processing the configuration. It is highly recommended to set
this option on configurations that are not changed often, as it helps detect
subtle mistakes and keep the configuration clean and forward-compatible. Note
that "haproxy -c" will also report errors in such a case. This option is
equivalent to command line argument "-dW".
3.4. Userlists
It is possible to control access to frontend/backend/listen sections or to
http stats by allowing only authenticated and authorized users. To do this,
it is required to create at least one userlist and to define users.
Creates new userlist with name <listname>. Many independent userlists can be
used to store authentication & authorization data for independent customers.
Adds group <groupname> to the current userlist. It is also possible to
attach users to this group by using a comma separated list of names
proceeded by "users" keyword.
Adds user <username> to the current userlist. Both secure (encrypted) and
insecure (unencrypted) passwords can be used. Encrypted passwords are
evaluated using the crypt(3) function, so depending on the system's
capabilities, different algorithms are supported. For example, modern Glibc
based Linux systems support MD5, SHA-256, SHA-512, and, of course, the
classic DES-based method of encrypting passwords.
Attention: Be aware that using encrypted passwords might cause significantly
increased CPU usage, depending on the number of requests, and the algorithm
used. For any of the hashed variants, the password for each request must
be processed through the chosen algorithm, before it can be compared to the
value specified in the config file. Most current algorithms are deliberately
designed to be expensive to compute to achieve resistance against brute
force attacks. They do not simply salt/hash the clear text password once,
but thousands of times. This can quickly become a major factor in HAProxy's
overall CPU consumption!
Example:
userlist L1
group G1 users tiger,scott
group G2 users xdb,scott
user tiger password $6$k6y3o.eP$JlKBx9za9667qe4(...)xHSwRv6J.C0/D7cV91
user scott insecure-password elgato
user xdb insecure-password hello
userlist L2
group G1
group G2
user tiger password $6$k6y3o.eP$JlKBx(...)xHSwRv6J.C0/D7cV91 groups G1
user scott insecure-password elgato groups G1,G2
user xdb insecure-password hello groups G2
Please note that both lists are functionally identical.
3.5. Peers
It is possible to propagate entries of any data-types in stick-tables between
several HAProxy instances over TCP connections in a multi-master fashion. Each
instance pushes its local updates and insertions to remote peers. The pushed
values overwrite remote ones without aggregation. Interrupted exchanges are
automatically detected and recovered from the last known point.
In addition, during a soft restart, the old process connects to the new one
using such a TCP connection to push all its entries before the new process
tries to connect to other peers. That ensures very fast replication during a
reload, it typically takes a fraction of a second even for large tables.
Note that Server IDs are used to identify servers remotely, so it is important
that configurations look similar or at least that the same IDs are forced on
each server on all participants.
Creates a new peer list with name <peersect>. It is an independent section,
which is referenced by one or more stick-tables.
Defines the binding parameters of the local peer of this "peers" section.
Such lines are not supported with "peer" line in the same "peers" section.
Disables a peers section. It disables both listening and any synchronization
related to this section. This is provided to disable synchronization of stick
tables without having to comment out all "peers" references.
Defines the binding parameters for the local peer, excepted its address.
Change default options for a server in a "peers" section.
Arguments:
<param*> is a list of parameters for this server. The "default-server" keyword accepts an important number of options and has a complete section dedicated to it. In a peers section, the transport parameters of a "default-server" line are supported. Please refer to section 5 for more details, and the "server" keyword below in this section for some of the restrictions.
This re-enables a peers section which was previously disabled via the
"disabled" keyword.
log <address> [len <length>] [format <format>] [sample <ranges>:<sample_size>]
<facility> [<level> [<minlevel>]]
"peers" sections support the same "log" keyword as for the proxies to
log information about the "peers" listener. See "log" option for proxies for
more details.
Defines a peer inside a peers section.
If <peername> is set to the local peer name (by default hostname, or forced
using "-L" command line option or "localpeer" global configuration setting),
HAProxy will listen for incoming remote peer connection on the provided
address. Otherwise, the address defines where to connect to in order to join
the remote peer, and <peername> is used at the protocol level to identify and
validate the remote peer on the server side.
During a soft restart, local peer address is used by the old instance to
connect the new one and initiate a complete replication (teaching process).
It is strongly recommended to have the exact same peers declaration on all
peers and to only rely on the "-L" command line argument or the "localpeer"
global configuration setting to change the local peer name. This makes it
easier to maintain coherent configuration files across all peers.
You may want to reference some environment variables in the address
parameter, see section 2.3 about environment variables.
Note: "peer" keyword may transparently be replaced by "server" keyword (see
"server" keyword explanation below).
As previously mentioned, "peer" keyword may be replaced by "server" keyword
with a support for all "server" parameters found in 5.2 paragraph that are
related to transport settings. If the underlying peer is local, the address
parameter must not be present; it must be provided on a "bind" line (see
"bind" keyword of this "peers" section).
A number of "server" parameters are irrelevant for "peers" sections. Peers by
nature do not support dynamic host name resolution nor health checks, hence
parameters like "init_addr", "resolvers", "check", "agent-check", or "track"
are not supported. Similarly, there is no load balancing nor stickiness, thus
parameters such as "weight" or "cookie" have no effect.
Example:
# The old way.
peers mypeers
peer haproxy1 192.168.0.1:1024
peer haproxy2 192.168.0.2:1024
peer haproxy3 10.2.0.1:1024
backend mybackend
mode tcp
balance roundrobin
stick-table type ip size 20k peers mypeers
stick on src
server srv1 192.168.0.30:80
server srv2 192.168.0.31:80
Example:
peers mypeers
bind 192.168.0.1:1024 ssl crt mycerts/pem
default-server ssl verify none
server haproxy1 #local peer
server haproxy2 192.168.0.2:1024
server haproxy3 10.2.0.1:1024
table <tablename> type {ip | integer | string [len <length>] | binary [len <length>]}
size <size> [expire <expire>] [nopurge] [store <data_type>]*
Configure a stickiness table for the current section. This line is parsed
exactly the same way as the "stick-table" keyword in others section, except
for the "peers" argument which is not required here and with an additional
mandatory first parameter to designate the stick-table. Contrary to others
sections, there may be several "table" lines in "peers" sections (see also
"stick-table" keyword).
Also be aware of the fact that "peers" sections have their own stick-table
namespaces to avoid collisions between stick-table names identical in
different "peers" section. This is internally handled prepending the "peers"
sections names to the name of the stick-tables followed by a '/' character.
If somewhere else in the configuration file you have to refer to such
stick-tables declared in "peers" sections you must use the prefixed version
of the stick-table name as follows:
peers mypeers
peer A ...
peer B ...
table t1 ...
frontend fe1
tcp-request content track-sc0 src table mypeers/t1
This is also this prefixed version of the stick-table names which must be
used to refer to stick-tables through the CLI.
About "peers" protocol, as only "peers" belonging to the same section may
communicate with each others, there is no need to do such a distinction.
Several "peers" sections may declare stick-tables with the same name.
This is shorter version of the stick-table name which is sent over the network.
There is only a '/' character as prefix to avoid stick-table name collisions between
stick-tables declared as backends and stick-table declared in "peers" sections
as follows in this weird but supported configuration:
peers mypeers
peer A ...
peer B ...
table t1 type string size 10m store gpc0
backend t1
stick-table type string size 10m store gpc0 peers mypeers
Here "t1" table declared in "mypeers" section has "mypeers/t1" as global name.
"t1" table declared as a backend as "t1" as global name. But at peer protocol
level the former table is named "/t1", the latter is again named "t1".
3.6. Mailers
It is possible to send email alerts when the state of servers changes.
If configured email alerts are sent to each mailer that is configured
in a mailers section. Email is sent to mailers using SMTP.
Creates a new mailer list with the name <mailersect>. It is an
independent section which is referenced by one or more proxies.
Defines a mailer inside a mailers section.
Example:
mailers mymailers
mailer smtp1 192.168.0.1:587
mailer smtp2 192.168.0.2:587
backend mybackend
mode tcp
balance roundrobin
email-alert mailers mymailers
email-alert from test1@horms.org
email-alert to test2@horms.org
server srv1 192.168.0.30:80
server srv2 192.168.0.31:80
Defines the time available for a mail/connection to be made and send to
the mail-server. If not defined the default value is 10 seconds. To allow
for at least two SYN-ACK packets to be send during initial TCP handshake it
is advised to keep this value above 4 seconds.
Example:
mailers mymailers
timeout mail 20s
mailer smtp1 192.168.0.1:587
3.7. Programs
In master-worker mode, it is possible to launch external binaries with the
master, these processes are called programs. These programs are launched and
managed the same way as the workers.
During a reload of HAProxy, those processes are dealing with the same
sequence as a worker:
- the master is re-executed
- the master sends a SIGUSR1 signal to the program
- if "option start-on-reload" is not disabled, the master launches a new
instance of the program
During a stop, or restart, a SIGTERM is sent to the programs.
This is a new program section, this section will create an instance <name>
which is visible in "show proc" on the master CLI. (See "9.4. Master CLI" in
the management guide).
Define the command to start with optional arguments. The command is looked
up in the current PATH if it does not include an absolute path. This is a
mandatory option of the program section. Arguments containing spaces must
be enclosed in quotes or double quotes or be prefixed by a backslash.
Changes the executed command user ID to the <user name> from /etc/passwd.
See also "group".
Changes the executed command group ID to the <group name> from /etc/group.
See also "user".
Start (or not) a new instance of the program upon a reload of the master.
The default is to start a new instance. This option may only be used in a
program section.
3.8. HTTP-errors
It is possible to globally declare several groups of HTTP errors, to be
imported afterwards in any proxy section. Same group may be referenced at
several places and can be fully or partially imported.
Create a new http-errors group with the name <name>. It is an independent
section that may be referenced by one or more proxies using its name.
Associate a file contents to an HTTP error code
Arguments :
<code> is the HTTP status code. Currently, HAProxy is capable of
generating codes 200, 400, 401, 403, 404, 405, 407, 408, 410,
425, 429, 500, 501, 502, 503, and 504.
<file> designates a file containing the full HTTP response. It is
recommended to follow the common practice of appending ".http" to
the filename so that people do not confuse the response with HTML
error pages, and to use absolute paths, since files are read
before any chroot is performed.
Example:
http-errors website-1
errorfile 400 /etc/haproxy/errorfiles/site1/400.http
errorfile 404 /etc/haproxy/errorfiles/site1/404.http
errorfile 408 /dev/null # work around Chrome pre-connect bug
http-errors website-2
errorfile 400 /etc/haproxy/errorfiles/site2/400.http
errorfile 404 /etc/haproxy/errorfiles/site2/404.http
errorfile 408 /dev/null # work around Chrome pre-connect bug
3.9. Rings
It is possible to globally declare ring-buffers, to be used as target for log
servers or traces.
Creates a new ring-buffer with name <ringname>.
The description is an optional description string of the ring. It will
appear on CLI. By default, <name> is reused to fill this field.
Format used to store events into the ring buffer.
Arguments:
<format> is the log format used when generating syslog messages. It may be
one of the following :
iso A message containing only the ISO date, followed by the text.
The PID, process name and system name are omitted. This is
designed to be used with a local log server.
local Analog to rfc3164 syslog message format except that hostname
field is stripped. This is the default.
Note: option "log-send-hostname" switches the default to
rfc3164.
raw A message containing only the text. The level, PID, date, time,
process name and system name are omitted. This is designed to be
used in containers or during development, where the severity
only depends on the file descriptor used (stdout/stderr). This
is the default.
rfc3164 The RFC3164 syslog message format.
(https://tools.ietf.org/html/rfc3164)
rfc5424 The RFC5424 syslog message format.
(https://tools.ietf.org/html/rfc5424)
short A message containing only a level between angle brackets such as
'<3>', followed by the text. The PID, date, time, process name
and system name are omitted. This is designed to be used with a
local log server. This format is compatible with what the systemd
logger consumes.
priority A message containing only a level plus syslog facility between angle
brackets such as '<63>', followed by the text. The PID, date, time,
process name and system name are omitted. This is designed to be used
with a local log server.
timed A message containing only a level between angle brackets such as
'<3>', followed by ISO date and by the text. The PID, process
name and system name are omitted. This is designed to be
used with a local log server.
The maximum length of an event message stored into the ring,
including formatted header. If an event message is longer than
<length>, it will be truncated to this length.
Used to configure a syslog tcp server to forward messages from ring buffer.
This supports for all "server" parameters found in 5.2 paragraph. Some of
these parameters are irrelevant for "ring" sections. Important point: there
is little reason to add more than one server to a ring, because all servers
will receive the exact same copy of the ring contents, and as such the ring
will progress at the speed of the slowest server. If one server does not
respond, it will prevent old messages from being purged and may block new
messages from being inserted into the ring. The proper way to send messages
to multiple servers is to use one distinct ring per log server, not to
attach multiple servers to the same ring. Note that specific server directive
"log-proto" is used to set the protocol used to send messages.
This is the optional size in bytes for the ring-buffer. Default value is
set to BUFSIZE.
Set the maximum time to wait for a connection attempt to a server to succeed.
Arguments :
<timeout> is the timeout value specified in milliseconds by default, but
can be in any other unit if the number is suffixed by the unit,
as explained at the top of this document.
Set the maximum time for pending data staying into output buffer.
Arguments :
<timeout> is the timeout value specified in milliseconds by default, but
can be in any other unit if the number is suffixed by the unit,
as explained at the top of this document.
Example:
global
log ring@myring local7
ring myring
description "My local buffer"
format rfc3164
maxlen 1200
size 32764
timeout connect 5s
timeout server 10s
server mysyslogsrv 127.0.0.1:6514 log-proto octet-count
3.10. Log forwarding
It is possible to declare one or multiple log forwarding section,
HAProxy will forward all received log messages to a log servers list.
Creates a new log forwarder proxy identified as <name>.
Give hints to the system about the approximate listen backlog desired size
on connections accept.
Used to configure a stream log listener to receive messages to forward.
This supports the "bind" parameters found in 5.1 paragraph including
those about ssl but some statements such as "alpn" may be irrelevant for
syslog protocol over TCP.
Those listeners support both "Octet Counting" and "Non-Transparent-Framing"
modes as defined in rfc-6587.
Used to configure a datagram log listener to receive messages to forward.
Addresses must be in IPv4 or IPv6 form,followed by a port. This supports
for some of the "bind" parameters found in 5.1 paragraph among which
"interface", "namespace" or "transparent", the other ones being
silently ignored as irrelevant for UDP/syslog case.
log <address> [len <length>] [format <format>] [sample <ranges>:<sample_size>]
<facility> [<level> [<minlevel>]]
Used to configure target log servers. See more details on proxies
documentation.
If no format specified, HAProxy tries to keep the incoming log format.
Configured facility is ignored, except if incoming message does not
present a facility but one is mandatory on the outgoing format.
If there is no timestamp available in the input format, but the field
exists in output format, HAProxy will use the local date.
Example:
global
log stderr format iso local7
ring myring
description "My local buffer"
format rfc5424
maxlen 1200
size 32764
timeout connect 5s
timeout server 10s
# syslog tcp server
server mysyslogsrv 127.0.0.1:514 log-proto octet-count
log-forward sylog-loadb
dgram-bind 127.0.0.1:1514
bind 127.0.0.1:1514
# all messages on stderr
log global
# all messages on local tcp syslog server
log ring@myring local0
# load balance messages on 4 udp syslog servers
log 127.0.0.1:10001 sample 1:4 local0
log 127.0.0.1:10002 sample 2:4 local0
log 127.0.0.1:10003 sample 3:4 local0
log 127.0.0.1:10004 sample 4:4 local0
Fix the maximum number of concurrent connections on a log forwarder.
10 is the default.
Set the maximum inactivity time on the client side.
3.11. Modules
It is possible to load modules that provides new functions or permit to
implement protocols under NDA. The modules are declared with the keyword
"module-load". The keyword "module-path" permit to specify default path
containing modules.
Give the module file to load. This file can be absolute path name, or relative
to the directory specified in the "module-path" entry.
Example:
module-load /usr/lib/haproxy/module-load my_protocol_under_nda.so
Give the default path containing modules. If more than one directives
"module-path" was found in the configuration file, only the last entry before
the directive "module-load" is used.
Example:
module-path /usr/lib/haproxy
module-load my_protocol_under_nda.so
3.12. HTTPClient tuning
HTTPClient is an internal HTTP library, it can be used by various subsystems,
for example in LUA scripts. HTTPClient is not used in the data path, in other
words it has nothing with HTTP traffic passing through HAProxy.
This option defines the resolvers section with which the httpclient will try
to resolve.
Default option is the "default" resolvers ID. By default, if this option is
not used, it will simply disable the resolving if the section is not found.
However, when this option is explicitly enabled it will trigger a
configuration error if it fails to load.
This option allows to chose which family of IP you want when resolving,
which is convenient when IPv6 is not available on your network. Default
option is "ipv6".
This option defines the ca-file which should be used to verify the server
certificate. It takes the same parameters as the "ca-file" option on the
server line.
By default and when this option is not used, the value is
"@system-ca" which tries to load the CA of the system. If it fails the SSL
will be disabled for the httpclient.
However, when this option is explicitly enabled it will trigger a
configuration error if it fails.
Works the same way as the verify option on server lines. If specified to 'none',
servers certificates are not verified. Default option is "required".
By default and when this option is not used, the value is
"required". If it fails the SSL will be disabled for the httpclient.
However, when this option is explicitly enabled it will trigger a
configuration error if it fails.
4. Proxies
Proxy configuration can be located in a set of sections :
- defaults [<name>] [ from <defaults_name> ]
- frontend <name> [ from <defaults_name> ]
- backend <name> [ from <defaults_name> ]
- listen <name> [ from <defaults_name> ]
A "frontend" section describes a set of listening sockets accepting client
connections.
A "backend" section describes a set of servers to which the proxy will connect
to forward incoming connections.
A "listen" section defines a complete proxy with its frontend and backend
parts combined in one section. It is generally useful for TCP-only traffic.
A "defaults" section resets all settings to the documented ones and presets new
ones for use by subsequent sections. All of "frontend", "backend" and "listen"
sections always take their initial settings from a defaults section, by default
the latest one that appears before the newly created section. It is possible to
explicitly designate a specific "defaults" section to load the initial settings
from by indicating its name on the section line after the optional keyword
"from". While "defaults" section do not impose a name, this use is encouraged
for better readability. It is also the only way to designate a specific section
to use instead of the default previous one. Since "defaults" section names are
optional, by default a very permissive check is applied on their name and these
are even permitted to overlap. However if a "defaults" section is referenced by
any other section, its name must comply with the syntax imposed on all proxy
names, and this name must be unique among the defaults sections. Please note
that regardless of what is currently permitted, it is recommended to avoid
duplicate section names in general and to respect the same syntax as for proxy
names. This rule might be enforced in a future version.
Note that it is even possible for a defaults section to take its initial
settings from another one, and as such, inherit settings across multiple levels
of defaults sections. This can be convenient to establish certain configuration
profiles to carry groups of default settings (e.g. TCP vs HTTP or short vs long
timeouts) but can quickly become confusing to follow.
All proxy names must be formed from upper and lower case letters, digits,
'-' (dash), '_' (underscore) , '.' (dot) and ':' (colon). ACL names are
case-sensitive, which means that "www" and "WWW" are two different proxies.
Historically, all proxy names could overlap, it just caused troubles in the
logs. Since the introduction of content switching, it is mandatory that two
proxies with overlapping capabilities (frontend/backend) have different names.
However, it is still permitted that a frontend and a backend share the same
name, as this configuration seems to be commonly encountered.
Right now, two major proxy modes are supported : "tcp", also known as layer 4,
and "http", also known as layer 7. In layer 4 mode, HAProxy simply forwards
bidirectional traffic between two sides. In layer 7 mode, HAProxy analyzes the
protocol, and can interact with it by allowing, blocking, switching, adding,
modifying, or removing arbitrary contents in requests or responses, based on
arbitrary criteria.
In HTTP mode, the processing applied to requests and responses flowing over
a connection depends in the combination of the frontend's HTTP options and
the backend's. HAProxy supports 3 connection modes :
- KAL : keep alive ("option http-keep-alive") which is the default mode : all
requests and responses are processed, and connections remain open but idle
between responses and new requests.
- SCL: server close ("option http-server-close") : the server-facing
connection is closed after the end of the response is received, but the
client-facing connection remains open.
- CLO: close ("option httpclose"): the connection is closed after the end of
the response and "Connection: close" appended in both directions.
The effective mode that will be applied to a connection passing through a
frontend and a backend can be determined by both proxy modes according to the
following matrix, but in short, the modes are symmetric, keep-alive is the
weakest option and close is the strongest.
Backend mode
| KAL | SCL | CLO
----+-----+-----+----
KAL | KAL | SCL | CLO
----+-----+-----+----
mode SCL | SCL | SCL | CLO
----+-----+-----+----
CLO | CLO | CLO | CLO
It is possible to chain a TCP frontend to an HTTP backend. It is pointless if
only HTTP traffic is handled. But it may be used to handle several protocols
within the same frontend. In this case, the client's connection is first handled
as a raw tcp connection before being upgraded to HTTP. Before the upgrade, the
content processings are performend on raw data. Once upgraded, data is parsed
and stored using an internal representation called HTX and it is no longer
possible to rely on raw representation. There is no way to go back.
There are two kind of upgrades, in-place upgrades and destructive upgrades. The
first ones involves a TCP to HTTP/1 upgrade. In HTTP/1, the request
processings are serialized, thus the applicative stream can be preserved. The
second one involves a TCP to HTTP/2 upgrade. Because it is a multiplexed
protocol, the applicative stream cannot be associated to any HTTP/2 stream and
is destroyed. New applicative streams are then created when HAProxy receives
new HTTP/2 streams at the lower level, in the H2 multiplexer. It is important
to understand this difference because that drastically changes the way to
process data. When an HTTP/1 upgrade is performed, the content processings
already performed on raw data are neither lost nor reexecuted while for an
HTTP/2 upgrade, applicative streams are distinct and all frontend rules are
evaluated systematically on each one. And as said, the first stream, the TCP
one, is destroyed, but only after the frontend rules were evaluated.
There is another importnat point to understand when HTTP processings are
performed from a TCP proxy. While HAProxy is able to parse HTTP/1 in-fly from
tcp-request content rules, it is not possible for HTTP/2. Only the HTTP/2
preface can be parsed. This is a huge limitation regarding the HTTP content
analysis in TCP. Concretely it is only possible to know if received data are
HTTP. For instance, it is not possible to choose a backend based on the Host
header value while it is trivial in HTTP/1. Hopefully, there is a solution to
mitigate this drawback.
There are two ways to perform an HTTP upgrade. The first one, the historical
method, is to select an HTTP backend. The upgrade happens when the backend is
set. Thus, for in-place upgrades, only the backend configuration is considered
in the HTTP data processing. For destructive upgrades, the applicative stream
is destroyed, thus its processing is stopped. With this method, possibilities
to choose a backend with an HTTP/2 connection are really limited, as mentioned
above, and a bit useless because the stream is destroyed. The second method is
to upgrade during the tcp-request content rules evaluation, thanks to the
"switch-mode http" action. In this case, the upgrade is performed in the
frontend context and it is possible to define HTTP directives in this
frontend. For in-place upgrades, it offers all the power of the HTTP analysis
as soon as possible. It is not that far from an HTTP frontend. For destructive
upgrades, it does not change anything except it is useless to choose a backend
on limited information. It is of course the recommended method. Thus, testing
the request protocol from the tcp-request content rules to perform an HTTP
upgrade is enough. All the remaining HTTP manipulation may be moved to the
frontend http-request ruleset. But keep in mind that tcp-request content rules
remains evaluated on each streams, that can't be changed.
4.1. Proxy keywords matrix
The following list of keywords is supported. Most of them may only be used in a
limited set of section types. Some of them are marked as "deprecated" because
they are inherited from an old syntax which may be confusing or functionally
limited, and there are new recommended keywords to replace them. Keywords
marked with "(*)" can be optionally inverted using the "no" prefix, e.g. "no
option contstats". This makes sense when the option has been enabled by default
and must be disabled for a specific instance. Such options may also be prefixed
with "default" in order to restore default settings regardless of what has been
specified in a previous "defaults" section.
4.2. Alphabetically sorted keywords reference
This section provides a description of each keyword and its usage.
Declare or complete an access list.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
no | yes | yes | yes |
Example:
acl invalid_src src 0.0.0.0/7 224.0.0.0/3
acl invalid_src src_port 0:1023
acl local_dst hdr(host) -i localhost
See section 7 about ACL usage.
Give hints to the system about the approximate listen backlog desired size
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments :
<conns> is the number of pending connections. Depending on the operating
system, it may represent the number of already acknowledged
connections, of non-acknowledged ones, or both.
In order to protect against SYN flood attacks, one solution is to increase
the system's SYN backlog size. Depending on the system, sometimes it is just
tunable via a system parameter, sometimes it is not adjustable at all, and
sometimes the system relies on hints given by the application at the time of
the listen() syscall. By default, HAProxy passes the frontend's maxconn value
to the listen() syscall. On systems which can make use of this value, it can
sometimes be useful to be able to specify a different value, hence this
backlog parameter.
On Linux 2.4, the parameter is ignored by the system. On Linux 2.6, it is
used as a hint and the system accepts up to the smallest greater power of
two, and never more than some limits (usually 32768).
See also : "maxconn" and the target operating system's tuning guide.
Define the load balancing algorithm to be used in a backend.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<algorithm> is the algorithm used to select a server when doing load
balancing. This only applies when no persistence information
is available, or when a connection is redispatched to another
server. <algorithm> may be one of the following :
roundrobin Each server is used in turns, according to their weights.
This is the smoothest and fairest algorithm when the server's
processing time remains equally distributed. This algorithm
is dynamic, which means that server weights may be adjusted
on the fly for slow starts for instance. It is limited by
design to 4095 active servers per backend. Note that in some
large farms, when a server becomes up after having been down
for a very short time, it may sometimes take a few hundreds
requests for it to be re-integrated into the farm and start
receiving traffic. This is normal, though very rare. It is
indicated here in case you would have the chance to observe
it, so that you don't worry.
static-rr Each server is used in turns, according to their weights.
This algorithm is as similar to roundrobin except that it is
static, which means that changing a server's weight on the
fly will have no effect. On the other hand, it has no design
limitation on the number of servers, and when a server goes
up, it is always immediately reintroduced into the farm, once
the full map is recomputed. It also uses slightly less CPU to
run (around -1%).
leastconn The server with the lowest number of connections receives the
connection. Round-robin is performed within groups of servers
of the same load to ensure that all servers will be used. Use
of this algorithm is recommended where very long sessions are
expected, such as LDAP, SQL, TSE, etc... but is not very well
suited for protocols using short sessions such as HTTP. This
algorithm is dynamic, which means that server weights may be
adjusted on the fly for slow starts for instance. It will
also consider the number of queued connections in addition to
the established ones in order to minimize queuing.
first The first server with available connection slots receives the
connection. The servers are chosen from the lowest numeric
identifier to the highest (see server parameter "id"), which
defaults to the server's position in the farm. Once a server
reaches its maxconn value, the next server is used. It does
not make sense to use this algorithm without setting maxconn.
The purpose of this algorithm is to always use the smallest
number of servers so that extra servers can be powered off
during non-intensive hours. This algorithm ignores the server
weight, and brings more benefit to long session such as RDP
or IMAP than HTTP, though it can be useful there too. In
order to use this algorithm efficiently, it is recommended
that a cloud controller regularly checks server usage to turn
them off when unused, and regularly checks backend queue to
turn new servers on when the queue inflates. Alternatively,
using "http-check send-state" may inform servers on the load.
source The source IP address is hashed and divided by the total
weight of the running servers to designate which server will
receive the request. This ensures that the same client IP
address will always reach the same server as long as no
server goes down or up. If the hash result changes due to the
number of running servers changing, many clients will be
directed to a different server. This algorithm is generally
used in TCP mode where no cookie may be inserted. It may also
be used on the Internet to provide a best-effort stickiness
to clients which refuse session cookies. This algorithm is
static by default, which means that changing a server's
weight on the fly will have no effect, but this can be
changed using "hash-type".
uri This algorithm hashes either the left part of the URI (before
the question mark) or the whole URI (if the "whole" parameter
is present) and divides the hash value by the total weight of
the running servers. The result designates which server will
receive the request. This ensures that the same URI will
always be directed to the same server as long as no server
goes up or down. This is used with proxy caches and
anti-virus proxies in order to maximize the cache hit rate.
Note that this algorithm may only be used in an HTTP backend.
This algorithm is static by default, which means that
changing a server's weight on the fly will have no effect,
but this can be changed using "hash-type".
This algorithm supports two optional parameters "len" and
"depth", both followed by a positive integer number. These
options may be helpful when it is needed to balance servers
based on the beginning of the URI only. The "len" parameter
indicates that the algorithm should only consider that many
characters at the beginning of the URI to compute the hash.
Note that having "len" set to 1 rarely makes sense since most
URIs start with a leading "/".
The "depth" parameter indicates the maximum directory depth
to be used to compute the hash. One level is counted for each
slash in the request. If both parameters are specified, the
evaluation stops when either is reached.
A "path-only" parameter indicates that the hashing key starts
at the first '/' of the path. This can be used to ignore the
authority part of absolute URIs, and to make sure that HTTP/1
and HTTP/2 URIs will provide the same hash.
url_param The URL parameter specified in argument will be looked up in
the query string of each HTTP GET request.
If the modifier "check_post" is used, then an HTTP POST
request entity will be searched for the parameter argument,
when it is not found in a query string after a question mark
('?') in the URL. The message body will only start to be
analyzed once either the advertised amount of data has been
received or the request buffer is full. In the unlikely event
that chunked encoding is used, only the first chunk is
scanned. Parameter values separated by a chunk boundary, may
be randomly balanced if at all. This keyword used to support
an optional <max_wait> parameter which is now ignored.
If the parameter is found followed by an equal sign ('=') and
a value, then the value is hashed and divided by the total
weight of the running servers. The result designates which
server will receive the request.
This is used to track user identifiers in requests and ensure
that a same user ID will always be sent to the same server as
long as no server goes up or down. If no value is found or if
the parameter is not found, then a round robin algorithm is
applied. Note that this algorithm may only be used in an HTTP
backend. This algorithm is static by default, which means
that changing a server's weight on the fly will have no
effect, but this can be changed using "hash-type".
hdr(<name>) The HTTP header <name> will be looked up in each HTTP
request. Just as with the equivalent ACL 'hdr()' function,
the header name in parenthesis is not case sensitive. If the
header is absent or if it does not contain any value, the
roundrobin algorithm is applied instead.
An optional 'use_domain_only' parameter is available, for
reducing the hash algorithm to the main domain part with some
specific headers such as 'Host'. For instance, in the Host
value "haproxy.1wt.eu", only "1wt" will be considered.
This algorithm is static by default, which means that
changing a server's weight on the fly will have no effect,
but this can be changed using "hash-type".
random
random(<draws>)
A random number will be used as the key for the consistent
hashing function. This means that the servers' weights are
respected, dynamic weight changes immediately take effect, as
well as new server additions. Random load balancing can be
useful with large farms or when servers are frequently added
or removed as it may avoid the hammering effect that could
result from roundrobin or leastconn in this situation. The
hash-balance-factor directive can be used to further improve
fairness of the load balancing, especially in situations
where servers show highly variable response times. When an
argument <draws> is present, it must be an integer value one
or greater, indicating the number of draws before selecting
the least loaded of these servers. It was indeed demonstrated
that picking the least loaded of two servers is enough to
significantly improve the fairness of the algorithm, by
always avoiding to pick the most loaded server within a farm
and getting rid of any bias that could be induced by the
unfair distribution of the consistent list. Higher values N
will take away N-1 of the highest loaded servers at the
expense of performance. With very high values, the algorithm
will converge towards the leastconn's result but much slower.
The default value is 2, which generally shows very good
distribution and performance. This algorithm is also known as
the Power of Two Random Choices and is described here :
http://www.eecs.harvard.edu/~michaelm/postscripts/handbook2001.pdf
rdp-cookie
rdp-cookie(<name>)
The RDP cookie <name> (or "mstshash" if omitted) will be
looked up and hashed for each incoming TCP request. Just as
with the equivalent ACL 'req.rdp_cookie()' function, the name
is not case-sensitive. This mechanism is useful as a degraded
persistence mode, as it makes it possible to always send the
same user (or the same session ID) to the same server. If the
cookie is not found, the normal roundrobin algorithm is
used instead.
Note that for this to work, the frontend must ensure that an
RDP cookie is already present in the request buffer. For this
you must use 'tcp-request content accept' rule combined with
a 'req.rdp_cookie_cnt' ACL.
This algorithm is static by default, which means that
changing a server's weight on the fly will have no effect,
but this can be changed using "hash-type".
<arguments> is an optional list of arguments which may be needed by some
algorithms. Right now, only "url_param" and "uri" support an
optional argument.
The load balancing algorithm of a backend is set to roundrobin when no other
algorithm, mode nor option have been set. The algorithm may only be set once
for each backend.
With authentication schemes that require the same connection like NTLM, URI
based algorithms must not be used, as they would cause subsequent requests
to be routed to different backend servers, breaking the invalid assumptions
NTLM relies on.
Examples :
balance roundrobin
balance url_param userid
balance url_param session_id check_post 64
balance hdr(User-Agent)
balance hdr(host)
balance hdr(Host) use_domain_only
Note: the following caveats and limitations on using the "check_post"
extension with "url_param" must be considered :
- all POST requests are eligible for consideration, because there is no way
to determine if the parameters will be found in the body or entity which
may contain binary data. Therefore another method may be required to
restrict consideration of POST requests that have no URL parameters in
the body. (see acl http_end)
- using a <max_wait> value larger than the request buffer size does not
make sense and is useless. The buffer size is set at build time, and
defaults to 16 kB.
- Content-Encoding is not supported, the parameter search will probably
fail; and load balancing will fall back to Round Robin.
- Expect: 100-continue is not supported, load balancing will fall back to
Round Robin.
- Transfer-Encoding (RFC7230 3.3.1) is only supported in the first chunk.
If the entire parameter value is not present in the first chunk, the
selection of server is undefined (actually, defined by how little
actually appeared in the first chunk).
- This feature does not support generation of a 100, 411 or 501 response.
- In some cases, requesting "check_post" MAY attempt to scan the entire
contents of a message body. Scanning normally terminates when linear
white space or control characters are found, indicating the end of what
might be a URL parameter list. This is probably not a concern with SGML
type message bodies.
Define one or several listening addresses and/or ports in a frontend.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | yes | yes | no |
Arguments :
<address> is optional and can be a host name, an IPv4 address, an IPv6
address, or '*'. It designates the address the frontend will
listen on. If unset, all IPv4 addresses of the system will be
listened on. The same will apply for '*' or the system's
special address "0.0.0.0". The IPv6 equivalent is '::'.
Optionally, an address family prefix may be used before the
address to force the family regardless of the address format,
which can be useful to specify a path to a unix socket with
no slash ('/'). Currently supported prefixes are :
- 'ipv4@' -> address is always IPv4
- 'ipv6@' -> address is always IPv6
- 'udp@' -> address is resolved as IPv4 or IPv6 and
protocol UDP is used. Currently those listeners are
supported only in log-forward sections.
- 'udp4@' -> address is always IPv4 and protocol UDP
is used. Currently those listeners are supported
only in log-forward sections.
- 'udp6@' -> address is always IPv6 and protocol UDP
is used. Currently those listeners are supported
only in log-forward sections.
- 'unix@' -> address is a path to a local unix socket
- 'abns@' -> address is in abstract namespace (Linux only).
Note: since abstract sockets are not "rebindable", they
do not cope well with multi-process mode during
soft-restart, so it is better to avoid them if
nbproc is greater than 1. The effect is that if the
new process fails to start, only one of the old ones
will be able to rebind to the socket.
- 'fd@<n>' -> use file descriptor <n> inherited from the
parent. The fd must be bound and may or may not already
be listening.
- 'sockpair@<n>'-> like fd@ but you must use the fd of a
connected unix socket or of a socketpair. The bind waits
to receive a FD over the unix socket and uses it as if it
was the FD of an accept(). Should be used carefully.
You may want to reference some environment variables in the
address parameter, see section 2.3 about environment
variables.
<port_range> is either a unique TCP port, or a port range for which the
proxy will accept connections for the IP address specified
above. The port is mandatory for TCP listeners. Note that in
the case of an IPv6 address, the port is always the number
after the last colon (':'). A range can either be :
- a numerical port (ex: '80')
- a dash-delimited ports range explicitly stating the lower
and upper bounds (ex: '2000-2100') which are included in
the range.
Particular care must be taken against port ranges, because
every <address:port> couple consumes one socket (= a file
descriptor), so it's easy to consume lots of descriptors
with a simple range, and to run out of sockets. Also, each
<address:port> couple must be used only once among all
instances running on a same system. Please note that binding
to ports lower than 1024 generally require particular
privileges to start the program, which are independent of
the 'uid' parameter.
<path> is a UNIX socket path beginning with a slash ('/'). This is
alternative to the TCP listening port. HAProxy will then
receive UNIX connections on the socket located at this place.
The path must begin with a slash and by default is absolute.
It can be relative to the prefix defined by "unix-bind" in
the global section. Note that the total length of the prefix
followed by the socket path cannot exceed some system limits
for UNIX sockets, which commonly are set to 107 characters.
<param*> is a list of parameters common to all sockets declared on the
same line. These numerous parameters depend on OS and build
options and have a complete section dedicated to them. Please
refer to section 5 to for more details.
It is possible to specify a list of address:port combinations delimited by
commas. The frontend will then listen on all of these addresses. There is no
fixed limit to the number of addresses and ports which can be listened on in
a frontend, as well as there is no limit to the number of "bind" statements
in a frontend.
Example :
listen http_proxy
bind :80,:443
bind 10.0.0.1:10080,10.0.0.1:10443
bind /var/run/ssl-frontend.sock user root mode 600 accept-proxy
listen http_https_proxy
bind :80
bind :443 ssl crt /etc/haproxy/site.pem
listen http_https_proxy_explicit
bind ipv6@:80
bind ipv4@public_ssl:443 ssl crt /etc/haproxy/site.pem
bind unix@ssl-frontend.sock user root mode 600 accept-proxy
listen external_bind_app1
bind "fd@${FD_APP1}"
Note: regarding Linux's abstract namespace sockets, HAProxy uses the whole
sun_path length is used for the address length. Some other programs
such as socat use the string length only by default. Pass the option
",unix-tightsocklen=0" to any abstract socket definition in socat to
make it compatible with HAProxy's.
See also : "source", "option forwardfor", "unix-bind" and the PROXY protocol documentation, and section 5 about bind options.
Limit visibility of an instance to a certain set of processes numbers.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
all All process will see this instance. This is the default. It
may be used to override a default value.
odd This instance will be enabled on processes 1,3,5,...63. This
option may be combined with other numbers.
even This instance will be enabled on processes 2,4,6,...64. This
option may be combined with other numbers. Do not use it
with less than 2 processes otherwise some instances might be
missing from all processes.
process_num The instance will be enabled on this process number or range,
whose values must all be between 1 and 32 or 64 depending on
the machine's word size. Ranges can be partially defined. The
higher bound can be omitted. In such case, it is replaced by
the corresponding maximum value. If a proxy is bound to
process numbers greater than the configured global.nbproc, it
will either be forced to process #1 if a single process was
specified, or to all processes otherwise.
This keyword limits binding of certain instances to certain processes. This
is useful in order not to have too many processes listening to the same
ports. For instance, on a dual-core machine, it might make sense to set
'nbproc 2' in the global section, then distributes the listeners among 'odd'
and 'even' instances.
At the moment, it is not possible to reference more than 32 or 64 processes
using this keyword, but this should be more than enough for most setups.
Please note that 'all' really means all processes regardless of the machine's
word size, and is not limited to the first 32 or 64.
Each "bind" line may further be limited to a subset of the proxy's processes,
please consult the "process" bind keyword in section 5.1.
When a frontend has no explicit "bind-process" line, it tries to bind to all
the processes referenced by its "bind" lines. That means that frontends can
easily adapt to their listeners' processes.
If some backends are referenced by frontends bound to other processes, the
backend automatically inherits the frontend's processes.
Example :
listen app_ip1
bind 10.0.0.1:80
bind-process odd
listen app_ip2
bind 10.0.0.2:80
bind-process even
listen management
bind 10.0.0.3:80
bind-process 1 2 3 4
listen management
bind 10.0.0.4:80
bind-process 1-4
Capture and log a cookie in the request and in the response.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | yes | yes | no |
Arguments :
<name> is the beginning of the name of the cookie to capture. In order
to match the exact name, simply suffix the name with an equal
sign ('='). The full name will appear in the logs, which is
useful with application servers which adjust both the cookie name
and value (e.g. ASPSESSIONXXX).
<length> is the maximum number of characters to report in the logs, which
include the cookie name, the equal sign and the value, all in the
standard "name=value" form. The string will be truncated on the
right if it exceeds <length>.
Only the first cookie is captured. Both the "cookie" request headers and the
"set-cookie" response headers are monitored. This is particularly useful to
check for application bugs causing session crossing or stealing between
users, because generally the user's cookies can only change on a login page.
When the cookie was not presented by the client, the associated log column
will report "-". When a request does not cause a cookie to be assigned by the
server, a "-" is reported in the response column.
The capture is performed in the frontend only because it is necessary that
the log format does not change for a given frontend depending on the
backends. This may change in the future. Note that there can be only one
"capture cookie" statement in a frontend. The maximum capture length is set
by the global "tune.http.cookielen" setting and defaults to 63 characters. It
is not possible to specify a capture in a "defaults" section.
Example:
capture cookie ASPSESSION len 32
Capture and log the last occurrence of the specified request header.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | yes | yes | no |
Arguments :
<name> is the name of the header to capture. The header names are not
case-sensitive, but it is a common practice to write them as they
appear in the requests, with the first letter of each word in
upper case. The header name will not appear in the logs, only the
value is reported, but the position in the logs is respected.
<length> is the maximum number of characters to extract from the value and
report in the logs. The string will be truncated on the right if
it exceeds <length>.
The complete value of the last occurrence of the header is captured. The
value will be added to the logs between braces ('{}'). If multiple headers
are captured, they will be delimited by a vertical bar ('|') and will appear
in the same order they were declared in the configuration. Non-existent
headers will be logged just as an empty string. Common uses for request
header captures include the "Host" field in virtual hosting environments, the
"Content-length" when uploads are supported, "User-agent" to quickly
differentiate between real users and robots, and "X-Forwarded-For" in proxied
environments to find where the request came from.
Note that when capturing headers such as "User-agent", some spaces may be
logged, making the log analysis more difficult. Thus be careful about what
you log if you know your log parser is not smart enough to rely on the
braces.
There is no limit to the number of captured request headers nor to their
length, though it is wise to keep them low to limit memory usage per session.
In order to keep log format consistent for a same frontend, header captures
can only be declared in a frontend. It is not possible to specify a capture
in a "defaults" section.
Example:
capture request header Host len 15
capture request header X-Forwarded-For len 15
capture request header Referer len 15
Capture and log the last occurrence of the specified response header.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | yes | yes | no |
Arguments :
<name> is the name of the header to capture. The header names are not
case-sensitive, but it is a common practice to write them as they
appear in the response, with the first letter of each word in
upper case. The header name will not appear in the logs, only the
value is reported, but the position in the logs is respected.
<length> is the maximum number of characters to extract from the value and
report in the logs. The string will be truncated on the right if
it exceeds <length>.
The complete value of the last occurrence of the header is captured. The
result will be added to the logs between braces ('{}') after the captured
request headers. If multiple headers are captured, they will be delimited by
a vertical bar ('|') and will appear in the same order they were declared in
the configuration. Non-existent headers will be logged just as an empty
string. Common uses for response header captures include the "Content-length"
header which indicates how many bytes are expected to be returned, the
"Location" header to track redirections.
There is no limit to the number of captured response headers nor to their
length, though it is wise to keep them low to limit memory usage per session.
In order to keep log format consistent for a same frontend, header captures
can only be declared in a frontend. It is not possible to specify a capture
in a "defaults" section.
Example:
capture response header Content-length len 9
capture response header Location len 15
Sets the maximum number of keepalive probes TCP should send before dropping
the connection on the client side.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments :
<count> is the maximum number of keepalive probes.
This keyword corresponds to the socket option TCP_KEEPCNT. If this keyword
is not specified, system-wide TCP parameter (tcp_keepalive_probes) is used.
The availability of this setting depends on the operating system. It is
known to work on Linux.
Sets the time the connection needs to remain idle before TCP starts sending
keepalive probes, if enabled the sending of TCP keepalive packets on the
client side.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments :
<timeout> is the time the connection needs to remain idle before TCP starts
sending keepalive probes. It is specified in seconds by default,
but can be in any other unit if the number is suffixed by the
unit, as explained at the top of this document.
This keyword corresponds to the socket option TCP_KEEPIDLE. If this keyword
is not specified, system-wide TCP parameter (tcp_keepalive_time) is used.
The availability of this setting depends on the operating system. It is
known to work on Linux.
Sets the time between individual keepalive probes on the client side.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments :
<timeout> is the time between individual keepalive probes. It is specified
in seconds by default, but can be in any other unit if the number
is suffixed by the unit, as explained at the top of this
document.
This keyword corresponds to the socket option TCP_KEEPINTVL. If this keyword
is not specified, system-wide TCP parameter (tcp_keepalive_intvl) is used.
The availability of this setting depends on the operating system. It is
known to work on Linux.
Enable HTTP compression.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
algo is followed by the list of supported compression algorithms. type is followed by the list of MIME types that will be compressed. offload makes HAProxy work as a compression offloader only (see notes).
The currently supported algorithms are :
identity this is mostly for debugging, and it was useful for developing
the compression feature. Identity does not apply any change on
data.
gzip applies gzip compression. This setting is only available when
support for zlib or libslz was built in.
deflate same as "gzip", but with deflate algorithm and zlib format.
Note that this algorithm has ambiguous support on many
browsers and no support at all from recent ones. It is
strongly recommended not to use it for anything else than
experimentation. This setting is only available when support
for zlib or libslz was built in.
raw-deflate same as "deflate" without the zlib wrapper, and used as an
alternative when the browser wants "deflate". All major
browsers understand it and despite violating the standards,
it is known to work better than "deflate", at least on MSIE
and some versions of Safari. Do not use it in conjunction
with "deflate", use either one or the other since both react
to the same Accept-Encoding token. This setting is only
available when support for zlib or libslz was built in.
Compression will be activated depending on the Accept-Encoding request
header. With identity, it does not take care of that header.
If backend servers support HTTP compression, these directives
will be no-op: HAProxy will see the compressed response and will not
compress again. If backend servers do not support HTTP compression and
there is Accept-Encoding header in request, HAProxy will compress the
matching response.
The "offload" setting makes HAProxy remove the Accept-Encoding header to
prevent backend servers from compressing responses. It is strongly
recommended not to do this because this means that all the compression work
will be done on the single point where HAProxy is located. However in some
deployment scenarios, HAProxy may be installed in front of a buggy gateway
with broken HTTP compression implementation which can't be turned off.
In that case HAProxy can be used to prevent that gateway from emitting
invalid payloads. In this case, simply removing the header in the
configuration does not work because it applies before the header is parsed,
so that prevents HAProxy from compressing. The "offload" setting should
then be used for such scenarios. Note: for now, the "offload" setting is
ignored when set in a defaults section.
Compression is disabled when:
* the request does not advertise a supported compression algorithm in the
"Accept-Encoding" header
* the response message is not HTTP/1.1 or above
* HTTP status code is not one of 200, 201, 202, or 203
* response contain neither a "Content-Length" header nor a
"Transfer-Encoding" whose last value is "chunked"
* response contains a "Content-Type" header whose first value starts with
"multipart"
* the response contains the "no-transform" value in the "Cache-control"
header
* User-Agent matches "Mozilla/4" unless it is MSIE 6 with XP SP2, or MSIE 7
and later
* The response contains a "Content-Encoding" header, indicating that the
response is already compressed (see compression offload)
* The response contains an invalid "ETag" header or multiple ETag headers
Note: The compression does not emit the Warning header.
Examples :
compression algo gzip
compression type text/html text/plain
cookie <name> [ rewrite | insert | prefix ] [ indirect ] [ nocache ]
[ postonly ] [ preserve ] [ httponly ] [ secure ]
[ domain <domain> ]* [ maxidle <idle> ] [ maxlife <life> ]
[ dynamic ] [ attr <value> ]*
Enable cookie-based persistence in a backend.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<name> is the name of the cookie which will be monitored, modified or
inserted in order to bring persistence. This cookie is sent to
the client via a "Set-Cookie" header in the response, and is
brought back by the client in a "Cookie" header in all requests.
Special care should be taken to choose a name which does not
conflict with any likely application cookie. Also, if the same
backends are subject to be used by the same clients (e.g.
HTTP/HTTPS), care should be taken to use different cookie names
between all backends if persistence between them is not desired.
rewrite This keyword indicates that the cookie will be provided by the
server and that HAProxy will have to modify its value to set the
server's identifier in it. This mode is handy when the management
of complex combinations of "Set-cookie" and "Cache-control"
headers is left to the application. The application can then
decide whether or not it is appropriate to emit a persistence
cookie. Since all responses should be monitored, this mode
doesn't work in HTTP tunnel mode. Unless the application
behavior is very complex and/or broken, it is advised not to
start with this mode for new deployments. This keyword is
incompatible with "insert" and "prefix".
insert This keyword indicates that the persistence cookie will have to
be inserted by HAProxy in server responses if the client did not
already have a cookie that would have permitted it to access this
server. When used without the "preserve" option, if the server
emits a cookie with the same name, it will be removed before
processing. For this reason, this mode can be used to upgrade
existing configurations running in the "rewrite" mode. The cookie
will only be a session cookie and will not be stored on the
client's disk. By default, unless the "indirect" option is added,
the server will see the cookies emitted by the client. Due to
caching effects, it is generally wise to add the "nocache" or
"postonly" keywords (see below). The "insert" keyword is not
compatible with "rewrite" and "prefix".
prefix This keyword indicates that instead of relying on a dedicated
cookie for the persistence, an existing one will be completed.
This may be needed in some specific environments where the client
does not support more than one single cookie and the application
already needs it. In this case, whenever the server sets a cookie
named <name>, it will be prefixed with the server's identifier
and a delimiter. The prefix will be removed from all client
requests so that the server still finds the cookie it emitted.
Since all requests and responses are subject to being modified,
this mode doesn't work with tunnel mode. The "prefix" keyword is
not compatible with "rewrite" and "insert". Note: it is highly
recommended not to use "indirect" with "prefix", otherwise server
cookie updates would not be sent to clients.
indirect When this option is specified, no cookie will be emitted to a
client which already has a valid one for the server which has
processed the request. If the server sets such a cookie itself,
it will be removed, unless the "preserve" option is also set. In
"insert" mode, this will additionally remove cookies from the
requests transmitted to the server, making the persistence
mechanism totally transparent from an application point of view.
Note: it is highly recommended not to use "indirect" with
"prefix", otherwise server cookie updates would not be sent to
clients.
nocache This option is recommended in conjunction with the insert mode
when there is a cache between the client and HAProxy, as it
ensures that a cacheable response will be tagged non-cacheable if
a cookie needs to be inserted. This is important because if all
persistence cookies are added on a cacheable home page for
instance, then all customers will then fetch the page from an
outer cache and will all share the same persistence cookie,
leading to one server receiving much more traffic than others.
See also the "insert" and "postonly" options.
postonly This option ensures that cookie insertion will only be performed
on responses to POST requests. It is an alternative to the
"nocache" option, because POST responses are not cacheable, so
this ensures that the persistence cookie will never get cached.
Since most sites do not need any sort of persistence before the
first POST which generally is a login request, this is a very
efficient method to optimize caching without risking to find a
persistence cookie in the cache.
See also the "insert" and "nocache" options.
preserve This option may only be used with "insert" and/or "indirect". It
allows the server to emit the persistence cookie itself. In this
case, if a cookie is found in the response, HAProxy will leave it
untouched. This is useful in order to end persistence after a
logout request for instance. For this, the server just has to
emit a cookie with an invalid value (e.g. empty) or with a date in
the past. By combining this mechanism with the "disable-on-404"
check option, it is possible to perform a completely graceful
shutdown because users will definitely leave the server after
they logout.
httponly This option tells HAProxy to add an "HttpOnly" cookie attribute
when a cookie is inserted. This attribute is used so that a
user agent doesn't share the cookie with non-HTTP components.
Please check RFC6265 for more information on this attribute.
secure This option tells HAProxy to add a "Secure" cookie attribute when
a cookie is inserted. This attribute is used so that a user agent
never emits this cookie over non-secure channels, which means
that a cookie learned with this flag will be presented only over
SSL/TLS connections. Please check RFC6265 for more information on
this attribute.
domain This option allows to specify the domain at which a cookie is
inserted. It requires exactly one parameter: a valid domain
name. If the domain begins with a dot, the browser is allowed to
use it for any host ending with that name. It is also possible to
specify several domain names by invoking this option multiple
times. Some browsers might have small limits on the number of
domains, so be careful when doing that. For the record, sending
10 domains to MSIE 6 or Firefox 2 works as expected.
maxidle This option allows inserted cookies to be ignored after some idle
time. It only works with insert-mode cookies. When a cookie is
sent to the client, the date this cookie was emitted is sent too.
Upon further presentations of this cookie, if the date is older
than the delay indicated by the parameter (in seconds), it will
be ignored. Otherwise, it will be refreshed if needed when the
response is sent to the client. This is particularly useful to
prevent users who never close their browsers from remaining for
too long on the same server (e.g. after a farm size change). When
this option is set and a cookie has no date, it is always
accepted, but gets refreshed in the response. This maintains the
ability for admins to access their sites. Cookies that have a
date in the future further than 24 hours are ignored. Doing so
lets admins fix timezone issues without risking kicking users off
the site.
maxlife This option allows inserted cookies to be ignored after some life
time, whether they're in use or not. It only works with insert
mode cookies. When a cookie is first sent to the client, the date
this cookie was emitted is sent too. Upon further presentations
of this cookie, if the date is older than the delay indicated by
the parameter (in seconds), it will be ignored. If the cookie in
the request has no date, it is accepted and a date will be set.
Cookies that have a date in the future further than 24 hours are
ignored. Doing so lets admins fix timezone issues without risking
kicking users off the site. Contrary to maxidle, this value is
not refreshed, only the first visit date counts. Both maxidle and
maxlife may be used at the time. This is particularly useful to
prevent users who never close their browsers from remaining for
too long on the same server (e.g. after a farm size change). This
is stronger than the maxidle method in that it forces a
redispatch after some absolute delay.
dynamic Activate dynamic cookies. When used, a session cookie is
dynamically created for each server, based on the IP and port
of the server, and a secret key, specified in the
"dynamic-cookie-key" backend directive.
The cookie will be regenerated each time the IP address change,
and is only generated for IPv4/IPv6.
attr This option tells HAProxy to add an extra attribute when a
cookie is inserted. The attribute value can contain any
characters except control ones or ";". This option may be
repeated.
There can be only one persistence cookie per HTTP backend, and it can be
declared in a defaults section. The value of the cookie will be the value
indicated after the "cookie" keyword in a "server" statement. If no cookie
is declared for a given server, the cookie is not set.
Examples :
cookie JSESSIONID prefix
cookie SRV insert indirect nocache
cookie SRV insert postonly indirect
cookie SRV insert indirect nocache maxidle 30m maxlife 8h
Declares a capture slot.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | yes | yes | no |
Arguments:
<length> is the length allowed for the capture.
This declaration is only available in the frontend or listen section, but the
reserved slot can be used in the backends. The "request" keyword allocates a
capture slot for use in the request, and "response" allocates a capture slot
for use in the response.
See also: "capture-req", "capture-res" (sample converters), "capture.req.hdr", "capture.res.hdr" (sample fetches), "http-request capture" and "http-response capture".
Change default options for a server in a backend
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments:
<param*> is a list of parameters for this server. The "default-server" keyword accepts an important number of options and has a complete section dedicated to it. Please refer to section 5 for more details.
Example :
default-server inter 1000 weight 13
Specify the backend to use when no "use_backend" rule has been matched.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments :
<backend> is the name of the backend to use.
When doing content-switching between frontend and backends using the
"use_backend" keyword, it is often useful to indicate which backend will be
used when no rule has matched. It generally is the dynamic backend which
will catch all undetermined requests.
Example :
use_backend dynamic if url_dyn
use_backend static if url_css url_img extension_img
default_backend dynamic
See also : "use_backend"
Describe a listen, frontend or backend.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | yes | yes | yes |
Arguments : string
Allows to add a sentence to describe the related object in the HAProxy HTML
stats page. The description will be printed on the right of the object name
it describes.
No need to backslash spaces in the <string> arguments.
Disable a proxy, frontend or backend.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments : none
The "disabled" keyword is used to disable an instance, mainly in order to
liberate a listening port or to temporarily disable a service. The instance
will still be created and its configuration will be checked, but it will be
created in the "stopped" state and will appear as such in the statistics. It
will not receive any traffic nor will it send any health-checks or logs. It
is possible to disable many instances at once by adding the "disabled"
keyword in a "defaults" section.
See also : "enabled"
Set a default server address
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | no | yes | yes |
Arguments :
<address> is the IPv4 address of the default server. Alternatively, a
resolvable hostname is supported, but this name will be resolved
during start-up.
<ports> is a mandatory port specification. All connections will be sent
to this port, and it is not permitted to use port offsets as is
possible with normal servers.
The "dispatch" keyword designates a default server for use when no other
server can take the connection. In the past it was used to forward non
persistent connections to an auxiliary load balancer. Due to its simple
syntax, it has also been used for simple TCP relays. It is recommended not to
use it for more clarity, and to use the "server" directive instead.
See also : "server"
Set the dynamic cookie secret key for a backend.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments : The secret key to be used.
When dynamic cookies are enabled (see the "dynamic" directive for cookie),
a dynamic cookie is created for each server (unless one is explicitly
specified on the "server" line), using a hash of the IP address of the
server, the TCP port, and the secret key.
That way, we can ensure session persistence across multiple load-balancers,
even if servers are dynamically added or removed.
Enable a proxy, frontend or backend.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments : none
The "enabled" keyword is used to explicitly enable an instance, when the
defaults has been set to "disabled". This is very rarely used.
See also : "disabled"
Return a file contents instead of errors generated by HAProxy
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
<code> is the HTTP status code. Currently, HAProxy is capable of
generating codes 200, 400, 401, 403, 404, 405, 407, 408, 410,
413, 425, 429, 500, 501, 502, 503, and 504.
<file> designates a file containing the full HTTP response. It is
recommended to follow the common practice of appending ".http" to
the filename so that people do not confuse the response with HTML
error pages, and to use absolute paths, since files are read
before any chroot is performed.
It is important to understand that this keyword is not meant to rewrite
errors returned by the server, but errors detected and returned by HAProxy.
This is why the list of supported errors is limited to a small set.
Code 200 is emitted in response to requests matching a "monitor-uri" rule.
The files are parsed when HAProxy starts and must be valid according to the
HTTP specification. They should not exceed the configured buffer size
(BUFSIZE), which generally is 16 kB, otherwise an internal error will be
returned. It is also wise not to put any reference to local contents
(e.g. images) in order to avoid loops between the client and HAProxy when all
servers are down, causing an error to be returned instead of an
image. Finally, The response cannot exceed (tune.bufsize - tune.maxrewrite)
so that "http-after-response" rules still have room to operate (see
"tune.maxrewrite").
The files are read at the same time as the configuration and kept in memory.
For this reason, the errors continue to be returned even when the process is
chrooted, and no file change is considered while the process is running. A
simple method for developing those files consists in associating them to the
403 status code and interrogating a blocked URL.
Example :
errorfile 400 /etc/haproxy/errorfiles/400badreq.http
errorfile 408 /dev/null # work around Chrome pre-connect bug
errorfile 403 /etc/haproxy/errorfiles/403forbid.http
errorfile 503 /etc/haproxy/errorfiles/503sorry.http
Import, fully or partially, the error files defined in the <name> http-errors
section.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
<name> is the name of an existing http-errors section.
<code> is a HTTP status code. Several status code may be listed.
Currently, HAProxy is capable of generating codes 200, 400, 401,
403, 404, 405, 407, 408, 410, 413, 425, 429, 500, 501, 502, 503,
and 504.
Errors defined in the http-errors section with the name <name> are imported
in the current proxy. If no status code is specified, all error files of the
http-errors section are imported. Otherwise, only error files associated to
the listed status code are imported. Those error files override the already
defined custom errors for the proxy. And they may be overridden by following
ones. Functionally, it is exactly the same as declaring all error files by
hand using "errorfile" directives.
See also : "http-error", "errorfile", "errorloc", "errorloc302" , "errorloc303" and section 3.8 about http-errors.
Example :
errorfiles generic
errorfiles site-1 403 404
Return an HTTP redirection to a URL instead of errors generated by HAProxy
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
<code> is the HTTP status code. Currently, HAProxy is capable of
generating codes 200, 400, 401, 403, 404, 405, 407, 408, 410,
413, 425, 429, 500, 501, 502, 503, and 504.
<url> it is the exact contents of the "Location" header. It may contain
either a relative URI to an error page hosted on the same site,
or an absolute URI designating an error page on another site.
Special care should be given to relative URIs to avoid redirect
loops if the URI itself may generate the same error (e.g. 500).
It is important to understand that this keyword is not meant to rewrite
errors returned by the server, but errors detected and returned by HAProxy.
This is why the list of supported errors is limited to a small set.
Code 200 is emitted in response to requests matching a "monitor-uri" rule.
Note that both keyword return the HTTP 302 status code, which tells the
client to fetch the designated URL using the same HTTP method. This can be
quite problematic in case of non-GET methods such as POST, because the URL
sent to the client might not be allowed for something other than GET. To
work around this problem, please use "errorloc303" which send the HTTP 303
status code, indicating to the client that the URL must be fetched with a GET
request.
Return an HTTP redirection to a URL instead of errors generated by HAProxy
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
<code> is the HTTP status code. Currently, HAProxy is capable of
generating codes 200, 400, 401, 403, 404, 405, 407, 408, 410,
413, 425, 429, 500, 501, 502, 503, and 504.
<url> it is the exact contents of the "Location" header. It may contain
either a relative URI to an error page hosted on the same site,
or an absolute URI designating an error page on another site.
Special care should be given to relative URIs to avoid redirect
loops if the URI itself may generate the same error (e.g. 500).
It is important to understand that this keyword is not meant to rewrite
errors returned by the server, but errors detected and returned by HAProxy.
This is why the list of supported errors is limited to a small set.
Code 200 is emitted in response to requests matching a "monitor-uri" rule.
Note that both keyword return the HTTP 303 status code, which tells the
client to fetch the designated URL using the same HTTP GET method. This
solves the usual problems associated with "errorloc" and the 302 code. It is
possible that some very old browsers designed before HTTP/1.1 do not support
it, but no such problem has been reported till now.
Declare the from email address to be used in both the envelope and header
of email alerts. This is the address that email alerts are sent from.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
<emailaddr> is the from email address to use when sending email alerts
Also requires "email-alert mailers" and "email-alert to" to be set
and if so sending email alerts is enabled for the proxy.
See also : "email-alert level", "email-alert mailers", "email-alert myhostname", "email-alert to", section 3.6 about mailers.
Declare the maximum log level of messages for which email alerts will be
sent. This acts as a filter on the sending of email alerts.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
<level> One of the 8 syslog levels:
emerg alert crit err warning notice info debug
The above syslog levels are ordered from lowest to highest.
By default level is alert
Also requires "email-alert from", "email-alert mailers" and
"email-alert to" to be set and if so sending email alerts is enabled
for the proxy.
Alerts are sent when :
* An un-paused server is marked as down and <level> is alert or lower
* A paused server is marked as down and <level> is notice or lower
* A server is marked as up or enters the drain state and <level>
is notice or lower
* "option log-health-checks" is enabled, <level> is info or lower,
and a health check status update occurs
See also : "email-alert from", "email-alert mailers", "email-alert myhostname", "email-alert to", section 3.6 about mailers.
Declare the mailers to be used when sending email alerts
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
<mailersect> is the name of the mailers section to send email alerts.
Also requires "email-alert from" and "email-alert to" to be set
and if so sending email alerts is enabled for the proxy.
See also : "email-alert from", "email-alert level", "email-alert myhostname", "email-alert to", section 3.6 about mailers.
Declare the to hostname address to be used when communicating with
mailers.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
<hostname> is the hostname to use when communicating with mailers
By default the systems hostname is used.
Also requires "email-alert from", "email-alert mailers" and
"email-alert to" to be set and if so sending email alerts is enabled
for the proxy.
See also : "email-alert from", "email-alert level", "email-alert mailers", "email-alert to", section 3.6 about mailers.
Declare both the recipient address in the envelope and to address in the
header of email alerts. This is the address that email alerts are sent to.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
<emailaddr> is the to email address to use when sending email alerts
Also requires "email-alert mailers" and "email-alert to" to be set
and if so sending email alerts is enabled for the proxy.
See also : "email-alert from", "email-alert level", "email-alert mailers", "email-alert myhostname", section 3.6 about mailers.
Declare a condition to force persistence on down servers
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | no | yes | yes |
By default, requests are not dispatched to down servers. It is possible to
force this using "option persist", but it is unconditional and redispatches
to a valid server if "option redispatch" is set. That leaves with very little
possibilities to force some requests to reach a server which is artificially
marked down for maintenance operations.
The "force-persist" statement allows one to declare various ACL-based
conditions which, when met, will cause a request to ignore the down status of
a server and still try to connect to it. That makes it possible to start a
server, still replying an error to the health checks, and run a specially
configured browser to test the service. Among the handy methods, one could
use a specific source IP address, or a specific cookie. The cookie also has
the advantage that it can easily be added/removed on the browser from a test
page. Once the service is validated, it is then possible to open the service
to the world by returning a valid response to health checks.
The forced persistence is enabled when an "if" condition is met, or unless an
"unless" condition is met. The final redispatch is always disabled when this
is used.
Add the filter <name> in the filter list attached to the proxy.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | yes | yes | yes |
Arguments :
<name> is the name of the filter. Officially supported filters are
referenced in section 9.
<param*> is a list of parameters accepted by the filter <name>. The
parsing of these parameters are the responsibility of the
filter. Please refer to the documentation of the corresponding
filter (section 9) for all details on the supported parameters.
Multiple occurrences of the filter line can be used for the same proxy. The
same filter can be referenced many times if needed.
Example:
listen
bind *:80
filter trace name BEFORE-HTTP-COMP
filter compression
filter trace name AFTER-HTTP-COMP
compression algo gzip
compression offload
server srv1 192.168.0.1:80
See also : section 9.
Specify at what backend load the servers will reach their maxconn
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<conns> is the number of connections on the backend which will make the
servers use the maximal number of connections.
When a server has a "maxconn" parameter specified, it means that its number
of concurrent connections will never go higher. Additionally, if it has a
"minconn" parameter, it indicates a dynamic limit following the backend's
load. The server will then always accept at least <minconn> connections,
never more than <maxconn>, and the limit will be on the ramp between both
values when the backend has less than <conns> concurrent connections. This
makes it possible to limit the load on the servers during normal loads, but
push it further for important loads without overloading the servers during
exceptional loads.
Since it's hard to get this value right, HAProxy automatically sets it to
10% of the sum of the maxconns of all frontends that may branch to this
backend (based on "use_backend" and "default_backend" rules). That way it's
safe to leave it unset. However, "use_backend" involving dynamic names are
not counted since there is no way to know if they could match or not.
Example :
# The servers will accept between 100 and 1000 concurrent connections each
# and the maximum of 1000 will be reached when the backend reaches 10000
# connections.
backend dynamic
fullconn 10000
server srv1 dyn1:80 minconn 100 maxconn 1000
server srv2 dyn2:80 minconn 100 maxconn 1000
Maintain a proxy operational for some time after a soft stop
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
<time> is the time (by default in milliseconds) for which the instance
will remain operational with the frontend sockets still listening
when a soft-stop is received via the SIGUSR1 signal.
This may be used to ensure that the services disappear in a certain order.
This was designed so that frontends which are dedicated to monitoring by an
external equipment fail immediately while other ones remain up for the time
needed by the equipment to detect the failure.
Note that currently, there is very little benefit in using this parameter,
and it may in fact complicate the soft-reconfiguration process more than
simplify it.
Specify the balancing factor for bounded-load consistent hashing
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | no | yes |
Arguments :
<factor> is the control for the maximum number of concurrent requests to
send to a server, expressed as a percentage of the average number
of concurrent requests across all of the active servers.
Specifying a "hash-balance-factor" for a server with "hash-type consistent"
enables an algorithm that prevents any one server from getting too many
requests at once, even if some hash buckets receive many more requests than
others. Setting <factor> to 0 (the default) disables the feature. Otherwise,
<factor> is a percentage greater than 100. For example, if <factor> is 150,
then no server will be allowed to have a load more than 1.5 times the average.
If server weights are used, they will be respected.
If the first-choice server is disqualified, the algorithm will choose another
server based on the request hash, until a server with additional capacity is
found. A higher <factor> allows more imbalance between the servers, while a
lower <factor> means that more servers will be checked on average, affecting
performance. Reasonable values are from 125 to 200.
This setting is also used by "balance random" which internally relies on the
consistent hashing mechanism.
Specify a method to use for mapping hashes to servers
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<method> is the method used to select a server from the hash computed by
the <function> :
map-based the hash table is a static array containing all alive servers.
The hashes will be very smooth, will consider weights, but
will be static in that weight changes while a server is up
will be ignored. This means that there will be no slow start.
Also, since a server is selected by its position in the array,
most mappings are changed when the server count changes. This
means that when a server goes up or down, or when a server is
added to a farm, most connections will be redistributed to
different servers. This can be inconvenient with caches for
instance.
consistent the hash table is a tree filled with many occurrences of each
server. The hash key is looked up in the tree and the closest
server is chosen. This hash is dynamic, it supports changing
weights while the servers are up, so it is compatible with the
slow start feature. It has the advantage that when a server
goes up or down, only its associations are moved. When a
server is added to the farm, only a few part of the mappings
are redistributed, making it an ideal method for caches.
However, due to its principle, the distribution will never be
very smooth and it may sometimes be necessary to adjust a
server's weight or its ID to get a more balanced distribution.
In order to get the same distribution on multiple load
balancers, it is important that all servers have the exact
same IDs. Note: consistent hash uses sdbm and avalanche if no
hash function is specified.
<function> is the hash function to be used :
sdbm this function was created initially for sdbm (a public-domain
reimplementation of ndbm) database library. It was found to do
well in scrambling bits, causing better distribution of the keys
and fewer splits. It also happens to be a good general hashing
function with good distribution, unless the total server weight
is a multiple of 64, in which case applying the avalanche
modifier may help.
djb2 this function was first proposed by Dan Bernstein many years ago
on comp.lang.c. Studies have shown that for certain workload this
function provides a better distribution than sdbm. It generally
works well with text-based inputs though it can perform extremely
poorly with numeric-only input or when the total server weight is
a multiple of 33, unless the avalanche modifier is also used.
wt6 this function was designed for HAProxy while testing other
functions in the past. It is not as smooth as the other ones, but
is much less sensible to the input data set or to the number of
servers. It can make sense as an alternative to sdbm+avalanche or
djb2+avalanche for consistent hashing or when hashing on numeric
data such as a source IP address or a visitor identifier in a URL
parameter.
crc32 this is the most common CRC32 implementation as used in Ethernet,
gzip, PNG, etc. It is slower than the other ones but may provide
a better distribution or less predictable results especially when
used on strings.
<modifier> indicates an optional method applied after hashing the key :
avalanche This directive indicates that the result from the hash
function above should not be used in its raw form but that
a 4-byte full avalanche hash must be applied first. The
purpose of this step is to mix the resulting bits from the
previous hash in order to avoid any undesired effect when
the input contains some limited values or when the number of
servers is a multiple of one of the hash's components (64
for SDBM, 33 for DJB2). Enabling avalanche tends to make the
result less predictable, but it's also not as smooth as when
using the original function. Some testing might be needed
with some workloads. This hash is one of the many proposed
by Bob Jenkins.
The default hash type is "map-based" and is recommended for most usages. The
default function is "sdbm", the selection of a function should be based on
the range of the values being hashed.
Access control for all Layer 7 responses (server, applet/service and internal
ones).
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | yes | yes | yes |
The http-after-response statement defines a set of rules which apply to layer
7 processing. The rules are evaluated in their declaration order when they
are met in a frontend, listen or backend section. Any rule may optionally be
followed by an ACL-based condition, in which case it will only be evaluated
if the condition is true. Since these rules apply on responses, the backend
rules are applied first, followed by the frontend's rules.
Unlike http-response rules, these ones are applied on all responses, the
server ones but also to all responses generated by HAProxy. These rules are
evaluated at the end of the responses analysis, before the data forwarding.
The first keyword is the rule's action. The supported actions are described
below.
There is no limit to the number of http-after-response statements per
instance.
Note: Errors emitted in early stage of the request parsing are handled by the
multiplexer at a lower level, before any http analysis. Thus no
http-after-response ruleset is evaluated on these errors.
Example:
http-after-response set-header Strict-Transport-Security "max-age=31536000"
http-after-response set-header Cache-Control "no-store,no-cache,private"
http-after-response set-header Pragma "no-cache"
This appends an HTTP header field whose name is specified in <name> and whose
value is defined by <fmt> which follows the log-format rules (see Custom Log
Format in section 8.2.4). This may be used to send a cookie to a client for
example, or to pass some internal information.
This rule is not final, so it is possible to add other similar rules.
Note that header addition is performed immediately, so one rule might reuse
the resulting header from a previous rule.
This stops the evaluation of the rules and lets the response pass the check.
No further "http-after-response" rules are evaluated.
This removes all HTTP header fields whose name is specified in <name>. <meth>
is the matching method, applied on the header name. Supported matching methods
are "str" (exact match), "beg" (prefix match), "end" (suffix match), "sub"
(substring match) and "reg" (regex match). If not specified, exact matching
method is used.
http-after-response replace-header <name> <regex-match> <replace-fmt>
[ { if | unless } <condition> ]
This works like "http-response replace-header".
Example:
http-after-response replace-header Set-Cookie (C=[^;]*);(.*) \1;ip=%bi;\2
# applied to:
Set-Cookie: C=1; expires=Tue, 14-Jun-2016 01:40:45 GMT
# outputs:
Set-Cookie: C=1;ip=192.168.1.20; expires=Tue, 14-Jun-2016 01:40:45 GMT
# assuming the backend IP is 192.168.1.20.
http-after-response replace-value <name> <regex-match> <replace-fmt>
[ { if | unless } <condition> ]
This works like "http-response replace-value".
Example:
http-after-response replace-value Cache-control ^public$ private
# applied to:
Cache-Control: max-age=3600, public
# outputs:
Cache-Control: max-age=3600, private
This does the same as "add-header" except that the header name is first
removed if it existed. This is useful when passing security information to
the server, where the header must not be manipulated by external users.
This replaces the response status code with <status> which must be an integer
between 100 and 999. Optionally, a custom reason text can be provided defined
by <str>, or the default reason for the specified code will be used as a
fallback.
Example:
# return "431 Request Header Fields Too Large"
http-response set-status 431
# return "503 Slow Down", custom reason
http-response set-status 503 reason "Slow Down"
This is used to set the contents of a variable. The variable is declared
inline.
Arguments:
<var-name> The name of the variable starts with an indication about its
scope. The scopes allowed are:
"proc" : the variable is shared with the whole process
"sess" : the variable is shared with the whole session
"txn" : the variable is shared with the transaction
(request and response)
"req" : the variable is shared only during request
processing
"res" : the variable is shared only during response
processing
This prefix is followed by a name. The separator is a '.'.
The name may only contain characters 'a-z', 'A-Z', '0-9', '.'
and '_'.
<expr> Is a standard HAProxy expression formed by a sample-fetch
followed by some converters.
<fmt> This is the value expressed using log-format rules (see Custom
Log Format in section 8.2.4).
Examples:
http-after-response set-var(sess.last_redir) res.hdr(location)
http-after-response set-var-fmt(sess.last_be_addr) %[bi]:%[bp]
This enables or disables the strict rewriting mode for following rules. It
does not affect rules declared before it and it is only applicable on rules
performing a rewrite on the responses. When the strict mode is enabled, any
rewrite failure triggers an internal error. Otherwise, such errors are
silently ignored. The purpose of the strict rewriting mode is to make some
rewrites optional while others must be performed to continue the response
processing.
By default, the strict rewriting mode is enabled. Its value is also reset
when a ruleset evaluation ends. So, for instance, if you change the mode on
the backend, the default mode is restored when HAProxy starts the frontend
rules evaluation.
This is used to unset a variable. See "http-after-response set-var" for
details about <var-name>.
Example:
http-after-response unset-var(sess.last_redir)
Defines a comment for the following the http-check rule, reported in logs if
it fails.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<string> is the comment message to add in logs if the following http-check
rule fails.
It only works for connect, send and expect rules. It is useful to make
user-friendly error reporting.
http-check connect [default] [port <expr>] [addr <ip>] [send-proxy]
[via-socks4] [ssl] [sni <sni>] [alpn <alpn>] [linger]
[proto <name>] [comment <msg>]
Opens a new connection to perform an HTTP health check
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
comment <msg> defines a message to report if the rule evaluation fails.
default Use default options of the server line to do the health
checks. The server options are used only if not redefined.
port <expr> if not set, check port or server port is used.
It tells HAProxy where to open the connection to.
<port> must be a valid TCP port source integer, from 1 to
65535 or an sample-fetch expression.
addr <ip> defines the IP address to do the health check.
send-proxy send a PROXY protocol string
via-socks4 enables outgoing health checks using upstream socks4 proxy.
ssl opens a ciphered connection
sni <sni> specifies the SNI to use to do health checks over SSL.
alpn <alpn> defines which protocols to advertise with ALPN. The protocol
list consists in a comma-delimited list of protocol names,
for instance: "h2,http/1.1". If it is not set, the server ALPN
is used.
proto <name> forces the multiplexer's protocol to use for this connection.
It must be an HTTP mux protocol and it must be usable on the
backend side. The list of available protocols is reported in
haproxy -vv.
linger cleanly close the connection instead of using a single RST.
Just like tcp-check health checks, it is possible to configure the connection
to use to perform HTTP health check. This directive should also be used to
describe a scenario involving several request/response exchanges, possibly on
different ports or with different servers.
When there are no TCP port configured on the server line neither server port
directive, then the first step of the http-check sequence must be to specify
the port with a "http-check connect".
In an http-check ruleset a 'connect' is required, it is also mandatory to start
the ruleset with a 'connect' rule. Purpose is to ensure admin know what they
do.
When a connect must start the ruleset, if may still be preceded by set-var,
unset-var or comment rules.
Examples :
# check HTTP and HTTPs services on a server.
# first open port 80 thanks to server line port directive, then
# tcp-check opens port 443, ciphered and run a request on it:
option httpchk
http-check connect
http-check send meth GET uri / ver HTTP/1.1 hdr host haproxy.1wt.eu
http-check expect status 200-399
http-check connect port 443 ssl sni haproxy.1wt.eu
http-check send meth GET uri / ver HTTP/1.1 hdr host haproxy.1wt.eu
http-check expect status 200-399
server www 10.0.0.1 check port 80
Enable a maintenance mode upon HTTP/404 response to health-checks
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments : none
When this option is set, a server which returns an HTTP code 404 will be
excluded from further load-balancing, but will still receive persistent
connections. This provides a very convenient method for Web administrators
to perform a graceful shutdown of their servers. It is also important to note
that a server which is detected as failed while it was in this mode will not
generate an alert, just a notice. If the server responds 2xx or 3xx again, it
will immediately be reinserted into the farm. The status on the stats page
reports "NOLB" for a server in this mode. It is important to note that this
option only works in conjunction with the "httpchk" option. If this option
is used with "http-check expect", then it has precedence over it so that 404
responses will still be considered as soft-stop. Note also that a stopped
server will stay stopped even if it replies 404s. This option is only
evaluated for running servers.
See also : "option httpchk" and "http-check expect".
http-check expect [min-recv <int>] [comment <msg>]
[ok-status <st>] [error-status <st>] [tout-status <st>]
[on-success <fmt>] [on-error <fmt>] [status-code <expr>]
[!] <match> <pattern>
Make HTTP health checks consider response contents or specific status codes
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
comment <msg> defines a message to report if the rule evaluation fails.
min-recv is optional and can define the minimum amount of data required to
evaluate the current expect rule. If the number of received bytes
is under this limit, the check will wait for more data. This
option can be used to resolve some ambiguous matching rules or to
avoid executing costly regex matches on content known to be still
incomplete. If an exact string is used, the minimum between the
string length and this parameter is used. This parameter is
ignored if it is set to -1. If the expect rule does not match,
the check will wait for more data. If set to 0, the evaluation
result is always conclusive.
ok-status <st> is optional and can be used to set the check status if
the expect rule is successfully evaluated and if it is
the last rule in the tcp-check ruleset. "L7OK", "L7OKC",
"L6OK" and "L4OK" are supported :
- L7OK : check passed on layer 7
- L7OKC : check conditionally passed on layer 7, set
server to NOLB state.
- L6OK : check passed on layer 6
- L4OK : check passed on layer 4
By default "L7OK" is used.
error-status <st> is optional and can be used to set the check status if
an error occurred during the expect rule evaluation.
"L7OKC", "L7RSP", "L7STS", "L6RSP" and "L4CON" are
supported :
- L7OKC : check conditionally passed on layer 7, set
server to NOLB state.
- L7RSP : layer 7 invalid response - protocol error
- L7STS : layer 7 response error, for example HTTP 5xx
- L6RSP : layer 6 invalid response - protocol error
- L4CON : layer 1-4 connection problem
By default "L7RSP" is used.
tout-status <st> is optional and can be used to set the check status if
a timeout occurred during the expect rule evaluation.
"L7TOUT", "L6TOUT", and "L4TOUT" are supported :
- L7TOUT : layer 7 (HTTP/SMTP) timeout
- L6TOUT : layer 6 (SSL) timeout
- L4TOUT : layer 1-4 timeout
By default "L7TOUT" is used.
on-success <fmt> is optional and can be used to customize the
informational message reported in logs if the expect
rule is successfully evaluated and if it is the last rule
in the tcp-check ruleset. <fmt> is a log-format string.
on-error <fmt> is optional and can be used to customize the
informational message reported in logs if an error
occurred during the expect rule evaluation. <fmt> is a
log-format string.
<match> is a keyword indicating how to look for a specific pattern in the
response. The keyword may be one of "status", "rstatus", "hdr",
"fhdr", "string", or "rstring". The keyword may be preceded by an
exclamation mark ("!") to negate the match. Spaces are allowed
between the exclamation mark and the keyword. See below for more
details on the supported keywords.
<pattern> is the pattern to look for. It may be a string, a regular
expression or a more complex pattern with several arguments. If
the string pattern contains spaces, they must be escaped with the
usual backslash ('\').
By default, "option httpchk" considers that response statuses 2xx and 3xx
are valid, and that others are invalid. When "http-check expect" is used,
it defines what is considered valid or invalid. Only one "http-check"
statement is supported in a backend. If a server fails to respond or times
out, the check obviously fails. The available matches are :
status <codes> : test the status codes found parsing <codes> string. it
must be a comma-separated list of status codes or range
codes. A health check response will be considered as
valid if the response's status code matches any status
code or is inside any range of the list. If the "status"
keyword is prefixed with "!", then the response will be
considered invalid if the status code matches.
rstatus <regex> : test a regular expression for the HTTP status code.
A health check response will be considered valid if the
response's status code matches the expression. If the
"rstatus" keyword is prefixed with "!", then the response
will be considered invalid if the status code matches.
This is mostly used to check for multiple codes.
hdr { name | name-lf } [ -m <meth> ] <name>
[ { value | value-lf } [ -m <meth> ] <value> :
test the specified header pattern on the HTTP response
headers. The name pattern is mandatory but the value
pattern is optional. If not specified, only the header
presence is verified. <meth> is the matching method,
applied on the header name or the header value. Supported
matching methods are "str" (exact match), "beg" (prefix
match), "end" (suffix match), "sub" (substring match) or
"reg" (regex match). If not specified, exact matching
method is used. If the "name-lf" parameter is used,
<name> is evaluated as a log-format string. If "value-lf"
parameter is used, <value> is evaluated as a log-format
string. These parameters cannot be used with the regex
matching method. Finally, the header value is considered
as comma-separated list. Note that matchings are case
insensitive on the header names.
fhdr { name | name-lf } [ -m <meth> ] <name>
[ { value | value-lf } [ -m <meth> ] <value> :
test the specified full header pattern on the HTTP
response headers. It does exactly the same than "hdr"
keyword, except the full header value is tested, commas
are not considered as delimiters.
string <string> : test the exact string match in the HTTP response body.
A health check response will be considered valid if the
response's body contains this exact string. If the
"string" keyword is prefixed with "!", then the response
will be considered invalid if the body contains this
string. This can be used to look for a mandatory word at
the end of a dynamic page, or to detect a failure when a
specific error appears on the check page (e.g. a stack
trace).
rstring <regex> : test a regular expression on the HTTP response body.
A health check response will be considered valid if the
response's body matches this expression. If the "rstring"
keyword is prefixed with "!", then the response will be
considered invalid if the body matches the expression.
This can be used to look for a mandatory word at the end
of a dynamic page, or to detect a failure when a specific
error appears on the check page (e.g. a stack trace).
string-lf <fmt> : test a log-format string match in the HTTP response body.
A health check response will be considered valid if the
response's body contains the string resulting of the
evaluation of <fmt>, which follows the log-format rules.
If prefixed with "!", then the response will be
considered invalid if the body contains the string.
It is important to note that the responses will be limited to a certain size
defined by the global "tune.bufsize" option, which defaults to 16384 bytes.
Thus, too large responses may not contain the mandatory pattern when using
"string" or "rstring". If a large response is absolutely required, it is
possible to change the default max size by setting the global variable.
However, it is worth keeping in mind that parsing very large responses can
waste some CPU cycles, especially when regular expressions are used, and that
it is always better to focus the checks on smaller resources.
In an http-check ruleset, the last expect rule may be implicit. If no expect
rule is specified after the last "http-check send", an implicit expect rule
is defined to match on 2xx or 3xx status codes. It means this rule is also
defined if there is no "http-check" rule at all, when only "option httpchk"
is set.
Last, if "http-check expect" is combined with "http-check disable-on-404",
then this last one has precedence when the server responds with 404.
Examples :
# only accept status 200 as valid
http-check expect status 200,201,300-310
# be sure a sessid coookie is set
http-check expect header name "set-cookie" value -m beg "sessid="
# consider SQL errors as errors
http-check expect ! string SQL\ Error
# consider status 5xx only as errors
http-check expect ! rstatus ^5
# check that we have a correct hexadecimal tag before /html
http-check expect rstring <!--tag:[0-9a-f]*--></html>
See also : "option httpchk", "http-check connect", "http-check disable-on-404" and "http-check send".
http-check send [meth <method>] [{ uri <uri> | uri-lf <fmt> }>] [ver <version>]
[hdr <name> <fmt>]* [{ body <string> | body-lf <fmt> }]
[comment <msg>]
Add a possible list of headers and/or a body to the request sent during HTTP
health checks.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
comment <msg> defines a message to report if the rule evaluation fails.
meth <method> is the optional HTTP method used with the requests. When not
set, the "OPTIONS" method is used, as it generally requires
low server processing and is easy to filter out from the
logs. Any method may be used, though it is not recommended
to invent non-standard ones.
uri <uri> is optional and set the URI referenced in the HTTP requests
to the string <uri>. It defaults to "/" which is accessible
by default on almost any server, but may be changed to any
other URI. Query strings are permitted.
uri-lf <fmt> is optional and set the URI referenced in the HTTP requests
using the log-format string <fmt>. It defaults to "/" which
is accessible by default on almost any server, but may be
changed to any other URI. Query strings are permitted.
ver <version> is the optional HTTP version string. It defaults to
"HTTP/1.0" but some servers might behave incorrectly in HTTP
1.0, so turning it to HTTP/1.1 may sometimes help. Note that
the Host field is mandatory in HTTP/1.1, use "hdr" argument
to add it.
hdr <name> <fmt> adds the HTTP header field whose name is specified in
<name> and whose value is defined by <fmt>, which follows
to the log-format rules.
body <string> add the body defined by <string> to the request sent during
HTTP health checks. If defined, the "Content-Length" header
is thus automatically added to the request.
body-lf <fmt> add the body defined by the log-format string <fmt> to the
request sent during HTTP health checks. If defined, the
"Content-Length" header is thus automatically added to the
request.
In addition to the request line defined by the "option httpchk" directive,
this one is the valid way to add some headers and optionally a body to the
request sent during HTTP health checks. If a body is defined, the associate
"Content-Length" header is automatically added. Thus, this header or
"Transfer-encoding" header should not be present in the request provided by
"http-check send". If so, it will be ignored. The old trick consisting to add
headers after the version string on the "option httpchk" line is now
deprecated.
Also "http-check send" doesn't support HTTP keep-alive. Keep in mind that it
will automatically append a "Connection: close" header, unless a Connection
header has already already been configured via a hdr entry.
Note that the Host header and the request authority, when both defined, are
automatically synchronized. It means when the HTTP request is sent, when a
Host is inserted in the request, the request authority is accordingly
updated. Thus, don't be surprised if the Host header value overwrites the
configured request authority.
Note also for now, no Host header is automatically added in HTTP/1.1 or above
requests. You should add it explicitly.
Enable emission of a state header with HTTP health checks
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments : none
When this option is set, HAProxy will systematically send a special header
"X-Haproxy-Server-State" with a list of parameters indicating to each server
how they are seen by HAProxy. This can be used for instance when a server is
manipulated without access to HAProxy and the operator needs to know whether
HAProxy still sees it up or not, or if the server is the last one in a farm.
The header is composed of fields delimited by semi-colons, the first of which
is a word ("UP", "DOWN", "NOLB"), possibly followed by a number of valid
checks on the total number before transition, just as appears in the stats
interface. Next headers are in the form "<variable>=<value>", indicating in
no specific order some values available in the stats interface :
- a variable "address", containing the address of the backend server.
This corresponds to the <address> field in the server declaration. For
unix domain sockets, it will read "unix".
- a variable "port", containing the port of the backend server. This
corresponds to the <port> field in the server declaration. For unix
domain sockets, it will read "unix".
- a variable "name", containing the name of the backend followed by a slash
("/") then the name of the server. This can be used when a server is
checked in multiple backends.
- a variable "node" containing the name of the HAProxy node, as set in the
global "node" variable, otherwise the system's hostname if unspecified.
- a variable "weight" indicating the weight of the server, a slash ("/")
and the total weight of the farm (just counting usable servers). This
helps to know if other servers are available to handle the load when this
one fails.
- a variable "scur" indicating the current number of concurrent connections
on the server, followed by a slash ("/") then the total number of
connections on all servers of the same backend.
- a variable "qcur" indicating the current number of requests in the
server's queue.
Example of a header received by the application server :
>>> X-Haproxy-Server-State: UP 2/3; name=bck/srv2; node=lb1; weight=1/2; \
scur=13/22; qcur=0
This operation sets the content of a variable. The variable is declared inline.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<var-name> The name of the variable starts with an indication about its
scope. The scopes allowed for http-check are:
"proc" : the variable is shared with the whole process.
"sess" : the variable is shared with the tcp-check session.
"check": the variable is declared for the lifetime of the tcp-check.
This prefix is followed by a name. The separator is a '.'.
The name may only contain characters 'a-z', 'A-Z', '0-9', '.',
and '-'.
<expr> Is a sample-fetch expression potentially followed by converters.
<fmt> This is the value expressed using log-format rules (see Custom
Log Format in section 8.2.4).
Examples :
http-check set-var(check.port) int(1234)
http-check set-var-fmt(check.port) "name=%H"
Free a reference to a variable within its scope.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<var-name> The name of the variable starts with an indication about its
scope. The scopes allowed for http-check are:
"proc" : the variable is shared with the whole process.
"sess" : the variable is shared with the tcp-check session.
"check": the variable is declared for the lifetime of the tcp-check.
This prefix is followed by a name. The separator is a '.'.
The name may only contain characters 'a-z', 'A-Z', '0-9', '.',
and '-'.
Examples :
http-check unset-var(check.port)
http-error status <code> [content-type <type>]
[ { default-errorfiles | errorfile <file> | errorfiles <name> |
file <file> | lf-file <file> | string <str> | lf-string <fmt> } ]
[ hdr <name> <fmt> ]*
Defines a custom error message to use instead of errors generated by HAProxy.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
status <code> is the HTTP status code. It must be specified.
Currently, HAProxy is capable of generating codes
200, 400, 401, 403, 404, 405, 407, 408, 410, 413, 425,
429, 500, 501, 502, 503, and 504.
content-type <type> is the response content type, for instance
"text/plain". This parameter is ignored and should be
omitted when an errorfile is configured or when the
payload is empty. Otherwise, it must be defined.
default-errorfiles Reset the previously defined error message for current
proxy for the status <code>. If used on a backend, the
frontend error message is used, if defined. If used on
a frontend, the default error message is used.
errorfile <file> designates a file containing the full HTTP response.
It is recommended to follow the common practice of
appending ".http" to the filename so that people do
not confuse the response with HTML error pages, and to
use absolute paths, since files are read before any
chroot is performed.
errorfiles <name> designates the http-errors section to use to import
the error message with the status code <code>. If no
such message is found, the proxy's error messages are
considered.
file <file> specifies the file to use as response payload. If the
file is not empty, its content-type must be set as
argument to "content-type", otherwise, any
"content-type" argument is ignored. <file> is
considered as a raw string.
string <str> specifies the raw string to use as response payload.
The content-type must always be set as argument to
"content-type".
lf-file <file> specifies the file to use as response payload. If the
file is not empty, its content-type must be set as
argument to "content-type", otherwise, any
"content-type" argument is ignored. <file> is
evaluated as a log-format string.
lf-string <str> specifies the log-format string to use as response
payload. The content-type must always be set as
argument to "content-type".
hdr <name> <fmt> adds to the response the HTTP header field whose name
is specified in <name> and whose value is defined by
<fmt>, which follows to the log-format rules.
This parameter is ignored if an errorfile is used.
This directive may be used instead of "errorfile", to define a custom error
message. As "errorfile" directive, it is used for errors detected and
returned by HAProxy. If an errorfile is defined, it is parsed when HAProxy
starts and must be valid according to the HTTP standards. The generated
response must not exceed the configured buffer size (BUFFSIZE), otherwise an
internal error will be returned. Finally, if you consider to use some
http-after-response rules to rewrite these errors, the reserved buffer space
should be available (see "tune.maxrewrite").
The files are read at the same time as the configuration and kept in memory.
For this reason, the errors continue to be returned even when the process is
chrooted, and no file change is considered while the process is running.
Note: 400/408/500 errors emitted in early stage of the request parsing are
handled by the multiplexer at a lower level. No custom formatting is
supported at this level. Thus only static error messages, defined with
"errorfile" directive, are supported. However, this limitation only
exists during the request headers parsing or between two transactions.
See also : "errorfile", "errorfiles", "errorloc", "errorloc302", "errorloc303" and section 3.8 about http-errors.
Access control for Layer 7 requests
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | yes | yes | yes |
The http-request statement defines a set of rules which apply to layer 7
processing. The rules are evaluated in their declaration order when they are
met in a frontend, listen or backend section. Any rule may optionally be
followed by an ACL-based condition, in which case it will only be evaluated
if the condition is true.
The first keyword is the rule's action. The supported actions are described
below.
There is no limit to the number of http-request statements per instance.
Example:
acl nagios src 192.168.129.3
acl local_net src 192.168.0.0/16
acl auth_ok http_auth(L1)
http-request allow if nagios
http-request allow if local_net auth_ok
http-request auth realm Gimme if local_net auth_ok
http-request deny
Example:
acl key req.hdr(X-Add-Acl-Key) -m found
acl add path /addacl
acl del path /delacl
acl myhost hdr(Host) -f myhost.lst
http-request add-acl(myhost.lst) %[req.hdr(X-Add-Acl-Key)] if key add
http-request del-acl(myhost.lst) %[req.hdr(X-Add-Acl-Key)] if key del
Example:
acl value req.hdr(X-Value) -m found
acl setmap path /setmap
acl delmap path /delmap
use_backend bk_appli if { hdr(Host),map_str(map.lst) -m found }
http-request set-map(map.lst) %[src] %[req.hdr(X-Value)] if setmap value
http-request del-map(map.lst) %[src] if delmap
This is used to add a new entry into an ACL. The ACL must be loaded from a
file (even a dummy empty file). The file name of the ACL to be updated is
passed between parentheses. It takes one argument: <key fmt>, which follows
log-format rules, to collect content of the new entry. It performs a lookup
in the ACL before insertion, to avoid duplicated (or more) values. This
lookup is done by a linear search and can be expensive with large lists!
It is the equivalent of the "add acl" command from the stats socket, but can
be triggered by an HTTP request.
This appends an HTTP header field whose name is specified in <name> and
whose value is defined by <fmt> which follows the log-format rules (see
Custom Log Format in section 8.2.4). This is particularly useful to pass
connection-specific information to the server (e.g. the client's SSL
certificate), or to combine several headers into one. This rule is not
final, so it is possible to add other similar rules. Note that header
addition is performed immediately, so one rule might reuse the resulting
header from a previous rule.
This stops the evaluation of the rules and lets the request pass the check.
No further "http-request" rules are evaluated.
This stops the evaluation of the rules and immediately responds with an
HTTP 401 or 407 error code to invite the user to present a valid user name
and password. No further "http-request" rules are evaluated. An optional
"realm" parameter is supported, it sets the authentication realm that is
returned with the response (typically the application's name).
The corresponding proxy's error message is used. It may be customized using
an "errorfile" or an "http-error" directive. For 401 responses, all
occurrences of the WWW-Authenticate header are removed and replaced by a new
one with a basic authentication challenge for realm "<realm>". For 407
responses, the same is done on the Proxy-Authenticate header. If the error
message must not be altered, consider to use "http-request return" rule
instead.
Example:
acl auth_ok http_auth_group(L1) G1
http-request auth unless auth_ok
See section 6.2 about cache setup.
This captures sample expression <sample> from the request buffer, and
converts it to a string of at most <len> characters. The resulting string is
stored into the next request "capture" slot, so it will possibly appear next
to some captured HTTP headers. It will then automatically appear in the logs,
and it will be possible to extract it using sample fetch rules to feed it
into headers or anything. The length should be limited given that this size
will be allocated for each capture during the whole session life.
Please check section 7.3 (Fetching samples) and "capture request header" for
more information.
If the keyword "id" is used instead of "len", the action tries to store the
captured string in a previously declared capture slot. This is useful to run
captures in backends. The slot id can be declared by a previous directive
"http-request capture" or with the "declare capture" keyword.
When using this action in a backend, double check that the relevant
frontend(s) have the required capture slots otherwise, this rule will be
ignored at run time. This can't be detected at configuration parsing time
due to HAProxy's ability to dynamically resolve backend name at runtime.
This is used to delete an entry from an ACL. The ACL must be loaded from a
file (even a dummy empty file). The file name of the ACL to be updated is
passed between parentheses. It takes one argument: <key fmt>, which follows
log-format rules, to collect content of the entry to delete.
It is the equivalent of the "del acl" command from the stats socket, but can
be triggered by an HTTP request.
This removes all HTTP header fields whose name is specified in <name>. <meth>
is the matching method, applied on the header name. Supported matching methods
are "str" (exact match), "beg" (prefix match), "end" (suffix match), "sub"
(substring match) and "reg" (regex match). If not specified, exact matching
method is used.
This is used to delete an entry from a MAP. The MAP must be loaded from a
file (even a dummy empty file). The file name of the MAP to be updated is
passed between parentheses. It takes one argument: <key fmt>, which follows
log-format rules, to collect content of the entry to delete.
It takes one argument: "file name" It is the equivalent of the "del map"
command from the stats socket, but can be triggered by an HTTP request.
http-request deny [ { status | deny_status } <code>] [content-type <type>]
[ { default-errorfiles | errorfile <file> | errorfiles <name> |
file <file> | lf-file <file> | string <str> | lf-string <fmt> } ]
[ hdr <name> <fmt> ]*
[ { if | unless } <condition> ]
This stops the evaluation of the rules and immediately rejects the request.
By default an HTTP 403 error is returned. But the response may be customized
using same syntax than "http-request return" rules. Thus, see "http-request
return" for details. For compatibility purpose, when no argument is defined,
or only "deny_status", the argument "default-errorfiles" is implied. It means
"http-request deny [deny_status <status>]" is an alias of
"http-request deny [status <status>] default-errorfiles".
No further "http-request" rules are evaluated.
See also "http-request return".
This disables any attempt to retry the request if it fails for any other
reason than a connection failure. This can be useful for example to make
sure POST requests aren't retried on failure.
This action performs a DNS resolution of the output of <expr> and stores
the result in the variable <var>. It uses the DNS resolvers section
pointed by <resolvers>.
It is possible to choose a resolution preference using the optional
arguments 'ipv4' or 'ipv6'.
When performing the DNS resolution, the client side connection is on
pause waiting till the end of the resolution.
If an IP address can be found, it is stored into <var>. If any kind of
error occurs, then <var> is not set.
One can use this action to discover a server IP address at run time and
based on information found in the request (IE a Host header).
If this action is used to find the server's IP address (using the
"set-dst" action), then the server IP address in the backend must be set
to 0.0.0.0. The do-resolve action takes an host-only parameter, any port must
be removed from the string.
Example:
resolvers mydns
nameserver local 127.0.0.53:53
nameserver google 8.8.8.8:53
timeout retry 1s
hold valid 10s
hold nx 3s
hold other 3s
hold obsolete 0s
accepted_payload_size 8192
frontend fe
bind 10.42.0.1:80
http-request do-resolve(txn.myip,mydns,ipv4) hdr(Host),lower,regsub(:[0-9]*$,)
http-request capture var(txn.myip) len 40
# return 503 when the variable is not set,
# which mean DNS resolution error
use_backend b_503 unless { var(txn.myip) -m found }
default_backend be
backend b_503
# dummy backend used to return 503.
# one can use the errorfile directive to send a nice
# 503 error page to end users
backend be
# rule to prevent HAProxy from reconnecting to services
# on the local network (forged DNS name used to scan the network)
http-request deny if { var(txn.myip) -m ip 127.0.0.0/8 10.0.0.0/8 }
http-request set-dst var(txn.myip)
server clear 0.0.0.0:0
NOTE: Don't forget to set the "protection" rules to ensure HAProxy won't
be used to scan the network or worst won't loop over itself...
This is used to build an HTTP 103 Early Hints response prior to any other one.
This appends an HTTP header field to this response whose name is specified in
<name> and whose value is defined by <fmt> which follows the log-format rules
(see Custom Log Format in section 8.2.4). This is particularly useful to pass
to the client some Link headers to preload resources required to render the
HTML documents.
See RFC 8297 for more information.
Performs normalization of the request's URI.
URI normalization in HAProxy 2.4 is currently available as an experimental
technical preview. As such, it requires the global directive
'expose-experimental-directives' first to be able to invoke it. You should be
prepared that the behavior of normalizers might change to fix possible
issues, possibly breaking proper request processing in your infrastructure.
Each normalizer handles a single type of normalization to allow for a
fine-grained selection of the level of normalization that is appropriate for
the supported backend.
As an example the "path-strip-dotdot" normalizer might be useful for a static
fileserver that directly maps the requested URI to the path within the local
filesystem. However it might break routing of an API that expects a specific
number of segments in the path.
It is important to note that some normalizers might result in unsafe
transformations for broken URIs. It might also be possible that a combination
of normalizers that are safe by themselves results in unsafe transformations
when improperly combined.
As an example the "percent-decode-unreserved" normalizer might result in
unexpected results when a broken URI includes bare percent characters. One
such a broken URI is "/%%36%36" which would be decoded to "/%66" which in
turn is equivalent to "/f". By specifying the "strict" option requests to
such a broken URI would safely be rejected.
The following normalizers are available:
- fragment-encode: Encodes "#" as "%23".
The "fragment-strip" normalizer should be preferred, unless it is known
that broken clients do not correctly encode '#' within the path component.
Example:
- /#foo -> /%23foo
- fragment-strip: Removes the URI's "fragment" component.
According to RFC 3986#3.5 the "fragment" component of an URI should not
be sent, but handled by the User Agent after retrieving a resource.
This normalizer should be applied first to ensure that the fragment is
not interpreted as part of the request's path component.
Example:
- /#foo -> /
- path-strip-dot: Removes "/./" segments within the "path" component
(RFC 3986#6.2.2.3).
Segments including percent encoded dots ("%2E") will not be detected. Use
the "percent-decode-unreserved" normalizer first if this is undesired.
Example:
- /. -> /
- /./bar/ -> /bar/
- /a/./a -> /a/a
- /.well-known/ -> /.well-known/ (no change)
- path-strip-dotdot: Normalizes "/../" segments within the "path" component
(RFC 3986#6.2.2.3).
This merges segments that attempt to access the parent directory with
their preceding segment.
Empty segments do not receive special treatment. Use the "merge-slashes"
normalizer first if this is undesired.
Segments including percent encoded dots ("%2E") will not be detected. Use
the "percent-decode-unreserved" normalizer first if this is undesired.
Example:
- /foo/../ -> /
- /foo/../bar/ -> /bar/
- /foo/bar/../ -> /foo/
- /../bar/ -> /../bar/
- /bar/../../ -> /../
- /foo//../ -> /foo/
- /foo/%2E%2E/ -> /foo/%2E%2E/
If the "full" option is specified then "../" at the beginning will be
removed as well:
Example:
- /../bar/ -> /bar/
- /bar/../../ -> /
- path-merge-slashes: Merges adjacent slashes within the "path" component
into a single slash.
Example:
- // -> /
- /foo//bar -> /foo/bar
- percent-decode-unreserved: Decodes unreserved percent encoded characters to
their representation as a regular character (RFC 3986#6.2.2.2).
The set of unreserved characters includes all letters, all digits, "-",
".", "_", and "~".
Example:
- /%61dmin -> /admin
- /foo%3Fbar=baz -> /foo%3Fbar=baz (no change)
- /%%36%36 -> /%66 (unsafe)
- /%ZZ -> /%ZZ
If the "strict" option is specified then invalid sequences will result
in a HTTP 400 Bad Request being returned.
Example:
- /%%36%36 -> HTTP 400
- /%ZZ -> HTTP 400
- percent-to-uppercase: Uppercases letters within percent-encoded sequences
(RFC 3986#6.2.2.1).
Example:
- /%6f -> /%6F
- /%zz -> /%zz
If the "strict" option is specified then invalid sequences will result
in a HTTP 400 Bad Request being returned.
Example:
- /%zz -> HTTP 400
- query-sort-by-name: Sorts the query string parameters by parameter name.
Parameters are assumed to be delimited by '&'. Shorter names sort before
longer names and identical parameter names maintain their relative order.
Example:
- /?c=3&a=1&b=2 -> /?a=1&b=2&c=3
- /?aaa=3&a=1&aa=2 -> /?a=1&aa=2&aaa=3
- /?a=3&b=4&a=1&b=5&a=2 -> /?a=3&a=1&a=2&b=4&b=5
This performs an HTTP redirection based on a redirect rule. This is exactly
the same as the "redirect" statement except that it inserts a redirect rule
which can be processed in the middle of other "http-request" rules and that
these rules use the "log-format" strings. See the "redirect" keyword for the
rule's syntax.
This stops the evaluation of the rules and immediately closes the connection
without sending any response. It acts similarly to the
"tcp-request content reject" rules. It can be useful to force an immediate
connection closure on HTTP/2 connections.
This matches the value of all occurrences of header field <name> against
<match-regex>. Matching is performed case-sensitively. Matching values are
completely replaced by <replace-fmt>. Format characters are allowed in
<replace-fmt> and work like <fmt> arguments in "http-request add-header".
Standard back-references using the backslash ('\') followed by a number are
supported.
This action acts on whole header lines, regardless of the number of values
they may contain. Thus it is well-suited to process headers naturally
containing commas in their value, such as If-Modified-Since. Headers that
contain a comma-separated list of values, such as Accept, should be processed
using "http-request replace-value".
Example:
http-request replace-header Cookie foo=([^;]*);(.*) foo=\1;ip=%bi;\2
# applied to:
Cookie: foo=foobar; expires=Tue, 14-Jun-2016 01:40:45 GMT;
# outputs:
Cookie: foo=foobar;ip=192.168.1.20; expires=Tue, 14-Jun-2016 01:40:45 GMT;
# assuming the backend IP is 192.168.1.20
http-request replace-header User-Agent curl foo
# applied to:
User-Agent: curl/7.47.0
# outputs:
User-Agent: foo
This works like "replace-header" except that it works on the request's path
component instead of a header. The path component starts at the first '/'
after an optional scheme+authority and ends before the question mark. Thus,
the replacement does not modify the scheme, the authority and the
query-string.
It is worth noting that regular expressions may be more expensive to evaluate
than certain ACLs, so rare replacements may benefit from a condition to avoid
performing the evaluation at all if it does not match.
Example:
# prefix /foo : turn /bar?q=1 into /foo/bar?q=1 :
http-request replace-path (.*) /foo\1
# strip /foo : turn /foo/bar?q=1 into /bar?q=1
http-request replace-path /foo/(.*) /\1
# or more efficient if only some requests match :
http-request replace-path /foo/(.*) /\1 if { url_beg /foo/ }
This does the same as "http-request replace-path" except that the path
contains the query-string if any is present. Thus, the path and the
query-string are replaced.
Example:
# suffix /foo : turn /bar?q=1 into /bar/foo?q=1 :
http-request replace-pathq ([^?]*)(\?(.*))? \1/foo\2
This works like "replace-header" except that it works on the request's URI part
instead of a header. The URI part may contain an optional scheme, authority or
query string. These are considered to be part of the value that is matched
against.
It is worth noting that regular expressions may be more expensive to evaluate
than certain ACLs, so rare replacements may benefit from a condition to avoid
performing the evaluation at all if it does not match.
IMPORTANT NOTE: historically in HTTP/1.x, the vast majority of requests sent
by browsers use the "origin form", which differs from the "absolute form" in
that they do not contain a scheme nor authority in the URI portion. Mostly
only requests sent to proxies, those forged by hand and some emitted by
certain applications use the absolute form. As such, "replace-uri" usually
works fine most of the time in HTTP/1.x with rules starting with a "/". But
with HTTP/2, clients are encouraged to send absolute URIs only, which look
like the ones HTTP/1 clients use to talk to proxies. Such partial replace-uri
rules may then fail in HTTP/2 when they work in HTTP/1. Either the rules need
to be adapted to optionally match a scheme and authority, or replace-path
should be used.
Example:
# rewrite all "http" absolute requests to "https":
http-request replace-uri ^http://(.*) https://\1
# prefix /foo : turn /bar?q=1 into /foo/bar?q=1 :
http-request replace-uri ([^/:]*://[^/]*)?(.*) \1/foo\2
This works like "replace-header" except that it matches the regex against
every comma-delimited value of the header field <name> instead of the
entire header. This is suited for all headers which are allowed to carry
more than one value. An example could be the Accept header.
Example:
http-request replace-value X-Forwarded-For ^192\.168\.(.*)$ 172.16.\1
# applied to:
X-Forwarded-For: 192.168.10.1, 192.168.13.24, 10.0.0.37
# outputs:
X-Forwarded-For: 172.16.10.1, 172.16.13.24, 10.0.0.37
http-request return [status <code>] [content-type <type>]
[ { default-errorfiles | errorfile <file> | errorfiles <name> |
file <file> | lf-file <file> | string <str> | lf-string <fmt> } ]
[ hdr <name> <fmt> ]*
[ { if | unless } <condition> ]
This stops the evaluation of the rules and immediately returns a response. The
default status code used for the response is 200. It can be optionally
specified as an arguments to "status". The response content-type may also be
specified as an argument to "content-type". Finally the response itself may
be defined. It can be a full HTTP response specifying the errorfile to use,
or the response payload specifying the file or the string to use. These rules
are followed to create the response :
* If neither the errorfile nor the payload to use is defined, a dummy
response is returned. Only the "status" argument is considered. It can be
any code in the range [200, 599]. The "content-type" argument, if any, is
ignored.
* If "default-errorfiles" argument is set, the proxy's errorfiles are
considered. If the "status" argument is defined, it must be one of the
status code handled by HAProxy (200, 400, 403, 404, 405, 408, 410, 413,
425, 429, 500, 501, 502, 503, and 504). The "content-type" argument, if
any, is ignored.
* If a specific errorfile is defined, with an "errorfile" argument, the
corresponding file, containing a full HTTP response, is returned. Only the
"status" argument is considered. It must be one of the status code handled
by HAProxy (200, 400, 403, 404, 405, 408, 410, 413, 425, 429, 500, 501,
502, 503, and 504). The "content-type" argument, if any, is ignored.
* If an http-errors section is defined, with an "errorfiles" argument, the
corresponding file in the specified http-errors section, containing a full
HTTP response, is returned. Only the "status" argument is considered. It
must be one of the status code handled by HAProxy (200, 400, 403, 404, 405,
408, 410, 413, 425, 429, 500, 501, 502, 503, and 504). The "content-type"
argument, if any, is ignored.
* If a "file" or a "lf-file" argument is specified, the file's content is
used as the response payload. If the file is not empty, its content-type
must be set as argument to "content-type". Otherwise, any "content-type"
argument is ignored. With a "lf-file" argument, the file's content is
evaluated as a log-format string. With a "file" argument, it is considered
as a raw content.
* If a "string" or "lf-string" argument is specified, the defined string is
used as the response payload. The content-type must always be set as
argument to "content-type". With a "lf-string" argument, the string is
evaluated as a log-format string. With a "string" argument, it is
considered as a raw string.
When the response is not based on an errorfile, it is possible to append HTTP
header fields to the response using "hdr" arguments. Otherwise, all "hdr"
arguments are ignored. For each one, the header name is specified in <name>
and its value is defined by <fmt> which follows the log-format rules.
Note that the generated response must be smaller than a buffer. And to avoid
any warning, when an errorfile or a raw file is loaded, the buffer space
reserved for the headers rewriting should also be free.
No further "http-request" rules are evaluated.
Example:
http-request return errorfile /etc/haproxy/errorfiles/200.http \
if { path /ping }
http-request return content-type image/x-icon file /var/www/favicon.ico \
if { path /favicon.ico }
http-request return status 403 content-type text/plain \
lf-string "Access denied. IP %[src] is blacklisted." \
if { src -f /etc/haproxy/blacklist.lst }
This actions increments the GPC0 or GPC1 counter according with the sticky
counter designated by <sc-id>. If an error occurs, this action silently fails
and the actions evaluation continues.
This action sets the 32-bit unsigned GPT0 tag according to the sticky counter
designated by <sc-id> and the value of <int>/<expr>. The expected result is a
boolean. If an error occurs, this action silently fails and the actions
evaluation continues.
This is used to set the destination IP address to the value of specified
expression. Useful when a proxy in front of HAProxy rewrites destination IP,
but provides the correct IP in a HTTP header; or you want to mask the IP for
privacy. If you want to connect to the new address/port, use '0.0.0.0:0' as a
server address in the backend.
Arguments:
<expr> Is a standard HAProxy expression formed by a sample-fetch followed
by some converters.
Example:
http-request set-dst hdr(x-dst)
http-request set-dst dst,ipmask(24)
When possible, set-dst preserves the original destination port as long as the
address family allows it, otherwise the destination port is set to 0.
This is used to set the destination port address to the value of specified
expression. If you want to connect to the new address/port, use '0.0.0.0:0'
as a server address in the backend.
Arguments:
<expr> Is a standard HAProxy expression formed by a sample-fetch
followed by some converters.
Example:
http-request set-dst-port hdr(x-port)
http-request set-dst-port int(4000)
When possible, set-dst-port preserves the original destination address as
long as the address family supports a port, otherwise it forces the
destination address to IPv4 "0.0.0.0" before rewriting the port.
This does the same as "http-request add-header" except that the header name
is first removed if it existed. This is useful when passing security
information to the server, where the header must not be manipulated by
external users. Note that the new value is computed before the removal so it
is possible to concatenate a value to an existing header.
Example:
http-request set-header X-Haproxy-Current-Date %T
http-request set-header X-SSL %[ssl_fc]
http-request set-header X-SSL-Session_ID %[ssl_fc_session_id,hex]
http-request set-header X-SSL-Client-Verify %[ssl_c_verify]
http-request set-header X-SSL-Client-DN %{+Q}[ssl_c_s_dn]
http-request set-header X-SSL-Client-CN %{+Q}[ssl_c_s_dn(cn)]
http-request set-header X-SSL-Issuer %{+Q}[ssl_c_i_dn]
http-request set-header X-SSL-Client-NotBefore %{+Q}[ssl_c_notbefore]
http-request set-header X-SSL-Client-NotAfter %{+Q}[ssl_c_notafter]
This is used to change the log level of the current request when a certain
condition is met. Valid levels are the 8 syslog levels (see the "log"
keyword) plus the special level "silent" which disables logging for this
request. This rule is not final so the last matching rule wins. This rule
can be useful to disable health checks coming from another equipment.
This is used to add a new entry into a MAP. The MAP must be loaded from a
file (even a dummy empty file). The file name of the MAP to be updated is
passed between parentheses. It takes 2 arguments: <key fmt>, which follows
log-format rules, used to collect MAP key, and <value fmt>, which follows
log-format rules, used to collect content for the new entry.
It performs a lookup in the MAP before insertion, to avoid duplicated (or
more) values. This lookup is done by a linear search and can be expensive
with large lists! It is the equivalent of the "set map" command from the
stats socket, but can be triggered by an HTTP request.
This is used to set the Netfilter/IPFW MARK on all packets sent to the client
to the value passed in <mark> on platforms which support it. This value is an
unsigned 32 bit value which can be matched by netfilter/ipfw and by the
routing table or monitoring the packets through DTrace. It can be expressed
both in decimal or hexadecimal format (prefixed by "0x").
This can be useful to force certain packets to take a different route (for
example a cheaper network path for bulk downloads). This works on Linux
kernels 2.6.32 and above and requires admin privileges, as well on FreeBSD.
This rewrites the request method with the result of the evaluation of format
string <fmt>. There should be very few valid reasons for having to do so as
this is more likely to break something than to fix it.
This sets the "nice" factor of the current request being processed. It only
has effect against the other requests being processed at the same time.
The default value is 0, unless altered by the "nice" setting on the "bind"
line. The accepted range is -1024..1024. The higher the value, the nicest
the request will be. Lower values will make the request more important than
other ones. This can be useful to improve the speed of some requests, or
lower the priority of non-important requests. Using this setting without
prior experimentation can cause some major slowdown.
This rewrites the request path with the result of the evaluation of format
string <fmt>. The query string, if any, is left intact. If a scheme and
authority is found before the path, they are left intact as well. If the
request doesn't have a path ("*"), this one is replaced with the format.
This can be used to prepend a directory component in front of a path for
example. See also "http-request set-query" and "http-request set-uri".
Example :
# prepend the host name before the path
http-request set-path /%[hdr(host)]%[path]
This does the same as "http-request set-path" except that the query-string is
also rewritten. It may be used to remove the query-string, including the
question mark (it is not possible using "http-request set-query").
This is used to set the queue priority class of the current request.
The value must be a sample expression which converts to an integer in the
range -2047..2047. Results outside this range will be truncated.
The priority class determines the order in which queued requests are
processed. Lower values have higher priority.
This is used to set the queue priority timestamp offset of the current
request. The value must be a sample expression which converts to an integer
in the range -524287..524287. Results outside this range will be truncated.
When a request is queued, it is ordered first by the priority class, then by
the current timestamp adjusted by the given offset in milliseconds. Lower
values have higher priority.
Note that the resulting timestamp is is only tracked with enough precision
for 524,287ms (8m44s287ms). If the request is queued long enough to where the
adjusted timestamp exceeds this value, it will be misidentified as highest
priority. Thus it is important to set "timeout queue" to a value, where when
combined with the offset, does not exceed this limit.
This rewrites the request's query string which appears after the first
question mark ("?") with the result of the evaluation of format string <fmt>.
The part prior to the question mark is left intact. If the request doesn't
contain a question mark and the new value is not empty, then one is added at
the end of the URI, followed by the new value. If a question mark was
present, it will never be removed even if the value is empty. This can be
used to add or remove parameters from the query string.
See also "http-request set-query" and "http-request set-uri".
Example:
# replace "%3D" with "=" in the query string
http-request set-query %[query,regsub(%3D,=,g)]
This is used to set the source IP address to the value of specified
expression. Useful when a proxy in front of HAProxy rewrites source IP, but
provides the correct IP in a HTTP header; or you want to mask source IP for
privacy. All subsequent calls to "src" fetch will return this value
(see example).
Arguments :
<expr> Is a standard HAProxy expression formed by a sample-fetch followed
by some converters.
See also "option forwardfor".
Example:
http-request set-src hdr(x-forwarded-for)
http-request set-src src,ipmask(24)
# After the masking this will track connections
# based on the IP address with the last byte zeroed out.
http-request track-sc0 src
When possible, set-src preserves the original source port as long as the
address family allows it, otherwise the source port is set to 0.
This is used to set the source port address to the value of specified
expression.
Arguments:
<expr> Is a standard HAProxy expression formed by a sample-fetch followed
by some converters.
Example:
http-request set-src-port hdr(x-port)
http-request set-src-port int(4000)
When possible, set-src-port preserves the original source address as long as
the address family supports a port, otherwise it forces the source address to
IPv4 "0.0.0.0" before rewriting the port.
This action overrides the specified "server" or "tunnel" timeout for the
current stream only. The timeout can be specified in millisecond or with any
other unit if the number is suffixed by the unit as explained at the top of
this document. It is also possible to write an expression which must returns
a number interpreted as a timeout in millisecond.
Note that the server/tunnel timeouts are only relevant on the backend side
and thus this rule is only available for the proxies with backend
capabilities. Also the timeout value must be non-null to obtain the expected
results.
Example:
http-request set-timeout tunnel 5s
http-request set-timeout server req.hdr(host),map_int(host.lst)
This is used to set the TOS or DSCP field value of packets sent to the client
to the value passed in <tos> on platforms which support this. This value
represents the whole 8 bits of the IP TOS field, and can be expressed both in
decimal or hexadecimal format (prefixed by "0x"). Note that only the 6 higher
bits are used in DSCP or TOS, and the two lower bits are always 0. This can
be used to adjust some routing behavior on border routers based on some
information from the request.
See RFC 2474, 2597, 3260 and 4594 for more information.
This rewrites the request URI with the result of the evaluation of format
string <fmt>. The scheme, authority, path and query string are all replaced
at once. This can be used to rewrite hosts in front of proxies, or to
perform complex modifications to the URI such as moving parts between the
path and the query string.
See also "http-request set-path" and "http-request set-query".
This is used to set the contents of a variable. The variable is declared
inline.
Arguments:
<var-name> The name of the variable starts with an indication about its
scope. The scopes allowed are:
"proc" : the variable is shared with the whole process
"sess" : the variable is shared with the whole session
"txn" : the variable is shared with the transaction
(request and response)
"req" : the variable is shared only during request
processing
"res" : the variable is shared only during response
processing
This prefix is followed by a name. The separator is a '.'.
The name may only contain characters 'a-z', 'A-Z', '0-9'
and '_'.
<expr> Is a standard HAProxy expression formed by a sample-fetch
followed by some converters.
<fmt> This is the value expressed using log-format rules (see Custom
Log Format in section 8.2.4).
Example:
http-request set-var(req.my_var) req.fhdr(user-agent),lower
http-request set-var-fmt(txn.from) %[src]:%[src_port]
This action is used to trigger sending of a group of SPOE messages. To do so,
the SPOE engine used to send messages must be defined, as well as the SPOE
group to send. Of course, the SPOE engine must refer to an existing SPOE
filter. If not engine name is provided on the SPOE filter line, the SPOE
agent name must be used.
Arguments:
<engine-name> The SPOE engine name.
<group-name> The SPOE group name as specified in the engine
configuration.
This stops the evaluation of the rules and makes the client-facing connection
suddenly disappear using a system-dependent way that tries to prevent the
client from being notified. The effect it then that the client still sees an
established connection while there's none on HAProxy. The purpose is to
achieve a comparable effect to "tarpit" except that it doesn't use any local
resource at all on the machine running HAProxy. It can resist much higher
loads than "tarpit", and slow down stronger attackers. It is important to
understand the impact of using this mechanism. All stateful equipment placed
between the client and HAProxy (firewalls, proxies, load balancers) will also
keep the established connection for a long time and may suffer from this
action.
On modern Linux systems running with enough privileges, the TCP_REPAIR socket
option is used to block the emission of a TCP reset. On other systems, the
socket's TTL is reduced to 1 so that the TCP reset doesn't pass the first
router, though it's still delivered to local networks. Do not use it unless
you fully understand how it works.
This enables or disables the strict rewriting mode for following rules. It
does not affect rules declared before it and it is only applicable on rules
performing a rewrite on the requests. When the strict mode is enabled, any
rewrite failure triggers an internal error. Otherwise, such errors are
silently ignored. The purpose of the strict rewriting mode is to make some
rewrites optional while others must be performed to continue the request
processing.
By default, the strict rewriting mode is enabled. Its value is also reset
when a ruleset evaluation ends. So, for instance, if you change the mode on
the frontend, the default mode is restored when HAProxy starts the backend
rules evaluation.
http-request tarpit [ { status | deny_status } <code>] [content-type <type>]
[ { default-errorfiles | errorfile <file> | errorfiles <name> |
file <file> | lf-file <file> | string <str> | lf-string <fmt> } ]
[ hdr <name> <fmt> ]*
[ { if | unless } <condition> ]
This stops the evaluation of the rules and immediately blocks the request
without responding for a delay specified by "timeout tarpit" or
"timeout connect" if the former is not set. After that delay, if the client
is still connected, a response is returned so that the client does not
suspect it has been tarpitted. Logs will report the flags "PT". The goal of
the tarpit rule is to slow down robots during an attack when they're limited
on the number of concurrent requests. It can be very efficient against very
dumb robots, and will significantly reduce the load on firewalls compared to
a "deny" rule. But when facing "correctly" developed robots, it can make
things worse by forcing HAProxy and the front firewall to support insane
number of concurrent connections. By default an HTTP error 500 is returned.
But the response may be customized using same syntax than
"http-request return" rules. Thus, see "http-request return" for details.
For compatibility purpose, when no argument is defined, or only "deny_status",
the argument "default-errorfiles" is implied. It means
"http-request tarpit [deny_status <status>]" is an alias of
"http-request tarpit [status <status>] default-errorfiles".
No further "http-request" rules are evaluated.
See also "http-request return" and "http-request silent-drop".
This enables tracking of sticky counters from current request. These rules do
not stop evaluation and do not change default action. The number of counters
that may be simultaneously tracked by the same connection is set in
MAX_SESS_STKCTR at build time (reported in haproxy -vv) which defaults to 3,
so the track-sc number is between 0 and (MAX_SESS_STKCTR-1). The first
"track-sc0" rule executed enables tracking of the counters of the specified
table as the first set. The first "track-sc1" rule executed enables tracking
of the counters of the specified table as the second set. The first
"track-sc2" rule executed enables tracking of the counters of the specified
table as the third set. It is a recommended practice to use the first set of
counters for the per-frontend counters and the second set for the per-backend
ones. But this is just a guideline, all may be used everywhere.
Arguments :
<key> is mandatory, and is a sample expression rule as described in
section 7.3. It describes what elements of the incoming request or
connection will be analyzed, extracted, combined, and used to
select which table entry to update the counters.
<table> is an optional table to be used instead of the default one, which
is the stick-table declared in the current proxy. All the counters
for the matches and updates for the key will then be performed in
that table until the session ends.
Once a "track-sc*" rule is executed, the key is looked up in the table and if
it is not found, an entry is allocated for it. Then a pointer to that entry
is kept during all the session's life, and this entry's counters are updated
as often as possible, every time the session's counters are updated, and also
systematically when the session ends. Counters are only updated for events
that happen after the tracking has been started. As an exception, connection
counters and request counters are systematically updated so that they reflect
useful information.
If the entry tracks concurrent connection counters, one connection is counted
for as long as the entry is tracked, and the entry will not expire during
that time. Tracking counters also provides a performance advantage over just
checking the keys, because only one table lookup is performed for all ACL
checks that make use of it.
This is used to unset a variable. See above for details about <var-name>.
Example:
http-request unset-var(req.my_var)
This directive executes the configured HTTP service to reply to the request
and stops the evaluation of the rules. An HTTP service may choose to reply by
sending any valid HTTP response or it may immediately close the connection
without sending any response. Outside natives services, for instance the
Prometheus exporter, it is possible to write your own services in Lua. No
further "http-request" rules are evaluated.
Arguments :
<service-name> is mandatory. It is the service to call
Example:
http-request use-service prometheus-exporter if { path /metrics }
This will delay the processing of the request or response until one of the
following conditions occurs:
- The full request body is received, in which case processing proceeds
normally.
- <bytes> bytes have been received, when the "at-least" argument is given and
<bytes> is non-zero, in which case processing proceeds normally.
- The request buffer is full, in which case processing proceeds normally. The
size of this buffer is determined by the "tune.bufsize" option.
- The request has been waiting for more than <time> milliseconds. In this
case HAProxy will respond with a 408 "Request Timeout" error to the client
and stop processing the request. Note that if any of the other conditions
happens first, this timeout will not occur even if the full body has
not yet been recieved.
This action may be used as a replacement for "option http-buffer-request".
Arguments :
<time> is mandatory. It is the maximum time to wait for the body. It
follows the HAProxy time format and is expressed in milliseconds.
<bytes> is optional. It is the minimum payload size to receive to stop to
wait. It follows the HAProxy size format and is expressed in
bytes. A value of 0 (the default) means no limit.
Example:
http-request wait-for-body time 1s at-least 1k if METH_POST
See also : "option http-buffer-request"
This will delay the processing of the request until the SSL handshake
happened. This is mostly useful to delay processing early data until we're
sure they are valid.
Access control for Layer 7 responses
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | yes | yes | yes |
The http-response statement defines a set of rules which apply to layer 7
processing. The rules are evaluated in their declaration order when they are
met in a frontend, listen or backend section. Any rule may optionally be
followed by an ACL-based condition, in which case it will only be evaluated
if the condition is true. Since these rules apply on responses, the backend
rules are applied first, followed by the frontend's rules.
The first keyword is the rule's action. The supported actions are described
below.
There is no limit to the number of http-response statements per instance.
Example:
acl key_acl res.hdr(X-Acl-Key) -m found
acl myhost hdr(Host) -f myhost.lst
http-response add-acl(myhost.lst) %[res.hdr(X-Acl-Key)] if key_acl
http-response del-acl(myhost.lst) %[res.hdr(X-Acl-Key)] if key_acl
Example:
acl value res.hdr(X-Value) -m found
use_backend bk_appli if { hdr(Host),map_str(map.lst) -m found }
http-response set-map(map.lst) %[src] %[res.hdr(X-Value)] if value
http-response del-map(map.lst) %[src] if ! value
This is used to add a new entry into an ACL. The ACL must be loaded from a
file (even a dummy empty file). The file name of the ACL to be updated is
passed between parentheses. It takes one argument: <key fmt>, which follows
log-format rules, to collect content of the new entry. It performs a lookup
in the ACL before insertion, to avoid duplicated (or more) values.
This lookup is done by a linear search and can be expensive with large lists!
It is the equivalent of the "add acl" command from the stats socket, but can
be triggered by an HTTP response.
This appends an HTTP header field whose name is specified in <name> and whose
value is defined by <fmt> which follows the log-format rules (see Custom Log
Format in section 8.2.4). This may be used to send a cookie to a client for
example, or to pass some internal information.
This rule is not final, so it is possible to add other similar rules.
Note that header addition is performed immediately, so one rule might reuse
the resulting header from a previous rule.
This stops the evaluation of the rules and lets the response pass the check.
No further "http-response" rules are evaluated for the current section.
See section 6.2 about cache setup.
This captures sample expression <sample> from the response buffer, and
converts it to a string. The resulting string is stored into the next request
"capture" slot, so it will possibly appear next to some captured HTTP
headers. It will then automatically appear in the logs, and it will be
possible to extract it using sample fetch rules to feed it into headers or
anything. Please check section 7.3 (Fetching samples) and
"capture response header" for more information.
The keyword "id" is the id of the capture slot which is used for storing the
string. The capture slot must be defined in an associated frontend.
This is useful to run captures in backends. The slot id can be declared by a
previous directive "http-response capture" or with the "declare capture"
keyword.
When using this action in a backend, double check that the relevant
frontend(s) have the required capture slots otherwise, this rule will be
ignored at run time. This can't be detected at configuration parsing time
due to HAProxy's ability to dynamically resolve backend name at runtime.
This is used to delete an entry from an ACL. The ACL must be loaded from a
file (even a dummy empty file). The file name of the ACL to be updated is
passed between parentheses. It takes one argument: <key fmt>, which follows
log-format rules, to collect content of the entry to delete.
It is the equivalent of the "del acl" command from the stats socket, but can
be triggered by an HTTP response.
This removes all HTTP header fields whose name is specified in <name>. <meth>
is the matching method, applied on the header name. Supported matching methods
are "str" (exact match), "beg" (prefix match), "end" (suffix match), "sub"
(substring match) and "reg" (regex match). If not specified, exact matching
method is used.
This is used to delete an entry from a MAP. The MAP must be loaded from a
file (even a dummy empty file). The file name of the MAP to be updated is
passed between parentheses. It takes one argument: <key fmt>, which follows
log-format rules, to collect content of the entry to delete.
It takes one argument: "file name" It is the equivalent of the "del map"
command from the stats socket, but can be triggered by an HTTP response.
http-response deny [ { status | deny_status } <code>] [content-type <type>]
[ { default-errorfiles | errorfile <file> | errorfiles <name> |
file <file> | lf-file <file> | string <str> | lf-string <fmt> } ]
[ hdr <name> <fmt> ]*
[ { if | unless } <condition> ]
This stops the evaluation of the rules and immediately rejects the response.
By default an HTTP 502 error is returned. But the response may be customized
using same syntax than "http-response return" rules. Thus, see
"http-response return" for details. For compatibility purpose, when no
argument is defined, or only "deny_status", the argument "default-errorfiles"
is implied. It means "http-response deny [deny_status <status>]" is an alias
of "http-response deny [status <status>] default-errorfiles".
No further "http-response" rules are evaluated.
See also "http-response return".
This performs an HTTP redirection based on a redirect rule.
This supports a format string similarly to "http-request redirect" rules,
with the exception that only the "location" type of redirect is possible on
the response. See the "redirect" keyword for the rule's syntax. When a
redirect rule is applied during a response, connections to the server are
closed so that no data can be forwarded from the server to the client.
This works like "http-request replace-header" except that it works on the
server's response instead of the client's request.
Example:
http-response replace-header Set-Cookie (C=[^;]*);(.*) \1;ip=%bi;\2
# applied to:
Set-Cookie: C=1; expires=Tue, 14-Jun-2016 01:40:45 GMT
# outputs:
Set-Cookie: C=1;ip=192.168.1.20; expires=Tue, 14-Jun-2016 01:40:45 GMT
# assuming the backend IP is 192.168.1.20.
This works like "http-request replace-value" except that it works on the
server's response instead of the client's request.
Example:
http-response replace-value Cache-control ^public$ private
# applied to:
Cache-Control: max-age=3600, public
# outputs:
Cache-Control: max-age=3600, private
http-response return [status <code>] [content-type <type>]
[ { default-errorfiles | errorfile <file> | errorfiles <name> |
file <file> | lf-file <file> | string <str> | lf-string <fmt> } ]
[ hdr <name> <value> ]*
[ { if | unless } <condition> ]
This stops the evaluation of the rules and immediately returns a response. The
default status code used for the response is 200. It can be optionally
specified as an arguments to "status". The response content-type may also be
specified as an argument to "content-type". Finally the response itself may
be defined. If can be a full HTTP response specifying the errorfile to use,
or the response payload specifying the file or the string to use. These rules
are followed to create the response :
* If neither the errorfile nor the payload to use is defined, a dummy
response is returned. Only the "status" argument is considered. It can be
any code in the range [200, 599]. The "content-type" argument, if any, is
ignored.
* If "default-errorfiles" argument is set, the proxy's errorfiles are
considered. If the "status" argument is defined, it must be one of the
status code handled by HAProxy (200, 400, 403, 404, 405, 408, 410, 413,
425, 429, 500, 501, 502, 503, and 504). The "content-type" argument, if
any, is ignored.
* If a specific errorfile is defined, with an "errorfile" argument, the
corresponding file, containing a full HTTP response, is returned. Only the
"status" argument is considered. It must be one of the status code handled
by HAProxy (200, 400, 403, 404, 405, 408, 410, 413, 425, 429, 500, 501,
502, 503, and 504). The "content-type" argument, if any, is ignored.
* If an http-errors section is defined, with an "errorfiles" argument, the
corresponding file in the specified http-errors section, containing a full
HTTP response, is returned. Only the "status" argument is considered. It
must be one of the status code handled by HAProxy (200, 400, 403, 404, 405,
408, 410, 413, 425, 429, 500, 501, 502, 503, and 504). The "content-type"
argument, if any, is ignored.
* If a "file" or a "lf-file" argument is specified, the file's content is
used as the response payload. If the file is not empty, its content-type
must be set as argument to "content-type". Otherwise, any "content-type"
argument is ignored. With a "lf-file" argument, the file's content is
evaluated as a log-format string. With a "file" argument, it is considered
as a raw content.
* If a "string" or "lf-string" argument is specified, the defined string is
used as the response payload. The content-type must always be set as
argument to "content-type". With a "lf-string" argument, the string is
evaluated as a log-format string. With a "string" argument, it is
considered as a raw string.
When the response is not based an errorfile, it is possible to appends HTTP
header fields to the response using "hdr" arguments. Otherwise, all "hdr"
arguments are ignored. For each one, the header name is specified in <name>
and its value is defined by <fmt> which follows the log-format rules.
Note that the generated response must be smaller than a buffer. And to avoid
any warning, when an errorfile or a raw file is loaded, the buffer space
reserved to the headers rewriting should also be free.
No further "http-response" rules are evaluated.
Example:
http-response return errorfile /etc/haproxy/errorfiles/200.http \
if { status eq 404 }
http-response return content-type text/plain \
string "This is the end !" \
if { status eq 500 }
This action increments the GPC0 or GPC1 counter according with the sticky
counter designated by <sc-id>. If an error occurs, this action silently fails
and the actions evaluation continues.
This action sets the 32-bit unsigned GPT0 tag according to the sticky counter
designated by <sc-id> and the value of <int>/<expr>. The expected result is a
boolean. If an error occurs, this action silently fails and the actions
evaluation continues.
This action is used to trigger sending of a group of SPOE messages. To do so,
the SPOE engine used to send messages must be defined, as well as the SPOE
group to send. Of course, the SPOE engine must refer to an existing SPOE
filter. If not engine name is provided on the SPOE filter line, the SPOE
agent name must be used.
Arguments:
<engine-name> The SPOE engine name.
<group-name> The SPOE group name as specified in the engine
configuration.
This does the same as "add-header" except that the header name is first
removed if it existed. This is useful when passing security information to
the server, where the header must not be manipulated by external users.
This is used to change the log level of the current request when a certain
condition is met. Valid levels are the 8 syslog levels (see the "log"
keyword) plus the special level "silent" which disables logging for this
request. This rule is not final so the last matching rule wins. This rule can
be useful to disable health checks coming from another equipment.
This is used to add a new entry into a MAP. The MAP must be loaded from a
file (even a dummy empty file). The file name of the MAP to be updated is
passed between parentheses. It takes 2 arguments: <key fmt>, which follows
log-format rules, used to collect MAP key, and <value fmt>, which follows
log-format rules, used to collect content for the new entry. It performs a
lookup in the MAP before insertion, to avoid duplicated (or more) values.
This lookup is done by a linear search and can be expensive with large lists!
It is the equivalent of the "set map" command from the stats socket, but can
be triggered by an HTTP response.
This is used to set the Netfilter/IPFW MARK on all packets sent to the client
to the value passed in <mark> on platforms which support it. This value is an
unsigned 32 bit value which can be matched by netfilter/ipfw and by the
routing table or monitoring the packets through DTrace.
It can be expressed both in decimal or hexadecimal format (prefixed by "0x").
This can be useful to force certain packets to take a different route (for
example a cheaper network path for bulk downloads). This works on Linux
kernels 2.6.32 and above and requires admin privileges, as well on FreeBSD.
This sets the "nice" factor of the current request being processed.
It only has effect against the other requests being processed at the same
time. The default value is 0, unless altered by the "nice" setting on the
"bind" line. The accepted range is -1024..1024. The higher the value, the
nicest the request will be. Lower values will make the request more important
than other ones. This can be useful to improve the speed of some requests, or
lower the priority of non-important requests. Using this setting without
prior experimentation can cause some major slowdown.
This replaces the response status code with <status> which must be an integer
between 100 and 999. Optionally, a custom reason text can be provided defined
by <str>, or the default reason for the specified code will be used as a
fallback.
Example:
# return "431 Request Header Fields Too Large"
http-response set-status 431
# return "503 Slow Down", custom reason
http-response set-status 503 reason "Slow Down".
This is used to set the TOS or DSCP field value of packets sent to the client
to the value passed in <tos> on platforms which support this.
This value represents the whole 8 bits of the IP TOS field, and can be
expressed both in decimal or hexadecimal format (prefixed by "0x"). Note that
only the 6 higher bits are used in DSCP or TOS, and the two lower bits are
always 0. This can be used to adjust some routing behavior on border routers
based on some information from the request.
See RFC 2474, 2597, 3260 and 4594 for more information.
This is used to set the contents of a variable. The variable is declared
inline.
Arguments:
<var-name> The name of the variable starts with an indication about its
scope. The scopes allowed are:
"proc" : the variable is shared with the whole process
"sess" : the variable is shared with the whole session
"txn" : the variable is shared with the transaction
(request and response)
"req" : the variable is shared only during request
processing
"res" : the variable is shared only during response
processing
This prefix is followed by a name. The separator is a '.'.
The name may only contain characters 'a-z', 'A-Z', '0-9', '.'
and '_'.
<expr> Is a standard HAProxy expression formed by a sample-fetch
followed by some converters.
<fmt> This is the value expressed using log-format rules (see Custom
Log Format in section 8.2.4).
Examples:
http-response set-var(sess.last_redir) res.hdr(location)
http-response set-var-fmt(sess.last_be_addr) %[bi]:%[bp]
This stops the evaluation of the rules and makes the client-facing connection
suddenly disappear using a system-dependent way that tries to prevent the
client from being notified. The effect it then that the client still sees an
established connection while there's none on HAProxy. The purpose is to
achieve a comparable effect to "tarpit" except that it doesn't use any local
resource at all on the machine running HAProxy. It can resist much higher
loads than "tarpit", and slow down stronger attackers. It is important to
understand the impact of using this mechanism. All stateful equipment placed
between the client and HAProxy (firewalls, proxies, load balancers) will also
keep the established connection for a long time and may suffer from this
action.
On modern Linux systems running with enough privileges, the TCP_REPAIR socket
option is used to block the emission of a TCP reset. On other systems, the
socket's TTL is reduced to 1 so that the TCP reset doesn't pass the first
router, though it's still delivered to local networks. Do not use it unless
you fully understand how it works.
This enables or disables the strict rewriting mode for following rules. It
does not affect rules declared before it and it is only applicable on rules
performing a rewrite on the responses. When the strict mode is enabled, any
rewrite failure triggers an internal error. Otherwise, such errors are
silently ignored. The purpose of the strict rewriting mode is to make some
rewrites optional while others must be performed to continue the response
processing.
By default, the strict rewriting mode is enabled. Its value is also reset
when a ruleset evaluation ends. So, for instance, if you change the mode on
the backend, the default mode is restored when HAProxy starts the frontend
rules evaluation.
This enables tracking of sticky counters from current response. Please refer
to "http-request track-sc" for a complete description. The only difference
from "http-request track-sc" is the <key> sample expression can only make use
of samples in response (e.g. res.*, status etc.) and samples below Layer 6
(e.g. SSL-related samples, see section 7.3.4). If the sample is not
supported, HAProxy will fail and warn while parsing the config.
This is used to unset a variable. See "http-response set-var" for details
about <var-name>.
Example:
http-response unset-var(sess.last_redir)
This will delay the processing of the response waiting for the payload for at
most <time> milliseconds. if "at-least" argument is specified, HAProxy stops
to wait the payload when the first <bytes> bytes are received. 0 means no
limit, it is the default value. Regardless the "at-least" argument value,
HAProxy stops to wait if the whole payload is received or if the response
buffer is full.
Arguments :
<time> is mandatory. It is the maximum time to wait for the body. It
follows the HAProxy time format and is expressed in milliseconds.
<bytes> is optional. It is the minimum payload size to receive to stop to
wait. It follows the HAProxy size format and is expressed in
bytes.
Example:
http-response wait-for-body time 1s at-least 10k
Declare how idle HTTP connections may be shared between requests
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
By default, a connection established between HAProxy and the backend server
which is considered safe for reuse is moved back to the server's idle
connections pool so that any other request can make use of it. This is the
"safe" strategy below.
The argument indicates the desired connection reuse strategy :
- "never" : idle connections are never shared between sessions. This mode
may be enforced to cancel a different strategy inherited from
a defaults section or for troubleshooting. For example, if an
old bogus application considers that multiple requests over
the same connection come from the same client and it is not
possible to fix the application, it may be desirable to
disable connection sharing in a single backend. An example of
such an application could be an old HAProxy using cookie
insertion in tunnel mode and not checking any request past the
first one.
- "safe" : this is the default and the recommended strategy. The first
request of a session is always sent over its own connection,
and only subsequent requests may be dispatched over other
existing connections. This ensures that in case the server
closes the connection when the request is being sent, the
browser can decide to silently retry it. Since it is exactly
equivalent to regular keep-alive, there should be no side
effects. There is also a special handling for the connections
using protocols subject to Head-of-line blocking (backend with
h2 or fcgi). In this case, when at least one stream is
processed, the used connection is reserved to handle streams
of the same session. When no more streams are processed, the
connection is released and can be reused.
- "aggressive" : this mode may be useful in webservices environments where
all servers are not necessarily known and where it would be
appreciable to deliver most first requests over existing
connections. In this case, first requests are only delivered
over existing connections that have been reused at least once,
proving that the server correctly supports connection reuse.
It should only be used when it's sure that the client can
retry a failed request once in a while and where the benefit
of aggressive connection reuse significantly outweighs the
downsides of rare connection failures.
- "always" : this mode is only recommended when the path to the server is
known for never breaking existing connections quickly after
releasing them. It allows the first request of a session to be
sent to an existing connection. This can provide a significant
performance increase over the "safe" strategy when the backend
is a cache farm, since such components tend to show a
consistent behavior and will benefit from the connection
sharing. It is recommended that the "http-keep-alive" timeout
remains low in this mode so that no dead connections remain
usable. In most cases, this will lead to the same performance
gains as "aggressive" but with more risks. It should only be
used when it improves the situation over "aggressive".
When http connection sharing is enabled, a great care is taken to respect the
connection properties and compatibility. Indeed, some properties are specific
and it is not possibly to reuse it blindly. Those are the SSL SNI, source
and destination address and proxy protocol block. A connection is reused only
if it shares the same set of properties with the request.
Also note that connections with certain bogus authentication schemes (relying
on the connection) like NTLM are marked private if possible and never shared.
This won't be the case however when using a protocol with multiplexing
abilities and using reuse mode level value greater than the default "safe"
strategy as in this case nothing prevents the connection from being already
shared.
A connection pool is involved and configurable with "pool-max-conn".
Note: connection reuse improves the accuracy of the "server maxconn" setting,
because almost no new connection will be established while idle connections
remain available. This is particularly true with the "always" strategy.
The rules to decide to keep an idle connection opened or to close it after
processing are also governed by the "tune.pool-low-fd-ratio" (default: 20%)
and "tune.pool-high-fd-ratio" (default: 25%). These correspond to the
percentage of total file descriptors spent in idle connections above which
haproxy will respectively refrain from keeping a connection opened after a
response, and actively kill idle connections. Some setups using a very high
ratio of idle connections, either because of too low a global "maxconn", or
due to a lot of HTTP/2 or HTTP/3 traffic on the frontend (few connections)
but HTTP/1 connections on the backend, may observe a lower reuse rate because
too few connections are kept open. It may be desirable in this case to adjust
such thresholds or simply to increase the global "maxconn" value.
Similarly, when thread groups are explicitly enabled, it is important to
understand that idle connections are only usable between threads from a same
group. As such it may happen that unfair load between groups leads to more
idle connections being needed, causing a lower reuse rate. The same solution
may then be applied (increase global "maxconn" or increase pool ratios).
See also : "option http-keep-alive", "server maxconn", "thread-groups", "tune.pool-high-fd-ratio", "tune.pool-low-fd-ratio"
Add the server name to a request. Use the header string given by <header>
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<header> The header string to use to send the server name
The "http-send-name-header" statement causes the header field named <header>
to be set to the name of the target server at the moment the request is about
to be sent on the wire. Any existing occurrences of this header are removed.
Upon retries and redispatches, the header field is updated to always reflect
the server being attempted to connect to. Given that this header is modified
very late in the connection setup, it may have unexpected effects on already
modified headers. For example using it with transport-level header such as
connection, content-length, transfer-encoding and so on will likely result in
invalid requests being sent to the server. Additionally it has been reported
that this directive is currently being used as a way to overwrite the Host
header field in outgoing requests; while this trick has been known to work
as a side effect of the feature for some time, it is not officially supported
and might possibly not work anymore in a future version depending on the
technical difficulties this feature induces. A long-term solution instead
consists in fixing the application which required this trick so that it binds
to the correct host name.
See also : "server"
Set a persistent ID to a proxy.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | yes | yes | yes |
Arguments : none
Set a persistent ID for the proxy. This ID must be unique and positive.
An unused ID will automatically be assigned if unset. The first assigned
value will be 1. This ID is currently only returned in statistics.
Declare a condition to ignore persistence
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | no | yes | yes |
By default, when cookie persistence is enabled, every requests containing
the cookie are unconditionally persistent (assuming the target server is up
and running).
The "ignore-persist" statement allows one to declare various ACL-based
conditions which, when met, will cause a request to ignore persistence.
This is sometimes useful to load balance requests for static files, which
often don't require persistence. This can also be used to fully disable
persistence for a specific User-Agent (for example, some web crawler bots).
The persistence is ignored when an "if" condition is met, or unless an
"unless" condition is met.
Example:
acl url_static path_beg /static /images /img /css
acl url_static path_end .gif .png .jpg .css .js
ignore-persist if url_static
Allow seamless reload of HAProxy
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
This directive points HAProxy to a file where server state from previous
running process has been saved. That way, when starting up, before handling
traffic, the new process can apply old states to servers exactly has if no
reload occurred. The purpose of the "load-server-state-from-file" directive is
to tell HAProxy which file to use. For now, only 2 arguments to either prevent
loading state or load states from a file containing all backends and servers.
The state file can be generated by running the command "show servers state"
over the stats socket and redirect output.
The format of the file is versioned and is very specific. To understand it,
please read the documentation of the "show servers state" command (chapter
9.3 of Management Guide).
Arguments:
global load the content of the file pointed by the global directive
named "server-state-file".
local load the content of the file pointed by the directive
"server-state-file-name" if set. If not set, then the backend
name is used as a file name.
none don't load any stat for this backend
Notes:
- server's IP address is preserved across reloads by default, but the
order can be changed thanks to the server's "init-addr" setting. This
means that an IP address change performed on the CLI at run time will
be preserved, and that any change to the local resolver (e.g. /etc/hosts)
will possibly not have any effect if the state file is in use.
- server's weight is applied from previous running process unless it has
has changed between previous and new configuration files.
Example:
Minimal configurationglobal stats socket /tmp/socket server-state-file /tmp/server_state defaults load-server-state-from-file global backend bk server s1 127.0.0.1:22 check weight 11 server s2 127.0.0.1:22 check weight 12
Then one can run :
socat /tmp/socket - <<< "show servers state" > /tmp/server_state
Content of the file /tmp/server_state would be like this:
1
# <field names skipped for the doc example>
1 bk 1 s1 127.0.0.1 2 0 11 11 4 6 3 4 6 0 0
1 bk 2 s2 127.0.0.1 2 0 12 12 4 6 3 4 6 0 0
Example:
Minimal configurationglobal stats socket /tmp/socket server-state-base /etc/haproxy/states defaults load-server-state-from-file local backend bk server s1 127.0.0.1:22 check weight 11 server s2 127.0.0.1:22 check weight 12
Then one can run :
socat /tmp/socket - <<< "show servers state bk" > /etc/haproxy/states/bk
Content of the file /etc/haproxy/states/bk would be like this:
1
# <field names skipped for the doc example>
1 bk 1 s1 127.0.0.1 2 0 11 11 4 6 3 4 6 0 0
1 bk 2 s2 127.0.0.1 2 0 12 12 4 6 3 4 6 0 0
See also: "server-state-file", "server-state-file-name", and "show servers state"
log <address> [len <length>] [format <format>] [sample <ranges>:<sample_size>]
<facility> [<level> [<minlevel>]]
Enable per-instance logging of events and traffic.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Prefix :
no should be used when the logger list must be flushed. For example,
if you don't want to inherit from the default logger list. This
prefix does not allow arguments.
Arguments :
global should be used when the instance's logging parameters are the
same as the global ones. This is the most common usage. "global"
replaces <address>, <facility> and <level> with those of the log
entries found in the "global" section. Only one "log global"
statement may be used per instance, and this form takes no other
parameter.
<address> indicates where to send the logs. It takes the same format as
for the "global" section's logs, and can be one of :
- An IPv4 address optionally followed by a colon (':') and a UDP
port. If no port is specified, 514 is used by default (the
standard syslog port).
- An IPv6 address followed by a colon (':') and optionally a UDP
port. If no port is specified, 514 is used by default (the
standard syslog port).
- A filesystem path to a UNIX domain socket, keeping in mind
considerations for chroot (be sure the path is accessible
inside the chroot) and uid/gid (be sure the path is
appropriately writable).
- A file descriptor number in the form "fd@<number>", which may
point to a pipe, terminal, or socket. In this case unbuffered
logs are used and one writev() call per log is performed. This
is a bit expensive but acceptable for most workloads. Messages
sent this way will not be truncated but may be dropped, in
which case the DroppedLogs counter will be incremented. The
writev() call is atomic even on pipes for messages up to
PIPE_BUF size, which POSIX recommends to be at least 512 and
which is 4096 bytes on most modern operating systems. Any
larger message may be interleaved with messages from other
processes. Exceptionally for debugging purposes the file
descriptor may also be directed to a file, but doing so will
significantly slow HAProxy down as non-blocking calls will be
ignored. Also there will be no way to purge nor rotate this
file without restarting the process. Note that the configured
syslog format is preserved, so the output is suitable for use
with a TCP syslog server. See also the "short" and "raw"
formats below.
- "stdout" / "stderr", which are respectively aliases for "fd@1"
and "fd@2", see above.
- A ring buffer in the form "ring@<name>", which will correspond
to an in-memory ring buffer accessible over the CLI using the
"show events" command, which will also list existing rings and
their sizes. Such buffers are lost on reload or restart but
when used as a complement this can help troubleshooting by
having the logs instantly available.
- An explicit stream address prefix such as "tcp@","tcp6@",
"tcp4@" or "uxst@" will allocate an implicit ring buffer with
a stream forward server targeting the given address.
You may want to reference some environment variables in the
address parameter, see section 2.3 about environment variables.
<length> is an optional maximum line length. Log lines larger than this
value will be truncated before being sent. The reason is that
syslog servers act differently on log line length. All servers
support the default value of 1024, but some servers simply drop
larger lines while others do log them. If a server supports long
lines, it may make sense to set this value here in order to avoid
truncating long lines. Similarly, if a server drops long lines,
it is preferable to truncate them before sending them. Accepted
values are 80 to 65535 inclusive. The default value of 1024 is
generally fine for all standard usages. Some specific cases of
long captures or JSON-formatted logs may require larger values.
<ranges> A list of comma-separated ranges to identify the logs to sample.
This is used to balance the load of the logs to send to the log
server. The limits of the ranges cannot be null. They are numbered
from 1. The size or period (in number of logs) of the sample must
be set with <sample_size> parameter.
<sample_size>
The size of the sample in number of logs to consider when balancing
their logging loads. It is used to balance the load of the logs to
send to the syslog server. This size must be greater or equal to the
maximum of the high limits of the ranges.
(see also <ranges> parameter).
<format> is the log format used when generating syslog messages. It may be
one of the following :
local Analog to rfc3164 syslog message format except that hostname
field is stripped. This is the default.
Note: option "log-send-hostname" switches the default to
rfc3164.
rfc3164 The RFC3164 syslog message format.
(https://tools.ietf.org/html/rfc3164)
rfc5424 The RFC5424 syslog message format.
(https://tools.ietf.org/html/rfc5424)
priority A message containing only a level plus syslog facility between
angle brackets such as '<63>', followed by the text. The PID,
date, time, process name and system name are omitted. This is
designed to be used with a local log server.
short A message containing only a level between angle brackets such as
'<3>', followed by the text. The PID, date, time, process name
and system name are omitted. This is designed to be used with a
local log server. This format is compatible with what the
systemd logger consumes.
timed A message containing only a level between angle brackets such as
'<3>', followed by ISO date and by the text. The PID, process
name and system name are omitted. This is designed to be
used with a local log server.
iso A message containing only the ISO date, followed by the text.
The PID, process name and system name are omitted. This is
designed to be used with a local log server.
raw A message containing only the text. The level, PID, date, time,
process name and system name are omitted. This is designed to
be used in containers or during development, where the severity
only depends on the file descriptor used (stdout/stderr).
<facility> must be one of the 24 standard syslog facilities :
kern user mail daemon auth syslog lpr news
uucp cron auth2 ftp ntp audit alert cron2
local0 local1 local2 local3 local4 local5 local6 local7
Note that the facility is ignored for the "short" and "raw"
formats, but still required as a positional field. It is
recommended to use "daemon" in this case to make it clear that
it's only supposed to be used locally.
<level> is optional and can be specified to filter outgoing messages. By
default, all messages are sent. If a level is specified, only
messages with a severity at least as important as this level
will be sent. An optional minimum level can be specified. If it
is set, logs emitted with a more severe level than this one will
be capped to this level. This is used to avoid sending "emerg"
messages on all terminals on some default syslog configurations.
Eight levels are known :
emerg alert crit err warning notice info debug
It is important to keep in mind that it is the frontend which decides what to
log from a connection, and that in case of content switching, the log entries
from the backend will be ignored. Connections are logged at level "info".
However, backend log declaration define how and where servers status changes
will be logged. Level "notice" will be used to indicate a server going up,
"warning" will be used for termination signals and definitive service
termination, and "alert" will be used for when a server goes down.
Note : According to RFC3164, messages are truncated to 1024 bytes before
being emitted.
Example :
log global
log stdout format short daemon # send log to systemd
log stdout format raw daemon # send everything to stdout
log stderr format raw daemon notice # send important events to stderr
log 127.0.0.1:514 local0 notice # only send important events
log tcp@127.0.0.1:514 local0 notice notice # same but limit output
# level and send in tcp
log "${LOCAL_SYSLOG}:514" local0 notice # send to local server
Specifies the log format string to use for traffic logs
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
This directive specifies the log format string that will be used for all logs
resulting from traffic passing through the frontend using this line. If the
directive is used in a defaults section, all subsequent frontends will use
the same log format. Please see section 8.2.4 which covers the log format
string in depth.
"log-format" directive overrides previous "option tcplog", "log-format" and
"option httplog" directives.
Specifies the RFC5424 structured-data log format string
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
This directive specifies the RFC5424 structured-data log format string that
will be used for all logs resulting from traffic passing through the frontend
using this line. If the directive is used in a defaults section, all
subsequent frontends will use the same log format. Please see section 8.2.4
which covers the log format string in depth.
See https://tools.ietf.org/html/rfc5424#section-6.3 for more information
about the RFC5424 structured-data part.
Note : This log format string will be used only for loggers that have set
log format to "rfc5424".
Example :
log-format-sd [exampleSDID@1234\ bytes=\"%B\"\ status=\"%ST\"]
Specifies the log tag to use for all outgoing logs
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Sets the tag field in the syslog header to this string. It defaults to the
log-tag set in the global section, otherwise the program name as launched
from the command line, which usually is "HAProxy". Sometimes it can be useful
to differentiate between multiple processes running on the same host, or to
differentiate customer instances running in the same process. In the backend,
logs about servers up/down will use this tag. As a hint, it can be convenient
to set a log-tag related to a hosted customer in a defaults section then put
all the frontends and backends for that customer, then start another customer
in a new defaults section. See also the global "log-tag" directive.
Set the maximum server queue size for maintaining keep-alive connections
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
HTTP keep-alive tries to reuse the same server connection whenever possible,
but sometimes it can be counter-productive, for example if a server has a lot
of connections while other ones are idle. This is especially true for static
servers.
The purpose of this setting is to set a threshold on the number of queued
connections at which HAProxy stops trying to reuse the same server and prefers
to find another one. The default value, -1, means there is no limit. A value
of zero means that keep-alive requests will never be queued. For very close
servers which can be reached with a low latency and which are not sensible to
breaking keep-alive, a low value is recommended (e.g. local static server can
use a value of 10 or less). For remote servers suffering from a high latency,
higher values might be needed to cover for the latency and/or the cost of
picking a different server.
Note that this has no impact on responses which are maintained to the same
server consecutively to a 401 response. They will still go to the same server
even if they have to be queued.
See also : "option http-server-close", "option prefer-last-server", server "maxconn" and cookie persistence.
Set the maximum number of outgoing connections we can keep idling for a given
client session. The default is 5 (it precisely equals MAX_SRV_LIST which is
defined at build time).
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Fix the maximum number of concurrent connections on a frontend
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments :
<conns> is the maximum number of concurrent connections the frontend will
accept to serve. Excess connections will be queued by the system
in the socket's listen queue and will be served once a connection
closes.
If the system supports it, it can be useful on big sites to raise this limit
very high so that HAProxy manages connection queues, instead of leaving the
clients with unanswered connection attempts. This value should not exceed the
global maxconn. Also, keep in mind that a connection contains two buffers
of tune.bufsize (16kB by default) each, as well as some other data resulting
in about 33 kB of RAM being consumed per established connection. That means
that a medium system equipped with 1GB of RAM can withstand around
20000-25000 concurrent connections if properly tuned.
Also, when <conns> is set to large values, it is possible that the servers
are not sized to accept such loads, and for this reason it is generally wise
to assign them some reasonable connection limits.
When this value is set to zero, which is the default, the global "maxconn"
value is used.
Set the running mode or protocol of the instance
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
tcp The instance will work in pure TCP mode. A full-duplex connection
will be established between clients and servers, and no layer 7
examination will be performed. This is the default mode. It
should be used for SSL, SSH, SMTP, ...
http The instance will work in HTTP mode. The client request will be
analyzed in depth before connecting to any server. Any request
which is not RFC-compliant will be rejected. Layer 7 filtering,
processing and switching will be possible. This is the mode which
brings HAProxy most of its value.
When doing content switching, it is mandatory that the frontend and the
backend are in the same mode (generally HTTP), otherwise the configuration
will be refused.
Example :
defaults http_instances
mode http
Add a condition to report a failure to a monitor HTTP request.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | yes | yes | no |
Arguments :
if <cond> the monitor request will fail if the condition is satisfied,
and will succeed otherwise. The condition should describe a
combined test which must induce a failure if all conditions
are met, for instance a low number of servers both in a
backend and its backup.
unless <cond> the monitor request will succeed only if the condition is
satisfied, and will fail otherwise. Such a condition may be
based on a test on the presence of a minimum number of active
servers in a list of backends.
This statement adds a condition which can force the response to a monitor
request to report a failure. By default, when an external component queries
the URI dedicated to monitoring, a 200 response is returned. When one of the
conditions above is met, HAProxy will return 503 instead of 200. This is
very useful to report a site failure to an external component which may base
routing advertisements between multiple sites on the availability reported by
HAProxy. In this case, one would rely on an ACL involving the "nbsrv"
criterion. Note that "monitor fail" only works in HTTP mode. Both status
messages may be tweaked using "errorfile" or "errorloc" if needed.
Example:
frontend www
mode http
acl site_dead nbsrv(dynamic) lt 2
acl site_dead nbsrv(static) lt 2
monitor-uri /site_alive
monitor fail if site_dead
Intercept a URI used by external components' monitor requests
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments :
<uri> is the exact URI which we want to intercept to return HAProxy's
health status instead of forwarding the request.
When an HTTP request referencing <uri> will be received on a frontend,
HAProxy will not forward it nor log it, but instead will return either
"HTTP/1.0 200 OK" or "HTTP/1.0 503 Service unavailable", depending on failure
conditions defined with "monitor fail". This is normally enough for any
front-end HTTP probe to detect that the service is UP and running without
forwarding the request to a backend server. Note that the HTTP method, the
version and all headers are ignored, but the request must at least be valid
at the HTTP level. This keyword may only be used with an HTTP-mode frontend.
Monitor requests are processed very early, just after the request is parsed
and even before any "http-request". The only rulesets applied before are the
tcp-request ones. They cannot be logged either, and it is the intended
purpose. Only one URI may be configured for monitoring; when multiple
"monitor-uri" statements are present, the last one will define the URI to
be used. They are only used to report HAProxy's health to an upper component,
nothing more. However, it is possible to add any number of conditions using
"monitor fail" and ACLs so that the result can be adjusted to whatever check
can be imagined (most often the number of available servers in a backend).
Note: if <uri> starts by a slash ('/'), the matching is performed against the
request's path instead of the request's uri. It is a workaround to let
the HTTP/2 requests match the monitor-uri. Indeed, in HTTP/2, clients
are encouraged to send absolute URIs only.
Example :
# Use /haproxy_test to report HAProxy's status
frontend www
mode http
monitor-uri /haproxy_test
See also : "monitor fail"
Enable or disable early dropping of aborted requests pending in queues.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments : none
In presence of very high loads, the servers will take some time to respond.
The per-instance connection queue will inflate, and the response time will
increase respective to the size of the queue times the average per-session
response time. When clients will wait for more than a few seconds, they will
often hit the "STOP" button on their browser, leaving a useless request in
the queue, and slowing down other users, and the servers as well, because the
request will eventually be served, then aborted at the first error
encountered while delivering the response.
As there is no way to distinguish between a full STOP and a simple output
close on the client side, HTTP agents should be conservative and consider
that the client might only have closed its output channel while waiting for
the response. However, this introduces risks of congestion when lots of users
do the same, and is completely useless nowadays because probably no client at
all will close the session while waiting for the response. Some HTTP agents
support this behavior (Squid, Apache, HAProxy), and others do not (TUX, most
hardware-based load balancers). So the probability for a closed input channel
to represent a user hitting the "STOP" button is close to 100%, and the risk
of being the single component to break rare but valid traffic is extremely
low, which adds to the temptation to be able to abort a session early while
still not served and not pollute the servers.
In HAProxy, the user can choose the desired behavior using the option
"abortonclose". By default (without the option) the behavior is HTTP
compliant and aborted requests will be served. But when the option is
specified, a session with an incoming channel closed will be aborted while
it is still possible, either pending in the queue for a connection slot, or
during the connection establishment if the server has not yet acknowledged
the connection request. This considerably reduces the queue size and the load
on saturated servers when users are tempted to click on STOP, which in turn
reduces the response time for other users.
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
Enable or disable relaxing of HTTP request parsing
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments : none
By default, HAProxy complies with RFC7230 in terms of message parsing. This
means that invalid characters in header names are not permitted and cause an
error to be returned to the client. This is the desired behavior as such
forbidden characters are essentially used to build attacks exploiting server
weaknesses, and bypass security filtering. Sometimes, a buggy browser or
server will emit invalid header names for whatever reason (configuration,
implementation) and the issue will not be immediately fixed. In such a case,
it is possible to relax HAProxy's header name parser to accept any character
even if that does not make sense, by specifying this option. Similarly, the
list of characters allowed to appear in a URI is well defined by RFC3986, and
chars 0-31, 32 (space), 34 ('"'), 60 ('<'), 62 ('>'), 92 ('\'), 94 ('^'), 96
('`'), 123 ('{'), 124 ('|'), 125 ('}'), 127 (delete) and anything above are
not allowed at all. HAProxy always blocks a number of them (0..32, 127). The
remaining ones are blocked by default unless this option is enabled. This
option also relaxes the test on the HTTP version, it allows HTTP/0.9 requests
to pass through (no version specified) and multiple digits for both the major
and the minor version. Finally, this option also allows incoming URLs to
contain fragment references ('#' after the path).
This option should never be enabled by default as it hides application bugs
and open security breaches. It should only be deployed after a problem has
been confirmed.
When this option is enabled, erroneous header names will still be accepted in
requests, but the complete request will be captured in order to permit later
analysis using the "show errors" request on the UNIX stats socket. Similarly,
requests containing invalid chars in the URI part will be logged. Doing this
also helps confirming that the issue has been solved.
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
See also : "option accept-invalid-http-response" and "show errors" on the stats socket.
Enable or disable relaxing of HTTP response parsing
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments : none
By default, HAProxy complies with RFC7230 in terms of message parsing. This
means that invalid characters in header names are not permitted and cause an
error to be returned to the client. This is the desired behavior as such
forbidden characters are essentially used to build attacks exploiting server
weaknesses, and bypass security filtering. Sometimes, a buggy browser or
server will emit invalid header names for whatever reason (configuration,
implementation) and the issue will not be immediately fixed. In such a case,
it is possible to relax HAProxy's header name parser to accept any character
even if that does not make sense, by specifying this option. This option also
relaxes the test on the HTTP version format, it allows multiple digits for
both the major and the minor version.
This option should never be enabled by default as it hides application bugs
and open security breaches. It should only be deployed after a problem has
been confirmed.
When this option is enabled, erroneous header names will still be accepted in
responses, but the complete response will be captured in order to permit
later analysis using the "show errors" request on the UNIX stats socket.
Doing this also helps confirming that the issue has been solved.
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
See also : "option accept-invalid-http-request" and "show errors" on the stats socket.
Use either all backup servers at a time or only the first one
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments : none
By default, the first operational backup server gets all traffic when normal
servers are all down. Sometimes, it may be preferred to use multiple backups
at once, because one will not be enough. When "option allbackups" is enabled,
the load balancing will be performed among all backup servers when all normal
ones are unavailable. The same load balancing algorithm will be used and the
servers' weights will be respected. Thus, there will not be any priority
order between the backup servers anymore.
This option is mostly used with static server farms dedicated to return a
"sorry" page when an application is completely offline.
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
Analyze all server responses and block responses with cacheable cookies
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments : none
Some high-level frameworks set application cookies everywhere and do not
always let enough control to the developer to manage how the responses should
be cached. When a session cookie is returned on a cacheable object, there is a
high risk of session crossing or stealing between users traversing the same
caches. In some situations, it is better to block the response than to let
some sensitive session information go in the wild.
The option "checkcache" enables deep inspection of all server responses for
strict compliance with HTTP specification in terms of cacheability. It
carefully checks "Cache-control", "Pragma" and "Set-cookie" headers in server
response to check if there's a risk of caching a cookie on a client-side
proxy. When this option is enabled, the only responses which can be delivered
to the client are :
- all those without "Set-Cookie" header;
- all those with a return code other than 200, 203, 204, 206, 300, 301,
404, 405, 410, 414, 501, provided that the server has not set a
"Cache-control: public" header field;
- all those that result from a request using a method other than GET, HEAD,
OPTIONS, TRACE, provided that the server has not set a 'Cache-Control:
public' header field;
- those with a 'Pragma: no-cache' header
- those with a 'Cache-control: private' header
- those with a 'Cache-control: no-store' header
- those with a 'Cache-control: max-age=0' header
- those with a 'Cache-control: s-maxage=0' header
- those with a 'Cache-control: no-cache' header
- those with a 'Cache-control: no-cache="set-cookie"' header
- those with a 'Cache-control: no-cache="set-cookie,' header
(allowing other fields after set-cookie)
If a response doesn't respect these requirements, then it will be blocked
just as if it was from an "http-response deny" rule, with an "HTTP 502 bad
gateway". The session state shows "PH--" meaning that the proxy blocked the
response during headers processing. Additionally, an alert will be sent in
the logs so that admins are informed that there's something to be fixed.
Due to the high impact on the application, the application should be tested
in depth with the option enabled before going to production. It is also a
good practice to always activate it during tests, even if it is not used in
production, as it will report potentially dangerous application behaviors.
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
Enable or disable the sending of TCP keepalive packets on the client side
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments : none
When there is a firewall or any session-aware component between a client and
a server, and when the protocol involves very long sessions with long idle
periods (e.g. remote desktops), there is a risk that one of the intermediate
components decides to expire a session which has remained idle for too long.
Enabling socket-level TCP keep-alives makes the system regularly send packets
to the other end of the connection, leaving it active. The delay between
keep-alive probes is controlled by the system only and depends both on the
operating system and its tuning parameters.
It is important to understand that keep-alive packets are neither emitted nor
received at the application level. It is only the network stacks which sees
them. For this reason, even if one side of the proxy already uses keep-alives
to maintain its connection alive, those keep-alive packets will not be
forwarded to the other side of the proxy.
Please note that this has nothing to do with HTTP keep-alive.
Using option "clitcpka" enables the emission of TCP keep-alive probes on the
client side of a connection, which should help when session expirations are
noticed between HAProxy and a client.
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
See also : "option srvtcpka", "option tcpka"
Enable continuous traffic statistics updates
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments : none
By default, counters used for statistics calculation are incremented
only when a session finishes. It works quite well when serving small
objects, but with big ones (for example large images or archives) or
with A/V streaming, a graph generated from HAProxy counters looks like
a hedgehog. With this option enabled counters get incremented frequently
along the session, typically every 5 seconds, which is often enough to
produce clean graphs. Recounting touches a hotpath directly so it is not
not enabled by default, as it can cause a lot of wakeups for very large
session counts and cause a small performance drop.
Enable or disable the implicit HTTP/2 upgrade from an HTTP/1.x client
connection.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments : none
By default, HAProxy is able to implicitly upgrade an HTTP/1.x client
connection to an HTTP/2 connection if the first request it receives from a
given HTTP connection matches the HTTP/2 connection preface (i.e. the string
"PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n"). This way, it is possible to support
HTTP/1.x and HTTP/2 clients on a non-SSL connections. This option must be
used to disable the implicit upgrade. Note this implicit upgrade is only
supported for HTTP proxies, thus this option too. Note also it is possible to
force the HTTP/2 on clear connections by specifying "proto h2" on the bind
line. Finally, this option is applied on all bind lines. To disable implicit
HTTP/2 upgrades for a specific bind line, it is possible to use "proto h1".
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
Enable or disable logging of normal, successful connections
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments : none
There are large sites dealing with several thousand connections per second
and for which logging is a major pain. Some of them are even forced to turn
logs off and cannot debug production issues. Setting this option ensures that
normal connections, those which experience no error, no timeout, no retry nor
redispatch, will not be logged. This leaves disk space for anomalies. In HTTP
mode, the response status code is checked and return codes 5xx will still be
logged.
It is strongly discouraged to use this option as most of the time, the key to
complex issues is in the normal logs which will not be logged here. If you
need to separate logs, see the "log-separate-errors" option instead.
Enable or disable logging of null connections
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments : none
In certain environments, there are components which will regularly connect to
various systems to ensure that they are still alive. It can be the case from
another load balancer as well as from monitoring systems. By default, even a
simple port probe or scan will produce a log. If those connections pollute
the logs too much, it is possible to enable option "dontlognull" to indicate
that a connection on which no data has been transferred will not be logged,
which typically corresponds to those probes. Note that errors will still be
returned to the client and accounted for in the stats. If this is not what is
desired, option http-ignore-probes can be used instead.
It is generally recommended not to use this option in uncontrolled
environments (e.g. internet), otherwise scans and other malicious activities
would not be logged.
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
Enable insertion of the X-Forwarded-For header to requests sent to servers
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
<network> is an optional argument used to disable this option for sources
matching <network>
<name> an optional argument to specify a different "X-Forwarded-For"
header name.
Since HAProxy works in reverse-proxy mode, the servers see its IP address as
their client address. This is sometimes annoying when the client's IP address
is expected in server logs. To solve this problem, the well-known HTTP header
"X-Forwarded-For" may be added by HAProxy to all requests sent to the server.
This header contains a value representing the client's IP address. Since this
header is always appended at the end of the existing header list, the server
must be configured to always use the last occurrence of this header only. See
the server's manual to find how to enable use of this standard header. Note
that only the last occurrence of the header must be used, since it is really
possible that the client has already brought one.
The keyword "header" may be used to supply a different header name to replace
the default "X-Forwarded-For". This can be useful where you might already
have a "X-Forwarded-For" header from a different application (e.g. stunnel),
and you need preserve it. Also if your backend server doesn't use the
"X-Forwarded-For" header and requires different one (e.g. Zeus Web Servers
require "X-Cluster-Client-IP").
Sometimes, a same HAProxy instance may be shared between a direct client
access and a reverse-proxy access (for instance when an SSL reverse-proxy is
used to decrypt HTTPS traffic). It is possible to disable the addition of the
header for a known source address or network by adding the "except" keyword
followed by the network address. In this case, any source IP matching the
network will not cause an addition of this header. Most common uses are with
private networks or 127.0.0.1. IPv4 and IPv6 are both supported.
Alternatively, the keyword "if-none" states that the header will only be
added if it is not present. This should only be used in perfectly trusted
environment, as this might cause a security issue if headers reaching HAProxy
are under the control of the end-user.
This option may be specified either in the frontend or in the backend. If at
least one of them uses it, the header will be added. Note that the backend's
setting of the header subargument takes precedence over the frontend's if
both are defined. In the case of the "if-none" argument, if at least one of
the frontend or the backend does not specify it, it wants the addition to be
mandatory, so it wins.
Example :
# Public HTTP address also used by stunnel on the same machine
frontend www
mode http
option forwardfor except 127.0.0.1 # stunnel already adds the header
# Those servers want the IP Address in X-Client
backend www
mode http
option forwardfor header X-Client
Enable or disable the case adjustment of HTTP/1 headers sent to bogus clients
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments : none
There is no standard case for header names because, as stated in RFC7230,
they are case-insensitive. So applications must handle them in a case-
insensitive manner. But some bogus applications violate the standards and
erroneously rely on the cases most commonly used by browsers. This problem
becomes critical with HTTP/2 because all header names must be exchanged in
lower case, and HAProxy follows the same convention. All header names are
sent in lower case to clients and servers, regardless of the HTTP version.
When HAProxy receives an HTTP/1 response, its header names are converted to
lower case and manipulated and sent this way to the clients. If a client is
known to violate the HTTP standards and to fail to process a response coming
from HAProxy, it is possible to transform the lower case header names to a
different format when the response is formatted and sent to the client, by
enabling this option and specifying the list of headers to be reformatted
using the global directives "h1-case-adjust" or "h1-case-adjust-file". This
must only be a temporary workaround for the time it takes the client to be
fixed, because clients which require such workarounds might be vulnerable to
content smuggling attacks and must absolutely be fixed.
Please note that this option will not affect standards-compliant clients.
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
Enable or disable the case adjustment of HTTP/1 headers sent to bogus servers
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments : none
There is no standard case for header names because, as stated in RFC7230,
they are case-insensitive. So applications must handle them in a case-
insensitive manner. But some bogus applications violate the standards and
erroneously rely on the cases most commonly used by browsers. This problem
becomes critical with HTTP/2 because all header names must be exchanged in
lower case, and HAProxy follows the same convention. All header names are
sent in lower case to clients and servers, regardless of the HTTP version.
When HAProxy receives an HTTP/1 request, its header names are converted to
lower case and manipulated and sent this way to the servers. If a server is
known to violate the HTTP standards and to fail to process a request coming
from HAProxy, it is possible to transform the lower case header names to a
different format when the request is formatted and sent to the server, by
enabling this option and specifying the list of headers to be reformatted
using the global directives "h1-case-adjust" or "h1-case-adjust-file". This
must only be a temporary workaround for the time it takes the server to be
fixed, because servers which require such workarounds might be vulnerable to
content smuggling attacks and must absolutely be fixed.
Please note that this option will not affect standards-compliant servers.
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
Enable or disable waiting for whole HTTP request body before proceeding
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments : none
It is sometimes desirable to wait for the body of an HTTP request before
taking a decision. This is what is being done by "balance url_param" for
example. The first use case is to buffer requests from slow clients before
connecting to the server. Another use case consists in taking the routing
decision based on the request body's contents. This option placed in a
frontend or backend forces the HTTP processing to wait until either the whole
body is received or the request buffer is full. It can have undesired side
effects with some applications abusing HTTP by expecting unbuffered
transmissions between the frontend and the backend, so this should definitely
not be used by default.
Enable or disable logging of null connections and request timeouts
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments : none
Recently some browsers started to implement a "pre-connect" feature
consisting in speculatively connecting to some recently visited web sites
just in case the user would like to visit them. This results in many
connections being established to web sites, which end up in 408 Request
Timeout if the timeout strikes first, or 400 Bad Request when the browser
decides to close them first. These ones pollute the log and feed the error
counters. There was already "option dontlognull" but it's insufficient in
this case. Instead, this option does the following things :
- prevent any 400/408 message from being sent to the client if nothing
was received over a connection before it was closed;
- prevent any log from being emitted in this situation;
- prevent any error counter from being incremented
That way the empty connection is silently ignored. Note that it is better
not to use this unless it is clear that it is needed, because it will hide
real problems. The most common reason for not receiving a request and seeing
a 408 is due to an MTU inconsistency between the client and an intermediary
element such as a VPN, which blocks too large packets. These issues are
generally seen with POST requests as well as GET with large cookies. The logs
are often the only way to detect them.
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
Enable or disable HTTP keep-alive from client to server for HTTP/1.x
connections
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments : none
By default HAProxy operates in keep-alive mode with regards to persistent
HTTP/1.x connections: for each connection it processes each request and
response, and leaves the connection idle on both sides. This mode may be
changed by several options such as "option http-server-close" or "option
httpclose". This option allows to set back the keep-alive mode, which can be
useful when another mode was used in a defaults section.
Setting "option http-keep-alive" enables HTTP keep-alive mode on the client-
and server- sides. This provides the lowest latency on the client side (slow
network) and the fastest session reuse on the server side at the expense
of maintaining idle connections to the servers. In general, it is possible
with this option to achieve approximately twice the request rate that the
"http-server-close" option achieves on small objects. There are mainly two
situations where this option may be useful :
- when the server is non-HTTP compliant and authenticates the connection
instead of requests (e.g. NTLM authentication)
- when the cost of establishing the connection to the server is significant
compared to the cost of retrieving the associated object from the server.
This last case can happen when the server is a fast static server of cache.
At the moment, logs will not indicate whether requests came from the same
session or not. The accept date reported in the logs corresponds to the end
of the previous request, and the request time corresponds to the time spent
waiting for a new request. The keep-alive request time is still bound to the
timeout defined by "timeout http-keep-alive" or "timeout http-request" if
not set.
This option disables and replaces any previous "option httpclose" or "option
http-server-close".
See also : "option httpclose",, "option http-server-close", "option prefer-last-server" and "option http-pretend-keepalive".
Instruct the system to favor low interactive delays over performance in HTTP
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments : none
In HTTP, each payload is unidirectional and has no notion of interactivity.
Any agent is expected to queue data somewhat for a reasonably low delay.
There are some very rare server-to-server applications that abuse the HTTP
protocol and expect the payload phase to be highly interactive, with many
interleaved data chunks in both directions within a single request. This is
absolutely not supported by the HTTP specification and will not work across
most proxies or servers. When such applications attempt to do this through
HAProxy, it works but they will experience high delays due to the network
optimizations which favor performance by instructing the system to wait for
enough data to be available in order to only send full packets. Typical
delays are around 200 ms per round trip. Note that this only happens with
abnormal uses. Normal uses such as CONNECT requests nor WebSockets are not
affected.
When "option http-no-delay" is present in either the frontend or the backend
used by a connection, all such optimizations will be disabled in order to
make the exchanges as fast as possible. Of course this offers no guarantee on
the functionality, as it may break at any other place. But if it works via
HAProxy, it will work as fast as possible. This option should never be used
by default, and should never be used at all unless such a buggy application
is discovered. The impact of using this option is an increase of bandwidth
usage and CPU usage, which may significantly lower performance in high
latency environments.
See also : "option http-buffer-request"
Define whether HAProxy will announce keepalive for HTTP/1.x connection to the
server or not
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments : none
When running with "option http-server-close" or "option httpclose", HAProxy
adds a "Connection: close" header to the HTTP/1.x request forwarded to the
server. Unfortunately, when some servers see this header, they automatically
refrain from using the chunked encoding for responses of unknown length,
while this is totally unrelated. The effect is that a client or a cache could
receive an incomplete response without being aware of it, and consider the
response complete.
By setting "option http-pretend-keepalive", HAProxy will make the server
believe it will keep the connection alive. The server will then not fall back
to the abnormal undesired above. When HAProxy gets the whole response, it
will close the connection with the server just as it would do with the
"option httpclose". That way the client gets a normal response and the
connection is correctly closed on the server side.
It is recommended not to enable this option by default, because most servers
will more efficiently close the connection themselves after the last packet,
and release its buffers slightly earlier. Also, the added packet on the
network could slightly reduce the overall peak performance. However it is
worth noting that when this option is enabled, HAProxy will have slightly
less work to do. So if HAProxy is the bottleneck on the whole architecture,
enabling this option might save a few CPU cycles.
This option may be set in backend and listen sections. Using it in a frontend
section will be ignored and a warning will be reported during startup. It is
a backend related option, so there is no real reason to set it on a
frontend.
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
Set HAProxy policy about HTTP request header names containing characters
outside the "[a-zA-Z0-9-]" charset
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
preserve disable the filtering. It is the default mode for HTTP proxies
with no FastCGI application configured.
delete remove request headers with a name containing a character
outside the "[a-zA-Z0-9-]" charset. It is the default mode for
HTTP backends with a configured FastCGI application.
reject reject the request with a 403-Forbidden response if it contains a
header name with a character outside the "[a-zA-Z0-9-]" charset.
This option may be used to restrict the request header names to alphanumeric
and hyphen characters ([A-Za-z0-9-]). This may be mandatory to interoperate
with non-HTTP compliant servers that fail to handle some characters in header
names. It may also be mandatory for FastCGI applications because all
non-alphanumeric characters in header names are replaced by an underscore
('_'). Thus, it is easily possible to mix up header names and bypass some
rules. For instance, "X-Forwarded-For" and "X_Forwarded-For" headers are both
converted to "HTTP_X_FORWARDED_FOR" in FastCGI.
Note this option is evaluated per proxy and after the http-request rules
evaluation.
Enable or disable HTTP/1.x connection closing on the server side
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments : none
By default HAProxy operates in keep-alive mode with regards to persistent
HTTP/1.x connections: for each connection it processes each request and
response, and leaves the connection idle on both sides. This mode may be
changed by several options such as "option http-server-close" or "option
httpclose". Setting "option http-server-close" enables HTTP connection-close
mode on the server side while keeping the ability to support HTTP keep-alive
and pipelining on the client side. This provides the lowest latency on the
client side (slow network) and the fastest session reuse on the server side
to save server resources, similarly to "option httpclose". It also permits
non-keepalive capable servers to be served in keep-alive mode to the clients
if they conform to the requirements of RFC7230. Please note that some servers
do not always conform to those requirements when they see "Connection: close"
in the request. The effect will be that keep-alive will never be used. A
workaround consists in enabling "option http-pretend-keepalive".
At the moment, logs will not indicate whether requests came from the same
session or not. The accept date reported in the logs corresponds to the end
of the previous request, and the request time corresponds to the time spent
waiting for a new request. The keep-alive request time is still bound to the
timeout defined by "timeout http-keep-alive" or "timeout http-request" if
not set.
This option may be set both in a frontend and in a backend. It is enabled if
at least one of the frontend or backend holding a connection has it enabled.
It disables and replaces any previous "option httpclose" or "option
http-keep-alive". Please check section 4 ("Proxies") to see how this option
combines with others when frontend and backend options differ.
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
Make use of non-standard Proxy-Connection header instead of Connection
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments : none
While RFC7230 explicitly states that HTTP/1.1 agents must use the
Connection header to indicate their wish of persistent or non-persistent
connections, both browsers and proxies ignore this header for proxied
connections and make use of the undocumented, non-standard Proxy-Connection
header instead. The issue begins when trying to put a load balancer between
browsers and such proxies, because there will be a difference between what
HAProxy understands and what the client and the proxy agree on.
By setting this option in a frontend, HAProxy can automatically switch to use
that non-standard header if it sees proxied requests. A proxied request is
defined here as one where the URI begins with neither a '/' nor a '*'. This
is incompatible with the HTTP tunnel mode. Note that this option can only be
specified in a frontend and will affect the request along its whole life.
Also, when this option is set, a request which requires authentication will
automatically switch to use proxy authentication headers if it is itself a
proxied request. That makes it possible to check or enforce authentication in
front of an existing proxy.
This option should normally never be used, except in front of a proxy.
See also : "option httpclose", and "option http-server-close".
Enables HTTP protocol to check on the servers health
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<method> is the optional HTTP method used with the requests. When not set,
the "OPTIONS" method is used, as it generally requires low server
processing and is easy to filter out from the logs. Any method
may be used, though it is not recommended to invent non-standard
ones.
<uri> is the URI referenced in the HTTP requests. It defaults to " / "
which is accessible by default on almost any server, but may be
changed to any other URI. Query strings are permitted.
<version> is the optional HTTP version string. It defaults to "HTTP/1.0"
but some servers might behave incorrectly in HTTP 1.0, so turning
it to HTTP/1.1 may sometimes help. Note that the Host field is
mandatory in HTTP/1.1, use "http-check send" directive to add it.
By default, server health checks only consist in trying to establish a TCP
connection. When "option httpchk" is specified, a complete HTTP request is
sent once the TCP connection is established, and responses 2xx and 3xx are
considered valid, while all other ones indicate a server failure, including
the lack of any response.
Combined with "http-check" directives, it is possible to customize the
request sent during the HTTP health checks or the matching rules on the
response. It is also possible to configure a send/expect sequence, just like
with the directive "tcp-check" for TCP health checks.
The server configuration is used by default to open connections to perform
HTTP health checks. By it is also possible to overwrite server parameters
using "http-check connect" rules.
"httpchk" option does not necessarily require an HTTP backend, it also works
with plain TCP backends. This is particularly useful to check simple scripts
bound to some dedicated ports using the inetd daemon. However, it will always
internally relies on an HTX multiplexer. Thus, it means the request
formatting and the response parsing will be strict.
Note : For a while, there was no way to add headers or body in the request
used for HTTP health checks. So a workaround was to hide it at the end
of the version string with a "\r\n" after the version. It is now
deprecated. The directive "http-check send" must be used instead.
Examples :
# Relay HTTPS traffic to Apache instance and check service availability
# using HTTP request "OPTIONS * HTTP/1.1" on port 80.
backend https_relay
mode tcp
option httpchk OPTIONS * HTTP/1.1
http-check send hdr Host www
server apache1 192.168.1.1:443 check port 80
See also : "option ssl-hello-chk", "option smtpchk", "option mysql-check", "option pgsql-check", "http-check" and the "check", "port" and "inter" server options.
Enable or disable HTTP/1.x connection closing
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments : none
By default HAProxy operates in keep-alive mode with regards to persistent
HTTP/1.x connections: for each connection it processes each request and
response, and leaves the connection idle on both sides. This mode may be
changed by several options such as "option http-server-close" or "option
httpclose".
If "option httpclose" is set, HAProxy will close the client or the server
connection, depending where the option is set. Only the frontend is
considered for client connections while the frontend and the backend are
considered for server ones. In this case the option is enabled if at least
one of the frontend or backend holding the connection has it enabled. If the
option is set on a listener, it is applied both on client and server
connections. It will check if a "Connection: close" header is already set in
each direction, and will add one if missing.
This option may also be combined with "option http-pretend-keepalive", which
will disable sending of the "Connection: close" request header, but will
still cause the connection to be closed once the whole response is received.
It disables and replaces any previous "option http-server-close" or "option
http-keep-alive".
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
See also : "option http-server-close".
Enable logging of HTTP request, session state and timers
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments :
clf if the "clf" argument is added, then the output format will be
the CLF format instead of HAProxy's default HTTP format. You can
use this when you need to feed HAProxy's logs through a specific
log analyzer which only support the CLF format and which is not
extensible.
By default, the log output format is very poor, as it only contains the
source and destination addresses, and the instance name. By specifying
"option httplog", each log line turns into a much richer format including,
but not limited to, the HTTP request, the connection timers, the session
status, the connections numbers, the captured headers and cookies, the
frontend, backend and server name, and of course the source address and
ports.
Specifying only "option httplog" will automatically clear the 'clf' mode
if it was set by default.
"option httplog" overrides any previous "log-format" directive.
See also : section 8 about logging.
Enable or disable plain HTTP proxy mode
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments : none
It sometimes happens that people need a pure HTTP proxy which understands
basic proxy requests without caching nor any fancy feature. In this case,
it may be worth setting up an HAProxy instance with the "option http_proxy"
set. In this mode, no server is declared, and the connection is forwarded to
the IP address and port found in the URL after the "http://" scheme.
No host address resolution is performed, so this only works when pure IP
addresses are passed. Since this option's usage perimeter is rather limited,
it will probably be used only by experts who know they need exactly it. This
is incompatible with the HTTP tunnel mode.
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
Example :
# this backend understands HTTP proxy requests and forwards them directly.
backend direct_forward
option httpclose
option http_proxy
See also : "option httpclose"
Enable or disable independent timeout processing for both directions
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments : none
By default, when data is sent over a socket, both the write timeout and the
read timeout for that socket are refreshed, because we consider that there is
activity on that socket, and we have no other means of guessing if we should
receive data or not.
While this default behavior is desirable for almost all applications, there
exists a situation where it is desirable to disable it, and only refresh the
read timeout if there are incoming data. This happens on sessions with large
timeouts and low amounts of exchanged data such as telnet session. If the
server suddenly disappears, the output data accumulates in the system's
socket buffers, both timeouts are correctly refreshed, and there is no way
to know the server does not receive them, so we don't timeout. However, when
the underlying protocol always echoes sent data, it would be enough by itself
to detect the issue using the read timeout. Note that this problem does not
happen with more verbose protocols because data won't accumulate long in the
socket buffers.
When this option is set on the frontend, it will disable read timeout updates
on data sent to the client. There probably is little use of this case. When
the option is set on the backend, it will disable read timeout updates on
data sent to the server. Doing so will typically break large HTTP posts from
slow lines, so use it with caution.
Use LDAPv3 health checks for server testing
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments : none
It is possible to test that the server correctly talks LDAPv3 instead of just
testing that it accepts the TCP connection. When this option is set, an
LDAPv3 anonymous simple bind message is sent to the server, and the response
is analyzed to find an LDAPv3 bind response message.
The server is considered valid only when the LDAP response contains success
resultCode (http://tools.ietf.org/html/rfc4511#section-4.1.9).
Logging of bind requests is server dependent see your documentation how to
configure it.
Example :
option ldap-check
See also : "option httpchk"
Use external processes for server health checks
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
It is possible to test the health of a server using an external command.
This is achieved by running the executable set using "external-check
command".
Requires the "external-check" global to be set.
Avoid closing idle frontend connections if a soft stop is in progress
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments : none
By default, idle connections will be closed during a soft stop. In some
environments, a client talking to the proxy may have prepared some idle
connections in order to send requests later. If there is no proper retry on
write errors, this can result in errors while haproxy is reloading. Even
though a proper implementation should retry on connection/write errors, this
option was introduced to support backwards compatibility with haproxy prior
to version 2.4. Indeed before v2.4, haproxy used to wait for a last request
and response to add a "connection: close" header before closing, thus
notifying the client that the connection would not be reusable.
In a real life example, this behavior was seen in AWS using the ALB in front
of a haproxy. The end result was ALB sending 502 during haproxy reloads.
Users are warned that using this option may increase the number of old
processes if connections remain idle for too long. Adjusting the client
timeouts and/or the "hard-stop-after" parameter accordingly might be
needed in case of frequent reloads.
Enable or disable logging of health checks status updates
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments : none
By default, failed health check are logged if server is UP and successful
health checks are logged if server is DOWN, so the amount of additional
information is limited.
When this option is enabled, any change of the health check status or to
the server's health will be logged, so that it becomes possible to know
that a server was failing occasional checks before crashing, or exactly when
it failed to respond a valid HTTP status, then when the port started to
reject connections, then when the server stopped responding at all.
Note that status changes not caused by health checks (e.g. enable/disable on
the CLI) are intentionally not logged by this option.
See also: "option httpchk", "option ldap-check", "option mysql-check", "option pgsql-check", "option redis-check", "option smtpchk", "option tcp-check", "log" and section 8 about logging.
Change log level for non-completely successful connections
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments : none
Sometimes looking for errors in logs is not easy. This option makes HAProxy
raise the level of logs containing potentially interesting information such
as errors, timeouts, retries, redispatches, or HTTP status codes 5xx. The
level changes from "info" to "err". This makes it possible to log them
separately to a different file with most syslog daemons. Be careful not to
remove them from the original file, otherwise you would lose ordering which
provides very important information.
Using this option, large sites dealing with several thousand connections per
second may log normal traffic to a rotating buffer and only archive smaller
error logs.
Enable or disable early logging.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments : none
By default, logs are emitted when all the log format variables and sample
fetches used in the definition of the log-format string return a value, or
when the session is terminated. This allows the built in log-format strings
to account for the transfer time, or the number of bytes in log messages.
When handling long lived connections such as large file transfers or RDP,
it may take a while for the request or connection to appear in the logs.
Using "option logasap", the log message is created as soon as the server
connection is established in mode tcp, or as soon as the server sends the
complete headers in mode http. Missing information in the logs will be the
total number of bytes which will only indicate the amount of data transferred
before the message was created and the total time which will not take the
remainder of the connection life or transfer time into account. For the case
of HTTP, it is good practice to capture the Content-Length response header
so that the logs at least indicate how many bytes are expected to be
transferred.
Examples :
listen http_proxy 0.0.0.0:80
mode http
option httplog
option logasap
log 192.168.2.200 local3
>>> Feb 6 12:14:14 localhost \
haproxy[14389]: 10.0.1.2:33317 [06/Feb/2009:12:14:14.655] http-in \
static/srv1 9/10/7/14/+30 200 +243 - - ---- 3/1/1/1/0 1/0 \
"GET /image.iso HTTP/1.0"
Use MySQL health checks for server testing
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<username> This is the username which will be used when connecting to MySQL
server.
post-41 Send post v4.1 client compatible checks (the default)
pre-41 Send pre v4.1 client compatible checks
If you specify a username, the check consists of sending two MySQL packet,
one Client Authentication packet, and one QUIT packet, to correctly close
MySQL session. We then parse the MySQL Handshake Initialization packet and/or
Error packet. It is a basic but useful test which does not produce error nor
aborted connect on the server. However, it requires an unlocked authorised
user without a password. To create a basic limited user in MySQL with
optional resource limits:
CREATE USER '<username>'@'<ip_of_haproxy|network_of_haproxy/netmask>'
/*!50701 WITH MAX_QUERIES_PER_HOUR 1 MAX_UPDATES_PER_HOUR 0 */
/*M!100201 MAX_STATEMENT_TIME 0.0001 */;
If you don't specify a username (it is deprecated and not recommended), the
check only consists in parsing the Mysql Handshake Initialization packet or
Error packet, we don't send anything in this mode. It was reported that it
can generate lockout if check is too frequent and/or if there is not enough
traffic. In fact, you need in this case to check MySQL "max_connect_errors"
value as if a connection is established successfully within fewer than MySQL
"max_connect_errors" attempts after a previous connection was interrupted,
the error count for the host is cleared to zero. If HAProxy's server get
blocked, the "FLUSH HOSTS" statement is the only way to unblock it.
Remember that this does not check database presence nor database consistency.
To do this, you can use an external check with xinetd for example.
The check requires MySQL >=3.22, for older version, please use TCP check.
Most often, an incoming MySQL server needs to see the client's IP address for
various purposes, including IP privilege matching and connection logging.
When possible, it is often wise to masquerade the client's IP address when
connecting to the server using the "usesrc" argument of the "source" keyword,
which requires the transparent proxy feature to be compiled in, and the MySQL
server to route the client via the machine hosting HAProxy.
See also: "option httpchk"
Enable or disable immediate session resource cleaning after close
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments : none
When clients or servers abort connections in a dirty way (e.g. they are
physically disconnected), the session timeouts triggers and the session is
closed. But it will remain in FIN_WAIT1 state for some time in the system,
using some resources and possibly limiting the ability to establish newer
connections.
When this happens, it is possible to activate "option nolinger" which forces
the system to immediately remove any socket's pending data on close. Thus,
a TCP RST is emitted, any pending data are truncated, and the session is
instantly purged from the system's tables. The generally visible effect for
a client is that responses are truncated if the close happens with a last
block of data (e.g. on a redirect or error response). On the server side,
it may help release the source ports immediately when forwarding a client
aborts in tunnels. In both cases, TCP resets are emitted and given that
the session is instantly destroyed, there will be no retransmit. On a lossy
network this can increase problems, especially when there is a firewall on
the lossy side, because the firewall might see and process the reset (hence
purge its session) and block any further traffic for this session,, including
retransmits from the other side. So if the other side doesn't receive it,
it will never receive any RST again, and the firewall might log many blocked
packets.
For all these reasons, it is strongly recommended NOT to use this option,
unless absolutely needed as a last resort. In most situations, using the
"client-fin" or "server-fin" timeouts achieves similar results with a more
reliable behavior. On Linux it's also possible to use the "tcp-ut" bind or
server setting.
This option may be used both on frontends and backends, depending on the side
where it is required. Use it on the frontend for clients, and on the backend
for servers. While this option is technically supported in "defaults"
sections, it must really not be used there as it risks to accidentally
propagate to sections that must no use it and to cause problems there.
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
Enable insertion of the X-Original-To header to requests sent to servers
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
<network> is an optional argument used to disable this option for sources
matching <network>
<name> an optional argument to specify a different "X-Original-To"
header name.
Since HAProxy can work in transparent mode, every request from a client can
be redirected to the proxy and HAProxy itself can proxy every request to a
complex SQUID environment and the destination host from SO_ORIGINAL_DST will
be lost. This is annoying when you want access rules based on destination ip
addresses. To solve this problem, a new HTTP header "X-Original-To" may be
added by HAProxy to all requests sent to the server. This header contains a
value representing the original destination IP address. Since this must be
configured to always use the last occurrence of this header only. Note that
only the last occurrence of the header must be used, since it is really
possible that the client has already brought one.
The keyword "header" may be used to supply a different header name to replace
the default "X-Original-To". This can be useful where you might already
have a "X-Original-To" header from a different application, and you need
preserve it. Also if your backend server doesn't use the "X-Original-To"
header and requires different one.
Sometimes, a same HAProxy instance may be shared between a direct client
access and a reverse-proxy access (for instance when an SSL reverse-proxy is
used to decrypt HTTPS traffic). It is possible to disable the addition of the
header for a known destination address or network by adding the "except"
keyword followed by the network address. In this case, any destination IP
matching the network will not cause an addition of this header. Most common
uses are with private networks or 127.0.0.1. IPv4 and IPv6 are both
supported.
This option may be specified either in the frontend or in the backend. If at
least one of them uses it, the header will be added. Note that the backend's
setting of the header subargument takes precedence over the frontend's if
both are defined.
Examples :
# Original Destination address
frontend www
mode http
option originalto except 127.0.0.1
# Those servers want the IP Address in X-Client-Dst
backend www
mode http
option originalto header X-Client-Dst
See also : "option httpclose", "option http-server-close".
Enable or disable forced persistence on down servers
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments : none
When an HTTP request reaches a backend with a cookie which references a dead
server, by default it is redispatched to another server. It is possible to
force the request to be sent to the dead server first using "option persist"
if absolutely needed. A common use case is when servers are under extreme
load and spend their time flapping. In this case, the users would still be
directed to the server they opened the session on, in the hope they would be
correctly served. It is recommended to use "option redispatch" in conjunction
with this option so that in the event it would not be possible to connect to
the server at all (server definitely dead), the client would finally be
redirected to another valid server.
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
Use PostgreSQL health checks for server testing
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<username> This is the username which will be used when connecting to
PostgreSQL server.
The check sends a PostgreSQL StartupMessage and waits for either
Authentication request or ErrorResponse message. It is a basic but useful
test which does not produce error nor aborted connect on the server.
This check is identical with the "mysql-check".
See also: "option httpchk"
Allow multiple load balanced requests to remain on the same server
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments : none
When the load balancing algorithm in use is not deterministic, and a previous
request was sent to a server to which HAProxy still holds a connection, it is
sometimes desirable that subsequent requests on a same session go to the same
server as much as possible. Note that this is different from persistence, as
we only indicate a preference which HAProxy tries to apply without any form
of warranty. The real use is for keep-alive connections sent to servers. When
this option is used, HAProxy will try to reuse the same connection that is
attached to the server instead of rebalancing to another server, causing a
close of the connection. This can make sense for static file servers. It does
not make much sense to use this in combination with hashing algorithms. Note,
HAProxy already automatically tries to stick to a server which sends a 401 or
to a proxy which sends a 407 (authentication required), when the load
balancing algorithm is not deterministic. This is mandatory for use with the
broken NTLM authentication challenge, and significantly helps in
troubleshooting some faulty applications. Option prefer-last-server might be
desirable in these environments as well, to avoid redistributing the traffic
after every other response.
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
See also: "option http-keep-alive"
Enable or disable session redistribution in case of connection failure
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<interval> The optional integer value that controls how often redispatches
occur when retrying connections. Positive value P indicates a
redispatch is desired on every Pth retry, and negative value
N indicate a redispatch is desired on the Nth retry prior to the
last retry. For example, the default of -1 preserves the
historical behavior of redispatching on the last retry, a
positive value of 1 would indicate a redispatch on every retry,
and a positive value of 3 would indicate a redispatch on every
third retry. You can disable redispatches with a value of 0.
In HTTP mode, if a server designated by a cookie is down, clients may
definitely stick to it because they cannot flush the cookie, so they will not
be able to access the service anymore.
Specifying "option redispatch" will allow the proxy to break cookie or
consistent hash based persistence and redistribute them to a working server.
Active servers are selected from a subset of the list of available
servers. Active servers that are not down or in maintenance (i.e., whose
health is not checked or that have been checked as "up"), are selected in the
following order:
1. Any active, non-backup server, if any, or,
2. If the "allbackups" option is not set, the first backup server in the
list, or
3. If the "allbackups" option is set, any backup server.
When a retry occurs, HAProxy tries to select another server than the last
one. The new server is selected from the current list of servers.
Sometimes, if the list is updated between retries (e.g., if numerous retries
occur and last longer than the time needed to check that a server is down,
remove it from the list and fall back on the list of backup servers),
connections may be redirected to a backup server, though.
It also allows to retry connections to another server in case of multiple
connection failures. Of course, it requires having "retries" set to a nonzero
value.
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
See also : "retries", "force-persist"
Use redis health checks for server testing
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments : none
It is possible to test that the server correctly talks REDIS protocol instead
of just testing that it accepts the TCP connection. When this option is set,
a PING redis command is sent to the server, and the response is analyzed to
find the "+PONG" response message.
Example :
option redis-check
Use SMTP health checks for server testing
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<hello> is an optional argument. It is the "hello" command to use. It can
be either "HELO" (for SMTP) or "EHLO" (for ESMTP). All other
values will be turned into the default command ("HELO").
<domain> is the domain name to present to the server. It may only be
specified (and is mandatory) if the hello command has been
specified. By default, "localhost" is used.
When "option smtpchk" is set, the health checks will consist in TCP
connections followed by an SMTP command. By default, this command is
"HELO localhost". The server's return code is analyzed and only return codes
starting with a "2" will be considered as valid. All other responses,
including a lack of response will constitute an error and will indicate a
dead server.
This test is meant to be used with SMTP servers or relays. Depending on the
request, it is possible that some servers do not log each connection attempt,
so you may want to experiment to improve the behavior. Using telnet on port
25 is often easier than adjusting the configuration.
Most often, an incoming SMTP server needs to see the client's IP address for
various purposes, including spam filtering, anti-spoofing and logging. When
possible, it is often wise to masquerade the client's IP address when
connecting to the server using the "usesrc" argument of the "source" keyword,
which requires the transparent proxy feature to be compiled in.
Example :
option smtpchk HELO mydomain.org
See also : "option httpchk", "source"
Enable or disable collecting & providing separate statistics for each socket.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments : none
Enable or disable automatic kernel acceleration on sockets in both directions
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments : none
When this option is enabled either on a frontend or on a backend, HAProxy
will automatically evaluate the opportunity to use kernel tcp splicing to
forward data between the client and the server, in either direction. HAProxy
uses heuristics to estimate if kernel splicing might improve performance or
not. Both directions are handled independently. Note that the heuristics used
are not much aggressive in order to limit excessive use of splicing. This
option requires splicing to be enabled at compile time, and may be globally
disabled with the global option "nosplice". Since splice uses pipes, using it
requires that there are enough spare pipes.
Important note: kernel-based TCP splicing is a Linux-specific feature which
first appeared in kernel 2.6.25. It offers kernel-based acceleration to
transfer data between sockets without copying these data to user-space, thus
providing noticeable performance gains and CPU cycles savings. Since many
early implementations are buggy, corrupt data and/or are inefficient, this
feature is not enabled by default, and it should be used with extreme care.
While it is not possible to detect the correctness of an implementation,
2.6.29 is the first version offering a properly working implementation. In
case of doubt, splicing may be globally disabled using the global "nosplice"
keyword.
Example :
option splice-auto
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
See also : "option splice-request", "option splice-response", and global options "nosplice" and "maxpipes"
Enable or disable automatic kernel acceleration on sockets for requests
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments : none
When this option is enabled either on a frontend or on a backend, HAProxy
will use kernel tcp splicing whenever possible to forward data going from
the client to the server. It might still use the recv/send scheme if there
are no spare pipes left. This option requires splicing to be enabled at
compile time, and may be globally disabled with the global option "nosplice".
Since splice uses pipes, using it requires that there are enough spare pipes.
Important note: see "option splice-auto" for usage limitations.
Example :
option splice-request
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
See also : "option splice-auto", "option splice-response", and global options "nosplice" and "maxpipes"
Enable or disable automatic kernel acceleration on sockets for responses
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments : none
When this option is enabled either on a frontend or on a backend, HAProxy
will use kernel tcp splicing whenever possible to forward data going from
the server to the client. It might still use the recv/send scheme if there
are no spare pipes left. This option requires splicing to be enabled at
compile time, and may be globally disabled with the global option "nosplice".
Since splice uses pipes, using it requires that there are enough spare pipes.
Important note: see "option splice-auto" for usage limitations.
Example :
option splice-response
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
See also : "option splice-auto", "option splice-request", and global options "nosplice" and "maxpipes"
Use SPOP health checks for server testing
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments : none
It is possible to test that the server correctly talks SPOP protocol instead
of just testing that it accepts the TCP connection. When this option is set,
a HELLO handshake is performed between HAProxy and the server, and the
response is analyzed to check no error is reported.
Example :
option spop-check
See also : "option httpchk"
Enable or disable the sending of TCP keepalive packets on the server side
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments : none
When there is a firewall or any session-aware component between a client and
a server, and when the protocol involves very long sessions with long idle
periods (e.g. remote desktops), there is a risk that one of the intermediate
components decides to expire a session which has remained idle for too long.
Enabling socket-level TCP keep-alives makes the system regularly send packets
to the other end of the connection, leaving it active. The delay between
keep-alive probes is controlled by the system only and depends both on the
operating system and its tuning parameters.
It is important to understand that keep-alive packets are neither emitted nor
received at the application level. It is only the network stacks which sees
them. For this reason, even if one side of the proxy already uses keep-alives
to maintain its connection alive, those keep-alive packets will not be
forwarded to the other side of the proxy.
Please note that this has nothing to do with HTTP keep-alive.
Using option "srvtcpka" enables the emission of TCP keep-alive probes on the
server side of a connection, which should help when session expirations are
noticed between HAProxy and a server.
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
See also : "option clitcpka", "option tcpka"
Use SSLv3 client hello health checks for server testing
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments : none
When some SSL-based protocols are relayed in TCP mode through HAProxy, it is
possible to test that the server correctly talks SSL instead of just testing
that it accepts the TCP connection. When "option ssl-hello-chk" is set, pure
SSLv3 client hello messages are sent once the connection is established to
the server, and the response is analyzed to find an SSL server hello message.
The server is considered valid only when the response contains this server
hello message.
All servers tested till there correctly reply to SSLv3 client hello messages,
and most servers tested do not even log the requests containing only hello
messages, which is appreciable.
Note that this check works even when SSL support was not built into HAProxy
because it forges the SSL message. When SSL support is available, it is best
to use native SSL health checks instead of this one.
See also: "option httpchk", "check-ssl"
Perform health checks using tcp-check send/expect sequences
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
This health check method is intended to be combined with "tcp-check" command
lists in order to support send/expect types of health check sequences.
TCP checks currently support 4 modes of operations :
- no "tcp-check" directive : the health check only consists in a connection
attempt, which remains the default mode.
- "tcp-check send" or "tcp-check send-binary" only is mentioned : this is
used to send a string along with a connection opening. With some
protocols, it helps sending a "QUIT" message for example that prevents
the server from logging a connection error for each health check. The
check result will still be based on the ability to open the connection
only.
- "tcp-check expect" only is mentioned : this is used to test a banner.
The connection is opened and HAProxy waits for the server to present some
contents which must validate some rules. The check result will be based
on the matching between the contents and the rules. This is suited for
POP, IMAP, SMTP, FTP, SSH, TELNET.
- both "tcp-check send" and "tcp-check expect" are mentioned : this is
used to test a hello-type protocol. HAProxy sends a message, the server
responds and its response is analyzed. the check result will be based on
the matching between the response contents and the rules. This is often
suited for protocols which require a binding or a request/response model.
LDAP, MySQL, Redis and SSL are example of such protocols, though they
already all have their dedicated checks with a deeper understanding of
the respective protocols.
In this mode, many questions may be sent and many answers may be
analyzed.
A fifth mode can be used to insert comments in different steps of the script.
For each tcp-check rule you create, you can add a "comment" directive,
followed by a string. This string will be reported in the log and stderr in
debug mode. It is useful to make user-friendly error reporting. The
"comment" is of course optional.
During the execution of a health check, a variable scope is made available to
store data samples, using the "tcp-check set-var" operation. Freeing those
variable is possible using "tcp-check unset-var".
Examples :
# perform a POP check (analyze only server's banner)
option tcp-check
tcp-check expect string +OK\ POP3\ ready comment POP\ protocol
# perform an IMAP check (analyze only server's banner)
option tcp-check
tcp-check expect string *\ OK\ IMAP4\ ready comment IMAP\ protocol
# look for the redis master server after ensuring it speaks well
# redis protocol, then it exits properly.
# (send a command then analyze the response 3 times)
option tcp-check
tcp-check comment PING\ phase
tcp-check send PING\r\n
tcp-check expect string +PONG
tcp-check comment role\ check
tcp-check send info\ replication\r\n
tcp-check expect string role:master
tcp-check comment QUIT\ phase
tcp-check send QUIT\r\n
tcp-check expect string +OK
forge a HTTP request, then analyze the response
(send many headers before analyzing)
option tcp-check
tcp-check comment forge\ and\ send\ HTTP\ request
tcp-check send HEAD\ /\ HTTP/1.1\r\n
tcp-check send Host:\ www.mydomain.com\r\n
tcp-check send User-Agent:\ HAProxy\ tcpcheck\r\n
tcp-check send \r\n
tcp-check expect rstring HTTP/1\..\ (2..|3..) comment check\ HTTP\ response
Enable or disable the saving of one ACK packet during the accept sequence
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments : none
When an HTTP connection request comes in, the system acknowledges it on
behalf of HAProxy, then the client immediately sends its request, and the
system acknowledges it too while it is notifying HAProxy about the new
connection. HAProxy then reads the request and responds. This means that we
have one TCP ACK sent by the system for nothing, because the request could
very well be acknowledged by HAProxy when it sends its response.
For this reason, in HTTP mode, HAProxy automatically asks the system to avoid
sending this useless ACK on platforms which support it (currently at least
Linux). It must not cause any problem, because the system will send it anyway
after 40 ms if the response takes more time than expected to come.
During complex network debugging sessions, it may be desirable to disable
this optimization because delayed ACKs can make troubleshooting more complex
when trying to identify where packets are delayed. It is then possible to
fall back to normal behavior by specifying "no option tcp-smart-accept".
It is also possible to force it for non-HTTP proxies by simply specifying
"option tcp-smart-accept". For instance, it can make sense with some services
such as SMTP where the server speaks first.
It is recommended to avoid forcing this option in a defaults section. In case
of doubt, consider setting it back to automatic values by prepending the
"default" keyword before it, or disabling it using the "no" keyword.
See also : "option tcp-smart-connect"
Enable or disable the saving of one ACK packet during the connect sequence
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments : none
On certain systems (at least Linux), HAProxy can ask the kernel not to
immediately send an empty ACK upon a connection request, but to directly
send the buffer request instead. This saves one packet on the network and
thus boosts performance. It can also be useful for some servers, because they
immediately get the request along with the incoming connection.
This feature is enabled when "option tcp-smart-connect" is set in a backend.
It is not enabled by default because it makes network troubleshooting more
complex.
It only makes sense to enable it with protocols where the client speaks first
such as HTTP. In other situations, if there is no data to send in place of
the ACK, a normal ACK is sent.
If this option has been enabled in a "defaults" section, it can be disabled
in a specific instance by prepending the "no" keyword before it.
See also : "option tcp-smart-accept"
Enable or disable the sending of TCP keepalive packets on both sides
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments : none
When there is a firewall or any session-aware component between a client and
a server, and when the protocol involves very long sessions with long idle
periods (e.g. remote desktops), there is a risk that one of the intermediate
components decides to expire a session which has remained idle for too long.
Enabling socket-level TCP keep-alives makes the system regularly send packets
to the other end of the connection, leaving it active. The delay between
keep-alive probes is controlled by the system only and depends both on the
operating system and its tuning parameters.
It is important to understand that keep-alive packets are neither emitted nor
received at the application level. It is only the network stacks which sees
them. For this reason, even if one side of the proxy already uses keep-alives
to maintain its connection alive, those keep-alive packets will not be
forwarded to the other side of the proxy.
Please note that this has nothing to do with HTTP keep-alive.
Using option "tcpka" enables the emission of TCP keep-alive probes on both
the client and server sides of a connection. Note that this is meaningful
only in "defaults" or "listen" sections. If this option is used in a
frontend, only the client side will get keep-alives, and if this option is
used in a backend, only the server side will get keep-alives. For this
reason, it is strongly recommended to explicitly use "option clitcpka" and
"option srvtcpka" when the configuration is split between frontends and
backends.
See also : "option clitcpka", "option srvtcpka"
Enable advanced logging of TCP connections with session state and timers
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments : none
By default, the log output format is very poor, as it only contains the
source and destination addresses, and the instance name. By specifying
"option tcplog", each log line turns into a much richer format including, but
not limited to, the connection timers, the session status, the connections
numbers, the frontend, backend and server name, and of course the source
address and ports. This option is useful for pure TCP proxies in order to
find which of the client or server disconnects or times out. For normal HTTP
proxies, it's better to use "option httplog" which is even more complete.
"option tcplog" overrides any previous "log-format" directive.
See also : "option httplog", and section 8 about logging.
Enable client-side transparent proxying
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments : none
This option was introduced in order to provide layer 7 persistence to layer 3
load balancers. The idea is to use the OS's ability to redirect an incoming
connection for a remote address to a local process (here HAProxy), and let
this process know what address was initially requested. When this option is
used, sessions without cookies will be forwarded to the original destination
IP address of the incoming request (which should match that of another
equipment), while requests with cookies will still be forwarded to the
appropriate server.
Note that contrary to a common belief, this option does NOT make HAProxy
present the client's IP to the server when establishing the connection.
See also: the "usesrc" argument of the "source" keyword, and the "transparent" option of the "bind" keyword.
Executable to run when performing an external-check
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<command> is the external command to run
The arguments passed to the to the command are:
<proxy_address> <proxy_port> <server_address> <server_port>
The <proxy_address> and <proxy_port> are derived from the first listener
that is either IPv4, IPv6 or a UNIX socket. In the case of a UNIX socket
listener the proxy_address will be the path of the socket and the
<proxy_port> will be the string "NOT_USED". In a backend section, it's not
possible to determine a listener, and both <proxy_address> and <proxy_port>
will have the string value "NOT_USED".
Some values are also provided through environment variables.
Environment variables :
HAPROXY_PROXY_ADDR The first bind address if available (or empty if not
applicable, for example in a "backend" section).
HAPROXY_PROXY_ID The backend id.
HAPROXY_PROXY_NAME The backend name.
HAPROXY_PROXY_PORT The first bind port if available (or empty if not
applicable, for example in a "backend" section or
for a UNIX socket).
HAPROXY_SERVER_ADDR The server address.
HAPROXY_SERVER_CURCONN The current number of connections on the server.
HAPROXY_SERVER_ID The server id.
HAPROXY_SERVER_MAXCONN The server max connections.
HAPROXY_SERVER_NAME The server name.
HAPROXY_SERVER_PORT The server port if available (or empty for a UNIX
socket).
PATH The PATH environment variable used when executing
the command may be set using "external-check path".
See also "2.3. Environment variables" for other variables.
If the command executed and exits with a zero status then the check is
considered to have passed, otherwise the check is considered to have
failed.
Example :
external-check command /bin/true
The value of the PATH environment variable used when running an external-check
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<path> is the path used when executing external command to run
The default path is "".
Example :
external-check path "/usr/bin:/bin"
Enable RDP cookie-based persistence
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<name> is the optional name of the RDP cookie to check. If omitted, the
default cookie name "msts" will be used. There currently is no
valid reason to change this name.
This statement enables persistence based on an RDP cookie. The RDP cookie
contains all information required to find the server in the list of known
servers. So when this option is set in the backend, the request is analyzed
and if an RDP cookie is found, it is decoded. If it matches a known server
which is still UP (or if "option persist" is set), then the connection is
forwarded to this server.
Note that this only makes sense in a TCP backend, but for this to work, the
frontend must have waited long enough to ensure that an RDP cookie is present
in the request buffer. This is the same requirement as with the "rdp-cookie"
load-balancing method. Thus it is highly recommended to put all statements in
a single "listen" section.
Also, it is important to understand that the terminal server will emit this
RDP cookie only if it is configured for "token redirection mode", which means
that the "IP address redirection" option is disabled.
Example :
listen tse-farm
bind :3389
# wait up to 5s for an RDP cookie in the request
tcp-request inspect-delay 5s
tcp-request content accept if RDP_COOKIE
# apply RDP cookie persistence
persist rdp-cookie
# if server is unknown, let's balance on the same cookie.
# alternatively, "balance leastconn" may be useful too.
balance rdp-cookie
server srv1 1.1.1.1:3389
server srv2 1.1.1.2:3389
See also : "balance rdp-cookie", "tcp-request" and the "req.rdp_cookie" ACL.
Set a limit on the number of new sessions accepted per second on a frontend
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments :
<rate> The <rate> parameter is an integer designating the maximum number
of new sessions per second to accept on the frontend.
When the frontend reaches the specified number of new sessions per second, it
stops accepting new connections until the rate drops below the limit again.
During this time, the pending sessions will be kept in the socket's backlog
(in system buffers) and HAProxy will not even be aware that sessions are
pending. When applying very low limit on a highly loaded service, it may make
sense to increase the socket's backlog using the "backlog" keyword.
This feature is particularly efficient at blocking connection-based attacks
or service abuse on fragile servers. Since the session rate is measured every
millisecond, it is extremely accurate. Also, the limit applies immediately,
no delay is needed at all to detect the threshold.
Example :
Limit the connection rate on SMTP to 10 per second maxlisten smtp mode tcp bind :25 rate-limit sessions 10 server smtp1 127.0.0.1:1025
Note : when the maximum rate is reached, the frontend's status is not changed
but its sockets appear as "WAITING" in the statistics if the
"socket-stats" option is enabled.
See also : the "backlog" keyword and the "fe_sess_rate" ACL criterion.
Return an HTTP redirection if/unless a condition is matched
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | yes | yes | yes |
If/unless the condition is matched, the HTTP request will lead to a redirect
response. If no condition is specified, the redirect applies unconditionally.
Arguments :
<loc> With "redirect location", the exact value in <loc> is placed into the HTTP "Location" header. When used in an "http-request" rule, <loc> value follows the log-format rules and can include some dynamic values (see Custom Log Format in section 8.2.4). <pfx> With "redirect prefix", the "Location" header is built from the concatenation of <pfx> and the complete URI path, including the query string, unless the "drop-query" option is specified (see below). As a special case, if <pfx> equals exactly "/", then nothing is inserted before the original URI. It allows one to redirect to the same URL (for instance, to insert a cookie). When used in an "http-request" rule, <pfx> value follows the log-format rules and can include some dynamic values (see Custom Log Format in section 8.2.4). <sch> With "redirect scheme", then the "Location" header is built by concatenating <sch> with "://" then the first occurrence of the "Host" header, and then the URI path, including the query string unless the "drop-query" option is specified (see below). If no path is found or if the path is "*", then "/" is used instead. If no "Host" header is found, then an empty host component will be returned, which most recent browsers interpret as redirecting to the same host. This directive is mostly used to redirect HTTP to HTTPS. When used in an "http-request" rule, <sch> value follows the log-format rules and can include some dynamic values (see Custom Log Format in section 8.2.4). <code> The code is optional. It indicates which type of HTTP redirection is desired. Only codes 301, 302, 303, 307 and 308 are supported, with 302 used by default if no code is specified. 301 means "Moved permanently", and a browser may cache the Location. 302 means "Moved temporarily" and means that the browser should not cache the redirection. 303 is equivalent to 302 except that the browser will fetch the location with a GET method. 307 is just like 302 but makes it clear that the same method must be reused. Likewise, 308 replaces 301 if the same method must be used. <option> There are several options which can be specified to adjust the expected behavior of a redirection : - "drop-query" When this keyword is used in a prefix-based redirection, then the location will be set without any possible query-string, which is useful for directing users to a non-secure page for instance. It has no effect with a location-type redirect. - "append-slash" This keyword may be used in conjunction with "drop-query" to redirect users who use a URL not ending with a '/' to the same one with the '/'. It can be useful to ensure that search engines will only see one URL. For this, a return code 301 is preferred. - "ignore-empty" This keyword only has effect when a location is produced using a log format expression (i.e. when used in http-request or http-response). It indicates that if the result of the expression is empty, the rule should silently be skipped. The main use is to allow mass-redirects of known paths using a simple map. - "set-cookie NAME[=value]" A "Set-Cookie" header will be added with NAME (and optionally "=value") to the response. This is sometimes used to indicate that a user has been seen, for instance to protect against some types of DoS. No other cookie option is added, so the cookie will be a session cookie. Note that for a browser, a sole cookie name without an equal sign is different from a cookie with an equal sign. - "clear-cookie NAME[=]" A "Set-Cookie" header will be added with NAME (and optionally "="), but with the "Max-Age" attribute set to zero. This will tell the browser to delete this cookie. It is useful for instance on logout pages. It is important to note that clearing the cookie "NAME" will not remove a cookie set with "NAME=value". You have to clear the cookie "NAME=" for that, because the browser makes the difference.
Example:
Move the login URL only to HTTPS.acl clear dst_port 80 acl secure dst_port 8080 acl login_page url_beg /login acl logout url_beg /logout acl uid_given url_reg /login?userid=[^&]+ acl cookie_set hdr_sub(cookie) SEEN=1 redirect prefix https://mysite.com set-cookie SEEN=1 if !cookie_set redirect prefix https://mysite.com if login_page !secure redirect prefix http://mysite.com drop-query if login_page !uid_given redirect location http://mysite.com/ if !login_page secure redirect location / clear-cookie USERID= if logout
Example:
Send redirects for request for articles without a '/'.acl missing_slash path_reg ^/article/[^/]*$ redirect code 301 prefix / drop-query append-slash if missing_slash
Example:
Redirect all HTTP traffic to HTTPS when SSL is handled by HAProxy.redirect scheme https if !{ ssl_fc }
Example:
Append 'www.' prefix in front of all hosts not having ithttp-request redirect code 301 location \ http://www.%[hdr(host)]%[capture.req.uri] \ unless { hdr_beg(host) -i www }
Example:
Permanently redirect only old URLs to new oneshttp-request redirect code 301 location \ %[path,map_str(old-blog-articles.map)] ignore-empty
See section 7 about ACL usage.
Set the number of retries to perform on a server after a failure
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<value> is the number of times a request or connection attempt should be
retried on a server after a failure.
By default, retries apply only to new connection attempts. However, when
the "retry-on" directive is used, other conditions might trigger a retry
(e.g. empty response, undesired status code), and each of them will count
one attempt, and when the total number attempts reaches the value here, an
error will be returned.
In order to avoid immediate reconnections to a server which is restarting,
a turn-around timer of min("timeout connect", one second) is applied before
a retry occurs on the same server.
When "option redispatch" is set, some retries may be performed on another
server even if a cookie references a different server. By default this will
only be the last retry unless an argument is passed to "option redispatch".
See also : "option redispatch"
Specify when to attempt to automatically retry a failed request.
This setting is only valid when "mode" is set to http and is silently ignored
otherwise.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<keywords> is a space-delimited list of keywords or HTTP status codes, each
representing a type of failure event on which an attempt to
retry the request is desired. Please read the notes at the
bottom before changing this setting. The following keywords are
supported :
none never retry
conn-failure retry when the connection or the SSL handshake failed
and the request could not be sent. This is the default.
empty-response retry when the server connection was closed after part
of the request was sent, and nothing was received from
the server. This type of failure may be caused by the
request timeout on the server side, poor network
condition, or a server crash or restart while
processing the request.
junk-response retry when the server returned something not looking
like a complete HTTP response. This includes partial
responses headers as well as non-HTTP contents. It
usually is a bad idea to retry on such events, which
may be caused a configuration issue (wrong server port)
or by the request being harmful to the server (buffer
overflow attack for example).
response-timeout the server timeout stroke while waiting for the server
to respond to the request. This may be caused by poor
network condition, the reuse of an idle connection
which has expired on the path, or by the request being
extremely expensive to process. It generally is a bad
idea to retry on such events on servers dealing with
heavy database processing (full scans, etc) as it may
amplify denial of service attacks.
0rtt-rejected retry requests which were sent over early data and were
rejected by the server. These requests are generally
considered to be safe to retry.
<status> any HTTP status code among "401" (Unauthorized), "403"
(Forbidden), "404" (Not Found), "408" (Request Timeout),
"425" (Too Early), "500" (Server Error), "501" (Not
Implemented), "502" (Bad Gateway), "503" (Service
Unavailable), "504" (Gateway Timeout).
all-retryable-errors
retry request for any error that are considered
retryable. This currently activates "conn-failure",
"empty-response", "junk-response", "response-timeout",
"0rtt-rejected", "500", "502", "503", and "504".
Using this directive replaces any previous settings with the new ones; it is
not cumulative.
Please note that using anything other than "none" and "conn-failure" requires
to allocate a buffer and copy the whole request into it, so it has memory and
performance impacts. Requests not fitting in a single buffer will never be
retried (see the global tune.bufsize setting).
You have to make sure the application has a replay protection mechanism built
in such as a unique transaction IDs passed in requests, or that replaying the
same request has no consequence, or it is very dangerous to use any retry-on
value beside "conn-failure" and "none". Static file servers and caches are
generally considered safe against any type of retry. Using a status code can
be useful to quickly leave a server showing an abnormal behavior (out of
memory, file system issues, etc), but in this case it may be a good idea to
immediately redispatch the connection to another server (please see "option
redispatch" for this). Last, it is important to understand that most causes
of failures are the requests themselves and that retrying a request causing a
server to misbehave will often make the situation even worse for this server,
or for the whole service in case of redispatch.
Unless you know exactly how the application deals with replayed requests, you
should not use this directive.
The default is "conn-failure".
Example:
retry-on 503 504
Declare a server in a backend
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | no | yes | yes |
Arguments :
<name> is the internal name assigned to this server. This name will
appear in logs and alerts. If "http-send-name-header" is
set, it will be added to the request header sent to the server.
<address> is the IPv4 or IPv6 address of the server. Alternatively, a
resolvable hostname is supported, but this name will be resolved
during start-up. Address "0.0.0.0" or "*" has a special meaning.
It indicates that the connection will be forwarded to the same IP
address as the one from the client connection. This is useful in
transparent proxy architectures where the client's connection is
intercepted and HAProxy must forward to the original destination
address. This is more or less what the "transparent" keyword does
except that with a server it's possible to limit concurrency and
to report statistics. Optionally, an address family prefix may be
used before the address to force the family regardless of the
address format, which can be useful to specify a path to a unix
socket with no slash ('/'). Currently supported prefixes are :
- 'ipv4@' -> address is always IPv4
- 'ipv6@' -> address is always IPv6
- 'unix@' -> address is a path to a local unix socket
- 'abns@' -> address is in abstract namespace (Linux only)
- 'sockpair@' -> address is the FD of a connected unix
socket or of a socketpair. During a connection, the
backend creates a pair of connected sockets, and passes
one of them over the FD. The bind part will use the
received socket as the client FD. Should be used
carefully.
You may want to reference some environment variables in the
address parameter, see section 2.3 about environment
variables. The "init-addr" setting can be used to modify the way
IP addresses should be resolved upon startup.
<port> is an optional port specification. If set, all connections will
be sent to this port. If unset, the same port the client
connected to will be used. The port may also be prefixed by a "+"
or a "-". In this case, the server's port will be determined by
adding this value to the client's port.
<param*> is a list of parameters for this server. The "server" keywords
accepts an important number of options and has a complete section
dedicated to it. Please refer to section 5 for more details.
Examples :
server first 10.1.1.1:1080 cookie first check inter 1000
server second 10.1.1.2:1080 cookie second check inter 1000
server transp ipv4@
server backup "${SRV_BACKUP}:1080" backup
server www1_dc1 "${LAN_DC1}.101:80"
server www1_dc2 "${LAN_DC2}.101:80"
Note: regarding Linux's abstract namespace sockets, HAProxy uses the whole
sun_path length is used for the address length. Some other programs
such as socat use the string length only by default. Pass the option
",unix-tightsocklen=0" to any abstract socket definition in socat to
make it compatible with HAProxy's.
Set the server state file to read, load and apply to servers available in
this backend.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | no | yes | yes |
It only applies when the directive "load-server-state-from-file" is set to
"local". When <file> is not provided, if "use-backend-name" is used or if
this directive is not set, then backend name is used. If <file> starts with a
slash '/', then it is considered as an absolute path. Otherwise, <file> is
concatenated to the global directive "server-state-base".
Example:
The minimal configuration below would make HAProxy look for the state server file '/etc/haproxy/states/bk':global server-state-file-base /etc/haproxy/states backend bk load-server-state-from-file
See also: "server-state-base", "load-server-state-from-file", and "show servers state"
Set a template to initialize servers with shared parameters.
The names of these servers are built from <prefix> and <num | range> parameters.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | no | yes | yes |
Arguments:
<prefix> A prefix for the server names to be built.
<num | range>
If <num> is provided, this template initializes <num> servers
with 1 up to <num> as server name suffixes. A range of numbers
<num_low>-<num_high> may also be used to use <num_low> up to
<num_high> as server name suffixes.
<fqdn> A FQDN for all the servers this template initializes.
<port> Same meaning as "server" <port> argument (see "server" keyword).
<params*>
Remaining server parameters among all those supported by "server"
keyword.
Examples:
# Initializes 3 servers with srv1, srv2 and srv3 as names,
# google.com as FQDN, and health-check enabled.
server-template srv 1-3 google.com:80 check
# or
server-template srv 3 google.com:80 check
# would be equivalent to:
server srv1 google.com:80 check
server srv2 google.com:80 check
server srv3 google.com:80 check
Set the source address for outgoing connections
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<addr> is the IPv4 address HAProxy will bind to before connecting to a
server. This address is also used as a source for health checks.
The default value of 0.0.0.0 means that the system will select
the most appropriate address to reach its destination. Optionally
an address family prefix may be used before the address to force
the family regardless of the address format, which can be useful
to specify a path to a unix socket with no slash ('/'). Currently
supported prefixes are :
- 'ipv4@' -> address is always IPv4
- 'ipv6@' -> address is always IPv6
- 'unix@' -> address is a path to a local unix socket
- 'abns@' -> address is in abstract namespace (Linux only)
You may want to reference some environment variables in the
address parameter, see section 2.3 about environment variables.
<port> is an optional port. It is normally not needed but may be useful
in some very specific contexts. The default value of zero means
the system will select a free port. Note that port ranges are not
supported in the backend. If you want to force port ranges, you
have to specify them on each "server" line.
<addr2> is the IP address to present to the server when connections are
forwarded in full transparent proxy mode. This is currently only
supported on some patched Linux kernels. When this address is
specified, clients connecting to the server will be presented
with this address, while health checks will still use the address
<addr>.
<port2> is the optional port to present to the server when connections
are forwarded in full transparent proxy mode (see <addr2> above).
The default value of zero means the system will select a free
port.
<hdr> is the name of a HTTP header in which to fetch the IP to bind to.
This is the name of a comma-separated header list which can
contain multiple IP addresses. By default, the last occurrence is
used. This is designed to work with the X-Forwarded-For header
and to automatically bind to the client's IP address as seen
by previous proxy, typically Stunnel. In order to use another
occurrence from the last one, please see the <occ> parameter
below. When the header (or occurrence) is not found, no binding
is performed so that the proxy's default IP address is used. Also
keep in mind that the header name is case insensitive, as for any
HTTP header.
<occ> is the occurrence number of a value to be used in a multi-value
header. This is to be used in conjunction with "hdr_ip(<hdr>)",
in order to specify which occurrence to use for the source IP
address. Positive values indicate a position from the first
occurrence, 1 being the first one. Negative values indicate
positions relative to the last one, -1 being the last one. This
is helpful for situations where an X-Forwarded-For header is set
at the entry point of an infrastructure and must be used several
proxy layers away. When this value is not specified, -1 is
assumed. Passing a zero here disables the feature.
<name> is an optional interface name to which to bind to for outgoing
traffic. On systems supporting this features (currently, only
Linux), this allows one to bind all traffic to the server to
this interface even if it is not the one the system would select
based on routing tables. This should be used with extreme care.
Note that using this option requires root privileges.
The "source" keyword is useful in complex environments where a specific
address only is allowed to connect to the servers. It may be needed when a
private address must be used through a public gateway for instance, and it is
known that the system cannot determine the adequate source address by itself.
An extension which is available on certain patched Linux kernels may be used
through the "usesrc" optional keyword. It makes it possible to connect to the
servers with an IP address which does not belong to the system itself. This
is called "full transparent proxy mode". For this to work, the destination
servers have to route their traffic back to this address through the machine
running HAProxy, and IP forwarding must generally be enabled on this machine.
In this "full transparent proxy" mode, it is possible to force a specific IP
address to be presented to the servers. This is not much used in fact. A more
common use is to tell HAProxy to present the client's IP address. For this,
there are two methods :
- present the client's IP and port addresses. This is the most transparent
mode, but it can cause problems when IP connection tracking is enabled on
the machine, because a same connection may be seen twice with different
states. However, this solution presents the huge advantage of not
limiting the system to the 64k outgoing address+port couples, because all
of the client ranges may be used.
- present only the client's IP address and select a spare port. This
solution is still quite elegant but slightly less transparent (downstream
firewalls logs will not match upstream's). It also presents the downside
of limiting the number of concurrent connections to the usual 64k ports.
However, since the upstream and downstream ports are different, local IP
connection tracking on the machine will not be upset by the reuse of the
same session.
This option sets the default source for all servers in the backend. It may
also be specified in a "defaults" section. Finer source address specification
is possible at the server level using the "source" server option. Refer to
section 5 for more information.
In order to work, "usesrc" requires root privileges.
Examples :
backend private
# Connect to the servers using our 192.168.1.200 source address
source 192.168.1.200
backend transparent_ssl1
# Connect to the SSL farm from the client's source address
source 192.168.1.200 usesrc clientip
backend transparent_ssl2
# Connect to the SSL farm from the client's source address and port
# not recommended if IP conntrack is present on the local machine.
source 192.168.1.200 usesrc client
backend transparent_ssl3
# Connect to the SSL farm from the client's source address. It
# is more conntrack-friendly.
source 192.168.1.200 usesrc clientip
backend transparent_smtp
# Connect to the SMTP farm from the client's source address/port
# with Tproxy version 4.
source 0.0.0.0 usesrc clientip
backend transparent_http
# Connect to the servers using the client's IP as seen by previous
# proxy.
source 0.0.0.0 usesrc hdr_ip(x-forwarded-for,-1)
See also : the "source" server option in section 5, the Tproxy patches for the Linux kernel on www.balabit.com, the "bind" keyword.
Sets the maximum number of keepalive probes TCP should send before dropping
the connection on the server side.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<count> is the maximum number of keepalive probes.
This keyword corresponds to the socket option TCP_KEEPCNT. If this keyword
is not specified, system-wide TCP parameter (tcp_keepalive_probes) is used.
The availability of this setting depends on the operating system. It is
known to work on Linux.
Sets the time the connection needs to remain idle before TCP starts sending
keepalive probes, if enabled the sending of TCP keepalive packets on the
server side.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<timeout> is the time the connection needs to remain idle before TCP starts
sending keepalive probes. It is specified in seconds by default,
but can be in any other unit if the number is suffixed by the
unit, as explained at the top of this document.
This keyword corresponds to the socket option TCP_KEEPIDLE. If this keyword
is not specified, system-wide TCP parameter (tcp_keepalive_time) is used.
The availability of this setting depends on the operating system. It is
known to work on Linux.
Sets the time between individual keepalive probes on the server side.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<timeout> is the time between individual keepalive probes. It is specified
in seconds by default, but can be in any other unit if the number
is suffixed by the unit, as explained at the top of this
document.
This keyword corresponds to the socket option TCP_KEEPINTVL. If this keyword
is not specified, system-wide TCP parameter (tcp_keepalive_intvl) is used.
The availability of this setting depends on the operating system. It is
known to work on Linux.
Enable statistics admin level if/unless a condition is matched
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | yes | yes | yes |
This statement enables the statistics admin level if/unless a condition is
matched.
The admin level allows to enable/disable servers from the web interface. By
default, statistics page is read-only for security reasons.
Note : Consider not using this feature in multi-process mode (nbproc > 1)
unless you know what you do : memory is not shared between the
processes, which can result in random behaviors.
Currently, the POST request is limited to the buffer size minus the reserved
buffer space, which means that if the list of servers is too long, the
request won't be processed. It is recommended to alter few servers at a
time.
Example :
# statistics admin level only for localhost
backend stats_localhost
stats enable
stats admin if LOCALHOST
Example :
# statistics admin level always enabled because of the authentication
backend stats_auth
stats enable
stats auth admin:AdMiN123
stats admin if TRUE
Example :
# statistics admin level depends on the authenticated user
userlist stats-auth
group admin users admin
user admin insecure-password AdMiN123
group readonly users haproxy
user haproxy insecure-password haproxy
backend stats_auth
stats enable
acl AUTH http_auth(stats-auth)
acl AUTH_ADMIN http_auth_group(stats-auth) admin
stats http-request auth unless AUTH
stats admin if AUTH_ADMIN
See also : "stats enable", "stats auth", "stats http-request", "nbproc", "bind-process", section 3.4 about userlists and section 7 about ACL usage.
Enable statistics with authentication and grant access to an account
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
<user> is a user name to grant access to <passwd> is the cleartext password associated to this user
This statement enables statistics with default settings, and restricts access
to declared users only. It may be repeated as many times as necessary to
allow as many users as desired. When a user tries to access the statistics
without a valid account, a "401 Forbidden" response will be returned so that
the browser asks the user to provide a valid user and password. The real
which will be returned to the browser is configurable using "stats realm".
Since the authentication method is HTTP Basic Authentication, the passwords
circulate in cleartext on the network. Thus, it was decided that the
configuration file would also use cleartext passwords to remind the users
that those ones should not be sensitive and not shared with any other account.
It is also possible to reduce the scope of the proxies which appear in the
report using "stats scope".
Though this statement alone is enough to enable statistics reporting, it is
recommended to set all other settings in order to avoid relying on default
unobvious parameters.
Example :
# public access (limited to this backend only)
backend public_www
server srv1 192.168.0.1:80
stats enable
stats hide-version
stats scope .
stats uri /admin?stats
stats realm HAProxy\ Statistics
stats auth admin1:AdMiN123
stats auth admin2:AdMiN321
# internal monitoring access (unlimited)
backend private_monitoring
stats enable
stats uri /admin?stats
stats refresh 5s
Enable statistics reporting with default settings
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments : none
This statement enables statistics reporting with default settings defined
at build time. Unless stated otherwise, these settings are used :
- stats uri : /haproxy?stats
- stats realm : "HAProxy Statistics"
- stats auth : no authentication
- stats scope : no restriction
Though this statement alone is enough to enable statistics reporting, it is
recommended to set all other settings in order to avoid relying on default
unobvious parameters.
Example :
# public access (limited to this backend only)
backend public_www
server srv1 192.168.0.1:80
stats enable
stats hide-version
stats scope .
stats uri /admin?stats
stats realm HAProxy\ Statistics
stats auth admin1:AdMiN123
stats auth admin2:AdMiN321
# internal monitoring access (unlimited)
backend private_monitoring
stats enable
stats uri /admin?stats
stats refresh 5s
Enable statistics and hide HAProxy version reporting
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments : none
By default, the stats page reports some useful status information along with
the statistics. Among them is HAProxy's version. However, it is generally
considered dangerous to report precise version to anyone, as it can help them
target known weaknesses with specific attacks. The "stats hide-version"
statement removes the version from the statistics report. This is recommended
for public sites or any site with a weak login/password.
Though this statement alone is enough to enable statistics reporting, it is
recommended to set all other settings in order to avoid relying on default
unobvious parameters.
Example :
# public access (limited to this backend only)
backend public_www
server srv1 192.168.0.1:80
stats enable
stats hide-version
stats scope .
stats uri /admin?stats
stats realm HAProxy\ Statistics
stats auth admin1:AdMiN123
stats auth admin2:AdMiN321
# internal monitoring access (unlimited)
backend private_monitoring
stats enable
stats uri /admin?stats
stats refresh 5s
Access control for statistics
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | no | yes | yes |
As "http-request", these set of options allow to fine control access to
statistics. Each option may be followed by if/unless and acl.
First option with matched condition (or option without condition) is final.
For "deny" a 403 error will be returned, for "allow" normal processing is
performed, for "auth" a 401/407 error code is returned so the client
should be asked to enter a username and password.
There is no fixed limit to the number of http-request statements per
instance.
Enable statistics and set authentication realm
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
<realm> is the name of the HTTP Basic Authentication realm reported to
the browser. The browser uses it to display it in the pop-up
inviting the user to enter a valid username and password.
The realm is read as a single word, so any spaces in it should be escaped
using a backslash ('\').
This statement is useful only in conjunction with "stats auth" since it is
only related to authentication.
Though this statement alone is enough to enable statistics reporting, it is
recommended to set all other settings in order to avoid relying on default
unobvious parameters.
Example :
# public access (limited to this backend only)
backend public_www
server srv1 192.168.0.1:80
stats enable
stats hide-version
stats scope .
stats uri /admin?stats
stats realm HAProxy\ Statistics
stats auth admin1:AdMiN123
stats auth admin2:AdMiN321
# internal monitoring access (unlimited)
backend private_monitoring
stats enable
stats uri /admin?stats
stats refresh 5s
Enable statistics with automatic refresh
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
<delay> is the suggested refresh delay, specified in seconds, which will
be returned to the browser consulting the report page. While the
browser is free to apply any delay, it will generally respect it
and refresh the page this every seconds. The refresh interval may
be specified in any other non-default time unit, by suffixing the
unit after the value, as explained at the top of this document.
This statement is useful on monitoring displays with a permanent page
reporting the load balancer's activity. When set, the HTML report page will
include a link "refresh"/"stop refresh" so that the user can select whether
they want automatic refresh of the page or not.
Though this statement alone is enough to enable statistics reporting, it is
recommended to set all other settings in order to avoid relying on default
unobvious parameters.
Example :
# public access (limited to this backend only)
backend public_www
server srv1 192.168.0.1:80
stats enable
stats hide-version
stats scope .
stats uri /admin?stats
stats realm HAProxy\ Statistics
stats auth admin1:AdMiN123
stats auth admin2:AdMiN321
# internal monitoring access (unlimited)
backend private_monitoring
stats enable
stats uri /admin?stats
stats refresh 5s
Enable statistics and limit access scope
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
<name> is the name of a listen, frontend or backend section to be
reported. The special name "." (a single dot) designates the
section in which the statement appears.
When this statement is specified, only the sections enumerated with this
statement will appear in the report. All other ones will be hidden. This
statement may appear as many times as needed if multiple sections need to be
reported. Please note that the name checking is performed as simple string
comparisons, and that it is never checked that a give section name really
exists.
Though this statement alone is enough to enable statistics reporting, it is
recommended to set all other settings in order to avoid relying on default
unobvious parameters.
Example :
# public access (limited to this backend only)
backend public_www
server srv1 192.168.0.1:80
stats enable
stats hide-version
stats scope .
stats uri /admin?stats
stats realm HAProxy\ Statistics
stats auth admin1:AdMiN123
stats auth admin2:AdMiN321
# internal monitoring access (unlimited)
backend private_monitoring
stats enable
stats uri /admin?stats
stats refresh 5s
Enable reporting of a description on the statistics page.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
<desc> is an optional description to be reported. If unspecified, the
description from global section is automatically used instead.
This statement is useful for users that offer shared services to their
customers, where node or description should be different for each customer.
Though this statement alone is enough to enable statistics reporting, it is
recommended to set all other settings in order to avoid relying on default
unobvious parameters. By default description is not shown.
Example :
# internal monitoring access (unlimited)
backend private_monitoring
stats enable
stats show-desc Master node for Europe, Asia, Africa
stats uri /admin?stats
stats refresh 5s
Enable reporting additional information on the statistics page
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments : none
Enable reporting additional information on the statistics page :
- cap: capabilities (proxy)
- mode: one of tcp, http or health (proxy)
- id: SNMP ID (proxy, socket, server)
- IP (socket, server)
- cookie (backend, server)
Though this statement alone is enough to enable statistics reporting, it is
recommended to set all other settings in order to avoid relying on default
unobvious parameters. Default behavior is not to show this information.
See also: "stats enable", "stats uri".
Enable display of extra statistics module on the statistics page
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments : none
New columns are added at the end of the line containing the extra statistics
values as a tooltip.
Though this statement alone is enough to enable statistics reporting, it is
recommended to set all other settings in order to avoid relying on default
unobvious parameters. Default behavior is not to show this information.
See also: "stats enable", "stats uri".
Enable reporting of a host name on the statistics page.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments:
<name> is an optional name to be reported. If unspecified, the
node name from global section is automatically used instead.
This statement is useful for users that offer shared services to their
customers, where node or description might be different on a stats page
provided for each customer. Default behavior is not to show host name.
Though this statement alone is enough to enable statistics reporting, it is
recommended to set all other settings in order to avoid relying on default
unobvious parameters.
Example:
# internal monitoring access (unlimited)
backend private_monitoring
stats enable
stats show-node Europe-1
stats uri /admin?stats
stats refresh 5s
Enable statistics and define the URI prefix to access them
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
<prefix> is the prefix of any URI which will be redirected to stats. This
prefix may contain a question mark ('?') to indicate part of a
query string.
The statistics URI is intercepted on the relayed traffic, so it appears as a
page within the normal application. It is strongly advised to ensure that the
selected URI will never appear in the application, otherwise it will never be
possible to reach it in the application.
The default URI compiled in HAProxy is "/haproxy?stats", but this may be
changed at build time, so it's better to always explicitly specify it here.
It is generally a good idea to include a question mark in the URI so that
intermediate proxies refrain from caching the results. Also, since any string
beginning with the prefix will be accepted as a stats request, the question
mark helps ensuring that no valid URI will begin with the same words.
It is sometimes very convenient to use "/" as the URI prefix, and put that
statement in a "listen" instance of its own. That makes it easy to dedicate
an address or a port to statistics only.
Though this statement alone is enough to enable statistics reporting, it is
recommended to set all other settings in order to avoid relying on default
unobvious parameters.
Example :
# public access (limited to this backend only)
backend public_www
server srv1 192.168.0.1:80
stats enable
stats hide-version
stats scope .
stats uri /admin?stats
stats realm HAProxy\ Statistics
stats auth admin1:AdMiN123
stats auth admin2:AdMiN321
# internal monitoring access (unlimited)
backend private_monitoring
stats enable
stats uri /admin?stats
stats refresh 5s
Define a request pattern matching condition to stick a user to a server
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | no | yes | yes |
Arguments :
<pattern> is a sample expression rule as described in section 7.3. It describes what elements of the incoming request or connection will be analyzed in the hope to find a matching entry in a stickiness table. This rule is mandatory. <table> is an optional stickiness table name. If unspecified, the same backend's table is used. A stickiness table is declared using the "stick-table" statement. <cond> is an optional matching condition. It makes it possible to match on a certain criterion only when other conditions are met (or not met). For instance, it could be used to match on a source IP address except when a request passes through a known proxy, in which case we'd match on a header containing that IP address.
Some protocols or applications require complex stickiness rules and cannot
always simply rely on cookies nor hashing. The "stick match" statement
describes a rule to extract the stickiness criterion from an incoming request
or connection. See section 7 for a complete list of possible patterns and
transformation rules.
The table has to be declared using the "stick-table" statement. It must be of
a type compatible with the pattern. By default it is the one which is present
in the same backend. It is possible to share a table with other backends by
referencing it using the "table" keyword. If another table is referenced,
the server's ID inside the backends are used. By default, all server IDs
start at 1 in each backend, so the server ordering is enough. But in case of
doubt, it is highly recommended to force server IDs using their "id" setting.
It is possible to restrict the conditions where a "stick match" statement
will apply, using "if" or "unless" followed by a condition. See section 7 for
ACL based conditions.
There is no limit on the number of "stick match" statements. The first that
applies and matches will cause the request to be directed to the same server
as was used for the request which created the entry. That way, multiple
matches can be used as fallbacks.
The stick rules are checked after the persistence cookies, so they will not
affect stickiness if a cookie has already been used to select a server. That
way, it becomes very easy to insert cookies and match on IP addresses in
order to maintain stickiness between HTTP and HTTPS.
Note : Consider not using this feature in multi-process mode (nbproc > 1)
unless you know what you do : memory is not shared between the
processes, which can result in random behaviors.
Example :
# forward SMTP users to the same server they just used for POP in the
# last 30 minutes
backend pop
mode tcp
balance roundrobin
stick store-request src
stick-table type ip size 200k expire 30m
server s1 192.168.1.1:110
server s2 192.168.1.1:110
backend smtp
mode tcp
balance roundrobin
stick match src table pop
server s1 192.168.1.1:25
server s2 192.168.1.1:25
See also : "stick-table", "stick on", "nbproc", "bind-process" and section 7 about ACLs and samples fetching.
Define a request pattern to associate a user to a server
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | no | yes | yes |
Note : This form is exactly equivalent to "stick match" followed by
"stick store-request", all with the same arguments. Please refer
to both keywords for details. It is only provided as a convenience
for writing more maintainable configurations.
Note : Consider not using this feature in multi-process mode (nbproc > 1)
unless you know what you do : memory is not shared between the
processes, which can result in random behaviors.
Examples :
# The following form ...
stick on src table pop if !localhost
# ...is strictly equivalent to this one :
stick match src table pop if !localhost
stick store-request src table pop if !localhost
# Use cookie persistence for HTTP, and stick on source address for HTTPS as
# well as HTTP without cookie. Share the same table between both accesses.
backend http
mode http
balance roundrobin
stick on src table https
cookie SRV insert indirect nocache
server s1 192.168.1.1:80 cookie s1
server s2 192.168.1.1:80 cookie s2
backend https
mode tcp
balance roundrobin
stick-table type ip size 200k expire 30m
stick on src
server s1 192.168.1.1:443
server s2 192.168.1.1:443
Define a request pattern used to create an entry in a stickiness table
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | no | yes | yes |
Arguments :
<pattern> is a sample expression rule as described in section 7.3. It describes what elements of the incoming request or connection will be analyzed, extracted and stored in the table once a server is selected. <table> is an optional stickiness table name. If unspecified, the same backend's table is used. A stickiness table is declared using the "stick-table" statement. <cond> is an optional storage condition. It makes it possible to store certain criteria only when some conditions are met (or not met). For instance, it could be used to store the source IP address except when the request passes through a known proxy, in which case we'd store a converted form of a header containing that IP address.
Some protocols or applications require complex stickiness rules and cannot
always simply rely on cookies nor hashing. The "stick store-request" statement
describes a rule to decide what to extract from the request and when to do
it, in order to store it into a stickiness table for further requests to
match it using the "stick match" statement. Obviously the extracted part must
make sense and have a chance to be matched in a further request. Storing a
client's IP address for instance often makes sense. Storing an ID found in a
URL parameter also makes sense. Storing a source port will almost never make
any sense because it will be randomly matched. See section 7 for a complete
list of possible patterns and transformation rules.
The table has to be declared using the "stick-table" statement. It must be of
a type compatible with the pattern. By default it is the one which is present
in the same backend. It is possible to share a table with other backends by
referencing it using the "table" keyword. If another table is referenced,
the server's ID inside the backends are used. By default, all server IDs
start at 1 in each backend, so the server ordering is enough. But in case of
doubt, it is highly recommended to force server IDs using their "id" setting.
It is possible to restrict the conditions where a "stick store-request"
statement will apply, using "if" or "unless" followed by a condition. This
condition will be evaluated while parsing the request, so any criteria can be
used. See section 7 for ACL based conditions.
There is no limit on the number of "stick store-request" statements, but
there is a limit of 8 simultaneous stores per request or response. This
makes it possible to store up to 8 criteria, all extracted from either the
request or the response, regardless of the number of rules. Only the 8 first
ones which match will be kept. Using this, it is possible to feed multiple
tables at once in the hope to increase the chance to recognize a user on
another protocol or access method. Using multiple store-request rules with
the same table is possible and may be used to find the best criterion to rely
on, by arranging the rules by decreasing preference order. Only the first
extracted criterion for a given table will be stored. All subsequent store-
request rules referencing the same table will be skipped and their ACLs will
not be evaluated.
The "store-request" rules are evaluated once the server connection has been
established, so that the table will contain the real server that processed
the request.
Note : Consider not using this feature in multi-process mode (nbproc > 1)
unless you know what you do : memory is not shared between the
processes, which can result in random behaviors.
Example :
# forward SMTP users to the same server they just used for POP in the
# last 30 minutes
backend pop
mode tcp
balance roundrobin
stick store-request src
stick-table type ip size 200k expire 30m
server s1 192.168.1.1:110
server s2 192.168.1.1:110
backend smtp
mode tcp
balance roundrobin
stick match src table pop
server s1 192.168.1.1:25
server s2 192.168.1.1:25
See also : "stick-table", "stick on", "nbproc", "bind-process" and section 7 about ACLs and sample fetching.
stick-table type {ip | integer | string [len <length>] | binary [len <length>]}
size <size> [expire <expire>] [nopurge] [peers <peersect>] [srvkey <srvkey>]
[store <data_type>]*
Configure the stickiness table for the current section
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | yes | yes | yes |
Arguments :
ip a table declared with "type ip" will only store IPv4 addresses.
This form is very compact (about 50 bytes per entry) and allows
very fast entry lookup and stores with almost no overhead. This
is mainly used to store client source IP addresses.
ipv6 a table declared with "type ipv6" will only store IPv6 addresses.
This form is very compact (about 60 bytes per entry) and allows
very fast entry lookup and stores with almost no overhead. This
is mainly used to store client source IP addresses.
integer a table declared with "type integer" will store 32bit integers
which can represent a client identifier found in a request for
instance.
string a table declared with "type string" will store substrings of up
to <len> characters. If the string provided by the pattern
extractor is larger than <len>, it will be truncated before
being stored. During matching, at most <len> characters will be
compared between the string in the table and the extracted
pattern. When not specified, the string is automatically limited
to 32 characters.
binary a table declared with "type binary" will store binary blocks
of <len> bytes. If the block provided by the pattern
extractor is larger than <len>, it will be truncated before
being stored. If the block provided by the sample expression
is shorter than <len>, it will be padded by 0. When not
specified, the block is automatically limited to 32 bytes.
<length> is the maximum number of characters that will be stored in a
"string" type table (See type "string" above). Or the number
of bytes of the block in "binary" type table. Be careful when
changing this parameter as memory usage will proportionally
increase.
<size> is the maximum number of entries that can fit in the table. This
value directly impacts memory usage. Count approximately
50 bytes per entry, plus the size of a string if any. The size
supports suffixes "k", "m", "g" for 2^10, 2^20 and 2^30 factors.
[nopurge] indicates that we refuse to purge older entries when the table
is full. When not specified and the table is full when HAProxy
wants to store an entry in it, it will flush a few of the oldest
entries in order to release some space for the new ones. This is
most often the desired behavior. In some specific cases, it
be desirable to refuse new entries instead of purging the older
ones. That may be the case when the amount of data to store is
far above the hardware limits and we prefer not to offer access
to new clients than to reject the ones already connected. When
using this parameter, be sure to properly set the "expire"
parameter (see below).
<peersect> is the name of the peers section to use for replication. Entries
which associate keys to server IDs are kept synchronized with
the remote peers declared in this section. All entries are also
automatically learned from the local peer (old process) during a
soft restart.
NOTE : each peers section may be referenced only by tables
belonging to the same unique process.
<expire> defines the maximum duration of an entry in the table since it
was last created, refreshed using 'track-sc' or matched using
'stick match' or 'stick on' rule. The expiration delay is
defined using the standard time format, similarly as the various
timeouts. The maximum duration is slightly above 24 days. See
section 2.5 for more information. If this delay is not specified,
the session won't automatically expire, but older entries will
be removed once full. Be sure not to use the "nopurge" parameter
if not expiration delay is specified.
Note: 'table_*' converters performs lookups but won't update touch
expire since they don't require 'track-sc'.
<srvkey> specifies how each server is identified for the purposes of the
stick table. The valid values are "name" and "addr". If "name" is
given, then <name> argument for the server (may be generated by
a template). If "addr" is given, then the server is identified
by its current network address, including the port. "addr" is
especially useful if you are using service discovery to generate
the addresses for servers with peered stick-tables and want
to consistently use the same host across peers for a stickiness
token.
<data_type> is used to store additional information in the stick-table. This
may be used by ACLs in order to control various criteria related
to the activity of the client matching the stick-table. For each
item specified here, the size of each entry will be inflated so
that the additional data can fit. Several data types may be
stored with an entry. Multiple data types may be specified after
the "store" keyword, as a comma-separated list. Alternatively,
it is possible to repeat the "store" keyword followed by one or
several data types. Except for the "server_id" type which is
automatically detected and enabled, all data types must be
explicitly declared to be stored. If an ACL references a data
type which is not stored, the ACL will simply not match. Some
data types require an argument which must be passed just after
the type between parenthesis. See below for the supported data
types and their arguments.
The data types that can be stored with an entry are the following :
- server_id : this is an integer which holds the numeric ID of the server a
request was assigned to. It is used by the "stick match", "stick store",
and "stick on" rules. It is automatically enabled when referenced.
- gpc0 : first General Purpose Counter. It is a positive 32-bit integer
integer which may be used for anything. Most of the time it will be used
to put a special tag on some entries, for instance to note that a
specific behavior was detected and must be known for future matches.
- gpc0_rate(<period>) : increment rate of the first General Purpose Counter
over a period. It is a positive 32-bit integer integer which may be used
for anything. Just like <gpc0>, it counts events, but instead of keeping
a cumulative number, it maintains the rate at which the counter is
incremented. Most of the time it will be used to measure the frequency of
occurrence of certain events (e.g. requests to a specific URL).
- gpc1 : second General Purpose Counter. It is a positive 32-bit integer
integer which may be used for anything. Most of the time it will be used
to put a special tag on some entries, for instance to note that a
specific behavior was detected and must be known for future matches.
- gpc1_rate(<period>) : increment rate of the second General Purpose Counter
over a period. It is a positive 32-bit integer integer which may be used
for anything. Just like <gpc1>, it counts events, but instead of keeping
a cumulative number, it maintains the rate at which the counter is
incremented. Most of the time it will be used to measure the frequency of
occurrence of certain events (e.g. requests to a specific URL).
- gpt0 : first General Purpose Tag. It is a positive 32-bit integer
integer which may be used for anything. Most of the time it will be used
to put a special tag on some entries, for instance to note that a
specific behavior was detected and must be known for future matches
- conn_cnt : Connection Count. It is a positive 32-bit integer which counts
the absolute number of connections received from clients which matched
this entry. It does not mean the connections were accepted, just that
they were received.
- conn_cur : Current Connections. It is a positive 32-bit integer which
stores the concurrent connection counts for the entry. It is incremented
once an incoming connection matches the entry, and decremented once the
connection leaves. That way it is possible to know at any time the exact
number of concurrent connections for an entry.
- conn_rate(<period>) : frequency counter (takes 12 bytes). It takes an
integer parameter <period> which indicates in milliseconds the length
of the period over which the average is measured. It reports the average
incoming connection rate over that period, in connections per period. The
result is an integer which can be matched using ACLs.
- sess_cnt : Session Count. It is a positive 32-bit integer which counts
the absolute number of sessions received from clients which matched this
entry. A session is a connection that was accepted by the layer 4 rules.
- sess_rate(<period>) : frequency counter (takes 12 bytes). It takes an
integer parameter <period> which indicates in milliseconds the length
of the period over which the average is measured. It reports the average
incoming session rate over that period, in sessions per period. The
result is an integer which can be matched using ACLs.
- http_req_cnt : HTTP request Count. It is a positive 32-bit integer which
counts the absolute number of HTTP requests received from clients which
matched this entry. It does not matter whether they are valid requests or
not. Note that this is different from sessions when keep-alive is used on
the client side.
- http_req_rate(<period>) : frequency counter (takes 12 bytes). It takes an
integer parameter <period> which indicates in milliseconds the length
of the period over which the average is measured. It reports the average
HTTP request rate over that period, in requests per period. The result is
an integer which can be matched using ACLs. It does not matter whether
they are valid requests or not. Note that this is different from sessions
when keep-alive is used on the client side.
- http_err_cnt : HTTP Error Count. It is a positive 32-bit integer which
counts the absolute number of HTTP requests errors induced by clients
which matched this entry. Errors are counted on invalid and truncated
requests, as well as on denied or tarpitted requests, and on failed
authentications. If the server responds with 4xx, then the request is
also counted as an error since it's an error triggered by the client
(e.g. vulnerability scan).
- http_err_rate(<period>) : frequency counter (takes 12 bytes). It takes an
integer parameter <period> which indicates in milliseconds the length
of the period over which the average is measured. It reports the average
HTTP request error rate over that period, in requests per period (see
http_err_cnt above for what is accounted as an error). The result is an
integer which can be matched using ACLs.
- http_fail_cnt : HTTP Failure Count. It is a positive 32-bit integer which
counts the absolute number of HTTP response failures induced by servers
which matched this entry. Errors are counted on invalid and truncated
responses, as well as any 5xx response other than 501 or 505. It aims at
being used combined with path or URI to detect service failures.
- http_fail_rate(<period>) : frequency counter (takes 12 bytes). It takes
an integer parameter <period> which indicates in milliseconds the length
of the period over which the average is measured. It reports the average
HTTP response failure rate over that period, in requests per period (see
http_fail_cnt above for what is accounted as a failure). The result is an
integer which can be matched using ACLs.
- bytes_in_cnt : client to server byte count. It is a positive 64-bit
integer which counts the cumulative number of bytes received from clients
which matched this entry. Headers are included in the count. This may be
used to limit abuse of upload features on photo or video servers.
- bytes_in_rate(<period>) : frequency counter (takes 12 bytes). It takes an
integer parameter <period> which indicates in milliseconds the length
of the period over which the average is measured. It reports the average
incoming bytes rate over that period, in bytes per period. It may be used
to detect users which upload too much and too fast. Warning: with large
uploads, it is possible that the amount of uploaded data will be counted
once upon termination, thus causing spikes in the average transfer speed
instead of having a smooth one. This may partially be smoothed with
"option contstats" though this is not perfect yet. Use of byte_in_cnt is
recommended for better fairness.
- bytes_out_cnt : server to client byte count. It is a positive 64-bit
integer which counts the cumulative number of bytes sent to clients which
matched this entry. Headers are included in the count. This may be used
to limit abuse of bots sucking the whole site.
- bytes_out_rate(<period>) : frequency counter (takes 12 bytes). It takes
an integer parameter <period> which indicates in milliseconds the length
of the period over which the average is measured. It reports the average
outgoing bytes rate over that period, in bytes per period. It may be used
to detect users which download too much and too fast. Warning: with large
transfers, it is possible that the amount of transferred data will be
counted once upon termination, thus causing spikes in the average
transfer speed instead of having a smooth one. This may partially be
smoothed with "option contstats" though this is not perfect yet. Use of
byte_out_cnt is recommended for better fairness.
There is only one stick-table per proxy. At the moment of writing this doc,
it does not seem useful to have multiple tables per proxy. If this happens
to be required, simply create a dummy backend with a stick-table in it and
reference it.
It is important to understand that stickiness based on learning information
has some limitations, including the fact that all learned associations are
lost upon restart unless peers are properly configured to transfer such
information upon restart (recommended). In general it can be good as a
complement but not always as an exclusive stickiness.
Last, memory requirements may be important when storing many data types.
Indeed, storing all indicators above at once in each entry requires 116 bytes
per entry, or 116 MB for a 1-million entries table. This is definitely not
something that can be ignored.
Example:
# Keep track of counters of up to 1 million IP addresses over 5 minutes
# and store a general purpose counter and the average connection rate
# computed over a sliding window of 30 seconds.
stick-table type ip size 1m expire 5m store gpc0,conn_rate(30s)
See also : "stick match", "stick on", "stick store-request", section 2.5 about time format and section 7 about ACLs.
Define a response pattern used to create an entry in a stickiness table
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | no | yes | yes |
Arguments :
<pattern> is a sample expression rule as described in section 7.3. It describes what elements of the response or connection will be analyzed, extracted and stored in the table once a server is selected. <table> is an optional stickiness table name. If unspecified, the same backend's table is used. A stickiness table is declared using the "stick-table" statement. <cond> is an optional storage condition. It makes it possible to store certain criteria only when some conditions are met (or not met). For instance, it could be used to store the SSL session ID only when the response is a SSL server hello.
Some protocols or applications require complex stickiness rules and cannot
always simply rely on cookies nor hashing. The "stick store-response"
statement describes a rule to decide what to extract from the response and
when to do it, in order to store it into a stickiness table for further
requests to match it using the "stick match" statement. Obviously the
extracted part must make sense and have a chance to be matched in a further
request. Storing an ID found in a header of a response makes sense.
See section 7 for a complete list of possible patterns and transformation
rules.
The table has to be declared using the "stick-table" statement. It must be of
a type compatible with the pattern. By default it is the one which is present
in the same backend. It is possible to share a table with other backends by
referencing it using the "table" keyword. If another table is referenced,
the server's ID inside the backends are used. By default, all server IDs
start at 1 in each backend, so the server ordering is enough. But in case of
doubt, it is highly recommended to force server IDs using their "id" setting.
It is possible to restrict the conditions where a "stick store-response"
statement will apply, using "if" or "unless" followed by a condition. This
condition will be evaluated while parsing the response, so any criteria can
be used. See section 7 for ACL based conditions.
There is no limit on the number of "stick store-response" statements, but
there is a limit of 8 simultaneous stores per request or response. This
makes it possible to store up to 8 criteria, all extracted from either the
request or the response, regardless of the number of rules. Only the 8 first
ones which match will be kept. Using this, it is possible to feed multiple
tables at once in the hope to increase the chance to recognize a user on
another protocol or access method. Using multiple store-response rules with
the same table is possible and may be used to find the best criterion to rely
on, by arranging the rules by decreasing preference order. Only the first
extracted criterion for a given table will be stored. All subsequent store-
response rules referencing the same table will be skipped and their ACLs will
not be evaluated. However, even if a store-request rule references a table, a
store-response rule may also use the same table. This means that each table
may learn exactly one element from the request and one element from the
response at once.
The table will contain the real server that processed the request.
Example :
# Learn SSL session ID from both request and response and create affinity.
backend https
mode tcp
balance roundrobin
# maximum SSL session ID length is 32 bytes.
stick-table type binary len 32 size 30k expire 30m
acl clienthello req.ssl_hello_type 1
acl serverhello res.ssl_hello_type 2
# use tcp content accepts to detects ssl client and server hello.
tcp-request inspect-delay 5s
tcp-request content accept if clienthello
# no timeout on response inspect delay by default.
tcp-response content accept if serverhello
# SSL session ID (SSLID) may be present on a client or server hello.
# Its length is coded on 1 byte at offset 43 and its value starts
# at offset 44.
# Match and learn on request if client hello.
stick on req.payload_lv(43,1) if clienthello
# Learn on response if server hello.
stick store-response resp.payload_lv(43,1) if serverhello
server s1 192.168.1.1:443
server s2 192.168.1.1:443
Defines a comment for the following the tcp-check rule, reported in logs if
it fails.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<string> is the comment message to add in logs if the following tcp-check
rule fails.
It only works for connect, send and expect rules. It is useful to make
user-friendly error reporting.
tcp-check connect [default] [port <expr>] [addr <ip>] [send-proxy] [via-socks4]
[ssl] [sni <sni>] [alpn <alpn>] [linger]
[proto <name>] [comment <msg>]
Opens a new connection
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
comment <msg> defines a message to report if the rule evaluation fails.
default Use default options of the server line to do the health
checks. The server options are used only if not redefined.
port <expr> if not set, check port or server port is used.
It tells HAProxy where to open the connection to.
<port> must be a valid TCP port source integer, from 1 to
65535 or an sample-fetch expression.
addr <ip> defines the IP address to do the health check.
send-proxy send a PROXY protocol string
via-socks4 enables outgoing health checks using upstream socks4 proxy.
ssl opens a ciphered connection
sni <sni> specifies the SNI to use to do health checks over SSL.
alpn <alpn> defines which protocols to advertise with ALPN. The protocol
list consists in a comma-delimited list of protocol names,
for instance: "http/1.1,http/1.0" (without quotes).
If it is not set, the server ALPN is used.
proto <name> forces the multiplexer's protocol to use for this connection.
It must be a TCP mux protocol and it must be usable on the
backend side. The list of available protocols is reported in
haproxy -vv.
linger cleanly close the connection instead of using a single RST.
When an application lies on more than a single TCP port or when HAProxy
load-balance many services in a single backend, it makes sense to probe all
the services individually before considering a server as operational.
When there are no TCP port configured on the server line neither server port
directive, then the 'tcp-check connect port <port>' must be the first step
of the sequence.
In a tcp-check ruleset a 'connect' is required, it is also mandatory to start
the ruleset with a 'connect' rule. Purpose is to ensure admin know what they
do.
When a connect must start the ruleset, if may still be preceded by set-var,
unset-var or comment rules.
Examples :
# check HTTP and HTTPs services on a server.
# first open port 80 thanks to server line port directive, then
# tcp-check opens port 443, ciphered and run a request on it:
option tcp-check
tcp-check connect
tcp-check send GET\ /\ HTTP/1.0\r\n
tcp-check send Host:\ haproxy.1wt.eu\r\n
tcp-check send \r\n
tcp-check expect rstring (2..|3..)
tcp-check connect port 443 ssl
tcp-check send GET\ /\ HTTP/1.0\r\n
tcp-check send Host:\ haproxy.1wt.eu\r\n
tcp-check send \r\n
tcp-check expect rstring (2..|3..)
server www 10.0.0.1 check port 80
# check both POP and IMAP from a single server:
option tcp-check
tcp-check connect port 110 linger
tcp-check expect string +OK\ POP3\ ready
tcp-check connect port 143
tcp-check expect string *\ OK\ IMAP4\ ready
server mail 10.0.0.1 check
tcp-check expect [min-recv <int>] [comment <msg>]
[ok-status <st>] [error-status <st>] [tout-status <st>]
[on-success <fmt>] [on-error <fmt>] [status-code <expr>]
[!] <match> <pattern>
Specify data to be collected and analyzed during a generic health check
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
comment <msg> defines a message to report if the rule evaluation fails.
min-recv is optional and can define the minimum amount of data required to
evaluate the current expect rule. If the number of received bytes
is under this limit, the check will wait for more data. This
option can be used to resolve some ambiguous matching rules or to
avoid executing costly regex matches on content known to be still
incomplete. If an exact string (string or binary) is used, the
minimum between the string length and this parameter is used.
This parameter is ignored if it is set to -1. If the expect rule
does not match, the check will wait for more data. If set to 0,
the evaluation result is always conclusive.
<match> is a keyword indicating how to look for a specific pattern in the
response. The keyword may be one of "string", "rstring", "binary" or
"rbinary".
The keyword may be preceded by an exclamation mark ("!") to negate
the match. Spaces are allowed between the exclamation mark and the
keyword. See below for more details on the supported keywords.
ok-status <st> is optional and can be used to set the check status if
the expect rule is successfully evaluated and if it is
the last rule in the tcp-check ruleset. "L7OK", "L7OKC",
"L6OK" and "L4OK" are supported :
- L7OK : check passed on layer 7
- L7OKC : check conditionally passed on layer 7, set
server to NOLB state.
- L6OK : check passed on layer 6
- L4OK : check passed on layer 4
By default "L7OK" is used.
error-status <st> is optional and can be used to set the check status if
an error occurred during the expect rule evaluation.
"L7OKC", "L7RSP", "L7STS", "L6RSP" and "L4CON" are
supported :
- L7OKC : check conditionally passed on layer 7, set
server to NOLB state.
- L7RSP : layer 7 invalid response - protocol error
- L7STS : layer 7 response error, for example HTTP 5xx
- L6RSP : layer 6 invalid response - protocol error
- L4CON : layer 1-4 connection problem
By default "L7RSP" is used.
tout-status <st> is optional and can be used to set the check status if
a timeout occurred during the expect rule evaluation.
"L7TOUT", "L6TOUT", and "L4TOUT" are supported :
- L7TOUT : layer 7 (HTTP/SMTP) timeout
- L6TOUT : layer 6 (SSL) timeout
- L4TOUT : layer 1-4 timeout
By default "L7TOUT" is used.
on-success <fmt> is optional and can be used to customize the
informational message reported in logs if the expect
rule is successfully evaluated and if it is the last rule
in the tcp-check ruleset. <fmt> is a log-format string.
on-error <fmt> is optional and can be used to customize the
informational message reported in logs if an error
occurred during the expect rule evaluation. <fmt> is a
log-format string.
status-code <expr> is optional and can be used to set the check status code
reported in logs, on success or on error. <expr> is a
standard HAProxy expression formed by a sample-fetch
followed by some converters.
<pattern> is the pattern to look for. It may be a string or a regular
expression. If the pattern contains spaces, they must be escaped
with the usual backslash ('\').
If the match is set to binary, then the pattern must be passed as
a series of hexadecimal digits in an even number. Each sequence of
two digits will represent a byte. The hexadecimal digits may be
used upper or lower case.
The available matches are intentionally similar to their http-check cousins :
string <string> : test the exact string matches in the response buffer.
A health check response will be considered valid if the
response's buffer contains this exact string. If the
"string" keyword is prefixed with "!", then the response
will be considered invalid if the body contains this
string. This can be used to look for a mandatory pattern
in a protocol response, or to detect a failure when a
specific error appears in a protocol banner.
rstring <regex> : test a regular expression on the response buffer.
A health check response will be considered valid if the
response's buffer matches this expression. If the
"rstring" keyword is prefixed with "!", then the response
will be considered invalid if the body matches the
expression.
string-lf <fmt> : test a log-format string match in the response's buffer.
A health check response will be considered valid if the
response's buffer contains the string resulting of the
evaluation of <fmt>, which follows the log-format rules.
If prefixed with "!", then the response will be
considered invalid if the buffer contains the string.
binary <hexstring> : test the exact string in its hexadecimal form matches
in the response buffer. A health check response will
be considered valid if the response's buffer contains
this exact hexadecimal string.
Purpose is to match data on binary protocols.
rbinary <regex> : test a regular expression on the response buffer, like
"rstring". However, the response buffer is transformed
into its hexadecimal form, including NUL-bytes. This
allows using all regex engines to match any binary
content. The hexadecimal transformation takes twice the
size of the original response. As such, the expected
pattern should work on at-most half the response buffer
size.
binary-lf <hexfmt> : test a log-format string in its hexadecimal form
match in the response's buffer. A health check response
will be considered valid if the response's buffer
contains the hexadecimal string resulting of the
evaluation of <fmt>, which follows the log-format
rules. If prefixed with "!", then the response will be
considered invalid if the buffer contains the
hexadecimal string. The hexadecimal string is converted
in a binary string before matching the response's
buffer.
It is important to note that the responses will be limited to a certain size
defined by the global "tune.bufsize" option, which defaults to 16384 bytes.
Thus, too large responses may not contain the mandatory pattern when using
"string", "rstring" or binary. If a large response is absolutely required, it
is possible to change the default max size by setting the global variable.
However, it is worth keeping in mind that parsing very large responses can
waste some CPU cycles, especially when regular expressions are used, and that
it is always better to focus the checks on smaller resources. Also, in its
current state, the check will not find any string nor regex past a null
character in the response. Similarly it is not possible to request matching
the null character.
Examples :
# perform a POP check
option tcp-check
tcp-check expect string +OK\ POP3\ ready
# perform an IMAP check
option tcp-check
tcp-check expect string *\ OK\ IMAP4\ ready
# look for the redis master server
option tcp-check
tcp-check send PING\r\n
tcp-check expect string +PONG
tcp-check send info\ replication\r\n
tcp-check expect string role:master
tcp-check send QUIT\r\n
tcp-check expect string +OK
See also : "option tcp-check", "tcp-check connect", "tcp-check send", "tcp-check send-binary", "http-check expect", tune.bufsize
Specify a string or a log-format string to be sent as a question during a
generic health check
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
comment <msg> defines a message to report if the rule evaluation fails.
<data> is the string that will be sent during a generic health
check session.
<fmt> is the log-format string that will be sent, once evaluated,
during a generic health check session.
Examples :
# look for the redis master server
option tcp-check
tcp-check send info\ replication\r\n
tcp-check expect string role:master
See also : "option tcp-check", "tcp-check connect", "tcp-check expect", "tcp-check send-binary", tune.bufsize
Specify an hex digits string or an hex digits log-format string to be sent as
a binary question during a raw tcp health check
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
comment <msg> defines a message to report if the rule evaluation fails.
<hexstring> is the hexadecimal string that will be send, once converted
to binary, during a generic health check session.
<hexfmt> is the hexadecimal log-format string that will be send, once
evaluated and converted to binary, during a generic health
check session.
Examples :
# redis check in binary
option tcp-check
tcp-check send-binary 50494e470d0a # PING\r\n
tcp-check expect binary 2b504F4e47 # +PONG
See also : "option tcp-check", "tcp-check connect", "tcp-check expect", "tcp-check send", tune.bufsize
This operation sets the content of a variable. The variable is declared inline.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<var-name> The name of the variable starts with an indication about its
scope. The scopes allowed for tcp-check are:
"proc" : the variable is shared with the whole process.
"sess" : the variable is shared with the tcp-check session.
"check": the variable is declared for the lifetime of the tcp-check.
This prefix is followed by a name. The separator is a '.'.
The name may only contain characters 'a-z', 'A-Z', '0-9', '.',
and '-'.
<expr> Is a sample-fetch expression potentially followed by converters.
<fmt> This is the value expressed using log-format rules (see Custom
Log Format in section 8.2.4).
Examples :
tcp-check set-var(check.port) int(1234)
tcp-check set-var-fmt(check.name) "%H"
Free a reference to a variable within its scope.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<var-name> The name of the variable starts with an indication about its
scope. The scopes allowed for tcp-check are:
"proc" : the variable is shared with the whole process.
"sess" : the variable is shared with the tcp-check session.
"check": the variable is declared for the lifetime of the tcp-check.
This prefix is followed by a name. The separator is a '.'.
The name may only contain characters 'a-z', 'A-Z', '0-9', '.',
and '-'.
Examples :
tcp-check unset-var(check.port)
Perform an action on an incoming connection depending on a layer 4 condition
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | yes | yes | no |
Arguments :
<action> defines the action to perform if the condition applies. See
below.
<condition> is a standard layer4-only ACL-based condition (see section 7).
Immediately after acceptance of a new incoming connection, it is possible to
evaluate some conditions to decide whether this connection must be accepted
or dropped or have its counters tracked. Those conditions cannot make use of
any data contents because the connection has not been read from yet, and the
buffers are not yet allocated. This is used to selectively and very quickly
accept or drop connections from various sources with a very low overhead. If
some contents need to be inspected in order to take the decision, the
"tcp-request content" statements must be used instead.
The "tcp-request connection" rules are evaluated in their exact declaration
order. If no rule matches or if there is no rule, the default action is to
accept the incoming connection. There is no specific limit to the number of
rules which may be inserted.
Four types of actions are supported :
- accept :
accepts the connection if the condition is true (when used with "if")
or false (when used with "unless"). The first such rule executed ends
the rules evaluation.
- reject :
rejects the connection if the condition is true (when used with "if")
or false (when used with "unless"). The first such rule executed ends
the rules evaluation. Rejected connections do not even become a
session, which is why they are accounted separately for in the stats,
as "denied connections". They are not considered for the session
rate-limit and are not logged either. The reason is that these rules
should only be used to filter extremely high connection rates such as
the ones encountered during a massive DDoS attack. Under these extreme
conditions, the simple action of logging each event would make the
system collapse and would considerably lower the filtering capacity. If
logging is absolutely desired, then "tcp-request content" rules should
be used instead, as "tcp-request session" rules will not log either.
- expect-proxy layer4 :
configures the client-facing connection to receive a PROXY protocol
header before any byte is read from the socket. This is equivalent to
having the "accept-proxy" keyword on the "bind" line, except that using
the TCP rule allows the PROXY protocol to be accepted only for certain
IP address ranges using an ACL. This is convenient when multiple layers
of load balancers are passed through by traffic coming from public
hosts.
- expect-netscaler-cip layer4 :
configures the client-facing connection to receive a NetScaler Client
IP insertion protocol header before any byte is read from the socket.
This is equivalent to having the "accept-netscaler-cip" keyword on the
"bind" line, except that using the TCP rule allows the PROXY protocol
to be accepted only for certain IP address ranges using an ACL. This
is convenient when multiple layers of load balancers are passed
through by traffic coming from public hosts.
- capture <sample> len <length> :
This only applies to "tcp-request content" rules. It captures sample
expression <sample> from the request buffer, and converts it to a
string of at most <len> characters. The resulting string is stored into
the next request "capture" slot, so it will possibly appear next to
some captured HTTP headers. It will then automatically appear in the
logs, and it will be possible to extract it using sample fetch rules to
feed it into headers or anything. The length should be limited given
that this size will be allocated for each capture during the whole
session life. Please check section 7.3 (Fetching samples) and "capture
request header" for more information.
- { track-sc0 | track-sc1 | track-sc2 } <key> [table <table>] :
enables tracking of sticky counters from current connection. These
rules do not stop evaluation and do not change default action. The
number of counters that may be simultaneously tracked by the same
connection is set in MAX_SESS_STKCTR at build time (reported in
haproxy -vv) which defaults to 3, so the track-sc number is between 0
and (MAX_SESS_STKCTR-1). The first "track-sc0" rule executed enables
tracking of the counters of the specified table as the first set. The
first "track-sc1" rule executed enables tracking of the counters of the
specified table as the second set. The first "track-sc2" rule executed
enables tracking of the counters of the specified table as the third
set. It is a recommended practice to use the first set of counters for
the per-frontend counters and the second set for the per-backend ones.
But this is just a guideline, all may be used everywhere.
These actions take one or two arguments :
<key> is mandatory, and is a sample expression rule as described
in section 7.3. It describes what elements of the incoming
request or connection will be analyzed, extracted, combined,
and used to select which table entry to update the counters.
Note that "tcp-request connection" cannot use content-based
fetches.
<table> is an optional table to be used instead of the default one,
which is the stick-table declared in the current proxy. All
the counters for the matches and updates for the key will
then be performed in that table until the session ends.
Once a "track-sc*" rule is executed, the key is looked up in the table
and if it is not found, an entry is allocated for it. Then a pointer to
that entry is kept during all the session's life, and this entry's
counters are updated as often as possible, every time the session's
counters are updated, and also systematically when the session ends.
Counters are only updated for events that happen after the tracking has
been started. For example, connection counters will not be updated when
tracking layer 7 information, since the connection event happens before
layer7 information is extracted.
If the entry tracks concurrent connection counters, one connection is
counted for as long as the entry is tracked, and the entry will not
expire during that time. Tracking counters also provides a performance
advantage over just checking the keys, because only one table lookup is
performed for all ACL checks that make use of it.
- sc-inc-gpc0(<sc-id>):
The "sc-inc-gpc0" increments the GPC0 counter according to the sticky
counter designated by <sc-id>. If an error occurs, this action silently
fails and the actions evaluation continues.
- sc-inc-gpc1(<sc-id>):
The "sc-inc-gpc1" increments the GPC1 counter according to the sticky
counter designated by <sc-id>. If an error occurs, this action silently
fails and the actions evaluation continues.
- sc-set-gpt0(<sc-id>) { <int> | <expr> }:
This action sets the 32-bit unsigned GPT0 tag according to the sticky
counter designated by <sc-id> and the value of <int>/<expr>. The
expected result is a boolean. If an error occurs, this action silently
fails and the actions evaluation continues.
- set-mark <mark>:
Is used to set the Netfilter/IPFW MARK in all packets sent to the client
to the value passed in <mark> on platforms which support it. This value
is an unsigned 32 bit value which can be matched by netfilter/ipfw and by
the routing table or monitoring the packets through DTrace.
It can be expressed both in decimal or hexadecimal format (prefixed by
"0x"). This can be useful to force certain packets to take a different
route (for example a cheaper network path for bulk downloads). This works
on Linux kernels 2.6.32 and above and requires admin privileges, as well
on FreeBSD.
- set-src <expr> :
Is used to set the source IP address to the value of specified
expression. Useful if you want to mask source IP for privacy.
If you want to provide an IP from a HTTP header use "http-request
set-src".
Arguments:
<expr> Is a standard HAProxy expression formed by a sample-fetch
followed by some converters.
Example:
tcp-request connection set-src src,ipmask(24)
When possible, set-src preserves the original source port as long as the
address family allows it, otherwise the source port is set to 0.
- set-src-port <expr> :
Is used to set the source port address to the value of specified
expression.
Arguments:
<expr> Is a standard HAProxy expression formed by a sample-fetch
followed by some converters.
Example:
tcp-request connection set-src-port int(4000)
When possible, set-src-port preserves the original source address as long
as the address family supports a port, otherwise it forces the source
address to IPv4 "0.0.0.0" before rewriting the port.
- set-dst <expr> :
Is used to set the destination IP address to the value of specified
expression. Useful if you want to mask IP for privacy in log.
If you want to provide an IP from a HTTP header use "http-request
set-dst". If you want to connect to the new address/port, use
'0.0.0.0:0' as a server address in the backend.
<expr> Is a standard HAProxy expression formed by a sample-fetch
followed by some converters.
Example:
tcp-request connection set-dst dst,ipmask(24)
tcp-request connection set-dst ipv4(10.0.0.1)
When possible, set-dst preserves the original destination port as long as
the address family allows it, otherwise the destination port is set to 0.
- set-dst-port <expr> :
Is used to set the destination port address to the value of specified
expression. If you want to connect to the new address/port, use
'0.0.0.0:0' as a server address in the backend.
<expr> Is a standard HAProxy expression formed by a sample-fetch
followed by some converters.
Example:
tcp-request connection set-dst-port int(4000)
When possible, set-dst-port preserves the original destination address as
long as the address family supports a port, otherwise it forces the
destination address to IPv4 "0.0.0.0" before rewriting the port.
- set-tos <tos>:
Is used to set the TOS or DSCP field value of packets sent to the client
to the value passed in <tos> on platforms which support this. This value
represents the whole 8 bits of the IP TOS field, and can be expressed
both in decimal or hexadecimal format (prefixed by "0x"). Note that only
the 6 higher bits are used in DSCP or TOS, and the two lower bits are
always 0. This can be used to adjust some routing behavior on border
routers based on some information from the request.
See RFC 2474, 2597, 3260 and 4594 for more information.
- "silent-drop" :
This stops the evaluation of the rules and makes the client-facing
connection suddenly disappear using a system-dependent way that tries
to prevent the client from being notified. The effect it then that the
client still sees an established connection while there's none on
HAProxy. The purpose is to achieve a comparable effect to "tarpit"
except that it doesn't use any local resource at all on the machine
running HAProxy. It can resist much higher loads than "tarpit", and
slow down stronger attackers. It is important to understand the impact
of using this mechanism. All stateful equipment placed between the
client and HAProxy (firewalls, proxies, load balancers) will also keep
the established connection for a long time and may suffer from this
action. On modern Linux systems running with enough privileges, the
TCP_REPAIR socket option is used to block the emission of a TCP
reset. On other systems, the socket's TTL is reduced to 1 so that the
TCP reset doesn't pass the first router, though it's still delivered to
local networks. Do not use it unless you fully understand how it works.
Note that the "if/unless" condition is optional. If no condition is set on
the action, it is simply performed unconditionally. That can be useful for
"track-sc*" actions as well as for changing the default action to a reject.
Example:
Accept all connections from white-listed hosts, reject too fast connection without counting them, and track accepted connections. This results in connection rate being capped from abusive sources.tcp-request connection accept if { src -f /etc/haproxy/whitelist.lst } tcp-request connection reject if { src_conn_rate gt 10 } tcp-request connection track-sc0 src
Example:
Accept all connections from white-listed hosts, count all other connections and reject too fast ones. This results in abusive ones being blocked as long as they don't slow down.tcp-request connection accept if { src -f /etc/haproxy/whitelist.lst } tcp-request connection track-sc0 src tcp-request connection reject if { sc0_conn_rate gt 10 }
Example:
Enable the PROXY protocol for traffic coming from all known proxies.tcp-request connection expect-proxy layer4 if { src -f proxies.lst }
See section 7 about ACL usage.
Perform an action on a new session depending on a layer 4-7 condition
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | yes | yes | yes |
Arguments :
<action> defines the action to perform if the condition applies. See
below.
<condition> is a standard layer 4-7 ACL-based condition (see section 7).
A request's contents can be analyzed at an early stage of request processing
called "TCP content inspection". During this stage, ACL-based rules are
evaluated every time the request contents are updated, until either an
"accept", a "reject" or a "switch-mode" rule matches, or the TCP request
inspection delay expires with no matching rule.
The first difference between these rules and "tcp-request connection" rules
is that "tcp-request content" rules can make use of contents to take a
decision. Most often, these decisions will consider a protocol recognition or
validity. The second difference is that content-based rules can be used in
both frontends and backends. In case of HTTP keep-alive with the client, all
tcp-request content rules are evaluated again, so HAProxy keeps a record of
what sticky counters were assigned by a "tcp-request connection" versus a
"tcp-request content" rule, and flushes all the content-related ones after
processing an HTTP request, so that they may be evaluated again by the rules
being evaluated again for the next request. This is of particular importance
when the rule tracks some L7 information or when it is conditioned by an
L7-based ACL, since tracking may change between requests.
Content-based rules are evaluated in their exact declaration order. If no
rule matches or if there is no rule, the default action is to accept the
contents. There is no specific limit to the number of rules which may be
inserted.
Several types of actions are supported :
- accept : the request is accepted
- do-resolve: perform a DNS resolution
- reject : the request is rejected and the connection is closed
- capture : the specified sample expression is captured
- set-priority-class <expr> | set-priority-offset <expr>
- { track-sc0 | track-sc1 | track-sc2 } <key> [table <table>]
- sc-inc-gpc0(<sc-id>)
- sc-inc-gpc1(<sc-id>)
- sc-set-gpt0(<sc-id>) { <int> | <expr> }
- set-dst <expr>
- set-dst-port <expr>
- set-log-level <level>
- set-mark <mark>
- set-nice <nice>
- set-src <expr>
- set-src-port <expr>
- set-tos <tos>
- set-var(<var-name>) <expr>
- set-var-fmt(<var-name>) <fmt>
- switch-mode http [ proto <name> ]
- unset-var(<var-name>)
- silent-drop
- send-spoe-group <engine-name> <group-name>
- use-service <service-name>
They have the same meaning as their counter-parts in "tcp-request connection"
so please refer to that section for a complete description.
For "do-resolve" action, please check the "http-request do-resolve"
configuration section.
While there is nothing mandatory about it, it is recommended to use the
track-sc0 in "tcp-request connection" rules, track-sc1 for "tcp-request
content" rules in the frontend, and track-sc2 for "tcp-request content"
rules in the backend, because that makes the configuration more readable
and easier to troubleshoot, but this is just a guideline and all counters
may be used everywhere.
Note that the "if/unless" condition is optional. If no condition is set on
the action, it is simply performed unconditionally. That can be useful for
"track-sc*" actions as well as for changing the default action to a reject.
Note also that it is recommended to use a "tcp-request session" rule to track
information that does *not* depend on Layer 7 contents, especially for HTTP
frontends. Some HTTP processing are performed at the session level and may
lead to an early rejection of the requests. Thus, the tracking at the content
level may be disturbed in such case. A warning is emitted during startup to
prevent, as far as possible, such unreliable usage.
It is perfectly possible to match layer 7 contents with "tcp-request content"
rules from a TCP proxy, since HTTP-specific ACL matches are able to
preliminarily parse the contents of a buffer before extracting the required
data. If the buffered contents do not parse as a valid HTTP message, then the
ACL does not match. The parser which is involved there is exactly the same
as for all other HTTP processing, so there is no risk of parsing something
differently. In an HTTP frontend or an HTTP backend, it is guaranteed that
HTTP contents will always be immediately present when the rule is evaluated
first because the HTTP parsing is performed in the early stages of the
connection processing, at the session level. But for such proxies, using
"http-request" rules is much more natural and recommended.
Tracking layer7 information is also possible provided that the information
are present when the rule is processed. The rule processing engine is able to
wait until the inspect delay expires when the data to be tracked is not yet
available.
The "set-dst" and "set-dst-port" are used to set respectively the destination
IP and port. More information on how to use it at "http-request set-dst".
The "set-log-level" is used to set the log level of the current session. More
information on how to use it at "http-request set-log-level".
The "set-mark" is used to set the Netfilter MARK in all packets sent to the
client. More information on how to use it at "http-request set-mark".
The "set-nice" is used to set the "nice" factor of the current session. More
information on how to use it at "http-request set-nice".
The "set-src" and "set-src-port" are used to set respectively the source IP
and port. More information on how to use it at "http-request set-src".
The "set-tos" is used to set the TOS or DSCP field value of packets sent to
the client. More information on how to use it at "http-request set-tos".
The "set-var" and "set-var-fmt" are used to set the contents of a variable.
The variable is declared inline. For "tcp-request session" rules, only
session-level variables can be used, without any layer7 contents. The
"set-var" action takes a regular expression while "set-var-fmt" takes a
format string.
<var-name> The name of the variable starts with an indication about
its scope. The scopes allowed are:
"proc" : the variable is shared with the whole process
"sess" : the variable is shared with the whole session
"txn" : the variable is shared with the transaction
(request and response)
"req" : the variable is shared only during request
processing
"res" : the variable is shared only during response
processing
This prefix is followed by a name. The separator is a '.'.
The name may only contain characters 'a-z', 'A-Z', '0-9',
'.' and '_'.
<expr> Is a standard HAProxy expression formed by a sample-fetch
followed by some converters.
<fmt> This is the value expressed using log-format rules (see Custom
Log Format in section 8.2.4).
The "switch-mode" is used to perform a connection upgrade. Only HTTP
upgrades are supported for now. The protocol may optionally be
specified. This action is only available for a proxy with the frontend
capability. The connection upgrade is immediately performed, following
"tcp-request content" rules are not evaluated. This upgrade method should be
preferred to the implicit one consisting to rely on the backend mode. When
used, it is possible to set HTTP directives in a frontend without any
warning. These directives will be conditionally evaluated if the HTTP upgrade
is performed. However, an HTTP backend must still be selected. It remains
unsupported to route an HTTP connection (upgraded or not) to a TCP server.
See section 4 about Proxies for more details on HTTP upgrades.
The "unset-var" is used to unset a variable. See above for details about
<var-name>.
The "set-priority-class" is used to set the queue priority class of the
current request. The value must be a sample expression which converts to an
integer in the range -2047..2047. Results outside this range will be
truncated. The priority class determines the order in which queued requests
are processed. Lower values have higher priority.
The "set-priority-offset" is used to set the queue priority timestamp offset
of the current request. The value must be a sample expression which converts
to an integer in the range -524287..524287. Results outside this range will be
truncated. When a request is queued, it is ordered first by the priority
class, then by the current timestamp adjusted by the given offset in
milliseconds. Lower values have higher priority.
Note that the resulting timestamp is is only tracked with enough precision for
524,287ms (8m44s287ms). If the request is queued long enough to where the
adjusted timestamp exceeds this value, it will be misidentified as highest
priority. Thus it is important to set "timeout queue" to a value, where when
combined with the offset, does not exceed this limit.
The "send-spoe-group" is used to trigger sending of a group of SPOE
messages. To do so, the SPOE engine used to send messages must be defined, as
well as the SPOE group to send. Of course, the SPOE engine must refer to an
existing SPOE filter. If not engine name is provided on the SPOE filter line,
the SPOE agent name must be used.
<engine-name> The SPOE engine name.
<group-name> The SPOE group name as specified in the engine configuration.
The "use-service" is used to executes a TCP service which will reply to the
request and stop the evaluation of the rules. This service may choose to
reply by sending any valid response or it may immediately close the
connection without sending anything. Outside natives services, it is possible
to write your own services in Lua. No further "tcp-request" rules are
evaluated.
Example:
tcp-request content use-service lua.deny if { src -f /etc/haproxy/blacklist.lst }
Example:
tcp-request content set-var(sess.my_var) src
tcp-request content set-var-fmt(sess.from) %[src]:%[src_port]
tcp-request content unset-var(sess.my_var2)
Example:
# Accept HTTP requests containing a Host header saying "example.com"
# and reject everything else. (Only works for HTTP/1 connections)
acl is_host_com hdr(Host) -i example.com
tcp-request inspect-delay 30s
tcp-request content accept if is_host_com
tcp-request content reject
# Accept HTTP requests containing a Host header saying "example.com"
# and reject everything else. (works for HTTP/1 and HTTP/2 connections)
acl is_host_com hdr(Host) -i example.com
tcp-request inspect-delay 5s
tcp-request switch-mode http if HTTP
tcp-request reject # non-HTTP traffic is implicit here
...
http-request reject unless is_host_com
Example:
# reject SMTP connection if client speaks first
tcp-request inspect-delay 30s
acl content_present req.len gt 0
tcp-request content reject if content_present
# Forward HTTPS connection only if client speaks
tcp-request inspect-delay 30s
acl content_present req.len gt 0
tcp-request content accept if content_present
tcp-request content reject
Example:
# Track the last IP(stick-table type string) from X-Forwarded-For
tcp-request inspect-delay 10s
tcp-request content track-sc0 hdr(x-forwarded-for,-1)
# Or track the last IP(stick-table type ip|ipv6) from X-Forwarded-For
tcp-request content track-sc0 req.hdr_ip(x-forwarded-for,-1)
Example:
# track request counts per "base" (concatenation of Host+URL)
tcp-request inspect-delay 10s
tcp-request content track-sc0 base table req-rate
Example:
Track per-frontend and per-backend counters, block abusers at the frontend when the backend detects abuse(and marks gpc0).frontend http # Use General Purpose Counter 0 in SC0 as a global abuse counter # protecting all our sites stick-table type ip size 1m expire 5m store gpc0 tcp-request connection track-sc0 src tcp-request connection reject if { sc0_get_gpc0 gt 0 } ... use_backend http_dynamic if { path_end .php } backend http_dynamic # if a source makes too fast requests to this dynamic site (tracked # by SC1), block it globally in the frontend. stick-table type ip size 1m expire 5m store http_req_rate(10s) acl click_too_fast sc1_http_req_rate gt 10 acl mark_as_abuser sc0_inc_gpc0(http) gt 0 tcp-request content track-sc1 src tcp-request content reject if click_too_fast mark_as_abuser
See section 7 about ACL usage.
See also : "tcp-request connection", "tcp-request session", "tcp-request inspect-delay", and "http-request".
Set the maximum allowed time to wait for data during content inspection
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | yes | yes | yes |
Arguments :
<timeout> is the timeout value specified in milliseconds by default, but
can be in any other unit if the number is suffixed by the unit,
as explained at the top of this document.
People using HAProxy primarily as a TCP relay are often worried about the
risk of passing any type of protocol to a server without any analysis. In
order to be able to analyze the request contents, we must first withhold
the data then analyze them. This statement simply enables withholding of
data for at most the specified amount of time.
TCP content inspection applies very early when a connection reaches a
frontend, then very early when the connection is forwarded to a backend. This
means that a connection may experience a first delay in the frontend and a
second delay in the backend if both have tcp-request rules.
Note that when performing content inspection, HAProxy will evaluate the whole
rules for every new chunk which gets in, taking into account the fact that
those data are partial. If no rule matches before the aforementioned delay,
a last check is performed upon expiration, this time considering that the
contents are definitive. If no delay is set, HAProxy will not wait at all
and will immediately apply a verdict based on the available information.
Obviously this is unlikely to be very useful and might even be racy, so such
setups are not recommended.
Note the inspection delay is shortened if an connection error or shutdown is
experienced or if the request buffer appears as full.
As soon as a rule matches, the request is released and continues as usual. If
the timeout is reached and no rule matches, the default policy will be to let
it pass through unaffected.
For most protocols, it is enough to set it to a few seconds, as most clients
send the full request immediately upon connection. Add 3 or more seconds to
cover TCP retransmits but that's all. For some protocols, it may make sense
to use large values, for instance to ensure that the client never talks
before the server (e.g. SMTP), or to wait for a client to talk before passing
data to the server (e.g. SSL). Note that the client timeout must cover at
least the inspection delay, otherwise it will expire first. If the client
closes the connection or if the buffer is full, the delay immediately expires
since the contents will not be able to change anymore.
See also : "tcp-request content accept", "tcp-request content reject", "timeout client".
Perform an action on a session response depending on a layer 4-7 condition
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | no | yes | yes |
Arguments :
<action> defines the action to perform if the condition applies. See
below.
<condition> is a standard layer 4-7 ACL-based condition (see section 7).
Response contents can be analyzed at an early stage of response processing
called "TCP content inspection". During this stage, ACL-based rules are
evaluated every time the response contents are updated, until either an
"accept", "close" or a "reject" rule matches, or a TCP response inspection
delay is set and expires with no matching rule.
Most often, these decisions will consider a protocol recognition or validity.
Content-based rules are evaluated in their exact declaration order. If no
rule matches or if there is no rule, the default action is to accept the
contents. There is no specific limit to the number of rules which may be
inserted.
Several types of actions are supported :
- accept :
accepts the response if the condition is true (when used with "if")
or false (when used with "unless"). The first such rule executed ends
the rules evaluation.
- close :
immediately closes the connection with the server if the condition is
true (when used with "if"), or false (when used with "unless"). The
first such rule executed ends the rules evaluation. The main purpose of
this action is to force a connection to be finished between a client
and a server after an exchange when the application protocol expects
some long time outs to elapse first. The goal is to eliminate idle
connections which take significant resources on servers with certain
protocols.
- reject :
rejects the response if the condition is true (when used with "if")
or false (when used with "unless"). The first such rule executed ends
the rules evaluation. Rejected session are immediately closed.
- set-log-level <level>
The "set-log-level" is used to set the log level of the current
session. More information on how to use it at "http-response
set-log-level".
- set-mark <mark>
The "set-mark" is used to set the Netfilter MARK in all packets sent to
the client. More information on how to use it at "http-response
set-mark".
- set-nice <nice>
The "set-nice" is used to set the "nice" factor of the current
session. More information on how to use it at "http-response
set-nice".
- set-tos <tos>
The "set-tos" is used to set the TOS or DSCP field value of packets
sent to the client. More information on how to use it at "http-response
set-tos".
- set-var(<var-name>) <expr>
Sets a variable from an expression.
- set-var-fmt(<var-name>) <fmt>
Sets a variable from a log format string.
- unset-var(<var-name>)
Unsets a variable.
- sc-inc-gpc0(<sc-id>):
This action increments the GPC0 counter according to the sticky
counter designated by <sc-id>. If an error occurs, this action fails
silently and the actions evaluation continues.
- sc-inc-gpc1(<sc-id>):
This action increments the GPC1 counter according to the sticky
counter designated by <sc-id>. If an error occurs, this action fails
silently and the actions evaluation continues.
- sc-set-gpt0(<sc-id>) { <int> | <expr> }
This action sets the 32-bit unsigned GPT0 tag according to the sticky
counter designated by <sc-id> and the value of <int>/<expr>. The
expected result is a boolean. If an error occurs, this action silently
fails and the actions evaluation continues.
- "silent-drop" :
This stops the evaluation of the rules and makes the client-facing
connection suddenly disappear using a system-dependent way that tries
to prevent the client from being notified. The effect it then that the
client still sees an established connection while there's none on
HAProxy. The purpose is to achieve a comparable effect to "tarpit"
except that it doesn't use any local resource at all on the machine
running HAProxy. It can resist much higher loads than "tarpit", and
slow down stronger attackers. It is important to understand the impact
of using this mechanism. All stateful equipment placed between the
client and HAProxy (firewalls, proxies, load balancers) will also keep
the established connection for a long time and may suffer from this
action. On modern Linux systems running with enough privileges, the
TCP_REPAIR socket option is used to block the emission of a TCP
reset. On other systems, the socket's TTL is reduced to 1 so that the
TCP reset doesn't pass the first router, though it's still delivered to
local networks. Do not use it unless you fully understand how it works.
- send-spoe-group <engine-name> <group-name>
Send a group of SPOE messages.
Note that the "if/unless" condition is optional. If no condition is set on
the action, it is simply performed unconditionally. That can be useful for
for changing the default action to a reject.
It is perfectly possible to match layer 7 contents with "tcp-response
content" rules, but then it is important to ensure that a full response has
been buffered, otherwise no contents will match. In order to achieve this,
the best solution involves detecting the HTTP protocol during the inspection
period.
The "set-var" is used to set the content of a variable. The variable is
declared inline.
<var-name> The name of the variable starts with an indication about
its scope. The scopes allowed are:
"proc" : the variable is shared with the whole process
"sess" : the variable is shared with the whole session
"txn" : the variable is shared with the transaction
(request and response)
"req" : the variable is shared only during request
processing
"res" : the variable is shared only during response
processing
This prefix is followed by a name. The separator is a '.'.
The name may only contain characters 'a-z', 'A-Z', '0-9',
'.' and '_'.
<expr> Is a standard HAProxy expression formed by a sample-fetch
followed by some converters.
<fmt> This is the value expressed using log-format rules (see Custom
Log Format in section 8.2.4).
The "unset-var" is used to unset a variable. See above for details about
<var-name>.
The "send-spoe-group" is used to trigger sending of a group of SPOE
messages. To do so, the SPOE engine used to send messages must be defined, as
well as the SPOE group to send. Of course, the SPOE engine must refer to an
existing SPOE filter. If not engine name is provided on the SPOE filter line,
the SPOE agent name must be used.
<engine-name> The SPOE engine name.
<group-name> The SPOE group name as specified in the engine configuration.
See section 7 about ACL usage.
See also : "tcp-request content", "tcp-response inspect-delay"
Perform an action on a validated session depending on a layer 5 condition
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | yes | yes | no |
Arguments :
<action> defines the action to perform if the condition applies. See
below.
<condition> is a standard layer5-only ACL-based condition (see section 7).
Once a session is validated, (i.e. after all handshakes have been completed),
it is possible to evaluate some conditions to decide whether this session
must be accepted or dropped or have its counters tracked. Those conditions
cannot make use of any data contents because no buffers are allocated yet and
the processing cannot wait at this stage. The main use case it to copy some
early information into variables (since variables are accessible in the
session), or to keep track of some information collected after the handshake,
such as SSL-level elements (SNI, ciphers, client cert's CN) or information
from the PROXY protocol header (e.g. track a source forwarded this way). The
extracted information can thus be copied to a variable or tracked using
"track-sc" rules. Of course it is also possible to decide to accept/reject as
with other rulesets. Most operations performed here could also be performed
in "tcp-request content" rules, except that in HTTP these rules are evaluated
for each new request, and that might not always be acceptable. For example a
rule might increment a counter on each evaluation. It would also be possible
that a country is resolved by geolocation from the source IP address,
assigned to a session-wide variable, then the source address rewritten from
an HTTP header for all requests. If some contents need to be inspected in
order to take the decision, the "tcp-request content" statements must be used
instead.
The "tcp-request session" rules are evaluated in their exact declaration
order. If no rule matches or if there is no rule, the default action is to
accept the incoming session. There is no specific limit to the number of
rules which may be inserted.
Several types of actions are supported :
- accept : the request is accepted
- reject : the request is rejected and the connection is closed
- { track-sc0 | track-sc1 | track-sc2 } <key> [table <table>]
- sc-inc-gpc0(<sc-id>)
- sc-inc-gpc1(<sc-id>)
- sc-set-gpt0(<sc-id>) { <int> | <expr> }
- set-mark <mark>
- set-dst <expr>
- set-dst-port <expr>
- set-src <expr>
- set-src-port <expr>
- set-tos <tos>
- set-var(<var-name>) <expr>
- set-var-fmt(<var-name>) <fmt>
- unset-var(<var-name>)
- silent-drop
These actions have the same meaning as their respective counter-parts in
"tcp-request connection" and "tcp-request content", so please refer to these
sections for a complete description.
Note that the "if/unless" condition is optional. If no condition is set on
the action, it is simply performed unconditionally. That can be useful for
"track-sc*" actions as well as for changing the default action to a reject.
Example:
Track the original source address by default, or the one advertised in the PROXY protocol header for connection coming from the local proxies. The first connection-level rule enables receipt of the PROXY protocol for these ones, the second rule tracks whatever address we decide to keep after optional decoding.tcp-request connection expect-proxy layer4 if { src -f proxies.lst } tcp-request session track-sc0 src
Example:
Accept all sessions from white-listed hosts, reject too fast sessions without counting them, and track accepted sessions. This results in session rate being capped from abusive sources.tcp-request session accept if { src -f /etc/haproxy/whitelist.lst } tcp-request session reject if { src_sess_rate gt 10 } tcp-request session track-sc0 src
Example:
Accept all sessions from white-listed hosts, count all other sessions and reject too fast ones. This results in abusive ones being blocked as long as they don't slow down.tcp-request session accept if { src -f /etc/haproxy/whitelist.lst } tcp-request session track-sc0 src tcp-request session reject if { sc0_sess_rate gt 10 }
See section 7 about ACL usage.
Set the maximum allowed time to wait for a response during content inspection
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | no | yes | yes |
Arguments :
<timeout> is the timeout value specified in milliseconds by default, but
can be in any other unit if the number is suffixed by the unit,
as explained at the top of this document.
See also : "tcp-response content", "tcp-request inspect-delay".
Set additional check timeout, but only after a connection has been already
established.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments:
<timeout> is the timeout value specified in milliseconds by default, but
can be in any other unit if the number is suffixed by the unit,
as explained at the top of this document.
If set, HAProxy uses min("timeout connect", "inter") as a connect timeout
for check and "timeout check" as an additional read timeout. The "min" is
used so that people running with *very* long "timeout connect" (e.g. those
who needed this due to the queue or tarpit) do not slow down their checks.
(Please also note that there is no valid reason to have such long connect
timeouts, because "timeout queue" and "timeout tarpit" can always be used to
avoid that).
If "timeout check" is not set HAProxy uses "inter" for complete check
timeout (connect + read) exactly like all <1.3.15 version.
In most cases check request is much simpler and faster to handle than normal
requests and people may want to kick out laggy servers so this timeout should
be smaller than "timeout server".
This parameter is specific to backends, but can be specified once for all in
"defaults" sections. This is in fact one of the easiest solutions not to
forget about it.
Set the maximum inactivity time on the client side.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments :
<timeout> is the timeout value specified in milliseconds by default, but
can be in any other unit if the number is suffixed by the unit,
as explained at the top of this document.
The inactivity timeout applies when the client is expected to acknowledge or
send data. In HTTP mode, this timeout is particularly important to consider
during the first phase, when the client sends the request, and during the
response while it is reading data sent by the server. That said, for the
first phase, it is preferable to set the "timeout http-request" to better
protect HAProxy from Slowloris like attacks. The value is specified in
milliseconds by default, but can be in any other unit if the number is
suffixed by the unit, as specified at the top of this document. In TCP mode
(and to a lesser extent, in HTTP mode), it is highly recommended that the
client timeout remains equal to the server timeout in order to avoid complex
situations to debug. It is a good practice to cover one or several TCP packet
losses by specifying timeouts that are slightly above multiples of 3 seconds
(e.g. 4 or 5 seconds). If some long-lived sessions are mixed with short-lived
sessions (e.g. WebSocket and HTTP), it's worth considering "timeout tunnel",
which overrides "timeout client" and "timeout server" for tunnels, as well as
"timeout client-fin" for half-closed connections.
This parameter is specific to frontends, but can be specified once for all in
"defaults" sections. This is in fact one of the easiest solutions not to
forget about it. An unspecified timeout results in an infinite timeout, which
is not recommended. Such a usage is accepted and works but reports a warning
during startup because it may result in accumulation of expired sessions in
the system if the system's timeouts are not configured either.
Set the inactivity timeout on the client side for half-closed connections.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments :
<timeout> is the timeout value specified in milliseconds by default, but
can be in any other unit if the number is suffixed by the unit,
as explained at the top of this document.
The inactivity timeout applies when the client is expected to acknowledge or
send data while one direction is already shut down. This timeout is different
from "timeout client" in that it only applies to connections which are closed
in one direction. This is particularly useful to avoid keeping connections in
FIN_WAIT state for too long when clients do not disconnect cleanly. This
problem is particularly common long connections such as RDP or WebSocket.
Note that this timeout can override "timeout tunnel" when a connection shuts
down in one direction. It is applied to idle HTTP/2 connections once a GOAWAY
frame was sent, often indicating an expectation that the connection quickly
ends.
This parameter is specific to frontends, but can be specified once for all in
"defaults" sections. By default it is not set, so half-closed connections
will use the other timeouts (timeout.client or timeout.tunnel).
Set the maximum time to wait for a connection attempt to a server to succeed.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<timeout> is the timeout value specified in milliseconds by default, but
can be in any other unit if the number is suffixed by the unit,
as explained at the top of this document.
If the server is located on the same LAN as HAProxy, the connection should be
immediate (less than a few milliseconds). Anyway, it is a good practice to
cover one or several TCP packet losses by specifying timeouts that are
slightly above multiples of 3 seconds (e.g. 4 or 5 seconds). By default, the
connect timeout also presets both queue and tarpit timeouts to the same value
if these have not been specified.
This parameter is specific to backends, but can be specified once for all in
"defaults" sections. This is in fact one of the easiest solutions not to
forget about it. An unspecified timeout results in an infinite timeout, which
is not recommended. Such a usage is accepted and works but reports a warning
during startup because it may result in accumulation of failed sessions in
the system if the system's timeouts are not configured either.
Set the maximum allowed time to wait for a new HTTP request to appear
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
<timeout> is the timeout value specified in milliseconds by default, but
can be in any other unit if the number is suffixed by the unit,
as explained at the top of this document.
By default, the time to wait for a new request in case of keep-alive is set
by "timeout http-request". However this is not always convenient because some
people want very short keep-alive timeouts in order to release connections
faster, and others prefer to have larger ones but still have short timeouts
once the request has started to present itself.
The "http-keep-alive" timeout covers these needs. It will define how long to
wait for a new HTTP request to start coming after a response was sent. Once
the first byte of request has been seen, the "http-request" timeout is used
to wait for the complete request to come. Note that empty lines prior to a
new request do not refresh the timeout and are not counted as a new request.
There is also another difference between the two timeouts : when a connection
expires during timeout http-keep-alive, no error is returned, the connection
just closes. If the connection expires in "http-request" while waiting for a
request to complete, an HTTP 408 error is returned to the client before
closing the connection, unless "option http-ignore-probes" is set in the
frontend.
In general "timeout http-keep-alive" is best used to prevent clients from
holding open an otherwise idle connection too long on sites seeing large
amounts of short connections. This can be accomplished by setting the value
to a few tens to hundreds of milliseconds in HTTP/1.1. This will close the
connection after the client requests a page without having to hold that
connection open to wait for more activity from the client. In that scenario,
a new activity from the browser would result in a new handshake at the TCP
and/or SSL layer. A common use case for this is HTTP sites serving only a
redirect to the HTTPS page. Such connections are better not kept idle too
long because they won't be reused, unless maybe to fetch a favicon.
Another use case is the exact opposite: some sites want to permit clients
to reuse idle connections for a long time (e.g. 30 seconds to one minute) but
do not want to wait that long for the first request, in order to avoid a very
inexpensive attack vector. In this case, the http-keep-alive timeout would be
set to a large value, but http-request would remain low (a few seconds).
When set to a very small value additional requests that are not pipelined
are likely going to be handled over another connection unless the requests
are truly pipelined, which is very rare with HTTP/1.1 (requests being sent
back-to-back without waiting for a response). Most HTTP/1.1 implementations
send a request, wait for a response and then send another request. A small
value here for HTTP/1.1 may be advantageous to use less memory and sockets
for sites with hundreds of thousands of clients, at the expense of an
increase in handshake computation costs.
Special care should be taken with small values when dealing with HTTP/2. The
nature of HTTP/2 is to multiplex requests over a connection in order to save
on the overhead of reconnecting the TCP and/or SSL layers. The protocol also
uses control frames which cope poorly with early TCP connection closures, on
very rare occasions this may result in truncated responses when data are
destroyed in flight after leaving HAProxy (which then cannot even log an
error). A suggested low starting value for HTTP/2 connections would be around
4 seconds. This would prevent most modern keep-alive implementations from
needlessly holding open stale connections, and at the same time would allow
subsequent requests to reuse the connection. However, this should be adjusted
as needed and is simply a starting point.
If this parameter is not set, the "http-request" timeout applies, and if both
are not set, "timeout client" still applies at the lower level. It should be
set in the frontend to take effect, unless the frontend is in TCP mode, in
which case the HTTP backend's timeout will be used.
See also : "timeout http-request", "timeout client".
Set the maximum allowed time to wait for a complete HTTP request
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
<timeout> is the timeout value specified in milliseconds by default, but
can be in any other unit if the number is suffixed by the unit,
as explained at the top of this document.
In order to offer DoS protection, it may be required to lower the maximum
accepted time to receive a complete HTTP request without affecting the client
timeout. This helps protecting against established connections on which
nothing is sent. The client timeout cannot offer a good protection against
this abuse because it is an inactivity timeout, which means that if the
attacker sends one character every now and then, the timeout will not
trigger. With the HTTP request timeout, no matter what speed the client
types, the request will be aborted if it does not complete in time. When the
timeout expires, an HTTP 408 response is sent to the client to inform it
about the problem, and the connection is closed. The logs will report
termination codes "cR". Some recent browsers are having problems with this
standard, well-documented behavior, so it might be needed to hide the 408
code using "option http-ignore-probes" or "errorfile 408 /dev/null". See
more details in the explanations of the "cR" termination code in section 8.5.
By default, this timeout only applies to the header part of the request,
and not to any data. As soon as the empty line is received, this timeout is
not used anymore. When combined with "option http-buffer-request", this
timeout also applies to the body of the request..
It is used again on keep-alive connections to wait for a second
request if "timeout http-keep-alive" is not set.
Generally it is enough to set it to a few seconds, as most clients send the
full request immediately upon connection. Add 3 or more seconds to cover TCP
retransmits but that's all. Setting it to very low values (e.g. 50 ms) will
generally work on local networks as long as there are no packet losses. This
will prevent people from sending bare HTTP requests using telnet.
If this parameter is not set, the client timeout still applies between each
chunk of the incoming request. It should be set in the frontend to take
effect, unless the frontend is in TCP mode, in which case the HTTP backend's
timeout will be used.
See also : "errorfile", "http-ignore-probes", "timeout http-keep-alive", and "timeout client", "option http-buffer-request".
Set the maximum time to wait in the queue for a connection slot to be free
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<timeout> is the timeout value specified in milliseconds by default, but
can be in any other unit if the number is suffixed by the unit,
as explained at the top of this document.
When a server's maxconn is reached, connections are left pending in a queue
which may be server-specific or global to the backend. In order not to wait
indefinitely, a timeout is applied to requests pending in the queue. If the
timeout is reached, it is considered that the request will almost never be
served, so it is dropped and a 503 error is returned to the client.
The "timeout queue" statement allows to fix the maximum time for a request to
be left pending in a queue. If unspecified, the same value as the backend's
connection timeout ("timeout connect") is used, for backwards compatibility
with older versions with no "timeout queue" parameter.
See also : "timeout connect".
Set the maximum inactivity time on the server side.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<timeout> is the timeout value specified in milliseconds by default, but
can be in any other unit if the number is suffixed by the unit,
as explained at the top of this document.
The inactivity timeout applies when the server is expected to acknowledge or
send data. In HTTP mode, this timeout is particularly important to consider
during the first phase of the server's response, when it has to send the
headers, as it directly represents the server's processing time for the
request. To find out what value to put there, it's often good to start with
what would be considered as unacceptable response times, then check the logs
to observe the response time distribution, and adjust the value accordingly.
The value is specified in milliseconds by default, but can be in any other
unit if the number is suffixed by the unit, as specified at the top of this
document. In TCP mode (and to a lesser extent, in HTTP mode), it is highly
recommended that the client timeout remains equal to the server timeout in
order to avoid complex situations to debug. Whatever the expected server
response times, it is a good practice to cover at least one or several TCP
packet losses by specifying timeouts that are slightly above multiples of 3
seconds (e.g. 4 or 5 seconds minimum). If some long-lived sessions are mixed
with short-lived sessions (e.g. WebSocket and HTTP), it's worth considering
"timeout tunnel", which overrides "timeout client" and "timeout server" for
tunnels.
This parameter is specific to backends, but can be specified once for all in
"defaults" sections. This is in fact one of the easiest solutions not to
forget about it. An unspecified timeout results in an infinite timeout, which
is not recommended. Such a usage is accepted and works but reports a warning
during startup because it may result in accumulation of expired sessions in
the system if the system's timeouts are not configured either.
See also : "timeout client" and "timeout tunnel".
Set the inactivity timeout on the server side for half-closed connections.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<timeout> is the timeout value specified in milliseconds by default, but
can be in any other unit if the number is suffixed by the unit,
as explained at the top of this document.
The inactivity timeout applies when the server is expected to acknowledge or
send data while one direction is already shut down. This timeout is different
from "timeout server" in that it only applies to connections which are closed
in one direction. This is particularly useful to avoid keeping connections in
FIN_WAIT state for too long when a remote server does not disconnect cleanly.
This problem is particularly common long connections such as RDP or WebSocket.
Note that this timeout can override "timeout tunnel" when a connection shuts
down in one direction. This setting was provided for completeness, but in most
situations, it should not be needed.
This parameter is specific to backends, but can be specified once for all in
"defaults" sections. By default it is not set, so half-closed connections
will use the other timeouts (timeout.server or timeout.tunnel).
Set the duration for which tarpitted connections will be maintained
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | yes |
Arguments :
<timeout> is the tarpit duration specified in milliseconds by default, but
can be in any other unit if the number is suffixed by the unit,
as explained at the top of this document.
When a connection is tarpitted using "http-request tarpit", it is maintained
open with no activity for a certain amount of time, then closed. "timeout
tarpit" defines how long it will be maintained open.
The value is specified in milliseconds by default, but can be in any other
unit if the number is suffixed by the unit, as specified at the top of this
document. If unspecified, the same value as the backend's connection timeout
("timeout connect") is used, for backwards compatibility with older versions
with no "timeout tarpit" parameter.
See also : "timeout connect".
Set the maximum inactivity time on the client and server side for tunnels.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments :
<timeout> is the timeout value specified in milliseconds by default, but
can be in any other unit if the number is suffixed by the unit,
as explained at the top of this document.
The tunnel timeout applies when a bidirectional connection is established
between a client and a server, and the connection remains inactive in both
directions. This timeout supersedes both the client and server timeouts once
the connection becomes a tunnel. In TCP, this timeout is used as soon as no
analyzer remains attached to either connection (e.g. tcp content rules are
accepted). In HTTP, this timeout is used when a connection is upgraded (e.g.
when switching to the WebSocket protocol, or forwarding a CONNECT request
to a proxy), or after the first response when no keepalive/close option is
specified.
Since this timeout is usually used in conjunction with long-lived connections,
it usually is a good idea to also set "timeout client-fin" to handle the
situation where a client suddenly disappears from the net and does not
acknowledge a close, or sends a shutdown and does not acknowledge pending
data anymore. This can happen in lossy networks where firewalls are present,
and is detected by the presence of large amounts of sessions in a FIN_WAIT
state.
The value is specified in milliseconds by default, but can be in any other
unit if the number is suffixed by the unit, as specified at the top of this
document. Whatever the expected normal idle time, it is a good practice to
cover at least one or several TCP packet losses by specifying timeouts that
are slightly above multiples of 3 seconds (e.g. 4 or 5 seconds minimum).
This parameter is specific to backends, but can be specified once for all in
"defaults" sections. This is in fact one of the easiest solutions not to
forget about it.
Example :
defaults http
option http-server-close
timeout connect 5s
timeout client 30s
timeout client-fin 30s
timeout server 30s
timeout tunnel 1h # timeout to use with WebSocket and CONNECT
Enable client-side transparent proxying
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | no | yes | yes |
Arguments : none
This keyword was introduced in order to provide layer 7 persistence to layer
3 load balancers. The idea is to use the OS's ability to redirect an incoming
connection for a remote address to a local process (here HAProxy), and let
this process know what address was initially requested. When this option is
used, sessions without cookies will be forwarded to the original destination
IP address of the incoming request (which should match that of another
equipment), while requests with cookies will still be forwarded to the
appropriate server.
The "transparent" keyword is deprecated, use "option transparent" instead.
Note that contrary to a common belief, this option does NOT make HAProxy
present the client's IP to the server when establishing the connection.
See also: "option transparent"
Generate a unique ID for each request.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments :
<string> is a log-format string.
This keyword creates a ID for each request using the custom log format. A
unique ID is useful to trace a request passing through many components of
a complex infrastructure. The newly created ID may also be logged using the
%ID tag the log-format string.
The format should be composed from elements that are guaranteed to be
unique when combined together. For instance, if multiple HAProxy instances
are involved, it might be important to include the node name. It is often
needed to log the incoming connection's source and destination addresses
and ports. Note that since multiple requests may be performed over the same
connection, including a request counter may help differentiate them.
Similarly, a timestamp may protect against a rollover of the counter.
Logging the process ID will avoid collisions after a service restart.
It is recommended to use hexadecimal notation for many fields since it
makes them more compact and saves space in logs.
Example:
unique-id-format %{+X}o\ %ci:%cp_%fi:%fp_%Ts_%rt:%pid
will generate:
7F000001:8296_7F00001E:1F90_4F7B0A69_0003:790A
See also: "unique-id-header"
Add a unique ID header in the HTTP request.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| yes | yes | yes | no |
Arguments :
<name> is the name of the header.
Add a unique-id header in the HTTP request sent to the server, using the
unique-id-format. It can't work if the unique-id-format doesn't exist.
Example:
unique-id-format %{+X}o\ %ci:%cp_%fi:%fp_%Ts_%rt:%pid
unique-id-header X-Unique-ID
will generate:
X-Unique-ID: 7F000001:8296_7F00001E:1F90_4F7B0A69_0003:790A
See also: "unique-id-format"
Switch to a specific backend if/unless an ACL-based condition is matched.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | yes | yes | no |
Arguments :
<backend> is the name of a valid backend or "listen" section, or a
"log-format" string resolving to a backend name.
<condition> is a condition composed of ACLs, as described in section 7. If
it is omitted, the rule is unconditionally applied.
When doing content-switching, connections arrive on a frontend and are then
dispatched to various backends depending on a number of conditions. The
relation between the conditions and the backends is described with the
"use_backend" keyword. While it is normally used with HTTP processing, it can
also be used in pure TCP, either without content using stateless ACLs (e.g.
source address validation) or combined with a "tcp-request" rule to wait for
some payload.
There may be as many "use_backend" rules as desired. All of these rules are
evaluated in their declaration order, and the first one which matches will
assign the backend.
In the first form, the backend will be used if the condition is met. In the
second form, the backend will be used if the condition is not met. If no
condition is valid, the backend defined with "default_backend" will be used.
If no default backend is defined, either the servers in the same section are
used (in case of a "listen" section) or, in case of a frontend, no server is
used and a 503 service unavailable response is returned.
Note that it is possible to switch from a TCP frontend to an HTTP backend. In
this case, either the frontend has already checked that the protocol is HTTP,
and backend processing will immediately follow, or the backend will wait for
a complete HTTP request to get in. This feature is useful when a frontend
must decode several protocols on a unique port, one of them being HTTP.
When <backend> is a simple name, it is resolved at configuration time, and an
error is reported if the specified backend does not exist. If <backend> is
a log-format string instead, no check may be done at configuration time, so
the backend name is resolved dynamically at run time. If the resulting
backend name does not correspond to any valid backend, no other rule is
evaluated, and the default_backend directive is applied instead. Note that
when using dynamic backend names, it is highly recommended to use a prefix
that no other backend uses in order to ensure that an unauthorized backend
cannot be forced from the request.
It is worth mentioning that "use_backend" rules with an explicit name are
used to detect the association between frontends and backends to compute the
backend's "fullconn" setting. This cannot be done for dynamic names.
Defines the FastCGI application to use for the backend.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | no | yes | yes |
Arguments :
<name> is the name of the FastCGI application to use.
See section 10.1 about FastCGI application setup for details.
Only use a specific server if/unless an ACL-based condition is matched.
May be used in sections :
| defaults | frontend | listen | backend |
|---|---|---|---|
| no | no | yes | yes |
Arguments :
<server> is the name of a valid server in the same backend section
or a "log-format" string resolving to a server name.
<condition> is a condition composed of ACLs, as described in section 7.
By default, connections which arrive to a backend are load-balanced across
the available servers according to the configured algorithm, unless a
persistence mechanism such as a cookie is used and found in the request.
Sometimes it is desirable to forward a particular request to a specific
server without having to declare a dedicated backend for this server. This
can be achieved using the "use-server" rules. These rules are evaluated after
the "redirect" rules and before evaluating cookies, and they have precedence
on them. There may be as many "use-server" rules as desired. All of these
rules are evaluated in their declaration order, and the first one which
matches will assign the server.
If a rule designates a server which is down, and "option persist" is not used
and no force-persist rule was validated, it is ignored and evaluation goes on
with the next rules until one matches.
In the first form, the server will be used if the condition is met. In the
second form, the server will be used if the condition is not met. If no
condition is valid, the processing continues and the server will be assigned
according to other persistence mechanisms.
Note that even if a rule is matched, cookie processing is still performed but
does not assign the server. This allows prefixed cookies to have their prefix
stripped.
The "use-server" statement works both in HTTP and TCP mode. This makes it
suitable for use with content-based inspection. For instance, a server could
be selected in a farm according to the TLS SNI field when using protocols with
implicit TLS (also see "req.ssl_sni"). And if these servers have their weight
set to zero, they will not be used for other traffic.
Example :
# intercept incoming TLS requests based on the SNI field
use-server www if { req.ssl_sni -i www.example.com }
server www 192.168.0.1:443 weight 0
use-server mail if { req.ssl_sni -i mail.example.com }
server mail 192.168.0.1:465 weight 0
use-server imap if { req.ssl_sni -i imap.example.com }
server imap 192.168.0.1:993 weight 0
# all the rest is forwarded to this server
server default 192.168.0.2:443 check
When <server> is a simple name, it is checked against existing servers in the
configuration and an error is reported if the specified server does not exist.
If it is a log-format, no check is performed when parsing the configuration,
and if we can't resolve a valid server name at runtime but the use-server rule
was conditioned by an ACL returning true, no other use-server rule is applied
and we fall back to load balancing.
5. Bind and server options
The "bind", "server" and "default-server" keywords support a number of settings
depending on some build options and on the system HAProxy was built on. These
settings generally each consist in one word sometimes followed by a value,
written on the same line as the "bind" or "server" line. All these options are
described in this section.
5.1. Bind options
The "bind" keyword supports a certain number of settings which are all passed
as arguments on the same line. The order in which those arguments appear makes
no importance, provided that they appear after the bind address. All of these
parameters are optional. Some of them consist in a single words (booleans),
while other ones expect a value after them. In this case, the value must be
provided immediately after the setting name.
The currently supported settings are the following ones.
Enforces the use of the NetScaler Client IP insertion protocol over any
connection accepted by any of the TCP sockets declared on the same line. The
NetScaler Client IP insertion protocol dictates the layer 3/4 addresses of
the incoming connection to be used everywhere an address is used, with the
only exception of "tcp-request connection" rules which will only see the
real connection address. Logs will reflect the addresses indicated in the
protocol, unless it is violated, in which case the real address will still
be used. This keyword combined with support from external components can be
used as an efficient and reliable alternative to the X-Forwarded-For
mechanism which is not always reliable and not even always usable. See also
"tcp-request connection expect-netscaler-cip" for a finer-grained setting of
which client is allowed to use the protocol.
Enforces the use of the PROXY protocol over any connection accepted by any of
the sockets declared on the same line. Versions 1 and 2 of the PROXY protocol
are supported and correctly detected. The PROXY protocol dictates the layer
3/4 addresses of the incoming connection to be used everywhere an address is
used, with the only exception of "tcp-request connection" rules which will
only see the real connection address. Logs will reflect the addresses
indicated in the protocol, unless it is violated, in which case the real
address will still be used. This keyword combined with support from external
components can be used as an efficient and reliable alternative to the
X-Forwarded-For mechanism which is not always reliable and not even always
usable. See also "tcp-request connection expect-proxy" for a finer-grained
setting of which client is allowed to use the protocol.
Allow receiving early data when using TLSv1.3. This is disabled by default,
due to security considerations. Because it is vulnerable to replay attacks,
you should only allow if for requests that are safe to replay, i.e. requests
that are idempotent. You can use the "wait-for-handshake" action for any
request that wouldn't be safe with early data.
This enables the TLS ALPN extension and advertises the specified protocol
list as supported on top of ALPN. The protocol list consists in a comma-
delimited list of protocol names, for instance: "http/1.1,http/1.0" (without
quotes). This requires that the SSL library is built with support for TLS
extensions enabled (check with haproxy -vv). The ALPN extension replaces the
initial NPN extension. ALPN is required to enable HTTP/2 on an HTTP frontend.
Versions of OpenSSL prior to 1.0.2 didn't support ALPN and only supposed the
now obsolete NPN extension. At the time of writing this, most browsers still
support both ALPN and NPN for HTTP/2 so a fallback to NPN may still work for
a while. But ALPN must be used whenever possible. If both HTTP/2 and HTTP/1.1
are expected to be supported, both versions can be advertised, in order of
preference, like below :
bind :443 ssl crt pub.pem alpn h2,http/1.1
Sets the socket's backlog to this value. If unspecified or 0, the frontend's
backlog is used instead, which generally defaults to the maxconn value.
This setting is only available when support for OpenSSL was built in. It
designates a PEM file from which to load CA certificates used to verify
client's certificate.
This setting is only available when support for OpenSSL was built in.
Sets a comma separated list of errorIDs to ignore during verify at depth > 0.
If set to 'all', all errors are ignored. SSL handshake is not aborted if an
error is ignored.
This setting is only available when support for OpenSSL was built in. It
designates a PEM file containing both the CA certificate and the CA private
key used to create and sign server's certificates. This is a mandatory
setting when the dynamic generation of certificates is enabled. See
'generate-certificates' for details.
This setting is only available when support for OpenSSL was built in. It is
the CA private key passphrase. This setting is optional and used only when
the dynamic generation of certificates is enabled. See
'generate-certificates' for details.
This setting designates a PEM file from which to load CA certificates used to
verify client's certificate. It designates CA certificates which must not be
included in CA names sent in server hello message. Typically, "ca-file" must
be defined with intermediate certificates, and "ca-verify-file" with
certificates to ending the chain, like root CA.
This setting is only available when support for OpenSSL was built in. It sets
the string describing the list of cipher algorithms ("cipher suite") that are
negotiated during the SSL/TLS handshake up to TLSv1.2. The format of the
string is defined in "man 1 ciphers" from OpenSSL man pages. For background
information and recommendations see e.g.
(https://wiki.mozilla.org/Security/Server_Side_TLS) and
(https://mozilla.github.io/server-side-tls/ssl-config-generator/). For TLSv1.3
cipher configuration, please check the "ciphersuites" keyword.
This setting is only available when support for OpenSSL was built in and
OpenSSL 1.1.1 or later was used to build HAProxy. It sets the string describing
the list of cipher algorithms ("cipher suite") that are negotiated during the
TLSv1.3 handshake. The format of the string is defined in "man 1 ciphers" from
OpenSSL man pages under the "ciphersuites" section. For cipher configuration
for TLSv1.2 and earlier, please check the "ciphers" keyword.
This setting might accept TLSv1.2 ciphersuites however this is an
undocumented behavior and not recommended as it could be inconsistent or buggy.
The default TLSv1.3 ciphersuites of OpenSSL are:
"TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256"
TLSv1.3 only supports 5 ciphersuites:
- TLS_AES_128_GCM_SHA256
- TLS_AES_256_GCM_SHA384
- TLS_CHACHA20_POLY1305_SHA256
- TLS_AES_128_CCM_SHA256
- TLS_AES_128_CCM_8_SHA256
Example:
ciphers ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-RSA-AES128-GCM-SHA256
ciphersuites TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
This setting is only available when support for OpenSSL was built in. It
designates a PEM file from which to load certificate revocation list used
to verify client's certificate. You need to provide a certificate revocation
list for every certificate of your certificate authority chain.
This setting is only available when support for OpenSSL was built in. It
designates a PEM file containing both the required certificates and any
associated private keys. This file can be built by concatenating multiple
PEM files into one (e.g. cat cert.pem key.pem > combined.pem). If your CA
requires an intermediate certificate, this can also be concatenated into this
file. Intermediate certificate can also be shared in a directory via
"issuers-chain-path" directive.
If the file does not contain a private key, HAProxy will try to load
the key at the same path suffixed by a ".key".
If the OpenSSL used supports Diffie-Hellman, parameters present in this file
are loaded.
If a directory name is used instead of a PEM file, then all files found in
that directory will be loaded in alphabetic order unless their name ends
with '.key', '.issuer', '.ocsp' or '.sctl' (reserved extensions). This
directive may be specified multiple times in order to load certificates from
multiple files or directories. The certificates will be presented to clients
who provide a valid TLS Server Name Indication field matching one of their
CN or alt subjects. Wildcards are supported, where a wildcard character '*'
is used instead of the first hostname component (e.g. *.example.org matches
www.example.org but not www.sub.example.org). If an empty directory is used,
HAProxy will not start unless the "strict-sni" keyword is used.
If no SNI is provided by the client or if the SSL library does not support
TLS extensions, or if the client provides an SNI hostname which does not
match any certificate, then the first loaded certificate will be presented.
This means that when loading certificates from a directory, it is highly
recommended to load the default one first as a file or to ensure that it will
always be the first one in the directory.
Note that the same cert may be loaded multiple times without side effects.
Some CAs (such as GoDaddy) offer a drop down list of server types that do not
include HAProxy when obtaining a certificate. If this happens be sure to
choose a web server that the CA believes requires an intermediate CA (for
GoDaddy, selection Apache Tomcat will get the correct bundle, but many
others, e.g. nginx, result in a wrong bundle that will not work for some
clients).
For each PEM file, HAProxy checks for the presence of file at the same path
suffixed by ".ocsp". If such file is found, support for the TLS Certificate
Status Request extension (also known as "OCSP stapling") is automatically
enabled. The content of this file is optional. If not empty, it must contain
a valid OCSP Response in DER format. In order to be valid an OCSP Response
must comply with the following rules: it has to indicate a good status,
it has to be a single response for the certificate of the PEM file, and it
has to be valid at the moment of addition. If these rules are not respected
the OCSP Response is ignored and a warning is emitted. In order to identify
which certificate an OCSP Response applies to, the issuer's certificate is
necessary. If the issuer's certificate is not found in the PEM file, it will
be loaded from a file at the same path as the PEM file suffixed by ".issuer"
if it exists otherwise it will fail with an error.
For each PEM file, HAProxy also checks for the presence of file at the same
path suffixed by ".sctl". If such file is found, support for Certificate
Transparency (RFC6962) TLS extension is enabled. The file must contain a
valid Signed Certificate Timestamp List, as described in RFC. File is parsed
to check basic syntax, but no signatures are verified.
There are cases where it is desirable to support multiple key types, e.g. RSA
and ECDSA in the cipher suites offered to the clients. This allows clients
that support EC certificates to be able to use EC ciphers, while
simultaneously supporting older, RSA only clients.
To achieve this, OpenSSL 1.1.1 is required, you can configure this behavior
by providing one crt entry per certificate type, or by configuring a "cert
bundle" like it was required before HAProxy 1.8. See "ssl-load-extra-files".
This setting is only available when support for OpenSSL was built in. Sets a
comma separated list of errorIDs to ignore during verify at depth == 0. If
set to 'all', all errors are ignored. SSL handshake is not aborted if an error
is ignored.
This setting is only available when support for OpenSSL was built in. It
designates a list of PEM file with an optional ssl configuration and a SNI
filter per certificate, with the following format for each line :
<crtfile> [\[<sslbindconf> ...\]] [[!]<snifilter> ...]
sslbindconf supports "allow-0rtt", "alpn", "ca-file", "ca-verify-file",
"ciphers", "ciphersuites", "crl-file", "curves", "ecdhe", "no-ca-names",
"npn", "verify" configuration. With BoringSSL and Openssl >= 1.1.1
"ssl-min-ver" and "ssl-max-ver" are also supported. It overrides the
configuration set in bind line for the certificate.
Wildcards are supported in the SNI filter. Negative filter are also supported,
useful in combination with a wildcard filter to exclude a particular SNI, or
after the first certificate to exclude a pattern from its CN or Subject Alt
Name (SAN). The certificates will be presented to clients who provide a valid
TLS Server Name Indication field matching one of the SNI filters. If no SNI
filter is specified, the CN and SAN are used. This directive may be specified
multiple times. See the "crt" option for more information. The default
certificate is still needed to meet OpenSSL expectations. If it is not used,
the 'strict-sni' option may be used.
Multi-cert bundling (see "ssl-load-extra-files") is supported with crt-list,
as long as only the base name is given in the crt-list. SNI filter will do
the same work on all bundled certificates.
Empty lines as well as lines beginning with a hash ('#') will be ignored.
The first declared certificate of a bind line is used as the default
certificate, either from crt or crt-list option, which HAProxy should use in
the TLS handshake if no other certificate matches. This certificate will also
be used if the provided SNI matches its CN or SAN, even if a matching SNI
filter is found on any crt-list. The SNI filter !* can be used after the first
declared certificate to not include its CN and SAN in the SNI tree, so it will
never match except if no other certificate matches. This way the first
declared certificate act as a fallback.
crt-list file example:
cert1.pem !*
# comment
cert2.pem [alpn h2,http/1.1]
certW.pem *.domain.tld !secure.domain.tld
certS.pem [curves X25519:P-256 ciphers ECDHE-ECDSA-AES256-GCM-SHA384] secure.domain.tld
This setting is only available when support for OpenSSL was built in. It sets
the string describing the list of elliptic curves algorithms ("curve suite")
that are negotiated during the SSL/TLS handshake with ECDHE. The format of the
string is a colon-delimited list of curve name.
Is an optional keyword which is supported only on certain Linux kernels. It
states that a connection will only be accepted once some data arrive on it,
or at worst after the first retransmit. This should be used only on protocols
for which the client talks first (e.g. HTTP). It can slightly improve
performance by ensuring that most of the request is already available when
the connection is accepted. On the other hand, it will not be able to detect
connections which don't talk. It is important to note that this option is
broken in all kernels up to 2.6.31, as the connection is never accepted until
the client talks. This can cause issues with front firewalls which would see
an established connection while the proxy will only see it in SYN_RECV. This
option is only supported on TCPv4/TCPv6 sockets and ignored by other ones.
This setting is only available when support for OpenSSL was built in. It sets
the named curve (RFC 4492) used to generate ECDH ephemeral keys. By default,
used named curve is prime256v1.
This option is only usable with the stats socket. It gives your stats socket
the capability to pass listeners FD to another HAProxy process.
During a reload with the master-worker mode, the process is automatically
reexecuted adding -x and one of the stats socket with this option.
See also "-x" in the management guide.
This option enforces use of SSLv3 only on SSL connections instantiated from
this listener. SSLv3 is generally less expensive than the TLS counterparts
for high connection rates. This option is also available on global statement
"ssl-default-bind-options". See also "ssl-min-ver" and "ssl-max-ver".
This option enforces use of TLSv1.0 only on SSL connections instantiated from
this listener. This option is also available on global statement
"ssl-default-bind-options". See also "ssl-min-ver" and "ssl-max-ver".
This option enforces use of TLSv1.1 only on SSL connections instantiated from
this listener. This option is also available on global statement
"ssl-default-bind-options". See also "ssl-min-ver" and "ssl-max-ver".
This option enforces use of TLSv1.2 only on SSL connections instantiated from
this listener. This option is also available on global statement
"ssl-default-bind-options". See also "ssl-min-ver" and "ssl-max-ver".
This option enforces use of TLSv1.3 only on SSL connections instantiated from
this listener. This option is also available on global statement
"ssl-default-bind-options". See also "ssl-min-ver" and "ssl-max-ver".
This setting is only available when support for OpenSSL was built in. It
enables the dynamic SSL certificates generation. A CA certificate and its
private key are necessary (see 'ca-sign-file'). When HAProxy is configured as
a transparent forward proxy, SSL requests generate errors because of a common
name mismatch on the certificate presented to the client. With this option
enabled, HAProxy will try to forge a certificate using the SNI hostname
indicated by the client. This is done only if no certificate matches the SNI
hostname (see 'crt-list'). If an error occurs, the default certificate is
used, else the 'strict-sni' option is set.
It can also be used when HAProxy is configured as a reverse proxy to ease the
deployment of an architecture with many backends.
Creating a SSL certificate is an expensive operation, so a LRU cache is used
to store forged certificates (see 'tune.ssl.ssl-ctx-cache-size'). It
increases the HAProxy's memory footprint to reduce latency when the same
certificate is used many times.
Sets the group of the UNIX sockets to the designated system gid. It can also
be set by default in the global section's "unix-bind" statement. Note that
some platforms simply ignore this. This setting is equivalent to the "group"
setting except that the group ID is used instead of its name. This setting is
ignored by non UNIX sockets.
Sets the group of the UNIX sockets to the designated system group. It can
also be set by default in the global section's "unix-bind" statement. Note
that some platforms simply ignore this. This setting is equivalent to the
"gid" setting except that the group name is used instead of its gid. This
setting is ignored by non UNIX sockets.
Fixes the socket ID. By default, socket IDs are automatically assigned, but
sometimes it is more convenient to fix them to ease monitoring. This value
must be strictly positive and unique within the listener/frontend. This
option can only be used when defining only a single socket.
Restricts the socket to a specific interface. When specified, only packets
received from that particular interface are processed by the socket. This is
currently only supported on Linux. The interface must be a primary system
interface, not an aliased interface. It is also possible to bind multiple
frontends to the same address if they are bound to different interfaces. Note
that binding to a network interface requires root privileges. This parameter
is only compatible with TCPv4/TCPv6 sockets. When specified, return traffic
uses the same interface as inbound traffic, and its associated routing table,
even if there are explicit routes through different interfaces configured.
This can prove useful to address asymmetric routing issues when the same
client IP addresses need to be able to reach frontends hosted on different
interfaces.
This setting is used with the stats sockets only to restrict the nature of
the commands that can be issued on the socket. It is ignored by other
sockets. <level> can be one of :
- "user" is the least privileged level; only non-sensitive stats can be
read, and no change is allowed. It would make sense on systems where it
is not easy to restrict access to the socket.
- "operator" is the default level and fits most common uses. All data can
be read, and only non-sensitive changes are permitted (e.g. clear max
counters).
- "admin" should be used with care, as everything is permitted (e.g. clear
all counters).
Limits the sockets to this number of concurrent connections. Extraneous
connections will remain in the system's backlog until a connection is
released. If unspecified, the limit will be the same as the frontend's
maxconn. Note that in case of port ranges or multiple addresses, the same
value will be applied to each socket. This setting enables different
limitations on expensive sockets, for instance SSL entries which may easily
eat all memory.
Sets the octal mode used to define access permissions on the UNIX socket. It
can also be set by default in the global section's "unix-bind" statement.
Note that some platforms simply ignore this. This setting is ignored by non
UNIX sockets.
Sets the TCP Maximum Segment Size (MSS) value to be advertised on incoming
connections. This can be used to force a lower MSS for certain specific
ports, for instance for connections passing through a VPN. Note that this
relies on a kernel feature which is theoretically supported under Linux but
was buggy in all versions prior to 2.6.28. It may or may not work on other
operating systems. It may also not change the advertised value but change the
effective size of outgoing segments. The commonly advertised value for TCPv4
over Ethernet networks is 1460 = 1500(MTU) - 40(IP+TCP). If this value is
positive, it will be used as the advertised MSS. If it is negative, it will
indicate by how much to reduce the incoming connection's advertised MSS for
outgoing segments. This parameter is only compatible with TCP v4/v6 sockets.
Sets an optional name for these sockets, which will be reported on the stats
page.
On Linux, it is possible to specify which network namespace a socket will
belong to. This directive makes it possible to explicitly bind a listener to
a namespace different from the default one. Please refer to your operating
system's documentation to find more details about network namespaces.
Sets the 'niceness' of connections initiated from the socket. Value must be
in the range -1024..1024 inclusive, and defaults to zero. Positive values
means that such connections are more friendly to others and easily offer
their place in the scheduler. On the opposite, negative values mean that
connections want to run with a higher priority than others. The difference
only happens under high loads when the system is close to saturation.
Negative values are appropriate for low-latency or administration services,
and high values are generally recommended for CPU intensive tasks such as SSL
processing or bulk transfers which are less sensible to latency. For example,
it may make sense to use a positive value for an SMTP socket and a negative
one for an RDP socket.
This setting is only available when support for OpenSSL was built in. It
prevents from send CA names in server hello message when ca-file is used.
Use "ca-verify-file" instead of "ca-file" with "no-ca-names".
This setting is only available when support for OpenSSL was built in. It
disables support for SSLv3 on any sockets instantiated from the listener when
SSL is supported. Note that SSLv2 is forced disabled in the code and cannot
be enabled using any configuration option. This option is also available on
global statement "ssl-default-bind-options". Use "ssl-min-ver" and
"ssl-max-ver" instead.
This setting is only available when support for OpenSSL was built in. It
disables the stateless session resumption (RFC 5077 TLS Ticket
extension) and force to use stateful session resumption. Stateless
session resumption is more expensive in CPU usage. This option is also
available on global statement "ssl-default-bind-options".
The TLS ticket mechanism is only used up to TLS 1.2.
Forward Secrecy is compromised with TLS tickets, unless ticket keys
are periodically rotated (via reload or by using "tls-ticket-keys").
This setting is only available when support for OpenSSL was built in. It
disables support for TLSv1.0 on any sockets instantiated from the listener
when SSL is supported. Note that SSLv2 is forced disabled in the code and
cannot be enabled using any configuration option. This option is also
available on global statement "ssl-default-bind-options". Use "ssl-min-ver"
and "ssl-max-ver" instead.
This setting is only available when support for OpenSSL was built in. It
disables support for TLSv1.1 on any sockets instantiated from the listener
when SSL is supported. Note that SSLv2 is forced disabled in the code and
cannot be enabled using any configuration option. This option is also
available on global statement "ssl-default-bind-options". Use "ssl-min-ver"
and "ssl-max-ver" instead.
This setting is only available when support for OpenSSL was built in. It
disables support for TLSv1.2 on any sockets instantiated from the listener
when SSL is supported. Note that SSLv2 is forced disabled in the code and
cannot be enabled using any configuration option. This option is also
available on global statement "ssl-default-bind-options". Use "ssl-min-ver"
and "ssl-max-ver" instead.
This setting is only available when support for OpenSSL was built in. It
disables support for TLSv1.3 on any sockets instantiated from the listener
when SSL is supported. Note that SSLv2 is forced disabled in the code and
cannot be enabled using any configuration option. This option is also
available on global statement "ssl-default-bind-options". Use "ssl-min-ver"
and "ssl-max-ver" instead.
This enables the NPN TLS extension and advertises the specified protocol list
as supported on top of NPN. The protocol list consists in a comma-delimited
list of protocol names, for instance: "http/1.1,http/1.0" (without quotes).
This requires that the SSL library is built with support for TLS extensions
enabled (check with haproxy -vv). Note that the NPN extension has been
replaced with the ALPN extension (see the "alpn" keyword), though this one is
only available starting with OpenSSL 1.0.2. If HTTP/2 is desired on an older
version of OpenSSL, NPN might still be used as most clients still support it
at the time of writing this. It is possible to enable both NPN and ALPN
though it probably doesn't make any sense out of testing.
Use the client's preference when selecting the cipher suite, by default
the server's preference is enforced. This option is also available on
global statement "ssl-default-bind-options".
Note that with OpenSSL >= 1.1.1 ChaCha20-Poly1305 is reprioritized anyway
(without setting this option), if a ChaCha20-Poly1305 cipher is at the top of
the client cipher list.
This restricts the list of processes or threads on which this listener is
allowed to run. It does not enforce any process but eliminates those which do
not match. If the frontend uses a "bind-process" setting, the intersection
between the two is applied. If in the end the listener is not allowed to run
on any remaining process, a warning is emitted, and the listener will either
run on the first process of the listener if a single process was specified,
or on all of its processes if multiple processes were specified. If a thread
set is specified, it limits the threads allowed to process incoming
connections for this listener, for the the process set. If multiple processes
and threads are configured, a warning is emitted, as it either results from a
configuration error or a misunderstanding of these models. For the unlikely
case where several ranges are needed, this directive may be repeated.
<process-set> and <thread-set> must use the format
all | odd | even | number[-[number]]
Ranges can be partially defined. The higher bound can be omitted. In such
case, it is replaced by the corresponding maximum value. The main purpose of
this directive is to be used with the stats sockets and have one different
socket per process. The second purpose is to have multiple bind lines sharing
the same IP:port but not the same process in a listener, so that the system
can distribute the incoming connections into multiple queues and allow a
smoother inter-process load balancing. Currently Linux 3.9 and above is known
for supporting this. See also "bind-process" and "nbproc".
Forces the multiplexer's protocol to use for the incoming connections. It
must be compatible with the mode of the frontend (TCP or HTTP). It must also
be usable on the frontend side. The list of available protocols is reported
in haproxy -vv. The protocols properties are reported : the mode (TCP/HTTP),
the side (FE/BE), the mux name and its flags.
Some protocols report errors on aborts (flag=CLEAN_ABRT). Some others are
subject to the head-of-line blocking on server side (flag=HOL_RISK). Finally
some protocols don't support upgrades (flag=NO_UPG). The HTX compatibility is
also reported (flag=HTX).
Here are the protocols that may be used as argument to a "proto" directive on
a bind line :
h2 : mode=HTTP side=FE|BE mux=H2 flags=HTX|CLEAN_ABRT|HOL_RISK|NO_UPG
h1 : mode=HTTP side=FE|BE mux=H1 flags=HTX|NO_UPG
none : mode=TCP side=FE|BE mux=PASS flags=NO_UPG
Idea behind this option is to bypass the selection of the best multiplexer's
protocol for all connections instantiated from this listening socket. For
instance, it is possible to force the http/2 on clear TCP by specifying "proto
h2" on the bind line.
This setting is used with the stats sockets only to configure severity
level output prepended to informational feedback messages. Severity
level of messages can range between 0 and 7, conforming to syslog
rfc5424. Valid and successful socket commands requesting data
(i.e. "show map", "get acl foo" etc.) will never have a severity level
prepended. It is ignored by other sockets. <format> can be one of :
- "none" (default) no severity level is prepended to feedback messages.
- "number" severity level is prepended as a number.
- "string" severity level is prepended as a string following the
rfc5424 convention.
This setting is only available when support for OpenSSL was built in. It
enables SSL deciphering on connections instantiated from this listener. A
certificate is necessary (see "crt" above). All contents in the buffers will
appear in clear text, so that ACLs and HTTP processing will only have access
to deciphered contents. SSLv3 is disabled per default, use "ssl-min-ver SSLv3"
to enable it.
This option enforces use of <version> or lower on SSL connections instantiated
from this listener. Using this setting without "ssl-min-ver" can be
ambiguous because the default ssl-min-ver value could change in future HAProxy
versions. This option is also available on global statement
"ssl-default-bind-options". See also "ssl-min-ver".
This option enforces use of <version> or upper on SSL connections
instantiated from this listener. The default value is "TLSv1.2". This option
is also available on global statement "ssl-default-bind-options".
See also "ssl-max-ver".
This setting is only available when support for OpenSSL was built in. The
SSL/TLS negotiation is allow only if the client provided an SNI which match
a certificate. The default certificate is not used. This option also allows
to start without any certificate on a bind line, so an empty directory could
be used and filled later from the stats socket.
See the "crt" option for more information. See "add ssl crt-list" command in
the management guide.
Sets the TCP User Timeout for all incoming connections instantiated from this
listening socket. This option is available on Linux since version 2.6.37. It
allows HAProxy to configure a timeout for sockets which contain data not
receiving an acknowledgment for the configured delay. This is especially
useful on long-lived connections experiencing long idle periods such as
remote terminals or database connection pools, where the client and server
timeouts must remain high to allow a long period of idle, but where it is
important to detect that the client has disappeared in order to release all
resources associated with its connection (and the server's session). The
argument is a delay expressed in milliseconds by default. This only works
for regular TCP connections, and is ignored for other protocols.
Is an optional keyword which is supported only on Linux kernels >= 3.7. It
enables TCP Fast Open on the listening socket, which means that clients which
support this feature will be able to send a request and receive a response
during the 3-way handshake starting from second connection, thus saving one
round-trip after the first connection. This only makes sense with protocols
that use high connection rates and where each round trip matters. This can
possibly cause issues with many firewalls which do not accept data on SYN
packets, so this option should only be enabled once well tested. This option
is only supported on TCPv4/TCPv6 sockets and ignored by other ones. You may
need to build HAProxy with USE_TFO=1 if your libc doesn't define
TCP_FASTOPEN.
Sets the TLS ticket keys file to load the keys from. The keys need to be 48
or 80 bytes long, depending if aes128 or aes256 is used, encoded with base64
with one line per key (ex. openssl rand 80 | openssl base64 -A | xargs echo).
The first key determines the key length used for next keys: you can't mix
aes128 and aes256 keys. Number of keys is specified by the TLS_TICKETS_NO
build option (default 3) and at least as many keys need to be present in
the file. Last TLS_TICKETS_NO keys will be used for decryption and the
penultimate one for encryption. This enables easy key rotation by just
appending new key to the file and reloading the process. Keys must be
periodically rotated (ex. every 12h) or Perfect Forward Secrecy is
compromised. It is also a good idea to keep the keys off any permanent
storage such as hard drives (hint: use tmpfs and don't swap those files).
Lifetime hint can be changed using tune.ssl.timeout.
Is an optional keyword which is supported only on certain Linux kernels. It
indicates that the addresses will be bound even if they do not belong to the
local machine, and that packets targeting any of these addresses will be
intercepted just as if the addresses were locally configured. This normally
requires that IP forwarding is enabled. Caution! do not use this with the
default address '*', as it would redirect any traffic for the specified port.
This keyword is available only when HAProxy is built with USE_LINUX_TPROXY=1.
This parameter is only compatible with TCPv4 and TCPv6 sockets, depending on
kernel version. Some distribution kernels include backports of the feature,
so check for support with your vendor.
Sets the owner of the UNIX sockets to the designated system uid. It can also
be set by default in the global section's "unix-bind" statement. Note that
some platforms simply ignore this. This setting is equivalent to the "user"
setting except that the user numeric ID is used instead of its name. This
setting is ignored by non UNIX sockets.
Sets the owner of the UNIX sockets to the designated system user. It can also
be set by default in the global section's "unix-bind" statement. Note that
some platforms simply ignore this. This setting is equivalent to the "uid"
setting except that the user name is used instead of its uid. This setting is
ignored by non UNIX sockets.
Is an optional keyword which is supported only on most recent systems
including Linux kernels >= 2.4.21. It is used to bind a socket to both IPv4
and IPv6 when it uses the default address. Doing so is sometimes necessary
on systems which bind to IPv6 only by default. It has no effect on non-IPv6
sockets, and is overridden by the "v6only" option.
Is an optional keyword which is supported only on most recent systems
including Linux kernels >= 2.4.21. It is used to bind a socket to IPv6 only
when it uses the default address. Doing so is sometimes preferred to doing it
system-wide as it is per-listener. It has no effect on non-IPv6 sockets and
has precedence over the "v4v6" option.
This setting is only available when support for OpenSSL was built in. If set
to 'none', client certificate is not requested. This is the default. In other
cases, a client certificate is requested. If the client does not provide a
certificate after the request and if 'verify' is set to 'required', then the
handshake is aborted, while it would have succeeded if set to 'optional'. The
certificate provided by the client is always verified using CAs from
'ca-file' and optional CRLs from 'crl-file'. On verify failure the handshake
is aborted, regardless of the 'verify' option, unless the error code exactly
matches one of those listed with 'ca-ignore-err' or 'crt-ignore-err'.
5.2. Server and default-server options
The "server" and "default-server" keywords support a certain number of settings
which are all passed as arguments on the server line. The order in which those
arguments appear does not count, and they are all optional. Some of those
settings are single words (booleans) while others expect one or several values
after them. In this case, the values must immediately follow the setting name.
Except default-server, all those settings must be specified after the server's
address if they are used:
server <name> <address>[:port] [settings ...]
default-server [settings ...]
Note that all these settings are supported both by "server" and "default-server"
keywords, except "id" which is only supported by "server".
The currently supported settings are the following ones.
Using the "addr" parameter, it becomes possible to use a different IP address
to send health-checks or to probe the agent-check. On some servers, it may be
desirable to dedicate an IP address to specific component able to perform
complex tests which are more suitable to health-checks than the application.
This parameter is ignored if the "check" parameter is not set. See also the
"port" parameter.
Enable an auxiliary agent check which is run independently of a regular
health check. An agent health check is performed by making a TCP connection
to the port set by the "agent-port" parameter and reading an ASCII string
terminated by the first '\r' or '\n' met. The string is made of a series of
words delimited by spaces, tabs or commas in any order, each consisting of :
- An ASCII representation of a positive integer percentage, e.g. "75%".
Values in this format will set the weight proportional to the initial
weight of a server as configured when HAProxy starts. Note that a zero
weight is reported on the stats page as "DRAIN" since it has the same
effect on the server (it's removed from the LB farm).
- The string "maxconn:" followed by an integer (no space between). Values
in this format will set the maxconn of a server. The maximum number of
connections advertised needs to be multiplied by the number of load
balancers and different backends that use this health check to get the
total number of connections the server might receive. Example: maxconn:30
- The word "ready". This will turn the server's administrative state to the
READY mode, thus canceling any DRAIN or MAINT state
- The word "drain". This will turn the server's administrative state to the
DRAIN mode, thus it will not accept any new connections other than those
that are accepted via persistence.
- The word "maint". This will turn the server's administrative state to the
MAINT mode, thus it will not accept any new connections at all, and health
checks will be stopped.
- The words "down", "fail", or "stopped", optionally followed by a
description string after a sharp ('#'). All of these mark the server's
operating state as DOWN, but since the word itself is reported on the stats
page, the difference allows an administrator to know if the situation was
expected or not : the service may intentionally be stopped, may appear up
but fail some validity tests, or may be seen as down (e.g. missing process,
or port not responding).
- The word "up" sets back the server's operating state as UP if health checks
also report that the service is accessible.
Parameters which are not advertised by the agent are not changed. For
example, an agent might be designed to monitor CPU usage and only report a
relative weight and never interact with the operating status. Similarly, an
agent could be designed as an end-user interface with 3 radio buttons
allowing an administrator to change only the administrative state. However,
it is important to consider that only the agent may revert its own actions,
so if a server is set to DRAIN mode or to DOWN state using the agent, the
agent must implement the other equivalent actions to bring the service into
operations again.
Failure to connect to the agent is not considered an error as connectivity
is tested by the regular health check which is enabled by the "check"
parameter. Warning though, it is not a good idea to stop an agent after it
reports "down", since only an agent reporting "up" will be able to turn the
server up again. Note that the CLI on the Unix stats socket is also able to
force an agent's result in order to work around a bogus agent if needed.
Requires the "agent-port" parameter to be set. See also the "agent-inter"
and "no-agent-check" parameters.
If this option is specified, HAProxy will send the given string (verbatim)
to the agent server upon connection. You could, for example, encode
the backend name into this string, which would enable your agent to send
different responses based on the backend. Make sure to include a '\n' if
you want to terminate your request with a newline.
The "agent-inter" parameter sets the interval between two agent checks
to <delay> milliseconds. If left unspecified, the delay defaults to 2000 ms.
Just as with every other time-based parameter, it may be entered in any
other explicit unit among { us, ms, s, m, h, d }. The "agent-inter"
parameter also serves as a timeout for agent checks "timeout check" is
not set. In order to reduce "resonance" effects when multiple servers are
hosted on the same hardware, the agent and health checks of all servers
are started with a small time offset between them. It is also possible to
add some random noise in the agent and health checks interval using the
global "spread-checks" keyword. This makes sense for instance when a lot
of backends use the same servers.
See also the "agent-check" and "agent-port" parameters.
The "agent-addr" parameter sets address for agent check.
You can offload agent-check to another target, so you can make single place
managing status and weights of servers defined in HAProxy in case you can't
make self-aware and self-managing services. You can specify both IP or
hostname, it will be resolved.
The "agent-port" parameter sets the TCP port used for agent checks.
See also the "agent-check" and "agent-inter" parameters.
Allow sending early data to the server when using TLS 1.3.
Note that early data will be sent only if the client used early data, or
if the backend uses "retry-on" with the "0rtt-rejected" keyword.
This enables the TLS ALPN extension and advertises the specified protocol
list as supported on top of ALPN. The protocol list consists in a comma-
delimited list of protocol names, for instance: "http/1.1,http/1.0" (without
quotes). This requires that the SSL library is built with support for TLS
extensions enabled (check with haproxy -vv). The ALPN extension replaces the
initial NPN extension. ALPN is required to connect to HTTP/2 servers.
Versions of OpenSSL prior to 1.0.2 didn't support ALPN and only supposed the
now obsolete NPN extension.
If both HTTP/2 and HTTP/1.1 are expected to be supported, both versions can
be advertised, in order of preference, like below :
server 127.0.0.1:443 ssl crt pub.pem alpn h2,http/1.1
See also "ws" to use an alternative ALPN for websocket streams.
When "backup" is present on a server line, the server is only used in load
balancing when all other non-backup servers are unavailable. Requests coming
with a persistence cookie referencing the server will always be served
though. By default, only the first operational backup server is used, unless
the "allbackups" option is set in the backend. See also the "no-backup" and
"allbackups" options.
This setting is only available when support for OpenSSL was built in. It
designates a PEM file from which to load CA certificates used to verify
server's certificate.
This option enables health checks on a server:
- when not set, no health checking is performed, and the server is always
considered available.
- when set and no other check method is configured, the server is considered
available when a connection can be established at the highest configured
transport layer. This means TCP by default, or SSL/TLS when "ssl" or
"check-ssl" are set, both possibly combined with connection prefixes such
as a PROXY protocol header when "send-proxy" or "check-send-proxy" are
set.
- when set and an application-level health check is defined, the
application-level exchanges are performed on top of the configured
transport layer and the server is considered available if all of the
exchanges succeed.
By default, health checks are performed on the same address and port as
configured on the server, using the same encapsulation parameters (SSL/TLS,
proxy-protocol header, etc... ). It is possible to change the destination
address using "addr" and the port using "port". When done, it is assumed the
server isn't checked on the service port, and configured encapsulation
parameters are not reused. One must explicitly set "check-send-proxy" to send
connection headers, "check-ssl" to use SSL/TLS.
When "sni" or "alpn" are set on the server line, their value is not used for
health checks and one must use "check-sni" or "check-alpn".
The default source address for health check traffic is the same as the one
defined in the backend. It can be changed with the "source" keyword.
The interval between checks can be set using the "inter" keyword, and the
"rise" and "fall" keywords can be used to define how many successful or
failed health checks are required to flag a server available or not
available.
Optional application-level health checks can be configured with "option
httpchk", "option mysql-check" "option smtpchk", "option pgsql-check",
"option ldap-check", or "option redis-check".
Example:
# simple tcp check
backend foo
server s1 192.168.0.1:80 check
# this does a tcp connect + tls handshake
backend foo
server s1 192.168.0.1:443 ssl check
# simple tcp check is enough for check success
backend foo
option tcp-check
tcp-check connect
server s1 192.168.0.1:443 ssl check
This option forces emission of a PROXY protocol line with outgoing health
checks, regardless of whether the server uses send-proxy or not for the
normal traffic. By default, the PROXY protocol is enabled for health checks
if it is already enabled for normal traffic and if no "port" nor "addr"
directive is present. However, if such a directive is present, the
"check-send-proxy" option needs to be used to force the use of the
protocol. See also the "send-proxy" option for more information.
Defines which protocols to advertise with ALPN. The protocol list consists in
a comma-delimited list of protocol names, for instance: "http/1.1,http/1.0"
(without quotes). If it is not set, the server ALPN is used.
Forces the multiplexer's protocol to use for the server's health-check
connections. It must be compatible with the health-check type (TCP or
HTTP). It must also be usable on the backend side. The list of available
protocols is reported in haproxy -vv. The protocols properties are
reported : the mode (TCP/HTTP), the side (FE/BE), the mux name and its flags.
Some protocols report errors on aborts (flag=CLEAN_ABRT). Some others are
subject to the head-of-line blocking on server side (flag=HOL_RISK). Finally
some protocols don't support upgrades (flag=NO_UPG). The HTX compatibility is
also reported (flag=HTX).
Here are the protocols that may be used as argument to a "check-proto"
directive on a server line:
h2 : mode=HTTP side=FE|BE mux=H2 flags=HTX|CLEAN_ABRT|HOL_RISK|NO_UPG
fcgi : mode=HTTP side=BE mux=FCGI flags=HTX|HOL_RISK|NO_UPG
h1 : mode=HTTP side=FE|BE mux=H1 flags=HTX|NO_UPG
none : mode=TCP side=FE|BE mux=PASS flags=NO_UPG
Idea behind this option is to bypass the selection of the best multiplexer's
protocol for health-check connections established to this server.
If not defined, the server one will be used, if set.
This option allows you to specify the SNI to be used when doing health checks
over SSL. It is only possible to use a string to set <sni>. If you want to
set a SNI for proxied traffic, see "sni".
This option forces encryption of all health checks over SSL, regardless of
whether the server uses SSL or not for the normal traffic. This is generally
used when an explicit "port" or "addr" directive is specified and SSL health
checks are not inherited. It is important to understand that this option
inserts an SSL transport layer below the checks, so that a simple TCP connect
check becomes an SSL connect, which replaces the old ssl-hello-chk. The most
common use is to send HTTPS checks by combining "httpchk" with SSL checks.
All SSL settings are common to health checks and traffic (e.g. ciphers).
See the "ssl" option for more information and "no-check-ssl" to disable
this option.
This option enables outgoing health checks using upstream socks4 proxy. By
default, the health checks won't go through socks tunnel even it was enabled
for normal traffic.
This setting is only available when support for OpenSSL was built in. This
option sets the string describing the list of cipher algorithms that is
negotiated during the SSL/TLS handshake with the server. The format of the
string is defined in "man 1 ciphers" from OpenSSL man pages. For background
information and recommendations see e.g.
(https://wiki.mozilla.org/Security/Server_Side_TLS) and
(https://mozilla.github.io/server-side-tls/ssl-config-generator/). For TLSv1.3
cipher configuration, please check the "ciphersuites" keyword.
This setting is only available when support for OpenSSL was built in and
OpenSSL 1.1.1 or later was used to build HAProxy. This option sets the string
describing the list of cipher algorithms that is negotiated during the TLS
1.3 handshake with the server. The format of the string is defined in
"man 1 ciphers" from OpenSSL man pages under the "ciphersuites" section.
For cipher configuration for TLSv1.2 and earlier, please check the "ciphers"
keyword.
The "cookie" parameter sets the cookie value assigned to the server to
<value>. This value will be checked in incoming requests, and the first
operational server possessing the same value will be selected. In return, in
cookie insertion or rewrite modes, this value will be assigned to the cookie
sent to the client. There is nothing wrong in having several servers sharing
the same cookie value, and it is in fact somewhat common between normal and
backup servers. See also the "cookie" keyword in backend section.
This setting is only available when support for OpenSSL was built in. It
designates a PEM file from which to load certificate revocation list used
to verify server's certificate.
This setting is only available when support for OpenSSL was built in.
It designates a PEM file from which to load both a certificate and the
associated private key. This file can be built by concatenating both PEM
files into one. This certificate will be sent if the server send a client
certificate request.
If the file does not contain a private key, HAProxy will try to load the key
at the same path suffixed by a ".key" (provided the "ssl-load-extra-files"
option is set accordingly).
The "disabled" keyword starts the server in the "disabled" state. That means
that it is marked down in maintenance mode, and no connection other than the
ones allowed by persist mode will reach it. It is very well suited to setup
new servers, because normal traffic will never reach them, while it is still
possible to test the service by making use of the force-persist mechanism.
See also "enabled" setting.
This option may be used as 'server' setting to reset any 'disabled'
setting which would have been inherited from 'default-server' directive as
default value.
It may also be used as 'default-server' setting to reset any previous
'default-server' 'disabled' setting.
If health observing is enabled, the "error-limit" parameter specifies the
number of consecutive errors that triggers event selected by the "on-error"
option. By default it is set to 10 consecutive errors.
See also the "check", "error-limit" and "on-error".
The "fall" parameter states that a server will be considered as dead after
<count> consecutive unsuccessful health checks. This value defaults to 3 if
unspecified. See also the "check", "inter" and "rise" parameters.
This option enforces use of SSLv3 only when SSL is used to communicate with
the server. SSLv3 is generally less expensive than the TLS counterparts for
high connection rates. This option is also available on global statement
"ssl-default-server-options". See also "ssl-min-ver" and ssl-max-ver".
This option enforces use of TLSv1.0 only when SSL is used to communicate with
the server. This option is also available on global statement
"ssl-default-server-options". See also "ssl-min-ver" and ssl-max-ver".
This option enforces use of TLSv1.1 only when SSL is used to communicate with
the server. This option is also available on global statement
"ssl-default-server-options". See also "ssl-min-ver" and ssl-max-ver".
This option enforces use of TLSv1.2 only when SSL is used to communicate with
the server. This option is also available on global statement
"ssl-default-server-options". See also "ssl-min-ver" and ssl-max-ver".
This option enforces use of TLSv1.3 only when SSL is used to communicate with
the server. This option is also available on global statement
"ssl-default-server-options". See also "ssl-min-ver" and ssl-max-ver".
Set a persistent ID for the server. This ID must be positive and unique for
the proxy. An unused ID will automatically be assigned if unset. The first
assigned value will be 1. This ID is currently only returned in statistics.
Indicate in what order the server's address should be resolved upon startup
if it uses an FQDN. Attempts are made to resolve the address by applying in
turn each of the methods mentioned in the comma-delimited list. The first
method which succeeds is used. If the end of the list is reached without
finding a working method, an error is thrown. Method "last" suggests to pick
the address which appears in the state file (see "server-state-file"). Method
"libc" uses the libc's internal resolver (gethostbyname() or getaddrinfo()
depending on the operating system and build options). Method "none"
specifically indicates that the server should start without any valid IP
address in a down state. It can be useful to ignore some DNS issues upon
startup, waiting for the situation to get fixed later. Finally, an IP address
(IPv4 or IPv6) may be provided. It can be the currently known address of the
server (e.g. filled by a configuration generator), or the address of a dummy
server used to catch old sessions and present them with a decent error
message for example. When the "first" load balancing algorithm is used, this
IP address could point to a fake server used to trigger the creation of new
instances on the fly. This option defaults to "last,libc" indicating that the
previous address found in the state file (if any) is used first, otherwise
the libc's resolver is used. This ensures continued compatibility with the
historic behavior.
Example:
defaults
# never fail on address resolution
default-server init-addr last,libc,none
The "inter" parameter sets the interval between two consecutive health checks
to <delay> milliseconds. If left unspecified, the delay defaults to 2000 ms.
It is also possible to use "fastinter" and "downinter" to optimize delays
between checks depending on the server state :
| Server state | Interval used |
|---|---|
| UP 100% (non-transitional) | "inter" |
| Transitionally UP (going down "fall"), Transitionally DOWN (going up "rise"), or yet unchecked. | "fastinter" if set, "inter" otherwise. |
| DOWN 100% (non-transitional) | "downinter" if set, "inter" otherwise. |
Just as with every other time-based parameter, they can be entered in any
other explicit unit among { us, ms, s, m, h, d }. The "inter" parameter also
serves as a timeout for health checks sent to servers if "timeout check" is
not set. In order to reduce "resonance" effects when multiple servers are
hosted on the same hardware, the agent and health checks of all servers
are started with a small time offset between them. It is also possible to
add some random noise in the agent and health checks interval using the
global "spread-checks" keyword. This makes sense for instance when a lot
of backends use the same servers.
The "log-proto" specifies the protocol used to forward event messages to
a server configured in a ring section. Possible values are "legacy"
and "octet-count" corresponding respectively to "Non-transparent-framing"
and "Octet counting" in rfc6587. "legacy" is the default.
The "maxconn" parameter specifies the maximal number of concurrent
connections that will be sent to this server. If the number of incoming
concurrent connections goes higher than this value, they will be queued,
waiting for a slot to be released. This parameter is very important as it can
save fragile servers from going down under extreme loads. If a "minconn"
parameter is specified, the limit becomes dynamic. The default value is "0"
which means unlimited. See also the "minconn" and "maxqueue" parameters, and
the backend's "fullconn" keyword.
In HTTP mode this parameter limits the number of concurrent requests instead
of the number of connections. Multiple requests might be multiplexed over a
single TCP connection to the server. As an example if you specify a maxconn
of 50 you might see between 1 and 50 actual server connections, but no more
than 50 concurrent requests.
The "maxqueue" parameter specifies the maximal number of connections which
will wait in the queue for this server. If this limit is reached, next
requests will be redispatched to other servers instead of indefinitely
waiting to be served. This will break persistence but may allow people to
quickly re-log in when the server they try to connect to is dying. Some load
balancing algorithms such as leastconn take this into account and accept to
add requests into a server's queue up to this value if it is explicitly set
to a value greater than zero, which often allows to better smooth the load
when dealing with single-digit maxconn values. The default value is "0" which
means the queue is unlimited. See also the "maxconn" and "minconn" parameters
and "balance leastconn".
The "max-reuse" argument indicates the HTTP connection processors that they
should not reuse a server connection more than this number of times to send
new requests. Permitted values are -1 (the default), which disables this
limit, or any positive value. Value zero will effectively disable keep-alive.
This is only used to work around certain server bugs which cause them to leak
resources over time. The argument is not necessarily respected by the lower
layers as there might be technical limitations making it impossible to
enforce. At least HTTP/2 connections to servers will respect it.
When the "minconn" parameter is set, the maxconn limit becomes a dynamic
limit following the backend's load. The server will always accept at least
<minconn> connections, never more than <maxconn>, and the limit will be on
the ramp between both values when the backend has less than <fullconn>
concurrent connections. This makes it possible to limit the load on the
server during normal loads, but push it further for important loads without
overloading the server during exceptional loads. See also the "maxconn"
and "maxqueue" parameters, as well as the "fullconn" backend keyword.
On Linux, it is possible to specify which network namespace a socket will
belong to. This directive makes it possible to explicitly bind a server to
a namespace different from the default one. Please refer to your operating
system's documentation to find more details about network namespaces.
This option may be used as "server" setting to reset any "agent-check"
setting which would have been inherited from "default-server" directive as
default value.
It may also be used as "default-server" setting to reset any previous
"default-server" "agent-check" setting.
This option may be used as "server" setting to reset any "backup"
setting which would have been inherited from "default-server" directive as
default value.
It may also be used as "default-server" setting to reset any previous
"default-server" "backup" setting.
This option may be used as "server" setting to reset any "check"
setting which would have been inherited from "default-server" directive as
default value.
It may also be used as "default-server" setting to reset any previous
"default-server" "check" setting.
This option may be used as "server" setting to reset any "check-ssl"
setting which would have been inherited from "default-server" directive as
default value.
It may also be used as "default-server" setting to reset any previous
"default-server" "check-ssl" setting.
This option may be used as "server" setting to reset any "send-proxy"
setting which would have been inherited from "default-server" directive as
default value.
It may also be used as "default-server" setting to reset any previous
"default-server" "send-proxy" setting.
This option may be used as "server" setting to reset any "send-proxy-v2"
setting which would have been inherited from "default-server" directive as
default value.
It may also be used as "default-server" setting to reset any previous
"default-server" "send-proxy-v2" setting.
This option may be used as "server" setting to reset any "send-proxy-v2-ssl"
setting which would have been inherited from "default-server" directive as
default value.
It may also be used as "default-server" setting to reset any previous
"default-server" "send-proxy-v2-ssl" setting.
This option may be used as "server" setting to reset any "send-proxy-v2-ssl-cn"
setting which would have been inherited from "default-server" directive as
default value.
It may also be used as "default-server" setting to reset any previous
"default-server" "send-proxy-v2-ssl-cn" setting.
This option may be used as "server" setting to reset any "ssl"
setting which would have been inherited from "default-server" directive as
default value.
It may also be used as "default-server" setting to reset any previous
"default-server" "ssl" setting.
Note that using `default-server ssl` setting and `no-ssl` on server will
however init SSL connection, so it can be later be enabled through the
runtime API: see `set server` commands in management doc.
This option disables SSL session reuse when SSL is used to communicate with
the server. It will force the server to perform a full handshake for every
new connection. It's probably only useful for benchmarking, troubleshooting,
and for paranoid users.
This option disables support for SSLv3 when SSL is used to communicate with
the server. Note that SSLv2 is disabled in the code and cannot be enabled
using any configuration option. Use "ssl-min-ver" and "ssl-max-ver" instead.
Supported in default-server: No
This setting is only available when support for OpenSSL was built in. It
disables the stateless session resumption (RFC 5077 TLS Ticket
extension) and force to use stateful session resumption. Stateless
session resumption is more expensive in CPU usage for servers. This option
is also available on global statement "ssl-default-server-options".
The TLS ticket mechanism is only used up to TLS 1.2.
Forward Secrecy is compromised with TLS tickets, unless ticket keys
are periodically rotated (via reload or by using "tls-ticket-keys").
See also "tls-tickets".
This option disables support for TLSv1.0 when SSL is used to communicate with
the server. Note that SSLv2 is disabled in the code and cannot be enabled
using any configuration option. TLSv1 is more expensive than SSLv3 so it
often makes sense to disable it when communicating with local servers. This
option is also available on global statement "ssl-default-server-options".
Use "ssl-min-ver" and "ssl-max-ver" instead.
Supported in default-server: No
This option disables support for TLSv1.1 when SSL is used to communicate with
the server. Note that SSLv2 is disabled in the code and cannot be enabled
using any configuration option. TLSv1 is more expensive than SSLv3 so it
often makes sense to disable it when communicating with local servers. This
option is also available on global statement "ssl-default-server-options".
Use "ssl-min-ver" and "ssl-max-ver" instead.
Supported in default-server: No
This option disables support for TLSv1.2 when SSL is used to communicate with
the server. Note that SSLv2 is disabled in the code and cannot be enabled
using any configuration option. TLSv1 is more expensive than SSLv3 so it
often makes sense to disable it when communicating with local servers. This
option is also available on global statement "ssl-default-server-options".
Use "ssl-min-ver" and "ssl-max-ver" instead.
Supported in default-server: No
This option disables support for TLSv1.3 when SSL is used to communicate with
the server. Note that SSLv2 is disabled in the code and cannot be enabled
using any configuration option. TLSv1 is more expensive than SSLv3 so it
often makes sense to disable it when communicating with local servers. This
option is also available on global statement "ssl-default-server-options".
Use "ssl-min-ver" and "ssl-max-ver" instead.
Supported in default-server: No
This option may be used as "server" setting to reset any "verifyhost"
setting which would have been inherited from "default-server" directive as
default value.
It may also be used as "default-server" setting to reset any previous
"default-server" "verifyhost" setting.
This option may be used as "server" setting to reset any "tfo"
setting which would have been inherited from "default-server" directive as
default value.
It may also be used as "default-server" setting to reset any previous
"default-server" "tfo" setting.
Never add connections allocated to this sever to a stick-table.
This may be used in conjunction with backup to ensure that
stick-table persistence is disabled for backup servers.
This enables the NPN TLS extension and advertises the specified protocol list
as supported on top of NPN. The protocol list consists in a comma-delimited
list of protocol names, for instance: "http/1.1,http/1.0" (without quotes).
This requires that the SSL library is built with support for TLS extensions
enabled (check with haproxy -vv). Note that the NPN extension has been
replaced with the ALPN extension (see the "alpn" keyword), though this one is
only available starting with OpenSSL 1.0.2.
This option enables health adjusting based on observing communication with
the server. By default this functionality is disabled and enabling it also
requires to enable health checks. There are two supported modes: "layer4" and
"layer7". In layer4 mode, only successful/unsuccessful tcp connections are
significant. In layer7, which is only allowed for http proxies, responses
received from server are verified, like valid/wrong http code, unparsable
headers, a timeout, etc. Valid status codes include 100 to 499, 501 and 505.
See also the "check", "on-error" and "error-limit".
Select what should happen when enough consecutive errors are detected.
Currently, four modes are available:
- fastinter: force fastinter
- fail-check: simulate a failed check, also forces fastinter (default)
- sudden-death: simulate a pre-fatal failed health check, one more failed
check will mark a server down, forces fastinter
- mark-down: mark the server immediately down and force fastinter
See also the "check", "observe" and "error-limit".
Modify what occurs when a server is marked down.
Currently one action is available:
- shutdown-sessions: Shutdown peer sessions. When this setting is enabled,
all connections to the server are immediately terminated when the server
goes down. It might be used if the health check detects more complex cases
than a simple connection status, and long timeouts would cause the service
to remain unresponsive for too long a time. For instance, a health check
might detect that a database is stuck and that there's no chance to reuse
existing connections anymore. Connections killed this way are logged with
a 'D' termination code (for "Down").
Actions are disabled by default
Modify what occurs when a server is marked up.
Currently one action is available:
- shutdown-backup-sessions: Shutdown sessions on all backup servers. This is
done only if the server is not in backup state and if it is not disabled
(it must have an effective weight > 0). This can be used sometimes to force
an active server to take all the traffic back after recovery when dealing
with long sessions (e.g. LDAP, SQL, ...). Doing this can cause more trouble
than it tries to solve (e.g. incomplete transactions), so use this feature
with extreme care. Sessions killed because a server comes up are logged
with an 'U' termination code (for "Up").
Actions are disabled by default
Set a low threshold on the number of idling connections for a server, below
which a thread will not try to steal a connection from another thread. This
can be useful to improve CPU usage patterns in scenarios involving many very
fast servers, in order to ensure all threads will keep a few idle connections
all the time instead of letting them accumulate over one thread and migrating
them from thread to thread. Typical values of twice the number of threads
seem to show very good performance already with sub-millisecond response
times. The default is zero, indicating that any idle connection can be used
at any time. It is the recommended setting for normal use. This only applies
to connections that can be shared according to the same principles as those
applying to "http-reuse". In case connection sharing between threads would
be disabled via "tune.idle-pool.shared", it can become very important to use
this setting to make sure each thread always has a few connections, or the
connection reuse rate will decrease as thread count increases.
Set the maximum number of idling connections for a server. -1 means unlimited
connections, 0 means no idle connections. The default is -1. When idle
connections are enabled, orphaned idle connections which do not belong to any
client session anymore are moved to a dedicated pool so that they remain
usable by future clients. This only applies to connections that can be shared
according to the same principles as those applying to "http-reuse".
Sets the delay to start purging idle connections. Each <delay> interval, half
of the idle connections are closed. 0 means we don't keep any idle connection.
The default is 5s.
Using the "port" parameter, it becomes possible to use a different port to
send health-checks or to probe the agent-check. On some servers, it may be
desirable to dedicate a port to a specific component able to perform complex
tests which are more suitable to health-checks than the application. It is
common to run a simple script in inetd for instance. This parameter is
ignored if the "check" parameter is not set. See also the "addr" parameter.
Forces the multiplexer's protocol to use for the outgoing connections to this
server. It must be compatible with the mode of the backend (TCP or HTTP). It
must also be usable on the backend side. The list of available protocols is
reported in haproxy -vv.The protocols properties are reported : the mode
(TCP/HTTP), the side (FE/BE), the mux name and its flags.
Some protocols report errors on aborts (flag=CLEAN_ABRT). Some others are
subject to the head-of-line blocking on server side (flag=HOL_RISK). Finally
some protocols don't support upgrades (flag=NO_UPG). The HTX compatibility is
also reported (flag=HTX).
Here are the protocols that may be used as argument to a "proto" directive on
a server line :
h2 : mode=HTTP side=FE|BE mux=H2 flags=HTX|CLEAN_ABRT|HOL_RISK|NO_UPG
fcgi : mode=HTTP side=BE mux=FCGI flags=HTX|HOL_RISK|NO_UPG
h1 : mode=HTTP side=FE|BE mux=H1 flags=HTX|NO_UPG
none : mode=TCP side=FE|BE mux=PASS flags=NO_UPG
Idea behind this option is to bypass the selection of the best multiplexer's
protocol for all connections established to this server.
See also "ws" to use an alternative protocol for websocket streams.
The "redir" parameter enables the redirection mode for all GET and HEAD
requests addressing this server. This means that instead of having HAProxy
forward the request to the server, it will send an "HTTP 302" response with
the "Location" header composed of this prefix immediately followed by the
requested URI beginning at the leading '/' of the path component. That means
that no trailing slash should be used after <prefix>. All invalid requests
will be rejected, and all non-GET or HEAD requests will be normally served by
the server. Note that since the response is completely forged, no header
mangling nor cookie insertion is possible in the response. However, cookies in
requests are still analyzed, making this solution completely usable to direct
users to a remote location in case of local disaster. Main use consists in
increasing bandwidth for static servers by having the clients directly
connect to them. Note: never use a relative location here, it would cause a
loop between the client and HAProxy!
Example :
server srv1 192.168.1.1:80 redir http://image1.mydomain.com check
The "rise" parameter states that a server will be considered as operational
after <count> consecutive successful health checks. This value defaults to 2
if unspecified. See also the "check", "inter" and "fall" parameters.
Comma separated list of options to apply to DNS resolution linked to this
server.
Available options:
* allow-dup-ip
By default, HAProxy prevents IP address duplication in a backend when DNS
resolution at runtime is in operation.
That said, for some cases, it makes sense that two servers (in the same
backend, being resolved by the same FQDN) have the same IP address.
For such case, simply enable this option.
This is the opposite of prevent-dup-ip.
* ignore-weight
Ignore any weight that is set within an SRV record. This is useful when
you would like to control the weights using an alternate method, such as
using an "agent-check" or through the runtime api.
* prevent-dup-ip
Ensure HAProxy's default behavior is enforced on a server: prevent re-using
an IP address already set to a server in the same backend and sharing the
same fqdn.
This is the opposite of allow-dup-ip.
Example:
backend b_myapp
default-server init-addr none resolvers dns
server s1 myapp.example.com:80 check resolve-opts allow-dup-ip
server s2 myapp.example.com:81 check resolve-opts allow-dup-ip
With the option allow-dup-ip set:
* if the nameserver returns a single IP address, then both servers will use
it
* If the nameserver returns 2 IP addresses, then each server will pick up a
different address
Default value: not set
When DNS resolution is enabled for a server and multiple IP addresses from
different families are returned, HAProxy will prefer using an IP address
from the family mentioned in the "resolve-prefer" parameter.
Available families: "ipv4" and "ipv6"
Default value: ipv6
Example:
server s1 app1.domain.com:80 resolvers mydns resolve-prefer ipv6
This option prioritizes the choice of an ip address matching a network. This is
useful with clouds to prefer a local ip. In some cases, a cloud high
availability service can be announced with many ip addresses on many
different datacenters. The latency between datacenter is not negligible, so
this patch permits to prefer a local datacenter. If no address matches the
configured network, another address is selected.
Example:
server s1 app1.domain.com:80 resolvers mydns resolve-net 10.0.0.0/8
Points to an existing "resolvers" section to resolve current server's
hostname.
Example:
server s1 app1.domain.com:80 check resolvers mydns
See also section 5.3
The "send-proxy" parameter enforces use of the PROXY protocol over any
connection established to this server. The PROXY protocol informs the other
end about the layer 3/4 addresses of the incoming connection, so that it can
know the client's address or the public address it accessed to, whatever the
upper layer protocol. For connections accepted by an "accept-proxy" or
"accept-netscaler-cip" listener, the advertised address will be used. Only
TCPv4 and TCPv6 address families are supported. Other families such as
Unix sockets, will report an UNKNOWN family. Servers using this option can
fully be chained to another instance of HAProxy listening with an
"accept-proxy" setting. This setting must not be used if the server isn't
aware of the protocol. When health checks are sent to the server, the PROXY
protocol is automatically used when this option is set, unless there is an
explicit "port" or "addr" directive, in which case an explicit
"check-send-proxy" directive would also be needed to use the PROXY protocol.
See also the "no-send-proxy" option of this section and "accept-proxy" and
"accept-netscaler-cip" option of the "bind" keyword.
The "send-proxy-v2" parameter enforces use of the PROXY protocol version 2
over any connection established to this server. The PROXY protocol informs
the other end about the layer 3/4 addresses of the incoming connection, so
that it can know the client's address or the public address it accessed to,
whatever the upper layer protocol. It also send ALPN information if an alpn
have been negotiated. This setting must not be used if the server isn't aware
of this version of the protocol. See also the "no-send-proxy-v2" option of
this section and send-proxy" option of the "bind" keyword.
The "proxy-v2-options" parameter add options to send in PROXY protocol
version 2 when "send-proxy-v2" is used. Options available are:
- ssl : See also "send-proxy-v2-ssl".
- cert-cn : See also "send-proxy-v2-ssl-cn".
- ssl-cipher: Name of the used cipher.
- cert-sig : Signature algorithm of the used certificate.
- cert-key : Key algorithm of the used certificate
- authority : Host name value passed by the client (only SNI from a TLS
connection is supported).
- crc32c : Checksum of the PROXYv2 header.
- unique-id : Send a unique ID generated using the frontend's
"unique-id-format" within the PROXYv2 header.
This unique-id is primarily meant for "mode tcp". It can
lead to unexpected results in "mode http", because the
generated unique ID is also used for the first HTTP request
within a Keep-Alive connection.
The "send-proxy-v2-ssl" parameter enforces use of the PROXY protocol version
2 over any connection established to this server. The PROXY protocol informs
the other end about the layer 3/4 addresses of the incoming connection, so
that it can know the client's address or the public address it accessed to,
whatever the upper layer protocol. In addition, the SSL information extension
of the PROXY protocol is added to the PROXY protocol header. This setting
must not be used if the server isn't aware of this version of the protocol.
See also the "no-send-proxy-v2-ssl" option of this section and the
"send-proxy-v2" option of the "bind" keyword.
The "send-proxy-v2-ssl" parameter enforces use of the PROXY protocol version
2 over any connection established to this server. The PROXY protocol informs
the other end about the layer 3/4 addresses of the incoming connection, so
that it can know the client's address or the public address it accessed to,
whatever the upper layer protocol. In addition, the SSL information extension
of the PROXY protocol, along along with the Common Name from the subject of
the client certificate (if any), is added to the PROXY protocol header. This
setting must not be used if the server isn't aware of this version of the
protocol. See also the "no-send-proxy-v2-ssl-cn" option of this section and
the "send-proxy-v2" option of the "bind" keyword.
The "slowstart" parameter for a server accepts a value in milliseconds which
indicates after how long a server which has just come back up will run at
full speed. Just as with every other time-based parameter, it can be entered
in any other explicit unit among { us, ms, s, m, h, d }. The speed grows
linearly from 0 to 100% during this time. The limitation applies to two
parameters :
- maxconn: the number of connections accepted by the server will grow from 1
to 100% of the usual dynamic limit defined by (minconn,maxconn,fullconn).
- weight: when the backend uses a dynamic weighted algorithm, the weight
grows linearly from 1 to 100%. In this case, the weight is updated at every
health-check. For this reason, it is important that the "inter" parameter
is smaller than the "slowstart", in order to maximize the number of steps.
The slowstart never applies when HAProxy starts, otherwise it would cause
trouble to running servers. It only applies when a server has been previously
seen as failed.
The "sni" parameter evaluates the sample fetch expression, converts it to a
string and uses the result as the host name sent in the SNI TLS extension to
the server. A typical use case is to send the SNI received from the client in
a bridged TCP/SSL scenario, using the "ssl_fc_sni" sample fetch for the
expression. THIS MUST NOT BE USED FOR HTTPS, where req.hdr(host) should be
used instead, since SNI in HTTPS must always match the Host field and clients
are allowed to use different host names over the same connection). If
"verify required" is set (which is the recommended setting), the resulting
name will also be matched against the server certificate's names. See the
"verify" directive for more details. If you want to set a SNI for health
checks, see the "check-sni" directive for more details.
The "source" parameter sets the source address which will be used when
connecting to the server. It follows the exact same parameters and principle
as the backend "source" keyword, except that it only applies to the server
referencing it. Please consult the "source" keyword for details.
Additionally, the "source" statement on a server line allows one to specify a
source port range by indicating the lower and higher bounds delimited by a
dash ('-'). Some operating systems might require a valid IP address when a
source port range is specified. It is permitted to have the same IP/range for
several servers. Doing so makes it possible to bypass the maximum of 64k
total concurrent connections. The limit will then reach 64k connections per
server.
Since Linux 4.2/libc 2.23 IP_BIND_ADDRESS_NO_PORT is set for connections
specifying the source address without port(s).
This option enables SSL ciphering on outgoing connections to the server. It
is critical to verify server certificates using "verify" when using SSL to
connect to servers, otherwise the communication is prone to trivial man in
the-middle attacks rendering SSL useless. When this option is used, health
checks are automatically sent in SSL too unless there is a "port" or an
"addr" directive indicating the check should be sent to a different location.
See the "no-ssl" to disable "ssl" option and "check-ssl" option to force
SSL health checks.
This option enforces use of <version> or lower when SSL is used to communicate
with the server. This option is also available on global statement
"ssl-default-server-options". See also "ssl-min-ver".
This option enforces use of <version> or upper when SSL is used to communicate
with the server. This option is also available on global statement
"ssl-default-server-options". See also "ssl-max-ver".
This option may be used as "server" setting to reset any "no-ssl-reuse"
setting which would have been inherited from "default-server" directive as
default value.
It may also be used as "default-server" setting to reset any previous
"default-server" "no-ssl-reuse" setting.
This option may be used as "server" setting to reset any "non-stick"
setting which would have been inherited from "default-server" directive as
default value.
It may also be used as "default-server" setting to reset any previous
"default-server" "non-stick" setting.
This option enables upstream socks4 tunnel for outgoing connections to the
server. Using this option won't force the health check to go via socks4 by
default. You will have to use the keyword "check-via-socks4" to enable it.
Sets the TCP User Timeout for all outgoing connections to this server. This
option is available on Linux since version 2.6.37. It allows HAProxy to
configure a timeout for sockets which contain data not receiving an
acknowledgment for the configured delay. This is especially useful on
long-lived connections experiencing long idle periods such as remote
terminals or database connection pools, where the client and server timeouts
must remain high to allow a long period of idle, but where it is important to
detect that the server has disappeared in order to release all resources
associated with its connection (and the client's session). One typical use
case is also to force dead server connections to die when health checks are
too slow or during a soft reload since health checks are then disabled. The
argument is a delay expressed in milliseconds by default. This only works for
regular TCP connections, and is ignored for other protocols.
This option enables using TCP fast open when connecting to servers, on
systems that support it (currently only the Linux kernel >= 4.11).
See the "tfo" bind option for more information about TCP fast open.
Please note that when using tfo, you should also use the "conn-failure",
"empty-response" and "response-timeout" keywords for "retry-on", or HAProxy
won't be able to retry the connection on failure. See also "no-tfo".
This option enables ability to set the current state of the server by tracking
another one. It is possible to track a server which itself tracks another
server, provided that at the end of the chain, a server has health checks
enabled. If <backend> is omitted the current one is used. If disable-on-404 is
used, it has to be enabled on both proxies.
This option may be used as "server" setting to reset any "no-tls-tickets"
setting which would have been inherited from "default-server" directive as
default value.
The TLS ticket mechanism is only used up to TLS 1.2.
Forward Secrecy is compromised with TLS tickets, unless ticket keys
are periodically rotated (via reload or by using "tls-ticket-keys").
It may also be used as "default-server" setting to reset any previous
"default-server" "no-tls-tickets" setting.
This setting is only available when support for OpenSSL was built in. If set
to 'none', server certificate is not verified. In the other case, The
certificate provided by the server is verified using CAs from 'ca-file' and
optional CRLs from 'crl-file' after having checked that the names provided in
the certificate's subject and subjectAlternateNames attributes match either
the name passed using the "sni" directive, or if not provided, the static
host name passed using the "verifyhost" directive. When no name is found, the
certificate's names are ignored. For this reason, without SNI it's important
to use "verifyhost". On verification failure the handshake is aborted. It is
critically important to verify server certificates when using SSL to connect
to servers, otherwise the communication is prone to trivial man-in-the-middle
attacks rendering SSL totally useless. Unless "ssl_server_verify" appears in
the global section, "verify" is set to "required" by default.
This setting is only available when support for OpenSSL was built in, and
only takes effect if 'verify required' is also specified. This directive sets
a default static hostname to check the server's certificate against when no
SNI was used to connect to the server. If SNI is not used, this is the only
way to enable hostname verification. This static hostname, when set, will
also be used for health checks (which cannot provide an SNI value). If none
of the hostnames in the certificate match the specified hostname, the
handshake is aborted. The hostnames in the server-provided certificate may
include wildcards. See also "verify", "sni" and "no-verifyhost" options.
The "weight" parameter is used to adjust the server's weight relative to
other servers. All servers will receive a load proportional to their weight
relative to the sum of all weights, so the higher the weight, the higher the
load. The default weight is 1, and the maximal value is 256. A value of 0
means the server will not participate in load-balancing but will still accept
persistent connections. If this parameter is used to distribute the load
according to server's capacity, it is recommended to start with values which
can both grow and shrink, for instance between 10 and 100 to leave enough
room above and below for later adjustments.
This option allows to configure the protocol used when relaying websocket
streams. This is most notably useful when using an HTTP/2 backend without the
support for H2 websockets through the RFC8441.
The default mode is "auto". This will reuse the same protocol as the main
one. The only difference is when using ALPN. In this case, it can try to
downgrade the ALPN to "http/1.1" only for websocket streams if the configured
server ALPN contains it.
The value "h1" is used to force HTTP/1.1 for websockets streams, through ALPN
if SSL ALPN is activated for the server. Similarly, "h2" can be used to
force HTTP/2.0 websockets. Use this value with care : the server must support
RFC8441 or an error will be reported by haproxy when relaying websockets.
Note that NPN is not taken into account as its usage has been deprecated in
favor of the ALPN extension.
See also "alpn" and "proto".
5.3. Server IP address resolution using DNS
HAProxy allows using a host name on the server line to retrieve its IP address
using name servers. By default, HAProxy resolves the name when parsing the
configuration file, at startup and cache the result for the process's life.
This is not sufficient in some cases, such as in Amazon where a server's IP
can change after a reboot or an ELB Virtual IP can change based on current
workload.
This chapter describes how HAProxy can be configured to process server's name
resolution at run time.
Whether run time server name resolution has been enable or not, HAProxy will
carry on doing the first resolution when parsing the configuration.
5.3.1. Global overview
As we've seen in introduction, name resolution in HAProxy occurs at two
different steps of the process life:
1. when starting up, HAProxy parses the server line definition and matches a
host name. It uses libc functions to get the host name resolved. This
resolution relies on /etc/resolv.conf file.
2. at run time, HAProxy performs periodically name resolutions for servers
requiring DNS resolutions.
A few other events can trigger a name resolution at run time:
- when a server's health check ends up in a connection timeout: this may be
because the server has a new IP address. So we need to trigger a name
resolution to know this new IP.
When using resolvers, the server name can either be a hostname, or a SRV label.
HAProxy considers anything that starts with an underscore as a SRV label. If a
SRV label is specified, then the corresponding SRV records will be retrieved
from the DNS server, and the provided hostnames will be used. The SRV label
will be checked periodically, and if any server are added or removed, HAProxy
will automatically do the same.
A few things important to notice:
- all the name servers are queried in the meantime. HAProxy will process the
first valid response.
- a resolution is considered as invalid (NX, timeout, refused), when all the
servers return an error.
5.3.2. The resolvers section
This section is dedicated to host information related to name resolution in
HAProxy. There can be as many as resolvers section as needed. Each section can
contain many name servers.
When multiple name servers are configured in a resolvers section, then HAProxy
uses the first valid response. In case of invalid responses, only the last one
is treated. Purpose is to give the chance to a slow server to deliver a valid
answer after a fast faulty or outdated server.
When each server returns a different error type, then only the last error is
used by HAProxy. The following processing is applied on this error:
1. HAProxy retries the same DNS query with a new query type. The A queries are
switch to AAAA or the opposite. SRV queries are not concerned here. Timeout
errors are also excluded.
2. When the fallback on the query type was done (or not applicable), HAProxy
retries the original DNS query, with the preferred query type.
3. HAProxy retries previous steps <resolve_retries> times. If no valid
response is received after that, it stops the DNS resolution and reports
the error.
For example, with 2 name servers configured in a resolvers section, the
following scenarios are possible:
- First response is valid and is applied directly, second response is
ignored
- First response is invalid and second one is valid, then second response is
applied
- First response is a NX domain and second one a truncated response, then
HAProxy retries the query with a new type
- First response is a NX domain and second one is a timeout, then HAProxy
retries the query with a new type
- Query timed out for both name servers, then HAProxy retries it with the
same query type
As a DNS server may not answer all the IPs in one DNS request, HAProxy keeps
a cache of previous answers, an answer will be considered obsolete after
<hold obsolete> seconds without the IP returned.
Creates a new name server list labeled <resolvers id>
A resolvers section accept the following parameters:
Defines the maximum payload size accepted by HAProxy and announced to all the
name servers configured in this resolvers section.
<nb> is in bytes. If not set, HAProxy announces 512. (minimal value defined
by RFC 6891)
Note: the maximum allowed value is 65535. Recommended value for UDP is
4096 and it is not recommended to exceed 8192 except if you are sure
that your system and network can handle this (over 65507 makes no sense
since is the maximum UDP payload size). If you are using only TCP
nameservers to handle huge DNS responses, you should put this value
to the max: 65535.
Used to configure a nameserver. <name> of the nameserver should ne unique.
By default the <address> is considered of type datagram. This means if an
IPv4 or IPv6 is configured without special address prefixes (paragraph 11.)
the UDP protocol will be used. If an stream protocol address prefix is used,
the nameserver will be considered as a stream server (TCP for instance) and
"server" parameters found in 5.2 paragraph which are relevant for DNS
resolving will be considered. Note: currently, in TCP mode, 4 queries are
pipelined on the same connections. A batch of idle connections are removed
every 5 seconds. "maxconn" can be configured to limit the amount of those
concurrent connections and TLS should also usable if the server supports.
Adds all nameservers found in /etc/resolv.conf to this resolvers nameservers
list. Ordered as if each nameserver in /etc/resolv.conf was individually
placed in the resolvers section in place of this directive.
Upon receiving the DNS response <status>, determines whether a server's state
should change from UP to DOWN. To make that determination, it checks whether
any valid status has been received during the past <period> in order to
counteract the just received invalid status.
<status> : last name resolution status.
nx After receiving an NXDOMAIN status, check for any valid
status during the concluding period.
refused After receiving a REFUSED status, check for any valid
status during the concluding period.
timeout After the "timeout retry" has struck, check for any
valid status during the concluding period.
other After receiving any other invalid status, check for any
valid status during the concluding period.
valid Applies only to "http-request do-resolve" and
"tcp-request content do-resolve" actions. It defines the
period for which the server will maintain a valid response
before triggering another resolution. It does not affect
dynamic resolution of servers.
obsolete Defines how long to wait before removing obsolete DNS
records after an updated answer record is received. It
applies to SRV records.
<period> : Amount of time into the past during which a valid response must
have been received. It follows the HAProxy time format and is in
milliseconds by default.
For a server that relies on dynamic DNS resolution to determine its IP
address, receiving an invalid DNS response, such as NXDOMAIN, will lead to
changing the server's state from UP to DOWN. The hold directives define how
far into the past to look for a valid response. If a valid response has been
received within <period>, the just received invalid status will be ignored.
Unless a valid response has been receiving during the concluding period, the
server will be marked as DOWN. For example, if "hold nx 30s" is set and the
last received DNS response was NXDOMAIN, the server will be marked DOWN
unless a valid response has been received during the last 30 seconds.
A server in the DOWN state will be marked UP immediately upon receiving a
valid status from the DNS server.
A separate behavior exists for "hold valid" and "hold obsolete".
Defines the number <nb> of queries to send to resolve a server name before
giving up.
Default value: 3
A retry occurs on name server timeout or when the full sequence of DNS query
type failover is over and we need to start up from the default ANY query
type.
Defines timeouts related to name resolution
<event> : the event on which the <time> timeout period applies to.
events available are:
- resolve : default time to trigger name resolutions when no
other time applied.
Default value: 1s
- retry : time between two DNS queries, when no valid response
have been received.
Default value: 1s
<time> : time related to the event. It follows the HAProxy time format.
<time> is expressed in milliseconds.
Example:
resolvers mydns
nameserver dns1 10.0.0.1:53
nameserver dns2 10.0.0.2:53
nameserver dns3 tcp@10.0.0.3:53
parse-resolv-conf
resolve_retries 3
timeout resolve 1s
timeout retry 1s
hold other 30s
hold refused 30s
hold nx 30s
hold timeout 30s
hold valid 10s
hold obsolete 30s
6. Cache
HAProxy provides a cache, which was designed to perform cache on small objects
(favicon, css...). This is a minimalist low-maintenance cache which runs in
RAM.
The cache is based on a memory which is shared between processes and threads,
this memory is split in blocks of 1k.
If an object is not used anymore, it can be deleted to store a new object
independently of its expiration date. The oldest objects are deleted first
when we try to allocate a new one.
The cache uses a hash of the host header and the URI as the key.
It's possible to view the status of a cache using the Unix socket command
"show cache" consult section 9.3 "Unix Socket commands" of Management Guide
for more details.
When an object is delivered from the cache, the server name in the log is
replaced by "<CACHE>".
6.1. Limitation
The cache won't store and won't deliver objects in these cases:
- If the response is not a 200
- If the response contains a Vary header and either the process-vary option is
disabled, or a currently unmanaged header is specified in the Vary value (only
accept-encoding and referer are managed for now)
- If the Content-Length + the headers size is greater than "max-object-size"
- If the response is not cacheable
- If the response does not have an explicit expiration time (s-maxage or max-age
Cache-Control directives or Expires header) or a validator (ETag or Last-Modified
headers)
- If the process-vary option is enabled and there are already max-secondary-entries
entries with the same primary key as the current response
- If the process-vary option is enabled and the response has an unknown encoding (not
mentioned in https://www.iana.org/assignments/http-parameters/http-parameters.xhtml)
while varying on the accept-encoding client header
- If the request is not a GET
- If the HTTP version of the request is smaller than 1.1
- If the request contains an Authorization header
6.2. Setup
To setup a cache, you must define a cache section and use it in a proxy with
the corresponding http-request and response actions.
6.2.1. Cache section
Declare a cache section, allocate a shared cache memory named <name>, the
size of cache is mandatory.
Define the size in RAM of the cache in megabytes. This size is split in
blocks of 1kB which are used by the cache entries. Its maximum value is 4095.
Define the maximum size of the objects to be cached. Must not be greater than
an half of "total-max-size". If not set, it equals to a 256th of the cache size.
All objects with sizes larger than "max-object-size" will not be cached.
Define the maximum expiration duration. The expiration is set as the lowest
value between the s-maxage or max-age (in this order) directive in the
Cache-Control response header and this value. The default value is 60
seconds, which means that you can't cache an object more than 60 seconds by
default.
Enable or disable the processing of the Vary header. When disabled, a response
containing such a header will never be cached. When enabled, we need to calculate
a preliminary hash for a subset of request headers on all the incoming requests
(which might come with a cpu cost) which will be used to build a secondary key
for a given request (see RFC 7234#4.1). The default value is off (disabled).
Define the maximum number of simultaneous secondary entries with the same primary
key in the cache. This needs the vary support to be enabled. Its default value is 10
and should be passed a strictly positive integer.
6.2.2. Proxy section
Try to deliver a cached object from the cache <name>. This directive is also
mandatory to store the cache as it calculates the cache hash. If you want to
use a condition for both storage and delivering that's a good idea to put it
after this one.
Store an http-response within the cache. The storage of the response headers
is done at this step, which means you can use others http-response actions
to modify headers before or after the storage of the response. This action
is responsible for the setup of the cache storage filter.
Example:
backend bck1
mode http
http-request cache-use foobar
http-response cache-store foobar
server srv1 127.0.0.1:80
cache foobar
total-max-size 4
max-age 240
7. Using ACLs and fetching samples
HAProxy is capable of extracting data from request or response streams, from
client or server information, from tables, environmental information etc...
The action of extracting such data is called fetching a sample. Once retrieved,
these samples may be used for various purposes such as a key to a stick-table,
but most common usages consist in matching them against predefined constant
data called patterns.
7.1. ACL basics
The use of Access Control Lists (ACL) provides a flexible solution to perform
content switching and generally to take decisions based on content extracted
from the request, the response or any environmental status. The principle is
simple :
- extract a data sample from a stream, table or the environment
- optionally apply some format conversion to the extracted sample
- apply one or multiple pattern matching methods on this sample
- perform actions only when a pattern matches the sample
The actions generally consist in blocking a request, selecting a backend, or
adding a header.
In order to define a test, the "acl" keyword is used. The syntax is :
acl <aclname> <criterion> [flags] [operator] [<value>] ...
This creates a new ACL <aclname> or completes an existing one with new tests.
Those tests apply to the portion of request/response specified in <criterion>
and may be adjusted with optional flags [flags]. Some criteria also support
an operator which may be specified before the set of values. Optionally some
conversion operators may be applied to the sample, and they will be specified
as a comma-delimited list of keywords just after the first keyword. The values
are of the type supported by the criterion, and are separated by spaces.
ACL names must be formed from upper and lower case letters, digits, '-' (dash),
'_' (underscore) , '.' (dot) and ':' (colon). ACL names are case-sensitive,
which means that "my_acl" and "My_Acl" are two different ACLs.
There is no enforced limit to the number of ACLs. The unused ones do not affect
performance, they just consume a small amount of memory.
The criterion generally is the name of a sample fetch method, or one of its ACL
specific declinations. The default test method is implied by the output type of
this sample fetch method. The ACL declinations can describe alternate matching
methods of a same sample fetch method. The sample fetch methods are the only
ones supporting a conversion.
Sample fetch methods return data which can be of the following types :
- boolean
- integer (signed or unsigned)
- IPv4 or IPv6 address
- string
- data block
Converters transform any of these data into any of these. For example, some
converters might convert a string to a lower-case string while other ones
would turn a string to an IPv4 address, or apply a netmask to an IP address.
The resulting sample is of the type of the last converter applied to the list,
which defaults to the type of the sample fetch method.
Each sample or converter returns data of a specific type, specified with its
keyword in this documentation. When an ACL is declared using a standard sample
fetch method, certain types automatically involved a default matching method
which are summarized in the table below :
+---------------------+-----------------+
| Sample or converter | Default |
| output type | matching method |
+---------------------+-----------------+
| boolean | bool |
+---------------------+-----------------+
| integer | int |
+---------------------+-----------------+
| ip | ip |
+---------------------+-----------------+
| string | str |
+---------------------+-----------------+
| binary | none, use "-m" |
+---------------------+-----------------+
Note that in order to match a binary samples, it is mandatory to specify a
matching method, see below.
The ACL engine can match these types against patterns of the following types :
- boolean
- integer or integer range
- IP address / network
- string (exact, substring, suffix, prefix, subdir, domain)
- regular expression
- hex block
The following ACL flags are currently supported :
-i : ignore case during matching of all subsequent patterns.
-f : load patterns from a file.
-m : use a specific pattern matching method
-n : forbid the DNS resolutions
-M : load the file pointed by -f like a map file.
-u : force the unique id of the ACL
-- : force end of flags. Useful when a string looks like one of the flags.
The "-f" flag is followed by the name of a file from which all lines will be
read as individual values. It is even possible to pass multiple "-f" arguments
if the patterns are to be loaded from multiple files. Empty lines as well as
lines beginning with a sharp ('#') will be ignored. All leading spaces and tabs
will be stripped. If it is absolutely necessary to insert a valid pattern
beginning with a sharp, just prefix it with a space so that it is not taken for
a comment. Depending on the data type and match method, HAProxy may load the
lines into a binary tree, allowing very fast lookups. This is true for IPv4 and
exact string matching. In this case, duplicates will automatically be removed.
The "-M" flag allows an ACL to use a map file. If this flag is set, the file is
parsed as two column file. The first column contains the patterns used by the
ACL, and the second column contain the samples. The sample can be used later by
a map. This can be useful in some rare cases where an ACL would just be used to
check for the existence of a pattern in a map before a mapping is applied.
The "-u" flag forces the unique id of the ACL. This unique id is used with the
socket interface to identify ACL and dynamically change its values. Note that a
file is always identified by its name even if an id is set.
Also, note that the "-i" flag applies to subsequent entries and not to entries
loaded from files preceding it. For instance :
acl valid-ua hdr(user-agent) -f exact-ua.lst -i -f generic-ua.lst test
In this example, each line of "exact-ua.lst" will be exactly matched against
the "user-agent" header of the request. Then each line of "generic-ua" will be
case-insensitively matched. Then the word "test" will be insensitively matched
as well.
The "-m" flag is used to select a specific pattern matching method on the input
sample. All ACL-specific criteria imply a pattern matching method and generally
do not need this flag. However, this flag is useful with generic sample fetch
methods to describe how they're going to be matched against the patterns. This
is required for sample fetches which return data type for which there is no
obvious matching method (e.g. string or binary). When "-m" is specified and
followed by a pattern matching method name, this method is used instead of the
default one for the criterion. This makes it possible to match contents in ways
that were not initially planned, or with sample fetch methods which return a
string. The matching method also affects the way the patterns are parsed.
The "-n" flag forbids the dns resolutions. It is used with the load of ip files.
By default, if the parser cannot parse ip address it considers that the parsed
string is maybe a domain name and try dns resolution. The flag "-n" disable this
resolution. It is useful for detecting malformed ip lists. Note that if the DNS
server is not reachable, the HAProxy configuration parsing may last many minutes
waiting for the timeout. During this time no error messages are displayed. The
flag "-n" disable this behavior. Note also that during the runtime, this
function is disabled for the dynamic acl modifications.
There are some restrictions however. Not all methods can be used with all
sample fetch methods. Also, if "-m" is used in conjunction with "-f", it must
be placed first. The pattern matching method must be one of the following :
- "found" : only check if the requested sample could be found in the stream,
but do not compare it against any pattern. It is recommended not
to pass any pattern to avoid confusion. This matching method is
particularly useful to detect presence of certain contents such
as headers, cookies, etc... even if they are empty and without
comparing them to anything nor counting them.
- "bool" : check the value as a boolean. It can only be applied to fetches
which return a boolean or integer value, and takes no pattern.
Value zero or false does not match, all other values do match.
- "int" : match the value as an integer. It can be used with integer and
boolean samples. Boolean false is integer 0, true is integer 1.
- "ip" : match the value as an IPv4 or IPv6 address. It is compatible
with IP address samples only, so it is implied and never needed.
- "bin" : match the contents against a hexadecimal string representing a
binary sequence. This may be used with binary or string samples.
- "len" : match the sample's length as an integer. This may be used with
binary or string samples.
- "str" : exact match : match the contents against a string. This may be
used with binary or string samples.
- "sub" : substring match : check that the contents contain at least one of
the provided string patterns. This may be used with binary or
string samples.
- "reg" : regex match : match the contents against a list of regular
expressions. This may be used with binary or string samples.
- "beg" : prefix match : check that the contents begin like the provided
string patterns. This may be used with binary or string samples.
- "end" : suffix match : check that the contents end like the provided
string patterns. This may be used with binary or string samples.
- "dir" : subdir match : check that a slash-delimited portion of the
contents exactly matches one of the provided string patterns.
This may be used with binary or string samples.
- "dom" : domain match : check that a dot-delimited portion of the contents
exactly match one of the provided string patterns. This may be
used with binary or string samples.
For example, to quickly detect the presence of cookie "JSESSIONID" in an HTTP
request, it is possible to do :
acl jsess_present req.cook(JSESSIONID) -m found
In order to apply a regular expression on the 500 first bytes of data in the
buffer, one would use the following acl :
acl script_tag req.payload(0,500) -m reg -i <script>
On systems where the regex library is much slower when using "-i", it is
possible to convert the sample to lowercase before matching, like this :
acl script_tag req.payload(0,500),lower -m reg <script>
All ACL-specific criteria imply a default matching method. Most often, these
criteria are composed by concatenating the name of the original sample fetch
method and the matching method. For example, "hdr_beg" applies the "beg" match
to samples retrieved using the "hdr" fetch method. This matching method is only
usable when the keyword is used alone, without any converter. In case any such
converter were to be applied after such an ACL keyword, the default matching
method from the ACL keyword is simply ignored since what will matter for the
matching is the output type of the last converter. Since all ACL-specific
criteria rely on a sample fetch method, it is always possible instead to use
the original sample fetch method and the explicit matching method using "-m".
If an alternate match is specified using "-m" on an ACL-specific criterion,
the matching method is simply applied to the underlying sample fetch method.
For example, all ACLs below are exact equivalent :
acl short_form hdr_beg(host) www.
acl alternate1 hdr_beg(host) -m beg www.
acl alternate2 hdr_dom(host) -m beg www.
acl alternate3 hdr(host) -m beg www.
The table below summarizes the compatibility matrix between sample or converter
types and the pattern types to fetch against. It indicates for each compatible
combination the name of the matching method to be used, surrounded with angle
brackets ">" and "<" when the method is the default one and will work by
default without "-m".
+-------------------------------------------------+
| Input sample type |
+----------------------+---------+---------+---------+---------+---------+
| pattern type | boolean | integer | ip | string | binary |
+----------------------+---------+---------+---------+---------+---------+
| none (presence only) | found | found | found | found | found |
+----------------------+---------+---------+---------+---------+---------+
| none (boolean value) |> bool <| bool | | bool | |
+----------------------+---------+---------+---------+---------+---------+
| integer (value) | int |> int <| int | int | |
+----------------------+---------+---------+---------+---------+---------+
| integer (length) | len | len | len | len | len |
+----------------------+---------+---------+---------+---------+---------+
| IP address | | |> ip <| ip | ip |
+----------------------+---------+---------+---------+---------+---------+
| exact string | str | str | str |> str <| str |
+----------------------+---------+---------+---------+---------+---------+
| prefix | beg | beg | beg | beg | beg |
+----------------------+---------+---------+---------+---------+---------+
| suffix | end | end | end | end | end |
+----------------------+---------+---------+---------+---------+---------+
| substring | sub | sub | sub | sub | sub |
+----------------------+---------+---------+---------+---------+---------+
| subdir | dir | dir | dir | dir | dir |
+----------------------+---------+---------+---------+---------+---------+
| domain | dom | dom | dom | dom | dom |
+----------------------+---------+---------+---------+---------+---------+
| regex | reg | reg | reg | reg | reg |
+----------------------+---------+---------+---------+---------+---------+
| hex block | | | | bin | bin |
+----------------------+---------+---------+---------+---------+---------+
7.1.1. Matching booleans
In order to match a boolean, no value is needed and all values are ignored.
Boolean matching is used by default for all fetch methods of type "boolean".
When boolean matching is used, the fetched value is returned as-is, which means
that a boolean "true" will always match and a boolean "false" will never match.
Boolean matching may also be enforced using "-m bool" on fetch methods which
return an integer value. Then, integer value 0 is converted to the boolean
"false" and all other values are converted to "true".
7.1.2. Matching integers
Integer matching applies by default to integer fetch methods. It can also be
enforced on boolean fetches using "-m int". In this case, "false" is converted
to the integer 0, and "true" is converted to the integer 1.
Integer matching also supports integer ranges and operators. Note that integer
matching only applies to positive values. A range is a value expressed with a
lower and an upper bound separated with a colon, both of which may be omitted.
For instance, "1024:65535" is a valid range to represent a range of
unprivileged ports, and "1024:" would also work. "0:1023" is a valid
representation of privileged ports, and ":1023" would also work.
As a special case, some ACL functions support decimal numbers which are in fact
two integers separated by a dot. This is used with some version checks for
instance. All integer properties apply to those decimal numbers, including
ranges and operators.
For an easier usage, comparison operators are also supported. Note that using
operators with ranges does not make much sense and is strongly discouraged.
Similarly, it does not make much sense to perform order comparisons with a set
of values.
Available operators for integer matching are :
eq : true if the tested value equals at least one value
ge : true if the tested value is greater than or equal to at least one value
gt : true if the tested value is greater than at least one value
le : true if the tested value is less than or equal to at least one value
lt : true if the tested value is less than at least one value
For instance, the following ACL matches any negative Content-Length header :
acl negative-length req.hdr_val(content-length) lt 0
This one matches SSL versions between 3.0 and 3.1 (inclusive) :
acl sslv3 req.ssl_ver 3:3.1
7.1.3. Matching strings
String matching applies to string or binary fetch methods, and exists in 6
different forms :
- exact match (-m str) : the extracted string must exactly match the
patterns;
- substring match (-m sub) : the patterns are looked up inside the
extracted string, and the ACL matches if any of them is found inside;
- prefix match (-m beg) : the patterns are compared with the beginning of
the extracted string, and the ACL matches if any of them matches.
- suffix match (-m end) : the patterns are compared with the end of the
extracted string, and the ACL matches if any of them matches.
- subdir match (-m dir) : the patterns are looked up anywhere inside the
extracted string, delimited with slashes ("/"), the beginning or the end
of the string. The ACL matches if any of them matches. As such, the string
"/images/png/logo/32x32.png", would match "/images", "/images/png",
"images/png", "/png/logo", "logo/32x32.png" or "32x32.png" but not "png"
nor "32x32".
- domain match (-m dom) : the patterns are looked up anywhere inside the
extracted string, delimited with dots ("."), colons (":"), slashes ("/"),
question marks ("?"), the beginning or the end of the string. This is made
to be used with URLs. Leading and trailing delimiters in the pattern are
ignored. The ACL matches if any of them matches. As such, in the example
string "http://www1.dc-eu.example.com:80/blah", the patterns "http",
"www1", ".www1", "dc-eu", "example", "com", "80", "dc-eu.example",
"blah", ":www1:", "dc-eu.example:80" would match, but not "eu" nor "dc".
Using it to match domain suffixes for filtering or routing is generally
not a good idea, as the routing could easily be fooled by prepending the
matching prefix in front of another domain for example.
String matching applies to verbatim strings as they are passed, with the
exception of the backslash ("\") which makes it possible to escape some
characters such as the space. If the "-i" flag is passed before the first
string, then the matching will be performed ignoring the case. In order
to match the string "-i", either set it second, or pass the "--" flag
before the first string. Same applies of course to match the string "--".
Do not use string matches for binary fetches which might contain null bytes
(0x00), as the comparison stops at the occurrence of the first null byte.
Instead, convert the binary fetch to a hex string with the hex converter first.
Example:
# matches if the string <tag> is present in the binary sample
acl tag_found req.payload(0,0),hex -m sub 3C7461673E
7.1.4. Matching regular expressions (regexes)
Just like with string matching, regex matching applies to verbatim strings as
they are passed, with the exception of the backslash ("\") which makes it
possible to escape some characters such as the space. If the "-i" flag is
passed before the first regex, then the matching will be performed ignoring
the case. In order to match the string "-i", either set it second, or pass
the "--" flag before the first string. Same principle applies of course to
match the string "--".
7.1.5. Matching arbitrary data blocks
It is possible to match some extracted samples against a binary block which may
not safely be represented as a string. For this, the patterns must be passed as
a series of hexadecimal digits in an even number, when the match method is set
to binary. Each sequence of two digits will represent a byte. The hexadecimal
digits may be used upper or lower case.
Example :
# match "Hello\n" in the input stream (\x48 \x65 \x6c \x6c \x6f \x0a)
acl hello req.payload(0,6) -m bin 48656c6c6f0a
7.1.6. Matching IPv4 and IPv6 addresses
IPv4 addresses values can be specified either as plain addresses or with a
netmask appended, in which case the IPv4 address matches whenever it is
within the network. Plain addresses may also be replaced with a resolvable
host name, but this practice is generally discouraged as it makes it more
difficult to read and debug configurations. If hostnames are used, you should
at least ensure that they are present in /etc/hosts so that the configuration
does not depend on any random DNS match at the moment the configuration is
parsed.
The dotted IPv4 address notation is supported in both regular as well as the
abbreviated form with all-0-octets omitted:
+------------------+------------------+------------------+
| Example 1 | Example 2 | Example 3 |
+------------------+------------------+------------------+
| 192.168.0.1 | 10.0.0.12 | 127.0.0.1 |
| 192.168.1 | 10.12 | 127.1 |
| 192.168.0.1/22 | 10.0.0.12/8 | 127.0.0.1/8 |
| 192.168.1/22 | 10.12/8 | 127.1/8 |
+------------------+------------------+------------------+
Notice that this is different from RFC 4632 CIDR address notation in which
192.168.42/24 would be equivalent to 192.168.42.0/24.
IPv6 may be entered in their usual form, with or without a netmask appended.
Only bit counts are accepted for IPv6 netmasks. In order to avoid any risk of
trouble with randomly resolved IP addresses, host names are never allowed in
IPv6 patterns.
HAProxy is also able to match IPv4 addresses with IPv6 addresses in the
following situations :
- tested address is IPv4, pattern address is IPv4, the match applies
in IPv4 using the supplied mask if any.
- tested address is IPv6, pattern address is IPv6, the match applies
in IPv6 using the supplied mask if any.
- tested address is IPv6, pattern address is IPv4, the match applies in IPv4
using the pattern's mask if the IPv6 address matches with 2002:IPV4::,
::IPV4 or ::ffff:IPV4, otherwise it fails.
- tested address is IPv4, pattern address is IPv6, the IPv4 address is first
converted to IPv6 by prefixing ::ffff: in front of it, then the match is
applied in IPv6 using the supplied IPv6 mask.
7.2. Using ACLs to form conditions
Some actions are only performed upon a valid condition. A condition is a
combination of ACLs with operators. 3 operators are supported :
- AND (implicit)
- OR (explicit with the "or" keyword or the "||" operator)
- Negation with the exclamation mark ("!")
A condition is formed as a disjunctive form:
[!]acl1 [!]acl2 ... [!]acln { or [!]acl1 [!]acl2 ... [!]acln } ...
Such conditions are generally used after an "if" or "unless" statement,
indicating when the condition will trigger the action.
For instance, to block HTTP requests to the "*" URL with methods other than
"OPTIONS", as well as POST requests without content-length, and GET or HEAD
requests with a content-length greater than 0, and finally every request which
is not either GET/HEAD/POST/OPTIONS !
acl missing_cl req.hdr_cnt(Content-length) eq 0
http-request deny if HTTP_URL_STAR !METH_OPTIONS || METH_POST missing_cl
http-request deny if METH_GET HTTP_CONTENT
http-request deny unless METH_GET or METH_POST or METH_OPTIONS
To select a different backend for requests to static contents on the "www" site
and to every request on the "img", "video", "download" and "ftp" hosts :
acl url_static path_beg /static /images /img /css
acl url_static path_end .gif .png .jpg .css .js
acl host_www hdr_beg(host) -i www
acl host_static hdr_beg(host) -i img. video. download. ftp.
# now use backend "static" for all static-only hosts, and for static URLs
# of host "www". Use backend "www" for the rest.
use_backend static if host_static or host_www url_static
use_backend www if host_www
It is also possible to form rules using "anonymous ACLs". Those are unnamed ACL
expressions that are built on the fly without needing to be declared. They must
be enclosed between braces, with a space before and after each brace (because
the braces must be seen as independent words). Example :
The following rule :
acl missing_cl req.hdr_cnt(Content-length) eq 0
http-request deny if METH_POST missing_cl
Can also be written that way :
http-request deny if METH_POST { req.hdr_cnt(Content-length) eq 0 }
It is generally not recommended to use this construct because it's a lot easier
to leave errors in the configuration when written that way. However, for very
simple rules matching only one source IP address for instance, it can make more
sense to use them than to declare ACLs with random names. Another example of
good use is the following :
With named ACLs :
acl site_dead nbsrv(dynamic) lt 2
acl site_dead nbsrv(static) lt 2
monitor fail if site_dead
With anonymous ACLs :
monitor fail if { nbsrv(dynamic) lt 2 } || { nbsrv(static) lt 2 }
See section 4.2 for detailed help on the "http-request deny" and "use_backend"
keywords.
7.3. Fetching samples
Historically, sample fetch methods were only used to retrieve data to match
against patterns using ACLs. With the arrival of stick-tables, a new class of
sample fetch methods was created, most often sharing the same syntax as their
ACL counterpart. These sample fetch methods are also known as "fetches". As
of now, ACLs and fetches have converged. All ACL fetch methods have been made
available as fetch methods, and ACLs may use any sample fetch method as well.
This section details all available sample fetch methods and their output type.
Some sample fetch methods have deprecated aliases that are used to maintain
compatibility with existing configurations. They are then explicitly marked as
deprecated and should not be used in new setups.
The ACL derivatives are also indicated when available, with their respective
matching methods. These ones all have a well defined default pattern matching
method, so it is never necessary (though allowed) to pass the "-m" option to
indicate how the sample will be matched using ACLs.
As indicated in the sample type versus matching compatibility matrix above,
when using a generic sample fetch method in an ACL, the "-m" option is
mandatory unless the sample type is one of boolean, integer, IPv4 or IPv6. When
the same keyword exists as an ACL keyword and as a standard fetch method, the
ACL engine will automatically pick the ACL-only one by default.
Some of these keywords support one or multiple mandatory arguments, and one or
multiple optional arguments. These arguments are strongly typed and are checked
when the configuration is parsed so that there is no risk of running with an
incorrect argument (e.g. an unresolved backend name). Fetch function arguments
are passed between parenthesis and are delimited by commas. When an argument
is optional, it will be indicated below between square brackets ('[ ]'). When
all arguments are optional, the parenthesis may be omitted.
Thus, the syntax of a standard sample fetch method is one of the following :
- name
- name(arg1)
- name(arg1,arg2)
7.3.1. Converters
Sample fetch methods may be combined with transformations to be applied on top
of the fetched sample (also called "converters"). These combinations form what
is called "sample expressions" and the result is a "sample". Initially this
was only supported by "stick on" and "stick store-request" directives but this
has now be extended to all places where samples may be used (ACLs, log-format,
unique-id-format, add-header, ...).
These transformations are enumerated as a series of specific keywords after the
sample fetch method. These keywords may equally be appended immediately after
the fetch keyword's argument, delimited by a comma. These keywords can also
support some arguments (e.g. a netmask) which must be passed in parenthesis.
A certain category of converters are bitwise and arithmetic operators which
support performing basic operations on integers. Some bitwise operations are
supported (and, or, xor, cpl) and some arithmetic operations are supported
(add, sub, mul, div, mod, neg). Some comparators are provided (odd, even, not,
bool) which make it possible to report a match without having to write an ACL.
The currently available list of transformation keywords include :
Returns values for the properties requested as a string, where values are
separated by the delimiter specified with "51degrees-property-separator".
The device is identified using the User-Agent header passed to the
converter. The function can be passed up to five property names, and if a
property name can't be found, the value "NoData" is returned.
Example :
# Here the header "X-51D-DeviceTypeMobileTablet" is added to the request,
# containing values for the three properties requested by using the
# User-Agent passed to the converter.
frontend http-in
bind *:8081
default_backend servers
http-request set-header X-51D-DeviceTypeMobileTablet \
%[req.fhdr(User-Agent),51d.single(DeviceType,IsMobile,IsTablet)]
Adds <value> to the input value of type signed integer, and returns the
result as a signed integer. <value> can be a numeric value or a variable
name. The name of the variable starts with an indication about its scope. The
scopes allowed are:
"proc" : the variable is shared with the whole process
"sess" : the variable is shared with the whole session
"txn" : the variable is shared with the transaction (request and response)
"req" : the variable is shared only during request processing
"res" : the variable is shared only during response processing
This prefix is followed by a name. The separator is a '.'. The name may only
contain characters 'a-z', 'A-Z', '0-9', '.' and '_'.
Decrypts the raw byte input using the AES128-GCM, AES192-GCM or
AES256-GCM algorithm, depending on the <bits> parameter. All other parameters
need to be base64 encoded and the returned result is in raw byte format.
If the <aead_tag> validation fails, the converter doesn't return any data.
The <nonce>, <key> and <aead_tag> can either be strings or variables. This
converter requires at least OpenSSL 1.0.1.
Example:
http-response set-header X-Decrypted-Text %[var(txn.enc),\
aes_gcm_dec(128,txn.nonce,Zm9vb2Zvb29mb29wZm9vbw==,txn.aead_tag)]
Performs a bitwise "AND" between <value> and the input value of type signed
integer, and returns the result as an signed integer. <value> can be a
numeric value or a variable name. The name of the variable starts with an
indication about its scope. The scopes allowed are:
"proc" : the variable is shared with the whole process
"sess" : the variable is shared with the whole session
"txn" : the variable is shared with the transaction (request and response)
"req" : the variable is shared only during request processing
"res" : the variable is shared only during response processing
This prefix is followed by a name. The separator is a '.'. The name may only
contain characters 'a-z', 'A-Z', '0-9', '.' and '_'.
Converts (decodes) a base64 encoded input string to its binary
representation. It performs the inverse operation of base64().
For base64url("URL and Filename Safe Alphabet" (RFC 4648)) variant
see "ub64dec".
Converts a binary input sample to a base64 string. It is used to log or
transfer binary content in a way that can be reliably transferred (e.g.
an SSL ID can be copied in a header). For base64url("URL and Filename
Safe Alphabet" (RFC 4648)) variant see "ub64enc".
Returns a boolean TRUE if the input value of type signed integer is
non-null, otherwise returns FALSE. Used in conjunction with and(), it can be
used to report true/false for bit testing on input values (e.g. verify the
presence of a flag).
Extracts some bytes from an input binary sample. The result is a binary
sample starting at an offset (in bytes) of the original sample and
optionally truncated at the given length.
Concatenates up to 3 fields after the current sample which is then turned to
a string. The first one, <start>, is a constant string, that will be appended
immediately after the existing sample. It may be omitted if not used. The
second one, <var>, is a variable name. The variable will be looked up, its
contents converted to a string, and it will be appended immediately after the
<first> part. If the variable is not found, nothing is appended. It may be
omitted as well. The third field, <end> is a constant string that will be
appended after the variable. It may also be omitted. Together, these elements
allow to concatenate variables with delimiters to an existing set of
variables. This can be used to build new variables made of a succession of
other variables, such as colon-delimited values. If commas or closing
parenthesis are needed as delimiters, they must be protected by quotes or
backslashes, themselves protected so that they are not stripped by the first
level parser. This is often used to build composite variables from other
ones, but sometimes using a format string with multiple fields may be more
convenient. See examples below.
Example:
tcp-request session set-var(sess.src) src
tcp-request session set-var(sess.dn) ssl_c_s_dn
tcp-request session set-var(txn.sig) str(),concat(<ip=,sess.ip,>),concat(<dn=,sess.dn,>)
tcp-request session set-var(txn.ipport) "str(),concat('addr=(',sess.ip),concat(',',sess.port,')')"
tcp-request session set-var-fmt(txn.ipport) "addr=(%[sess.ip],%[sess.port])" ## does the same
http-request set-header x-hap-sig %[var(txn.sig)]
Takes the input value of type signed integer, applies a ones-complement
(flips all bits) and returns the result as an signed integer.
Hashes a binary input sample into an unsigned 32-bit quantity using the CRC32
hash function. Optionally, it is possible to apply a full avalanche hash
function to the output if the optional <avalanche> argument equals 1. This
converter uses the same functions as used by the various hash-based load
balancing algorithms, so it will provide exactly the same results. It is
provided for compatibility with other software which want a CRC32 to be
computed on some input keys, so it follows the most common implementation as
found in Ethernet, Gzip, PNG, etc... It is slower than the other algorithms
but may provide a better or at least less predictable distribution. It must
not be used for security purposes as a 32-bit hash is trivial to break. See
also "djb2", "sdbm", "wt6", "crc32c" and the "hash-type" directive.
Hashes a binary input sample into an unsigned 32-bit quantity using the CRC32C
hash function. Optionally, it is possible to apply a full avalanche hash
function to the output if the optional <avalanche> argument equals 1. This
converter uses the same functions as described in RFC4960, Appendix B [8].
It is provided for compatibility with other software which want a CRC32C to be
computed on some input keys. It is slower than the other algorithms and it must
not be used for security purposes as a 32-bit hash is trivial to break. See
also "djb2", "sdbm", "wt6", "crc32" and the "hash-type" directive.
Cuts the string representation of the input sample on the first carriage
return ('\r') or newline ('\n') character found. Only the string length is
updated.
Asks the DeviceAtlas converter to identify the User Agent string passed on
input, and to emit a string made of the concatenation of the properties
enumerated in argument, delimited by the separator defined by the global
keyword "deviceatlas-property-separator", or by default the pipe character
('|'). There's a limit of 12 different properties imposed by the HAProxy
configuration language.
Example:
frontend www
bind *:8881
default_backend servers
http-request set-header X-DeviceAtlas-Data %[req.fhdr(User-Agent),da-csv(primaryHardwareType,osName,osVersion,browserName,browserVersion,browserRenderingEngine)]
This converter is used as debug tool. It takes a capture of the input sample
and sends it to event sink <destination>, which may designate a ring buffer
such as "buf0", as well as "stdout", or "stderr". Available sinks may be
checked at run time by issuing "show events" on the CLI. When not specified,
the output will be "buf0", which may be consulted via the CLI's "show events"
command. An optional prefix <prefix> may be passed to help distinguish
outputs from multiple expressions. It will then appear before the colon in
the output message. The input sample is passed as-is on the output, so that
it is safe to insert the debug converter anywhere in a chain, even with non-
printable sample types.
Example:
tcp-request connection track-sc0 src,debug(track-sc)
Converts a binary input sample to a message digest. The result is a binary
sample. The <algorithm> must be an OpenSSL message digest name (e.g. sha256).
Please note that this converter is only available when HAProxy has been
compiled with USE_OPENSSL.
Divides the input value of type signed integer by <value>, and returns the
result as an signed integer. If <value> is null, the largest unsigned
integer is returned (typically 2^63-1). <value> can be a numeric value or a
variable name. The name of the variable starts with an indication about its
scope. The scopes allowed are:
"proc" : the variable is shared with the whole process
"sess" : the variable is shared with the whole session
"txn" : the variable is shared with the transaction (request and response)
"req" : the variable is shared only during request processing
"res" : the variable is shared only during response processing
This prefix is followed by a name. The separator is a '.'. The name may only
contain characters 'a-z', 'A-Z', '0-9', '.' and '_'.
Hashes a binary input sample into an unsigned 32-bit quantity using the DJB2
hash function. Optionally, it is possible to apply a full avalanche hash
function to the output if the optional <avalanche> argument equals 1. This
converter uses the same functions as used by the various hash-based load
balancing algorithms, so it will provide exactly the same results. It is
mostly intended for debugging, but can be used as a stick-table entry to
collect rough statistics. It must not be used for security purposes as a
32-bit hash is trivial to break. See also "crc32", "sdbm", "wt6", "crc32c",
and the "hash-type" directive.
Returns a boolean TRUE if the input value of type signed integer is even
otherwise returns FALSE. It is functionally equivalent to "not,and(1),bool".
Extracts the substring at the given index counting from the beginning
(positive index) or from the end (negative index) considering given delimiters
from an input string. Indexes start at 1 or -1 and delimiters are a string
formatted list of chars. Optionally you can specify <count> of fields to
extract (default: 1). Value of 0 indicates extraction of all remaining
fields.
Example :
str(f1_f2_f3__f5),field(4,_) # <empty>
str(f1_f2_f3__f5),field(5,_) # f5
str(f1_f2_f3__f5),field(2,_,0) # f2_f3__f5
str(f1_f2_f3__f5),field(2,_,2) # f2_f3
str(f1_f2_f3__f5),field(-2,_,3) # f2_f3_
str(f1_f2_f3__f5),field(-3,_,0) # f1_f2_f3
Parses a binary payload and performs sanity checks regarding FIX (Financial
Information eXchange):
- checks that all tag IDs and values are not empty and the tags IDs are well
numeric
- checks the BeginString tag is the first tag with a valid FIX version
- checks the BodyLength tag is the second one with the right body length
- checks the MsgType tag is the third tag.
- checks that last tag in the message is the CheckSum tag with a valid
checksum
Due to current HAProxy design, only the first message sent by the client and
the server can be parsed.
This converter returns a boolean, true if the payload contains a valid FIX
message, false if not.
See also the fix_tag_value converter.
Example:
tcp-request inspect-delay 10s
tcp-request content reject unless { req.payload(0,0),fix_is_valid }
Parses a FIX (Financial Information eXchange) message and extracts the value
from the tag <tag>. <tag> can be a string or an integer pointing to the
desired tag. Any integer value is accepted, but only the following strings
are translated into their integer equivalent: BeginString, BodyLength,
MsgType, SenderCompID, TargetCompID, CheckSum. More tag names can be easily
added.
Due to current HAProxy design, only the first message sent by the client and
the server can be parsed. No message validation is performed by this
converter. It is highly recommended to validate the message first using
fix_is_valid converter.
See also the fix_is_valid converter.
Example:
tcp-request inspect-delay 10s
tcp-request content reject unless { req.payload(0,0),fix_is_valid }
# MsgType tag ID is 35, so both lines below will return the same content
tcp-request content set-var(txn.foo) req.payload(0,0),fix_tag_value(35)
tcp-request content set-var(txn.bar) req.payload(0,0),fix_tag_value(MsgType)
Converts a binary input sample to a hex string containing two hex digits per
input byte. It is used to log or transfer hex dumps of some binary input data
in a way that can be reliably transferred (e.g. an SSL ID can be copied in a
header).
Converts a hex string containing two hex digits per input byte to an
integer. If the input value cannot be converted, then zero is returned.
Converts the input integer value to its 32-bit binary representation in the
network byte order. Because sample fetches own signed 64-bit integer, when
this converter is used, the input integer value is first casted to an
unsigned 32-bit integer.
Converts a binary input sample to a message authentication code with the given
key. The result is a binary sample. The <algorithm> must be one of the
registered OpenSSL message digest names (e.g. sha256). The <key> parameter must
be base64 encoded and can either be a string or a variable.
Please note that this converter is only available when HAProxy has been
compiled with USE_OPENSSL.
Converts an integer supposed to contain a date since epoch to a string
representing this date in a format suitable for use in HTTP header fields. If
an offset value is specified, then it is added to the date before the
conversion is operated. This is particularly useful to emit Date header fields,
Expires values in responses when combined with a positive offset, or
Last-Modified values when the offset is negative.
If a unit value is specified, then consider the timestamp as either
"s" for seconds (default behavior), "ms" for milliseconds, or "us" for
microseconds since epoch. Offset is assumed to have the same unit as
input timestamp.
Returns the <true> string if the input value is true. Returns the <false>
string otherwise.
Example:
http-request set-header x-forwarded-proto %[ssl_fc,iif(https,http)]
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, a boolean false
is returned. Otherwise a boolean true is returned. This can be used to verify
the presence of a certain key in a table tracking some elements (e.g. whether
or not a source IP address or an Authorization header was already seen).
Apply a mask to an IP address, and use the result for lookups and storage.
This can be used to make all hosts within a certain mask to share the same
table entries and as such use the same server. The mask4 can be passed in
dotted form (e.g. 255.255.255.0) or in CIDR form (e.g. 24). The mask6 can
be passed in quadruplet form (e.g. ffff:ffff::) or in CIDR form (e.g. 64).
If no mask6 is given IPv6 addresses will fail to convert for backwards
compatibility reasons.
Escapes the input string and produces an ASCII output string ready to use as a
JSON string. The converter tries to decode the input string according to the
<input-code> parameter. It can be "ascii", "utf8", "utf8s", "utf8p" or
"utf8ps". The "ascii" decoder never fails. The "utf8" decoder detects 3 types
of errors:
- bad UTF-8 sequence (lone continuation byte, bad number of continuation
bytes, ...)
- invalid range (the decoded value is within a UTF-8 prohibited range),
- code overlong (the value is encoded with more bytes than necessary).
The UTF-8 JSON encoding can produce a "too long value" error when the UTF-8
character is greater than 0xffff because the JSON string escape specification
only authorizes 4 hex digits for the value encoding. The UTF-8 decoder exists
in 4 variants designated by a combination of two suffix letters : "p" for
"permissive" and "s" for "silently ignore". The behaviors of the decoders
are :
- "ascii" : never fails;
- "utf8" : fails on any detected errors;
- "utf8s" : never fails, but removes characters corresponding to errors;
- "utf8p" : accepts and fixes the overlong errors, but fails on any other
error;
- "utf8ps" : never fails, accepts and fixes the overlong errors, but removes
characters corresponding to the other errors.
This converter is particularly useful for building properly escaped JSON for
logging to servers which consume JSON-formatted traffic logs.
Example:
capture request header Host len 15
capture request header user-agent len 150
log-format '{"ip":"%[src]","user-agent":"%[capture.req.hdr(1),json(utf8s)]"}'
Input request from client 127.0.0.1:
GET / HTTP/1.0
User-Agent: Very "Ugly" UA 1/2
Output log:
{"ip":"127.0.0.1","user-agent":"Very \"Ugly\" UA 1\/2"}
The json_query converter supports the JSON types string, boolean and
number. Floating point numbers will be returned as a string. By
specifying the output_type 'int' the value will be converted to an
Integer. If conversion is not possible the json_query converter fails.
<json_path> must be a valid JSON Path string as defined in
https://datatracker.ietf.org/doc/draft-ietf-jsonpath-base/
Example:
# get a integer value from the request body
# "{"integer":4}" => 5
http-request set-var(txn.pay_int) req.body,json_query('$.integer','int'),add(1)
# get a key with '.' in the name
# {"my.key":"myvalue"} => myvalue
http-request set-var(txn.pay_mykey) req.body,json_query('$.my\\.key')
# {"boolean-false":false} => 0
http-request set-var(txn.pay_boolean_false) req.body,json_query('$.boolean-false')
# get the value of the key 'iss' from a JWT Bearer token
http-request set-var(txn.token_payload) req.hdr(Authorization),word(2,.),ub64dec,json_query('$.iss')
When given a JSON Web Token (JWT) in input, either returns the decoded header
part of the token (the first base64-url encoded part of the JWT) if no
parameter is given, or performs a json_query on the decoded header part of
the token. See "json_query" converter for details about the accepted
json_path and output_type parameters.
Please note that this converter is only available when HAProxy has been
compiled with USE_OPENSSL.
When given a JSON Web Token (JWT) in input, either returns the decoded
payload part of the token (the second base64-url encoded part of the JWT) if
no parameter is given, or performs a json_query on the decoded payload part
of the token. See "json_query" converter for details about the accepted
json_path and output_type parameters.
Please note that this converter is only available when HAProxy has been
compiled with USE_OPENSSL.
Performs a signature verification for the JSON Web Token (JWT) given in input
by using the <alg> algorithm and the <key> parameter, which should either
hold a secret or a path to a public certificate. Returns 1 in case of
verification success, 0 in case of verification error and a strictly negative
value for any other error. Because of all those non-null error return values,
the result of this converter should never be converted to a boolean. See
below for a full list of the possible return values.
For now, only JWS tokens using the Compact Serialization format can be
processed (three dot-separated base64-url encoded strings). Among the
accepted algorithms for a JWS (see section 3.1 of RFC7518), the PSXXX ones
are not managed yet.
If the used algorithm is of the HMAC family, <key> should be the secret used
in the HMAC signature calculation. Otherwise, <key> should be the path to the
public certificate that can be used to validate the token's signature. All
the certificates that might be used to verify JWTs must be known during init
in order to be added into a dedicated certificate cache so that no disk
access is required during runtime. For this reason, any used certificate must
be mentioned explicitely at least once in a jwt_verify call. Passing an
intermediate variable as second parameter is then not advised.
This converter only verifies the signature of the token and does not perform
a full JWT validation as specified in section 7.2 of RFC7519. We do not
ensure that the header and payload contents are fully valid JSON's once
decoded for instance, and no checks are performed regarding their respective
contents.
The possible return values are the following :
+----+----------------------------------------------------------------------+
| ID | message |
+----+----------------------------------------------------------------------+
| 0 | "Verification failure" |
| 1 | "Verification sucess" |
| -1 | "Unknown algorithm (not mentioned in RFC7518)" |
| -2 | "Unmanaged algorithm (PSXXX algorithm family)" |
| -3 | "Invalid token" |
| -4 | "Out of memory" |
| -5 | "Unknown certificate" |
+----+----------------------------------------------------------------------+
Please note that this converter is only available when HAProxy has been
compiled with USE_OPENSSL.
Example:
# Get a JWT from the authorization header, extract the "alg" field of its
# JOSE header and use a public certificate to verify a signature
http-request set-var(txn.bearer) http_auth_bearer
http-request set-var(txn.jwt_alg) var(txn.bearer),jwt_header_query('$.alg')
http-request deny unless { var(txn.jwt_alg) "RS256" }
http-request deny unless { var(txn.bearer),jwt_verify(txn.jwt_alg,"/path/to/crt.pem") 1 }
Returns the value with the highest q-factor from a list as extracted from the
"accept-language" header using "req.fhdr". Values with no q-factor have a
q-factor of 1. Values with a q-factor of 0 are dropped. Only values which
belong to the list of semi-colon delimited <values> will be considered. The
argument <value> syntax is "lang[;lang[;lang[;...]]]". If no value matches the
given list and a default value is provided, it is returned. Note that language
names may have a variant after a dash ('-'). If this variant is present in the
list, it will be matched, but if it is not, only the base language is checked.
The match is case-sensitive, and the output string is always one of those
provided in arguments. The ordering of arguments is meaningless, only the
ordering of the values in the request counts, as the first value among
multiple sharing the same q-factor is used.
Example :
# this configuration switches to the backend matching a
# given language based on the request :
acl es req.fhdr(accept-language),language(es;fr;en) -m str es
acl fr req.fhdr(accept-language),language(es;fr;en) -m str fr
acl en req.fhdr(accept-language),language(es;fr;en) -m str en
use_backend spanish if es
use_backend french if fr
use_backend english if en
default_backend choose_your_language
Get the length of the string. This can only be placed after a string
sample fetch function or after a transformation keyword returning a string
type. The result is of type integer.
Convert a string sample to lower case. This can only be placed after a string
sample fetch function or after a transformation keyword returning a string
type. The result is of type string.
Converts an integer supposed to contain a date since epoch to a string
representing this date in local time using a format defined by the <format>
string using strftime(3). The purpose is to allow any date format to be used
in logs. An optional <offset> in seconds may be applied to the input date
(positive or negative). See the strftime() man page for the format supported
by your operating system. See also the utime converter.
Example :
# Emit two colons, one with the local time and another with ip:port
# e.g. 20140710162350 127.0.0.1:57325
log-format %[date,ltime(%Y%m%d%H%M%S)]\ %ci:%cp
Skips any characters from <chars> from the beginning of the string
representation of the input sample.
map_<match_type>(<map_file>[,<default_value>])
map_<match_type>_<output_type>(<map_file>[,<default_value>])
Search the input value from <map_file> using the <match_type> matching method,
and return the associated value converted to the type <output_type>. If the
input value cannot be found in the <map_file>, the converter returns the
<default_value>. If the <default_value> is not set, the converter fails and
acts as if no input value could be fetched. If the <match_type> is not set, it
defaults to "str". Likewise, if the <output_type> is not set, it defaults to
"str". For convenience, the "map" keyword is an alias for "map_str" and maps a
string to another string.
It is important to avoid overlapping between the keys : IP addresses and
strings are stored in trees, so the first of the finest match will be used.
Other keys are stored in lists, so the first matching occurrence will be used.
The following array contains the list of all map functions available sorted by
input type, match type and output type.
| input type | match method | output type str | output type int | output type ip |
|---|---|---|---|---|
| str | str | map_str | map_str_int | map_str_ip |
| str | beg | map_beg | map_beg_int | map_end_ip |
| str | sub | map_sub | map_sub_int | map_sub_ip |
| str | dir | map_dir | map_dir_int | map_dir_ip |
| str | dom | map_dom | map_dom_int | map_dom_ip |
| str | end | map_end | map_end_int | map_end_ip |
| str | reg | map_reg | map_reg_int | map_reg_ip |
| str | reg | map_regm | map_reg_int | map_reg_ip |
| int | int | map_int | map_int_int | map_int_ip |
| ip | ip | map_ip | map_ip_int | map_ip_ip |
The special map called "map_regm" expect matching zone in the regular
expression and modify the output replacing back reference (like "\1") by
the corresponding match text.
The file contains one key + value per line. Lines which start with '#' are
ignored, just like empty lines. Leading tabs and spaces are stripped. The key
is then the first "word" (series of non-space/tabs characters), and the value
is what follows this series of space/tab till the end of the line excluding
trailing spaces/tabs.
Example :
# this is a comment and is ignored
2.22.246.0/23 United Kingdom \n
<-><-----------><--><------------><---->
| | | | `- trailing spaces ignored
| | | `---------- value
| | `-------------------- middle spaces ignored
| `---------------------------- key
`------------------------------------ leading spaces ignored
Divides the input value of type signed integer by <value>, and returns the
remainder as an signed integer. If <value> is null, then zero is returned.
<value> can be a numeric value or a variable name. The name of the variable
starts with an indication about its scope. The scopes allowed are:
"proc" : the variable is shared with the whole process
"sess" : the variable is shared with the whole session
"txn" : the variable is shared with the transaction (request and response)
"req" : the variable is shared only during request processing
"res" : the variable is shared only during response processing
This prefix is followed by a name. The separator is a '.'. The name may only
contain characters 'a-z', 'A-Z', '0-9', '.' and '_'.
Returns value of <fieldname> found in input MQTT payload of type
<packettype>.
<packettype> can be either a string (case insensitive matching) or a numeric
value corresponding to the type of packet we're supposed to extract data
from.
Supported string and integers can be found here:
https://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Toc398718021
https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc3901022
<fieldname> depends on <packettype> and can be any of the following below.
(note that <fieldname> matching is case insensitive).
<property id> can only be found in MQTT v5.0 streams. check this table:
https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc3901029
- CONNECT (or 1): flags, protocol_name, protocol_version, client_identifier,
will_topic, will_payload, username, password, keepalive
OR any property ID as a numeric value (for MQTT v5.0
packets only):
17: Session Expiry Interval
33: Receive Maximum
39: Maximum Packet Size
34: Topic Alias Maximum
25: Request Response Information
23: Request Problem Information
21: Authentication Method
22: Authentication Data
18: Will Delay Interval
1: Payload Format Indicator
2: Message Expiry Interval
3: Content Type
8: Response Topic
9: Correlation Data
Not supported yet:
38: User Property
- CONNACK (or 2): flags, protocol_version, reason_code
OR any property ID as a numeric value (for MQTT v5.0
packets only):
17: Session Expiry Interval
33: Receive Maximum
36: Maximum QoS
37: Retain Available
39: Maximum Packet Size
18: Assigned Client Identifier
34: Topic Alias Maximum
31: Reason String
40; Wildcard Subscription Available
41: Subscription Identifiers Available
42: Shared Subscription Available
19: Server Keep Alive
26: Response Information
28: Server Reference
21: Authentication Method
22: Authentication Data
Not supported yet:
38: User Property
Due to current HAProxy design, only the first message sent by the client and
the server can be parsed. Thus this converter can extract data only from
CONNECT and CONNACK packet types. CONNECT is the first message sent by the
client and CONNACK is the first response sent by the server.
Example:
acl data_in_buffer req.len ge 4
tcp-request content set-var(txn.username) \
req.payload(0,0),mqtt_field_value(connect,protocol_name) \
if data_in_buffer
# do the same as above
tcp-request content set-var(txn.username) \
req.payload(0,0),mqtt_field_value(1,protocol_name) \
if data_in_buffer
Checks that the binary input is a valid MQTT packet. It returns a boolean.
Due to current HAProxy design, only the first message sent by the client and
the server can be parsed. Thus this converter can extract data only from
CONNECT and CONNACK packet types. CONNECT is the first message sent by the
client and CONNACK is the first response sent by the server.
Only MQTT 3.1, 3.1.1 and 5.0 are supported.
Example:
acl data_in_buffer req.len ge 4
tcp-request content reject unless { req.payload(0,0),mqtt_is_valid }
Multiplies the input value of type signed integer by <value>, and returns
the product as an signed integer. In case of overflow, the largest possible
value for the sign is returned so that the operation doesn't wrap around.
<value> can be a numeric value or a variable name. The name of the variable
starts with an indication about its scope. The scopes allowed are:
"proc" : the variable is shared with the whole process
"sess" : the variable is shared with the whole session
"txn" : the variable is shared with the transaction (request and response)
"req" : the variable is shared only during request processing
"res" : the variable is shared only during response processing
This prefix is followed by a name. The separator is a '.'. The name may only
contain characters 'a-z', 'A-Z', '0-9', '.' and '_'.
Takes an input value of type string, interprets it as a backend name and
returns the number of usable servers in that backend. Can be used in places
where we want to look up a backend from a dynamic name, like a result of a
map lookup.
Takes the input value of type signed integer, computes the opposite value,
and returns the remainder as an signed integer. 0 is identity. This operator
is provided for reversed subtracts : in order to subtract the input from a
constant, simply perform a "neg,add(value)".
Returns a boolean FALSE if the input value of type signed integer is
non-null, otherwise returns TRUE. Used in conjunction with and(), it can be
used to report true/false for bit testing on input values (e.g. verify the
absence of a flag).
Returns a boolean TRUE if the input value of type signed integer is odd
otherwise returns FALSE. It is functionally equivalent to "and(1),bool".
Performs a bitwise "OR" between <value> and the input value of type signed
integer, and returns the result as an signed integer. <value> can be a
numeric value or a variable name. The name of the variable starts with an
indication about its scope. The scopes allowed are:
"proc" : the variable is shared with the whole process
"sess" : the variable is shared with the whole session
"txn" : the variable is shared with the transaction (request and response)
"req" : the variable is shared only during request processing
"res" : the variable is shared only during response processing
This prefix is followed by a name. The separator is a '.'. The name may only
contain characters 'a-z', 'A-Z', '0-9', '.' and '_'.
This extracts the protocol buffers message field in raw mode of an input binary
sample representation of a protocol buffer message with <field_number> as field
number (dotted notation) if <field_type> is not present, or as an integer sample
if this field is present (see also "ungrpc" below).
The list of the authorized types is the following one: "int32", "int64", "uint32",
"uint64", "sint32", "sint64", "bool", "enum" for the "varint" wire type 0
"fixed64", "sfixed64", "double" for the 64bit wire type 1, "fixed32", "sfixed32",
"float" for the wire type 5. Note that "string" is considered as a length-delimited
type, so it does not require any <field_type> argument to be extracted.
More information may be found here about the protocol buffers message field types:
https://developers.google.com/protocol-buffers/docs/encoding
Applies a regex-based substitution to the input string. It does the same
operation as the well-known "sed" utility with "s/<regex>/<subst>/". By
default it will replace in the input string the first occurrence of the
largest part matching the regular expression <regex> with the substitution
string <subst>. It is possible to replace all occurrences instead by adding
the flag "g" in the third argument <flags>. It is also possible to make the
regex case insensitive by adding the flag "i" in <flags>. Since <flags> is a
string, it is made up from the concatenation of all desired flags. Thus if
both "i" and "g" are desired, using "gi" or "ig" will have the same effect.
The first use of this converter is to replace certain characters or sequence
of characters with other ones.
It is highly recommended to enclose the regex part using protected quotes to
improve clarity and never have a closing parenthesis from the regex mixed up
with the parenthesis from the function. Just like in Bourne shell, the first
level of quotes is processed when delimiting word groups on the line, a
second level is usable for argument. It is recommended to use single quotes
outside since these ones do not try to resolve backslashes nor dollar signs.
Examples:
# de-duplicate "/" in header "x-path".
# input: x-path: /////a///b/c/xzxyz/
# output: x-path: /a/b/c/xzxyz/
http-request set-header x-path "%[hdr(x-path),regsub('/+','/','g')]"
# copy query string to x-query and drop all leading '?', ';' and '&'
http-request set-header x-query "%[query,regsub([?;&]*,'')]"
# capture groups and backreferences
# both lines do the same.
http-request redirect location %[url,'regsub("(foo|bar)([0-9]+)?","\2\1",i)']
http-request redirect location %[url,regsub(\"(foo|bar)([0-9]+)?\",\"\2\1\",i)]
Capture the string entry in the request slot <id> and returns the entry as
is. If the slot doesn't exist, the capture fails silently.
See also: "declare capture", "http-request capture", "http-response capture", "capture.req.hdr" and "capture.res.hdr" (sample fetches).
Capture the string entry in the response slot <id> and returns the entry as
is. If the slot doesn't exist, the capture fails silently.
See also: "declare capture", "http-request capture", "http-response capture", "capture.req.hdr" and "capture.res.hdr" (sample fetches).
Skips any characters from <chars> from the end of the string representation
of the input sample.
Hashes a binary input sample into an unsigned 32-bit quantity using the SDBM
hash function. Optionally, it is possible to apply a full avalanche hash
function to the output if the optional <avalanche> argument equals 1. This
converter uses the same functions as used by the various hash-based load
balancing algorithms, so it will provide exactly the same results. It is
mostly intended for debugging, but can be used as a stick-table entry to
collect rough statistics. It must not be used for security purposes as a
32-bit hash is trivial to break. See also "crc32", "djb2", "wt6", "crc32c",
and the "hash-type" directive.
Compares the contents of <var> with the input value. Both values are treated
as a binary string. Returns a boolean indicating whether both binary strings
match.
If both binary strings have the same length then the comparison will be
performed in constant time.
Please note that this converter is only available when HAProxy has been
compiled with USE_OPENSSL.
Example :
http-request set-var(txn.token) hdr(token)
# Check whether the token sent by the client matches the secret token
# value, without leaking the contents using a timing attack.
acl token_given str(my_secret_token),secure_memcmp(txn.token)
Sets a variable with the input content and returns the content on the output
as-is. The variable keeps the value and the associated input type. The name of
the variable starts with an indication about its scope. The scopes allowed are:
"proc" : the variable is shared with the whole process
"sess" : the variable is shared with the whole session
"txn" : the variable is shared with the transaction (request and
response),
"req" : the variable is shared only during request processing,
"res" : the variable is shared only during response processing.
This prefix is followed by a name. The separator is a '.'. The name may only
contain characters 'a-z', 'A-Z', '0-9', '.' and '_'.
Converts a binary input sample to a SHA-1 digest. The result is a binary
sample with length of 20 bytes.
Converts a binary input sample to a digest in the SHA-2 family. The result
is a binary sample with length of <bits>/8 bytes.
Valid values for <bits> are 224, 256, 384, 512, each corresponding to
SHA-<bits>. The default value is 256.
Please note that this converter is only available when HAProxy has been
compiled with USE_OPENSSL.
Takes an input value of type string, either a server name or <backend>/<server>
format and returns the number of queued sessions on that server. Can be used
in places where we want to look up queued sessions from a dynamic name, like a
cookie value (e.g. req.cook(SRVID),srv_queue) and then make a decision to break
persistence or direct a request elsewhere.
Compares the contents of <var> with the input value of type string. Returns
the result as a signed integer compatible with strcmp(3): 0 if both strings
are identical. A value less than 0 if the left string is lexicographically
smaller than the right string or if the left string is shorter. A value greater
than 0 otherwise (right string greater than left string or the right string is
shorter).
See also the secure_memcmp converter if you need to compare two binary
strings in constant time.
Example :
http-request set-var(txn.host) hdr(host)
# Check whether the client is attempting domain fronting.
acl ssl_sni_http_host_match ssl_fc_sni,strcmp(txn.host) eq 0
Subtracts <value> from the input value of type signed integer, and returns
the result as an signed integer. Note: in order to subtract the input from
a constant, simply perform a "neg,add(value)". <value> can be a numeric value
or a variable name. The name of the variable starts with an indication about
its scope. The scopes allowed are:
"proc" : the variable is shared with the whole process
"sess" : the variable is shared with the whole session
"txn" : the variable is shared with the transaction (request and
response),
"req" : the variable is shared only during request processing,
"res" : the variable is shared only during response processing.
This prefix is followed by a name. The separator is a '.'. The name may only
contain characters 'a-z', 'A-Z', '0-9', '.' and '_'.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, integer value zero
is returned. Otherwise the converter returns the average client-to-server
bytes rate associated with the input sample in the designated table, measured
in amount of bytes over the period configured in the table. See also the
sc_bytes_in_rate sample fetch keyword.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, integer value zero
is returned. Otherwise the converter returns the average server-to-client
bytes rate associated with the input sample in the designated table, measured
in amount of bytes over the period configured in the table. See also the
sc_bytes_out_rate sample fetch keyword.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, integer value zero
is returned. Otherwise the converter returns the cumulative number of incoming
connections associated with the input sample in the designated table. See
also the sc_conn_cnt sample fetch keyword.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, integer value zero
is returned. Otherwise the converter returns the current amount of concurrent
tracked connections associated with the input sample in the designated table.
See also the sc_conn_cur sample fetch keyword.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, integer value zero
is returned. Otherwise the converter returns the average incoming connection
rate associated with the input sample in the designated table. See also the
sc_conn_rate sample fetch keyword.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, boolean value zero
is returned. Otherwise the converter returns the current value of the first
general purpose tag associated with the input sample in the designated table.
See also the sc_get_gpt0 sample fetch keyword.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, integer value zero
is returned. Otherwise the converter returns the current value of the first
general purpose counter associated with the input sample in the designated
table. See also the sc_get_gpc0 sample fetch keyword.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, integer value zero
is returned. Otherwise the converter returns the frequency which the gpc0
counter was incremented over the configured period in the table, associated
with the input sample in the designated table. See also the sc_get_gpc0_rate
sample fetch keyword.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, integer value zero
is returned. Otherwise the converter returns the current value of the second
general purpose counter associated with the input sample in the designated
table. See also the sc_get_gpc1 sample fetch keyword.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, integer value zero
is returned. Otherwise the converter returns the frequency which the gpc1
counter was incremented over the configured period in the table, associated
with the input sample in the designated table. See also the sc_get_gpc1_rate
sample fetch keyword.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, integer value zero
is returned. Otherwise the converter returns the cumulative number of HTTP
errors associated with the input sample in the designated table. See also the
sc_http_err_cnt sample fetch keyword.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, integer value zero
is returned. Otherwise the average rate of HTTP errors associated with the
input sample in the designated table, measured in amount of errors over the
period configured in the table. See also the sc_http_err_rate sample fetch
keyword.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, integer value zero
is returned. Otherwise the converter returns the cumulative number of HTTP
failures associated with the input sample in the designated table. See also
the sc_http_fail_cnt sample fetch keyword.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, integer value zero
is returned. Otherwise the average rate of HTTP failures associated with the
input sample in the designated table, measured in amount of failures over the
period configured in the table. See also the sc_http_fail_rate sample fetch
keyword.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, integer value zero
is returned. Otherwise the converter returns the cumulative number of HTTP
requests associated with the input sample in the designated table. See also
the sc_http_req_cnt sample fetch keyword.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, integer value zero
is returned. Otherwise the average rate of HTTP requests associated with the
input sample in the designated table, measured in amount of requests over the
period configured in the table. See also the sc_http_req_rate sample fetch
keyword.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, integer value zero
is returned. Otherwise the converter returns the cumulative number of client-
to-server data associated with the input sample in the designated table,
measured in kilobytes. The test is currently performed on 32-bit integers,
which limits values to 4 terabytes. See also the sc_kbytes_in sample fetch
keyword.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, integer value zero
is returned. Otherwise the converter returns the cumulative number of server-
to-client data associated with the input sample in the designated table,
measured in kilobytes. The test is currently performed on 32-bit integers,
which limits values to 4 terabytes. See also the sc_kbytes_out sample fetch
keyword.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, integer value zero
is returned. Otherwise the converter returns the server ID associated with
the input sample in the designated table. A server ID is associated to a
sample by a "stick" rule when a connection to a server succeeds. A server ID
zero means that no server is associated with this key.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, integer value zero
is returned. Otherwise the converter returns the cumulative number of incoming
sessions associated with the input sample in the designated table. Note that
a session here refers to an incoming connection being accepted by the
"tcp-request connection" rulesets. See also the sc_sess_cnt sample fetch
keyword.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, integer value zero
is returned. Otherwise the converter returns the average incoming session
rate associated with the input sample in the designated table. Note that a
session here refers to an incoming connection being accepted by the
"tcp-request connection" rulesets. See also the sc_sess_rate sample fetch
keyword.
Uses the string representation of the input sample to perform a look up in
the specified table. If the key is not found in the table, integer value zero
is returned. Otherwise the converter returns the current amount of concurrent
connections tracking the same key as the input sample in the designated
table. It differs from table_conn_cur in that it does not rely on any stored
information but on the table's reference count (the "use" value which is
returned by "show table" on the CLI). This may sometimes be more suited for
layer7 tracking. It can be used to tell a server how many concurrent
connections there are from a given address for example. See also the
sc_trackers sample fetch keyword.
This converter is the base64url variant of b64dec converter. base64url
encoding is the "URL and Filename Safe Alphabet" variant of base64 encoding.
It is also the encoding used in JWT (JSON Web Token) standard.
Example:
# Decoding a JWT payload:
http-request set-var(txn.token_payload) req.hdr(Authorization),word(2,.),ub64dec
This converter is the base64url variant of base64 converter.
Convert a string sample to upper case. This can only be placed after a string
sample fetch function or after a transformation keyword returning a string
type. The result is of type string.
Takes an url-encoded string provided as input and returns the decoded version
as output. The input and the output are of type string. If the <in_form>
argument is set to a non-zero integer value, the input string is assumed to
be part of a form or query string and the '+' character will be turned into a
space (' '). Otherwise this will only happen after a question mark indicating
a query string ('?').
Takes a string provided as input and returns the encoded version as output.
The input and the output are of type string. By default the type of encoding
is meant for `query` type. There is no other type supported for now but the
optional argument is here for future changes.
This extracts the protocol buffers message field in raw mode of an input binary
sample representation of a gRPC message with <field_number> as field number
(dotted notation) if <field_type> is not present, or as an integer sample if this
field is present.
The list of the authorized types is the following one: "int32", "int64", "uint32",
"uint64", "sint32", "sint64", "bool", "enum" for the "varint" wire type 0
"fixed64", "sfixed64", "double" for the 64bit wire type 1, "fixed32", "sfixed32",
"float" for the wire type 5. Note that "string" is considered as a length-delimited
type, so it does not require any <field_type> argument to be extracted.
More information may be found here about the protocol buffers message field types:
https://developers.google.com/protocol-buffers/docs/encoding
Example:
// with such a protocol buffer .proto file content adapted from
// https://github.com/grpc/grpc/blob/master/examples/protos/route_guide.proto
message Point {
int32 latitude = 1;
int32 longitude = 2;
}
message PPoint {
Point point = 59;
}
message Rectangle {
// One corner of the rectangle.
PPoint lo = 48;
// The other corner of the rectangle.
PPoint hi = 49;
}
let's say a body request is made of a "Rectangle" object value (two PPoint
protocol buffers messages), the four protocol buffers fields could be
extracted with these "ungrpc" directives:
req.body,ungrpc(48.59.1,int32) # "latitude" of "lo" first PPoint
req.body,ungrpc(48.59.2,int32) # "longitude" of "lo" first PPoint
req.body,ungrpc(49.59.1,int32) # "latitude" of "hi" second PPoint
req.body,ungrpc(49.59.2,int32) # "longitude" of "hi" second PPoint
We could also extract the intermediary 48.59 field as a binary sample as follows:
req.body,ungrpc(48.59)
As a gRPC message is always made of a gRPC header followed by protocol buffers
messages, in the previous example the "latitude" of "lo" first PPoint
could be extracted with these equivalent directives:
req.body,ungrpc(48.59),protobuf(1,int32)
req.body,ungrpc(48),protobuf(59.1,int32)
req.body,ungrpc(48),protobuf(59),protobuf(1,int32)
Note that the first convert must be "ungrpc", the remaining ones must be
"protobuf" and only the last one may have or not a second argument to
interpret the previous binary sample.
Unsets a variable if the input content is defined. The name of the variable
starts with an indication about its scope. The scopes allowed are:
"proc" : the variable is shared with the whole process
"sess" : the variable is shared with the whole session
"txn" : the variable is shared with the transaction (request and
response),
"req" : the variable is shared only during request processing,
"res" : the variable is shared only during response processing.
This prefix is followed by a name. The separator is a '.'. The name may only
contain characters 'a-z', 'A-Z', '0-9', '.' and '_'.
Converts an integer supposed to contain a date since epoch to a string
representing this date in UTC time using a format defined by the <format>
string using strftime(3). The purpose is to allow any date format to be used
in logs. An optional <offset> in seconds may be applied to the input date
(positive or negative). See the strftime() man page for the format supported
by your operating system. See also the ltime converter.
Example :
# Emit two colons, one with the UTC time and another with ip:port
# e.g. 20140710162350 127.0.0.1:57325
log-format %[date,utime(%Y%m%d%H%M%S)]\ %ci:%cp
Extracts the nth word counting from the beginning (positive index) or from
the end (negative index) considering given delimiters from an input string.
Indexes start at 1 or -1 and delimiters are a string formatted list of chars.
Empty words are skipped. This means that delimiters at the start or end of
the input string are ignored and consecutive delimiters within the input
string are considered to be a single delimiter.
Optionally you can specify <count> of words to extract (default: 1).
Value of 0 indicates extraction of all remaining words.
Example :
str(f1_f2_f3__f5),word(4,_) # f5
str(f1_f2_f3__f5),word(5,_) # <not found>
str(f1_f2_f3__f5),word(2,_,0) # f2_f3__f5
str(f1_f2_f3__f5),word(3,_,2) # f3__f5
str(f1_f2_f3__f5),word(-2,_,3) # f1_f2_f3
str(f1_f2_f3__f5),word(-3,_,0) # f1_f2
str(/f1/f2/f3/f4),word(1,/) # f1
str(/f1////f2/f3/f4),word(1,/) # f2
Hashes a binary input sample into an unsigned 32-bit quantity using the WT6
hash function. Optionally, it is possible to apply a full avalanche hash
function to the output if the optional <avalanche> argument equals 1. This
converter uses the same functions as used by the various hash-based load
balancing algorithms, so it will provide exactly the same results. It is
mostly intended for debugging, but can be used as a stick-table entry to
collect rough statistics. It must not be used for security purposes as a
32-bit hash is trivial to break. See also "crc32", "djb2", "sdbm", "crc32c",
and the "hash-type" directive.
Performs a bitwise "XOR" (exclusive OR) between <value> and the input value
of type signed integer, and returns the result as an signed integer.
<value> can be a numeric value or a variable name. The name of the variable
starts with an indication about its scope. The scopes allowed are:
"proc" : the variable is shared with the whole process
"sess" : the variable is shared with the whole session
"txn" : the variable is shared with the transaction (request and
response),
"req" : the variable is shared only during request processing,
"res" : the variable is shared only during response processing.
This prefix is followed by a name. The separator is a '.'. The name may only
contain characters 'a-z', 'A-Z', '0-9', '.' and '_'.
Hashes a binary input sample into a signed 64-bit quantity using the XXH3
64-bit variant of the XXhash hash function. This hash supports a seed which
defaults to zero but a different value maybe passed as the <seed> argument.
This hash is known to be very good and very fast so it can be used to hash
URLs and/or URL parameters for use as stick-table keys to collect statistics
with a low collision rate, though care must be taken as the algorithm is not
considered as cryptographically secure.
Hashes a binary input sample into an unsigned 32-bit quantity using the 32-bit
variant of the XXHash hash function. This hash supports a seed which defaults
to zero but a different value maybe passed as the <seed> argument. This hash
is known to be very good and very fast so it can be used to hash URLs and/or
URL parameters for use as stick-table keys to collect statistics with a low
collision rate, though care must be taken as the algorithm is not considered
as cryptographically secure.
Hashes a binary input sample into a signed 64-bit quantity using the 64-bit
variant of the XXHash hash function. This hash supports a seed which defaults
to zero but a different value maybe passed as the <seed> argument. This hash
is known to be very good and very fast so it can be used to hash URLs and/or
URL parameters for use as stick-table keys to collect statistics with a low
collision rate, though care must be taken as the algorithm is not considered
as cryptographically secure.
7.3.2. Fetching samples from internal states
A first set of sample fetch methods applies to internal information which does
not even relate to any client information. These ones are sometimes used with
"monitor-fail" directives to report an internal status to external watchers.
The sample fetch methods described in this section are usable anywhere.
always_false : boolean
Always returns the boolean "false" value. It may be used with ACLs as a
temporary replacement for another one when adjusting configurations.
always_true : boolean
Always returns the boolean "true" value. It may be used with ACLs as a
temporary replacement for another one when adjusting configurations.
Returns the total number of queued connections of the designated backend
divided by the number of active servers. The current backend is used if no
backend is specified. This is very similar to "queue" except that the size of
the farm is considered, in order to give a more accurate measurement of the
time it may take for a new connection to be processed. The main usage is with
ACL to return a sorry page to new users when it becomes certain they will get
a degraded service, or to pass to the backend servers in a header so that
they decide to work in degraded mode or to disable some functions to speed up
the processing a bit. Note that in the event there would not be any active
server anymore, twice the number of queued connections would be considered as
the measured value. This is a fair estimate, as we expect one server to get
back soon anyway, but we still prefer to send new traffic to another backend
if in better shape. See also the "queue", "be_conn", and "be_sess_rate"
sample fetches.
Applies to the number of currently established connections on the backend,
possibly including the connection being evaluated. If no backend name is
specified, the current one is used. But it is also possible to check another
backend. It can be used to use a specific farm when the nominal one is full.
See also the "fe_conn", "queue", "be_conn_free", and "be_sess_rate" criteria.
Returns an integer value corresponding to the number of available connections
across available servers in the backend. Queue slots are not included. Backup
servers are also not included, unless all other servers are down. If no
backend name is specified, the current one is used. But it is also possible
to check another backend. It can be used to use a specific farm when the
nominal one is full. See also the "be_conn", "connslots", and "srv_conn_free"
criteria.
OTHER CAVEATS AND NOTES: if any of the server maxconn, or maxqueue is 0
(meaning unlimited), then this fetch clearly does not make sense, in which
case the value returned will be -1.
Returns an integer value corresponding to the sessions creation rate on the
backend, in number of new sessions per second. This is used with ACLs to
switch to an alternate backend when an expensive or fragile one reaches too
high a session rate, or to limit abuse of service (e.g. prevent sucking of an
online dictionary). It can also be useful to add this element to logs using a
log-format directive.
Example :
# Redirect to an error page if the dictionary is requested too often
backend dynamic
mode http
acl being_scanned be_sess_rate gt 100
redirect location /denied.html if being_scanned
Returns a binary chain. The input is the hexadecimal representation
of the string.
Returns a boolean value. <bool> can be 'true', 'false', '1' or '0'.
'false' and '0' are the same. 'true' and '1' are the same.
Returns an integer value corresponding to the number of connection slots
still available in the backend, by totaling the maximum amount of
connections on all servers and the maximum queue size. This is probably only
used with ACLs.
The basic idea here is to be able to measure the number of connection "slots"
still available (connection + queue), so that anything beyond that (intended
usage; see "use_backend" keyword) can be redirected to a different backend.
'connslots' = number of available server connection slots, + number of
available server queue slots.
Note that while "fe_conn" may be used, "connslots" comes in especially
useful when you have a case of traffic going to one single ip, splitting into
multiple backends (perhaps using ACLs to do name-based load balancing) and
you want to be able to differentiate between different backends, and their
available "connslots". Also, whereas "nbsrv" only measures servers that are
actually *down*, this fetch is more fine-grained and looks into the number of
available connection slots as well. See also "queue" and "avg_queue".
OTHER CAVEATS AND NOTES: at this point in time, the code does not take care
of dynamic connections. Also, if any of the server maxconn, or maxqueue is 0,
then this fetch clearly does not make sense, in which case the value returned
will be -1.
cpu_calls : integer
Returns the number of calls to the task processing the stream or current
request since it was allocated. This number is reset for each new request on
the same connections in case of HTTP keep-alive. This value should usually be
low and stable (around 2 calls for a typically simple request) but may become
high if some processing (compression, caching or analysis) is performed. This
is purely for performance monitoring purposes.
cpu_ns_avg : integer
Returns the average number of nanoseconds spent in each call to the task
processing the stream or current request. This number is reset for each new
request on the same connections in case of HTTP keep-alive. This value
indicates the overall cost of processing the request or the connection for
each call. There is no good nor bad value but the time spent in a call
automatically causes latency for other processing (see lat_ns_avg below),
and may affect other connection's apparent response time. Certain operations
like compression, complex regex matching or heavy Lua operations may directly
affect this value, and having it in the logs will make it easier to spot the
faulty processing that needs to be fixed to recover decent performance.
Note: this value is exactly cpu_ns_tot divided by cpu_calls.
cpu_ns_tot : integer
Returns the total number of nanoseconds spent in each call to the task
processing the stream or current request. This number is reset for each new
request on the same connections in case of HTTP keep-alive. This value
indicates the overall cost of processing the request or the connection for
each call. There is no good nor bad value but the time spent in a call
automatically causes latency for other processing (see lat_ns_avg below),
induces CPU costs on the machine, and may affect other connection's apparent
response time. Certain operations like compression, complex regex matching or
heavy Lua operations may directly affect this value, and having it in the
logs will make it easier to spot the faulty processing that needs to be fixed
to recover decent performance. The value may be artificially high due to a
high cpu_calls count, for example when processing many HTTP chunks, and for
this reason it is often preferred to log cpu_ns_avg instead.
Returns the current date as the epoch (number of seconds since 01/01/1970).
If an offset value is specified, then it is added to the current date before
returning the value. This is particularly useful to compute relative dates,
as both positive and negative offsets are allowed.
It is useful combined with the http_date converter.
<unit> is facultative, and can be set to "s" for seconds (default behavior),
"ms" for milliseconds or "us" for microseconds.
If unit is set, return value is an integer reflecting either seconds,
milliseconds or microseconds since epoch, plus offset.
It is useful when a time resolution of less than a second is needed.
Example :
# set an expires header to now+1 hour in every response
http-response set-header Expires %[date(3600),http_date]
# set an expires header to now+1 hour in every response, with
# millisecond granularity
http-response set-header Expires %[date(3600000,ms),http_date(0,ms)]
date_us : integer
Return the microseconds part of the date (the "second" part is returned by
date sample). This sample is coherent with the date sample as it is comes
from the same timeval structure.
Parses a distcc message and returns the body associated to occurrence #<occ>
of the token <token>. Occurrences start at 1, and when unspecified, any may
match though in practice only the first one is checked for now. This can be
used to extract file names or arguments in files built using distcc through
HAProxy. Please refer to distcc's protocol documentation for the complete
list of supported tokens.
Parses a distcc message and returns the parameter associated to occurrence
#<occ> of the token <token>. Occurrences start at 1, and when unspecified,
any may match though in practice only the first one is checked for now. This
can be used to extract certain information such as the protocol version, the
file size or the argument in files built using distcc through HAProxy.
Another use case consists in waiting for the start of the preprocessed file
contents before connecting to the server to avoid keeping idle connections.
Please refer to distcc's protocol documentation for the complete list of
supported tokens.
Example :
# wait up to 20s for the pre-processed file to be uploaded
tcp-request inspect-delay 20s
tcp-request content accept if { distcc_param(DOTI) -m found }
# send large files to the big farm
use_backend big_farm if { distcc_param(DOTI) gt 1000000 }
Returns a string containing the value of environment variable <name>. As a
reminder, environment variables are per-process and are sampled when the
process starts. This can be useful to pass some information to a next hop
server, or with ACLs to take specific action when the process is started a
certain way.
Examples :
# Pass the Via header to next hop with the local hostname in it
http-request add-header Via 1.1\ %[env(HOSTNAME)]
# reject cookie-less requests when the STOP environment variable is set
http-request deny if !{ req.cook(SESSIONID) -m found } { env(STOP) -m found }
Returns the number of currently established connections on the frontend,
possibly including the connection being evaluated. If no frontend name is
specified, the current one is used. But it is also possible to check another
frontend. It can be used to return a sorry page before hard-blocking, or to
use a specific backend to drain new requests when the farm is considered
full. This is mostly used with ACLs but can also be used to pass some
statistics to servers in HTTP headers. See also the "dst_conn", "be_conn",
"fe_sess_rate" fetches.
Returns an integer value corresponding to the number of HTTP requests per
second sent to a frontend. This number can differ from "fe_sess_rate" in
situations where client-side keep-alive is enabled.
Returns an integer value corresponding to the sessions creation rate on the
frontend, in number of new sessions per second. This is used with ACLs to
limit the incoming session rate to an acceptable range in order to prevent
abuse of service at the earliest moment, for example when combined with other
layer 4 ACLs in order to force the clients to wait a bit for the rate to go
down below the limit. It can also be useful to add this element to logs using
a log-format directive. See also the "rate-limit sessions" directive for use
in frontends.
Example :
# This frontend limits incoming mails to 10/s with a max of 100
# concurrent connections. We accept any connection below 10/s, and
# force excess clients to wait for 100 ms. Since clients are limited to
# 100 max, there cannot be more than 10 incoming mails per second.
frontend mail
bind :25
mode tcp
maxconn 100
acl too_fast fe_sess_rate ge 10
tcp-request inspect-delay 100ms
tcp-request content accept if ! too_fast
tcp-request content accept if WAIT_END
hostname : string
Returns the system hostname.
Returns a signed integer.
Returns an ipv4.
Returns an ipv6.
lat_ns_avg : integer
Returns the average number of nanoseconds spent between the moment the task
handling the stream is woken up and the moment it is effectively called. This
number is reset for each new request on the same connections in case of HTTP
keep-alive. This value indicates the overall latency inflicted to the current
request by all other requests being processed in parallel, and is a direct
indicator of perceived performance due to noisy neighbours. In order to keep
the value low, it is possible to reduce the scheduler's run queue depth using
"tune.runqueue-depth", to reduce the number of concurrent events processed at
once using "tune.maxpollevents", to decrease the stream's nice value using
the "nice" option on the "bind" lines or in the frontend, to enable low
latency scheduling using "tune.sched.low-latency", or to look for other heavy
requests in logs (those exhibiting large values of "cpu_ns_avg"), whose
processing needs to be adjusted or fixed. Compression of large buffers could
be a culprit, like heavy regex or long lists of regex. Note: this value is
exactly lat_ns_tot divided by cpu_calls.
lat_ns_tot : integer
Returns the total number of nanoseconds spent between the moment the task
handling the stream is woken up and the moment it is effectively called. This
number is reset for each new request on the same connections in case of HTTP
keep-alive. This value indicates the overall latency inflicted to the current
request by all other requests being processed in parallel, and is a direct
indicator of perceived performance due to noisy neighbours. In order to keep
the value low, it is possible to reduce the scheduler's run queue depth using
"tune.runqueue-depth", to reduce the number of concurrent events processed at
once using "tune.maxpollevents", to decrease the stream's nice value using
the "nice" option on the "bind" lines or in the frontend, to enable low
latency scheduling using "tune.sched.low-latency", or to look for other heavy
requests in logs (those exhibiting large values of "cpu_ns_avg"), whose
processing needs to be adjusted or fixed. Compression of large buffers could
be a culprit, like heavy regex or long lists of regex. Note: while it
may intuitively seem that the total latency adds to a transfer time, it is
almost never true because while a task waits for the CPU, network buffers
continue to fill up and the next call will process more at once. The value
may be artificially high due to a high cpu_calls count, for example when
processing many HTTP chunks, and for this reason it is often preferred to log
lat_ns_avg instead, which is a more relevant performance indicator.
Returns a method.
nbproc : integer
Returns an integer value corresponding to the number of processes that were
started (it equals the global "nbproc" setting). This is useful for logging
and debugging purposes.
Returns an integer value corresponding to the number of usable servers of
either the current backend or the named backend. This is mostly used with
ACLs but can also be useful when added to logs. This is normally used to
switch to an alternate backend when the number of servers is too low to
to handle some load. It is useful to report a failure when combined with
"monitor fail".
prio_class : integer
Returns the priority class of the current session for http mode or connection
for tcp mode. The value will be that set by the last call to "http-request
set-priority-class" or "tcp-request content set-priority-class".
prio_offset : integer
Returns the priority offset of the current session for http mode or
connection for tcp mode. The value will be that set by the last call to
"http-request set-priority-offset" or "tcp-request content
set-priority-offset".
proc : integer
Returns an integer value corresponding to the position of the process calling
the function, between 1 and global.nbproc. This is useful for logging and
debugging purposes.
Returns the total number of queued connections of the designated backend,
including all the connections in server queues. If no backend name is
specified, the current one is used, but it is also possible to check another
one. This is useful with ACLs or to pass statistics to backend servers. This
can be used to take actions when queuing goes above a known level, generally
indicating a surge of traffic or a massive slowdown on the servers. One
possible action could be to reject new users but still accept old ones. See
also the "avg_queue", "be_conn", and "be_sess_rate" fetches.
Returns a random integer value within a range of <range> possible values,
starting at zero. If the range is not specified, it defaults to 2^32, which
gives numbers between 0 and 4294967295. It can be useful to pass some values
needed to take some routing decisions for example, or just for debugging
purposes. This random must not be used for security purposes.
Returns an integer value corresponding to the number of currently established
connections on the designated server, possibly including the connection being
evaluated. If <backend> is omitted, then the server is looked up in the
current backend. It can be used to use a specific farm when one server is
full, or to inform the server about our view of the number of active
connections with it. See also the "fe_conn", "be_conn", "queue", and
"srv_conn_free" fetch methods.
Returns an integer value corresponding to the number of available connections
on the designated server, possibly including the connection being evaluated.
The value does not include queue slots. If <backend> is omitted, then the
server is looked up in the current backend. It can be used to use a specific
farm when one server is full, or to inform the server about our view of the
number of active connections with it. See also the "be_conn_free" and
"srv_conn" fetch methods.
OTHER CAVEATS AND NOTES: If the server maxconn is 0, then this fetch clearly
does not make sense, in which case the value returned will be -1.
Returns true when the designated server is UP, and false when it is either
DOWN or in maintenance mode. If <backend> is omitted, then the server is
looked up in the current backend. It is mainly used to take action based on
an external status reported via a health check (e.g. a geographical site's
availability). Another possible use which is more of a hack consists in
using dummy servers as boolean variables that can be enabled or disabled from
the CLI, so that rules depending on those ACLs can be tweaked in realtime.
Returns an integer value corresponding to the number of connections currently
pending in the designated server's queue. If <backend> is omitted, then the
server is looked up in the current backend. It can sometimes be used together
with the "use-server" directive to force to use a known faster server when it
is not much loaded. See also the "srv_conn", "avg_queue" and "queue" sample
fetch methods.
Returns an integer corresponding to the sessions creation rate on the
designated server, in number of new sessions per second. If <backend> is
omitted, then the server is looked up in the current backend. This is mostly
used with ACLs but can make sense with logs too. This is used to switch to an
alternate backend when an expensive or fragile one reaches too high a session
rate, or to limit abuse of service (e.g. prevent latent requests from
overloading servers).
Example :
# Redirect to a separate back
acl srv1_full srv_sess_rate(be1/srv1) gt 50
acl srv2_full srv_sess_rate(be1/srv2) gt 50
use_backend be2 if srv1_full or srv2_full
Returns an integer corresponding to the server's initial weight. If <backend>
is omitted, then the server is looked up in the current backend. See also
"srv_weight" and "srv_uweight".
Returns an integer corresponding to the user visible server's weight. If
<backend> is omitted, then the server is looked up in the current
backend. See also "srv_weight" and "srv_iweight".
Returns an integer corresponding to the current (or effective) server's
weight. If <backend> is omitted, then the server is looked up in the current
backend. See also "srv_iweight" and "srv_uweight".
stopping : boolean
Returns TRUE if the process calling the function is currently stopping. This
can be useful for logging, or for relaxing certain checks or helping close
certain connections upon graceful shutdown.
Returns a string.
Returns the total number of available entries in the current proxy's
stick-table or in the designated stick-table. See also table_cnt.
Returns the total number of entries currently in use in the current proxy's
stick-table or in the designated stick-table. See also src_conn_cnt and
table_avl for other entry counting methods.
thread : integer
Returns an integer value corresponding to the position of the thread calling
the function, between 0 and (global.nbthread-1). This is useful for logging
and debugging purposes.
Returns a UUID following the RFC4122 standard. If the version is not
specified, a UUID version 4 (fully random) is returned.
Currently, only version 4 is supported.
Returns a variable with the stored type. If the variable is not set, the
sample fetch fails, unless a default value is provided, in which case it will
return it as a string. Empty strings are permitted. The name of the variable
starts with an indication about its scope. The scopes allowed are:
"proc" : the variable is shared with the whole process
"sess" : the variable is shared with the whole session
"txn" : the variable is shared with the transaction (request and
response),
"req" : the variable is shared only during request processing,
"res" : the variable is shared only during response processing.
This prefix is followed by a name. The separator is a '.'. The name may only
contain characters 'a-z', 'A-Z', '0-9', '.' and '_'.
7.3.3. Fetching samples at Layer 4
The layer 4 usually describes just the transport layer which in HAProxy is
closest to the connection, where no content is yet made available. The fetch
methods described here are usable as low as the "tcp-request connection" rule
sets unless they require some future information. Those generally include
TCP/IP addresses and ports, as well as elements from stick-tables related to
the incoming connection. For retrieving a value from a sticky counters, the
counter number can be explicitly set as 0, 1, or 2 using the pre-defined
"sc0_", "sc1_", or "sc2_" prefix. These three pre-defined prefixes can only be
used if MAX_SESS_STKCTR value does not exceed 3, otherwise the counter number
can be specified as the first integer argument when using the "sc_" prefix.
Starting from "sc_0" to "sc_N" where N is (MAX_SESS_STKCTR-1). An optional
table may be specified with the "sc*" form, in which case the currently
tracked key will be looked up into this alternate table instead of the table
currently being tracked.
bc_dst : ip
This is the destination ip address of the connection on the server side,
which is the server address HAProxy connected to. It is of type IP and works
on both IPv4 and IPv6 tables. On IPv6 tables, IPv4 address is mapped to its
IPv6 equivalent, according to RFC 4291.
bc_dst_port : integer
Returns an integer value corresponding to the destination TCP port of the
connection on the server side, which is the port HAProxy connected to.
bc_http_major : integer
Returns the backend connection's HTTP major version encoding, which may be 1
for HTTP/0.9 to HTTP/1.1 or 2 for HTTP/2. Note, this is based on the on-wire
encoding and not the version present in the request header.
bc_src : ip
This is the source ip address of the connection on the server side, which is
the server address HAProxy connected from. It is of type IP and works on both
IPv4 and IPv6 tables. On IPv6 tables, IPv4 addresses are mapped to their IPv6
equivalent, according to RFC 4291.
bc_src_port : integer
Returns an integer value corresponding to the TCP source port of the
connection on the server side, which is the port HAProxy connected from.
be_id : integer
Returns an integer containing the current backend's id. It can be used in
frontends with responses to check which backend processed the request. It can
also be used in a tcp-check or an http-check ruleset.
be_name : string
Returns a string containing the current backend's name. It can be used in
frontends with responses to check which backend processed the request. It can
also be used in a tcp-check or an http-check ruleset.
be_server_timeout : integer
Returns the configuration value in millisecond for the server timeout of the
current backend. This timeout can be overwritten by a "set-timeout" rule. See
also the "cur_server_timeout".
be_tunnel_timeout : integer
Returns the configuration value in millisecond for the tunnel timeout of the
current backend. This timeout can be overwritten by a "set-timeout" rule. See
also the "cur_tunnel_timeout".
cur_server_timeout : integer
Returns the currently applied server timeout in millisecond for the stream.
In the default case, this will be equal to be_server_timeout unless a
"set-timeout" rule has been applied. See also "be_server_timeout".
cur_tunnel_timeout : integer
Returns the currently applied tunnel timeout in millisecond for the stream.
In the default case, this will be equal to be_tunnel_timeout unless a
"set-timeout" rule has been applied. See also "be_tunnel_timeout".
dst : ip
This is the destination IPv4 address of the connection on the client side,
which is the address the client connected to. It can be useful when running
in transparent mode. It is of type IP and works on both IPv4 and IPv6 tables.
On IPv6 tables, IPv4 address is mapped to its IPv6 equivalent, according to
RFC 4291. When the incoming connection passed through address translation or
redirection involving connection tracking, the original destination address
before the redirection will be reported. On Linux systems, the source and
destination may seldom appear reversed if the nf_conntrack_tcp_loose sysctl
is set, because a late response may reopen a timed out connection and switch
what is believed to be the source and the destination.
dst_conn : integer
Returns an integer value corresponding to the number of currently established
connections on the same socket including the one being evaluated. It is
normally used with ACLs but can as well be used to pass the information to
servers in an HTTP header or in logs. It can be used to either return a sorry
page before hard-blocking, or to use a specific backend to drain new requests
when the socket is considered saturated. This offers the ability to assign
different limits to different listening ports or addresses. See also the
"fe_conn" and "be_conn" fetches.
dst_is_local : boolean
Returns true if the destination address of the incoming connection is local
to the system, or false if the address doesn't exist on the system, meaning
that it was intercepted in transparent mode. It can be useful to apply
certain rules by default to forwarded traffic and other rules to the traffic
targeting the real address of the machine. For example the stats page could
be delivered only on this address, or SSH access could be locally redirected.
Please note that the check involves a few system calls, so it's better to do
it only once per connection.
dst_port : integer
Returns an integer value corresponding to the destination TCP port of the
connection on the client side, which is the port the client connected to.
This might be used when running in transparent mode, when assigning dynamic
ports to some clients for a whole application session, to stick all users to
a same server, or to pass the destination port information to a server using
an HTTP header.
fc_fackets : integer
Returns the fack counter measured by the kernel for the client
connection. If the server connection is not established, if the connection is
not TCP or if the operating system does not support TCP_INFO, for example
Linux kernels before 2.4, the sample fetch fails.
fc_http_major : integer
Reports the front connection's HTTP major version encoding, which may be 1
for HTTP/0.9 to HTTP/1.1 or 2 for HTTP/2. Note, this is based on the on-wire
encoding and not on the version present in the request header.
fc_lost : integer
Returns the lost counter measured by the kernel for the client
connection. If the server connection is not established, if the connection is
not TCP or if the operating system does not support TCP_INFO, for example
Linux kernels before 2.4, the sample fetch fails.
fc_pp_authority : string
Returns the authority TLV sent by the client in the PROXY protocol header,
if any.
fc_pp_unique_id : string
Returns the unique ID TLV sent by the client in the PROXY protocol header,
if any.
fc_rcvd_proxy : boolean
Returns true if the client initiated the connection with a PROXY protocol
header.
fc_reordering : integer
Returns the reordering counter measured by the kernel for the client
connection. If the server connection is not established, if the connection is
not TCP or if the operating system does not support TCP_INFO, for example
Linux kernels before 2.4, the sample fetch fails.
fc_retrans : integer
Returns the retransmits counter measured by the kernel for the client
connection. If the server connection is not established, if the connection is
not TCP or if the operating system does not support TCP_INFO, for example
Linux kernels before 2.4, the sample fetch fails.
Returns the Round Trip Time (RTT) measured by the kernel for the client
connection. <unit> is facultative, by default the unit is milliseconds. <unit>
can be set to "ms" for milliseconds or "us" for microseconds. If the server
connection is not established, if the connection is not TCP or if the
operating system does not support TCP_INFO, for example Linux kernels before
2.4, the sample fetch fails.
Returns the Round Trip Time (RTT) variance measured by the kernel for the
client connection. <unit> is facultative, by default the unit is milliseconds.
<unit> can be set to "ms" for milliseconds or "us" for microseconds. If the
server connection is not established, if the connection is not TCP or if the
operating system does not support TCP_INFO, for example Linux kernels before
2.4, the sample fetch fails.
fc_sacked : integer
Returns the sacked counter measured by the kernel for the client connection.
If the server connection is not established, if the connection is not TCP or
if the operating system does not support TCP_INFO, for example Linux kernels
before 2.4, the sample fetch fails.
fc_unacked : integer
Returns the unacked counter measured by the kernel for the client connection.
If the server connection is not established, if the connection is not TCP or
if the operating system does not support TCP_INFO, for example Linux kernels
before 2.4, the sample fetch fails.
fe_defbe : string
Returns a string containing the frontend's default backend name. It can be
used in frontends to check which backend will handle requests by default.
fe_id : integer
Returns an integer containing the current frontend's id. It can be used in
backends to check from which frontend it was called, or to stick all users
coming via a same frontend to the same server.
fe_name : string
Returns a string containing the current frontend's name. It can be used in
backends to check from which frontend it was called, or to stick all users
coming via a same frontend to the same server.
fe_client_timeout : integer
Returns the configuration value in millisecond for the client timeout of the
current frontend.
Returns the average client-to-server bytes rate from the currently tracked
counters, measured in amount of bytes over the period configured in the
table. See also src_bytes_in_rate.
Returns the average server-to-client bytes rate from the currently tracked
counters, measured in amount of bytes over the period configured in the
table. See also src_bytes_out_rate.
Clears the first General Purpose Counter associated to the currently tracked
counters, and returns its previous value. Before the first invocation, the
stored value is zero, so first invocation will always return zero. This is
typically used as a second ACL in an expression in order to mark a connection
when a first ACL was verified :
Example:
# block if 5 consecutive requests continue to come faster than 10 sess
# per second, and reset the counter as soon as the traffic slows down.
acl abuse sc0_http_req_rate gt 10
acl kill sc0_inc_gpc0 gt 5
acl save sc0_clr_gpc0 ge 0
tcp-request connection accept if !abuse save
tcp-request connection reject if abuse kill
Clears the second General Purpose Counter associated to the currently tracked
counters, and returns its previous value. Before the first invocation, the
stored value is zero, so first invocation will always return zero. This is
typically used as a second ACL in an expression in order to mark a connection
when a first ACL was verified.
Returns the cumulative number of incoming connections from currently tracked
counters. See also src_conn_cnt.
Returns the current amount of concurrent connections tracking the same
tracked counters. This number is automatically incremented when tracking
begins and decremented when tracking stops. See also src_conn_cur.
Returns the average connection rate from the currently tracked counters,
measured in amount of connections over the period configured in the table.
See also src_conn_rate.
Returns the value of the first General Purpose Counter associated to the
currently tracked counters. See also src_get_gpc0 and sc/sc0/sc1/sc2_inc_gpc0.
Returns the value of the second General Purpose Counter associated to the
currently tracked counters. See also src_get_gpc1 and sc/sc0/sc1/sc2_inc_gpc1.
Returns the value of the first General Purpose Tag associated to the
currently tracked counters. See also src_get_gpt0.
Returns the average increment rate of the first General Purpose Counter
associated to the currently tracked counters. It reports the frequency
which the gpc0 counter was incremented over the configured period. See also
src_gpc0_rate, sc/sc0/sc1/sc2_get_gpc0, and sc/sc0/sc1/sc2_inc_gpc0. Note
that the "gpc0_rate" counter must be stored in the stick-table for a value to
be returned, as "gpc0" only holds the event count.
Returns the average increment rate of the second General Purpose Counter
associated to the currently tracked counters. It reports the frequency
which the gpc1 counter was incremented over the configured period. See also
src_gpcA_rate, sc/sc0/sc1/sc2_get_gpc1, and sc/sc0/sc1/sc2_inc_gpc1. Note
that the "gpc1_rate" counter must be stored in the stick-table for a value to
be returned, as "gpc1" only holds the event count.
Returns the cumulative number of HTTP errors from the currently tracked
counters. This includes the both request errors and 4xx error responses.
See also src_http_err_cnt.
Returns the average rate of HTTP errors from the currently tracked counters,
measured in amount of errors over the period configured in the table. This
includes the both request errors and 4xx error responses. See also
src_http_err_rate.
Returns the cumulative number of HTTP response failures from the currently
tracked counters. This includes the both response errors and 5xx status codes
other than 501 and 505. See also src_http_fail_cnt.
Returns the average rate of HTTP response failures from the currently tracked
counters, measured in amount of failures over the period configured in the
table. This includes the both response errors and 5xx status codes other than
501 and 505. See also src_http_fail_rate.
Returns the cumulative number of HTTP requests from the currently tracked
counters. This includes every started request, valid or not. See also
src_http_req_cnt.
Returns the average rate of HTTP requests from the currently tracked
counters, measured in amount of requests over the period configured in
the table. This includes every started request, valid or not. See also
src_http_req_rate.
Increments the first General Purpose Counter associated to the currently
tracked counters, and returns its new value. Before the first invocation,
the stored value is zero, so first invocation will increase it to 1 and will
return 1. This is typically used as a second ACL in an expression in order
to mark a connection when a first ACL was verified :
Example:
acl abuse sc0_http_req_rate gt 10
acl kill sc0_inc_gpc0 gt 0
tcp-request connection reject if abuse kill
Increments the second General Purpose Counter associated to the currently
tracked counters, and returns its new value. Before the first invocation,
the stored value is zero, so first invocation will increase it to 1 and will
return 1. This is typically used as a second ACL in an expression in order
to mark a connection when a first ACL was verified.
Returns the total amount of client-to-server data from the currently tracked
counters, measured in kilobytes. The test is currently performed on 32-bit
integers, which limits values to 4 terabytes. See also src_kbytes_in.
Returns the total amount of server-to-client data from the currently tracked
counters, measured in kilobytes. The test is currently performed on 32-bit
integers, which limits values to 4 terabytes. See also src_kbytes_out.
Returns the cumulative number of incoming connections that were transformed
into sessions, which means that they were accepted by a "tcp-request
connection" rule, from the currently tracked counters. A backend may count
more sessions than connections because each connection could result in many
backend sessions if some HTTP keep-alive is performed over the connection
with the client. See also src_sess_cnt.
Returns the average session rate from the currently tracked counters,
measured in amount of sessions over the period configured in the table. A
session is a connection that got past the early "tcp-request connection"
rules. A backend may count more sessions than connections because each
connection could result in many backend sessions if some HTTP keep-alive is
performed over the connection with the client. See also src_sess_rate.
Returns true if the designated session counter is currently being tracked by
the current session. This can be useful when deciding whether or not we want
to set some values in a header passed to the server.
Returns the current amount of concurrent connections tracking the same
tracked counters. This number is automatically incremented when tracking
begins and decremented when tracking stops. It differs from sc0_conn_cur in
that it does not rely on any stored information but on the table's reference
count (the "use" value which is returned by "show table" on the CLI). This
may sometimes be more suited for layer7 tracking. It can be used to tell a
server how many concurrent connections there are from a given address for
example.
so_id : integer
Returns an integer containing the current listening socket's id. It is useful
in frontends involving many "bind" lines, or to stick all users coming via a
same socket to the same server.
so_name : string
Returns a string containing the current listening socket's name, as defined
with name on a "bind" line. It can serve the same purposes as so_id but with
strings instead of integers.
src : ip
This is the source IPv4 address of the client of the session. It is of type
IP and works on both IPv4 and IPv6 tables. On IPv6 tables, IPv4 addresses are
mapped to their IPv6 equivalent, according to RFC 4291. Note that it is the
TCP-level source address which is used, and not the address of a client
behind a proxy. However if the "accept-proxy" or "accept-netscaler-cip" bind
directive is used, it can be the address of a client behind another
PROXY-protocol compatible component for all rule sets except
"tcp-request connection" which sees the real address. When the incoming
connection passed through address translation or redirection involving
connection tracking, the original destination address before the redirection
will be reported. On Linux systems, the source and destination may seldom
appear reversed if the nf_conntrack_tcp_loose sysctl is set, because a late
response may reopen a timed out connection and switch what is believed to be
the source and the destination.
Example:
# add an HTTP header in requests with the originating address' country
http-request set-header X-Country %[src,map_ip(geoip.lst)]
Returns the average bytes rate from the incoming connection's source address
in the current proxy's stick-table or in the designated stick-table, measured
in amount of bytes over the period configured in the table. If the address is
not found, zero is returned. See also sc/sc0/sc1/sc2_bytes_in_rate.
Returns the average bytes rate to the incoming connection's source address in
the current proxy's stick-table or in the designated stick-table, measured in
amount of bytes over the period configured in the table. If the address is
not found, zero is returned. See also sc/sc0/sc1/sc2_bytes_out_rate.
Clears the first General Purpose Counter associated to the incoming
connection's source address in the current proxy's stick-table or in the
designated stick-table, and returns its previous value. If the address is not
found, an entry is created and 0 is returned. This is typically used as a
second ACL in an expression in order to mark a connection when a first ACL
was verified :
Example:
# block if 5 consecutive requests continue to come faster than 10 sess
# per second, and reset the counter as soon as the traffic slows down.
acl abuse src_http_req_rate gt 10
acl kill src_inc_gpc0 gt 5
acl save src_clr_gpc0 ge 0
tcp-request connection accept if !abuse save
tcp-request connection reject if abuse kill
Clears the second General Purpose Counter associated to the incoming
connection's source address in the current proxy's stick-table or in the
designated stick-table, and returns its previous value. If the address is not
found, an entry is created and 0 is returned. This is typically used as a
second ACL in an expression in order to mark a connection when a first ACL
was verified.
Returns the cumulative number of connections initiated from the current
incoming connection's source address in the current proxy's stick-table or in
the designated stick-table. If the address is not found, zero is returned.
See also sc/sc0/sc1/sc2_conn_cnt.
Returns the current amount of concurrent connections initiated from the
current incoming connection's source address in the current proxy's
stick-table or in the designated stick-table. If the address is not found,
zero is returned. See also sc/sc0/sc1/sc2_conn_cur.
Returns the average connection rate from the incoming connection's source
address in the current proxy's stick-table or in the designated stick-table,
measured in amount of connections over the period configured in the table. If
the address is not found, zero is returned. See also sc/sc0/sc1/sc2_conn_rate.
Returns the value of the first General Purpose Counter associated to the
incoming connection's source address in the current proxy's stick-table or in
the designated stick-table. If the address is not found, zero is returned.
See also sc/sc0/sc1/sc2_get_gpc0 and src_inc_gpc0.
Returns the value of the second General Purpose Counter associated to the
incoming connection's source address in the current proxy's stick-table or in
the designated stick-table. If the address is not found, zero is returned.
See also sc/sc0/sc1/sc2_get_gpc1 and src_inc_gpc1.
Returns the value of the first General Purpose Tag associated to the
incoming connection's source address in the current proxy's stick-table or in
the designated stick-table. If the address is not found, zero is returned.
See also sc/sc0/sc1/sc2_get_gpt0.
Returns the average increment rate of the first General Purpose Counter
associated to the incoming connection's source address in the current proxy's
stick-table or in the designated stick-table. It reports the frequency
which the gpc0 counter was incremented over the configured period. See also
sc/sc0/sc1/sc2_gpc0_rate, src_get_gpc0, and sc/sc0/sc1/sc2_inc_gpc0. Note
that the "gpc0_rate" counter must be stored in the stick-table for a value to
be returned, as "gpc0" only holds the event count.
Returns the average increment rate of the second General Purpose Counter
associated to the incoming connection's source address in the current proxy's
stick-table or in the designated stick-table. It reports the frequency
which the gpc1 counter was incremented over the configured period. See also
sc/sc0/sc1/sc2_gpc1_rate, src_get_gpc1, and sc/sc0/sc1/sc2_inc_gpc1. Note
that the "gpc1_rate" counter must be stored in the stick-table for a value to
be returned, as "gpc1" only holds the event count.
Returns the cumulative number of HTTP errors from the incoming connection's
source address in the current proxy's stick-table or in the designated
stick-table. This includes the both request errors and 4xx error responses.
See also sc/sc0/sc1/sc2_http_err_cnt. If the address is not found, zero is
returned.
Returns the average rate of HTTP errors from the incoming connection's source
address in the current proxy's stick-table or in the designated stick-table,
measured in amount of errors over the period configured in the table. This
includes the both request errors and 4xx error responses. If the address is
not found, zero is returned. See also sc/sc0/sc1/sc2_http_err_rate.
Returns the cumulative number of HTTP response failures triggered by the
incoming connection's source address in the current proxy's stick-table or in
the designated stick-table. This includes the both response errors and 5xx
status codes other than 501 and 505. See also sc/sc0/sc1/sc2_http_fail_cnt.
If the address is not found, zero is returned.
Returns the average rate of HTTP response failures triggered by the incoming
connection's source address in the current proxy's stick-table or in the
designated stick-table, measured in amount of failures over the period
configured in the table. This includes the both response errors and 5xx
status codes other than 501 and 505. If the address is not found, zero is
returned. See also sc/sc0/sc1/sc2_http_fail_rate.
Returns the cumulative number of HTTP requests from the incoming connection's
source address in the current proxy's stick-table or in the designated stick-
table. This includes every started request, valid or not. If the address is
not found, zero is returned. See also sc/sc0/sc1/sc2_http_req_cnt.
Returns the average rate of HTTP requests from the incoming connection's
source address in the current proxy's stick-table or in the designated stick-
table, measured in amount of requests over the period configured in the
table. This includes every started request, valid or not. If the address is
not found, zero is returned. See also sc/sc0/sc1/sc2_http_req_rate.
Increments the first General Purpose Counter associated to the incoming
connection's source address in the current proxy's stick-table or in the
designated stick-table, and returns its new value. If the address is not
found, an entry is created and 1 is returned. See also sc0/sc2/sc2_inc_gpc0.
This is typically used as a second ACL in an expression in order to mark a
connection when a first ACL was verified :
Example:
acl abuse src_http_req_rate gt 10
acl kill src_inc_gpc0 gt 0
tcp-request connection reject if abuse kill
Increments the second General Purpose Counter associated to the incoming
connection's source address in the current proxy's stick-table or in the
designated stick-table, and returns its new value. If the address is not
found, an entry is created and 1 is returned. See also sc0/sc2/sc2_inc_gpc1.
This is typically used as a second ACL in an expression in order to mark a
connection when a first ACL was verified.
src_is_local : boolean
Returns true if the source address of the incoming connection is local to the
system, or false if the address doesn't exist on the system, meaning that it
comes from a remote machine. Note that UNIX addresses are considered local.
It can be useful to apply certain access restrictions based on where the
client comes from (e.g. require auth or https for remote machines). Please
note that the check involves a few system calls, so it's better to do it only
once per connection.
Returns the total amount of data received from the incoming connection's
source address in the current proxy's stick-table or in the designated
stick-table, measured in kilobytes. If the address is not found, zero is
returned. The test is currently performed on 32-bit integers, which limits
values to 4 terabytes. See also sc/sc0/sc1/sc2_kbytes_in.
Returns the total amount of data sent to the incoming connection's source
address in the current proxy's stick-table or in the designated stick-table,
measured in kilobytes. If the address is not found, zero is returned. The
test is currently performed on 32-bit integers, which limits values to 4
terabytes. See also sc/sc0/sc1/sc2_kbytes_out.
src_port : integer
Returns an integer value corresponding to the TCP source port of the
connection on the client side, which is the port the client connected from.
Usage of this function is very limited as modern protocols do not care much
about source ports nowadays.
Returns the cumulative number of connections initiated from the incoming
connection's source IPv4 address in the current proxy's stick-table or in the
designated stick-table, that were transformed into sessions, which means that
they were accepted by "tcp-request" rules. If the address is not found, zero
is returned. See also sc/sc0/sc1/sc2_sess_cnt.
Returns the average session rate from the incoming connection's source
address in the current proxy's stick-table or in the designated stick-table,
measured in amount of sessions over the period configured in the table. A
session is a connection that went past the early "tcp-request" rules. If the
address is not found, zero is returned. See also sc/sc0/sc1/sc2_sess_rate.
Creates or updates the entry associated to the incoming connection's source
address in the current proxy's stick-table or in the designated stick-table.
This table must be configured to store the "conn_cnt" data type, otherwise
the match will be ignored. The current count is incremented by one, and the
expiration timer refreshed. The updated count is returned, so this match
can't return zero. This was used to reject service abusers based on their
source address. Note: it is recommended to use the more complete "track-sc*"
actions in "tcp-request" rules instead.
Example :
# This frontend limits incoming SSH connections to 3 per 10 second for
# each source address, and rejects excess connections until a 10 second
# silence is observed. At most 20 addresses are tracked.
listen ssh
bind :22
mode tcp
maxconn 100
stick-table type ip size 20 expire 10s store conn_cnt
tcp-request content reject if { src_updt_conn_cnt gt 3 }
server local 127.0.0.1:22
srv_id : integer
Returns an integer containing the server's id when processing the response.
While it's almost only used with ACLs, it may be used for logging or
debugging. It can also be used in a tcp-check or an http-check ruleset.
srv_name : string
Returns a string containing the server's name when processing the response.
While it's almost only used with ACLs, it may be used for logging or
debugging. It can also be used in a tcp-check or an http-check ruleset.
7.3.4. Fetching samples at Layer 5
The layer 5 usually describes just the session layer which in HAProxy is
closest to the session once all the connection handshakes are finished, but
when no content is yet made available. The fetch methods described here are
usable as low as the "tcp-request content" rule sets unless they require some
future information. Those generally include the results of SSL negotiations.
Returns values for the properties requested as a string, where values are
separated by the delimiter specified with "51degrees-property-separator".
The device is identified using all the important HTTP headers from the
request. The function can be passed up to five property names, and if a
property name can't be found, the value "NoData" is returned.
Example :
# Here the header "X-51D-DeviceTypeMobileTablet" is added to the request
# containing the three properties requested using all relevant headers from
# the request.
frontend http-in
bind *:8081
default_backend servers
http-request set-header X-51D-DeviceTypeMobileTablet \
%[51d.all(DeviceType,IsMobile,IsTablet)]
ssl_bc : boolean
Returns true when the back connection was made via an SSL/TLS transport
layer and is locally deciphered. This means the outgoing connection was made
to a server with the "ssl" option. It can be used in a tcp-check or an
http-check ruleset.
ssl_bc_alg_keysize : integer
Returns the symmetric cipher key size supported in bits when the outgoing
connection was made over an SSL/TLS transport layer. It can be used in a
tcp-check or an http-check ruleset.
ssl_bc_alpn : string
This extracts the Application Layer Protocol Negotiation field from an
outgoing connection made via a TLS transport layer.
The result is a string containing the protocol name negotiated with the
server. The SSL library must have been built with support for TLS
extensions enabled (check haproxy -vv). Note that the TLS ALPN extension is
not advertised unless the "alpn" keyword on the "server" line specifies a
protocol list. Also, nothing forces the server to pick a protocol from this
list, any other one may be requested. The TLS ALPN extension is meant to
replace the TLS NPN extension. See also "ssl_bc_npn". It can be used in a
tcp-check or an http-check ruleset.
ssl_bc_cipher : string
Returns the name of the used cipher when the outgoing connection was made
over an SSL/TLS transport layer. It can be used in a tcp-check or an
http-check ruleset.
ssl_bc_client_random : binary
Returns the client random of the back connection when the incoming connection
was made over an SSL/TLS transport layer. It is useful to to decrypt traffic
sent using ephemeral ciphers. This requires OpenSSL >= 1.1.0, or BoringSSL.
It can be used in a tcp-check or an http-check ruleset.
ssl_bc_is_resumed : boolean
Returns true when the back connection was made over an SSL/TLS transport
layer and the newly created SSL session was resumed using a cached
session or a TLS ticket. It can be used in a tcp-check or an http-check
ruleset.
ssl_bc_npn : string
This extracts the Next Protocol Negotiation field from an outgoing connection
made via a TLS transport layer. The result is a string containing the
protocol name negotiated with the server . The SSL library must have been
built with support for TLS extensions enabled (check haproxy -vv). Note that
the TLS NPN extension is not advertised unless the "npn" keyword on the
"server" line specifies a protocol list. Also, nothing forces the server to
pick a protocol from this list, any other one may be used. Please note that
the TLS NPN extension was replaced with ALPN. It can be used in a tcp-check
or an http-check ruleset.
ssl_bc_protocol : string
Returns the name of the used protocol when the outgoing connection was made
over an SSL/TLS transport layer. It can be used in a tcp-check or an
http-check ruleset.
ssl_bc_unique_id : binary
When the outgoing connection was made over an SSL/TLS transport layer,
returns the TLS unique ID as defined in RFC5929 section 3. The unique id
can be encoded to base64 using the converter: "ssl_bc_unique_id,base64". It
can be used in a tcp-check or an http-check ruleset.
ssl_bc_server_random : binary
Returns the server random of the back connection when the incoming connection
was made over an SSL/TLS transport layer. It is useful to to decrypt traffic
sent using ephemeral ciphers. This requires OpenSSL >= 1.1.0, or BoringSSL.
It can be used in a tcp-check or an http-check ruleset.
ssl_bc_session_id : binary
Returns the SSL ID of the back connection when the outgoing connection was
made over an SSL/TLS transport layer. It is useful to log if we want to know
if session was reused or not. It can be used in a tcp-check or an http-check
ruleset.
ssl_bc_session_key : binary
Returns the SSL session master key of the back connection when the outgoing
connection was made over an SSL/TLS transport layer. It is useful to decrypt
traffic sent using ephemeral ciphers. This requires OpenSSL >= 1.1.0, or
BoringSSL. It can be used in a tcp-check or an http-check ruleset.
ssl_bc_use_keysize : integer
Returns the symmetric cipher key size used in bits when the outgoing
connection was made over an SSL/TLS transport layer. It can be used in a
tcp-check or an http-check ruleset.
ssl_c_ca_err : integer
When the incoming connection was made over an SSL/TLS transport layer,
returns the ID of the first error detected during verification of the client
certificate at depth > 0, or 0 if no error was encountered during this
verification process. Please refer to your SSL library's documentation to
find the exhaustive list of error codes.
ssl_c_ca_err_depth : integer
When the incoming connection was made over an SSL/TLS transport layer,
returns the depth in the CA chain of the first error detected during the
verification of the client certificate. If no error is encountered, 0 is
returned.
ssl_c_chain_der : binary
Returns the DER formatted chain certificate presented by the client when the
incoming connection was made over an SSL/TLS transport layer. When used for
an ACL, the value(s) to match against can be passed in hexadecimal form. One
can parse the result with any lib accepting ASN.1 DER data. It currently
does not support resumed sessions.
ssl_c_der : binary
Returns the DER formatted certificate presented by the client when the
incoming connection was made over an SSL/TLS transport layer. When used for
an ACL, the value(s) to match against can be passed in hexadecimal form.
ssl_c_err : integer
When the incoming connection was made over an SSL/TLS transport layer,
returns the ID of the first error detected during verification at depth 0, or
0 if no error was encountered during this verification process. Please refer
to your SSL library's documentation to find the exhaustive list of error
codes.
When the incoming connection was made over an SSL/TLS transport layer,
returns the full distinguished name of the issuer of the certificate
presented by the client when no <entry> is specified, or the value of the
first given entry found from the beginning of the DN. If a positive/negative
occurrence number is specified as the optional second argument, it returns
the value of the nth given entry value from the beginning/end of the DN.
For instance, "ssl_c_i_dn(OU,2)" the second organization unit, and
"ssl_c_i_dn(CN)" retrieves the common name.
The <format> parameter allows you to receive the DN suitable for
consumption by different protocols. Currently supported is rfc2253 for
LDAP v3.
If you'd like to modify the format only you can specify an empty string
and zero for the first two parameters. Example: ssl_c_i_dn(,0,rfc2253)
ssl_c_key_alg : string
Returns the name of the algorithm used to generate the key of the certificate
presented by the client when the incoming connection was made over an SSL/TLS
transport layer.
ssl_c_notafter : string
Returns the end date presented by the client as a formatted string
YYMMDDhhmmss[Z] when the incoming connection was made over an SSL/TLS
transport layer.
ssl_c_notbefore : string
Returns the start date presented by the client as a formatted string
YYMMDDhhmmss[Z] when the incoming connection was made over an SSL/TLS
transport layer.
When the incoming connection was made over an SSL/TLS transport layer,
returns the full distinguished name of the subject of the certificate
presented by the client when no <entry> is specified, or the value of the
first given entry found from the beginning of the DN. If a positive/negative
occurrence number is specified as the optional second argument, it returns
the value of the nth given entry value from the beginning/end of the DN.
For instance, "ssl_c_s_dn(OU,2)" the second organization unit, and
"ssl_c_s_dn(CN)" retrieves the common name.
The <format> parameter allows you to receive the DN suitable for
consumption by different protocols. Currently supported is rfc2253 for
LDAP v3.
If you'd like to modify the format only you can specify an empty string
and zero for the first two parameters. Example: ssl_c_s_dn(,0,rfc2253)
ssl_c_serial : binary
Returns the serial of the certificate presented by the client when the
incoming connection was made over an SSL/TLS transport layer. When used for
an ACL, the value(s) to match against can be passed in hexadecimal form.
ssl_c_sha1 : binary
Returns the SHA-1 fingerprint of the certificate presented by the client when
the incoming connection was made over an SSL/TLS transport layer. This can be
used to stick a client to a server, or to pass this information to a server.
Note that the output is binary, so if you want to pass that signature to the
server, you need to encode it in hex or base64, such as in the example below:
Example:
http-request set-header X-SSL-Client-SHA1 %[ssl_c_sha1,hex]
ssl_c_sig_alg : string
Returns the name of the algorithm used to sign the certificate presented by
the client when the incoming connection was made over an SSL/TLS transport
layer.
ssl_c_used : boolean
Returns true if current SSL session uses a client certificate even if current
connection uses SSL session resumption. See also "ssl_fc_has_crt".
ssl_c_verify : integer
Returns the verify result error ID when the incoming connection was made over
an SSL/TLS transport layer, otherwise zero if no error is encountered. Please
refer to your SSL library's documentation for an exhaustive list of error
codes.
ssl_c_version : integer
Returns the version of the certificate presented by the client when the
incoming connection was made over an SSL/TLS transport layer.
ssl_f_der : binary
Returns the DER formatted certificate presented by the frontend when the
incoming connection was made over an SSL/TLS transport layer. When used for
an ACL, the value(s) to match against can be passed in hexadecimal form.
When the incoming connection was made over an SSL/TLS transport layer,
returns the full distinguished name of the issuer of the certificate
presented by the frontend when no <entry> is specified, or the value of the
first given entry found from the beginning of the DN. If a positive/negative
occurrence number is specified as the optional second argument, it returns
the value of the nth given entry value from the beginning/end of the DN.
For instance, "ssl_f_i_dn(OU,2)" the second organization unit, and
"ssl_f_i_dn(CN)" retrieves the common name.
The <format> parameter allows you to receive the DN suitable for
consumption by different protocols. Currently supported is rfc2253 for
LDAP v3.
If you'd like to modify the format only you can specify an empty string
and zero for the first two parameters. Example: ssl_f_i_dn(,0,rfc2253)
ssl_f_key_alg : string
Returns the name of the algorithm used to generate the key of the certificate
presented by the frontend when the incoming connection was made over an
SSL/TLS transport layer.
ssl_f_notafter : string
Returns the end date presented by the frontend as a formatted string
YYMMDDhhmmss[Z] when the incoming connection was made over an SSL/TLS
transport layer.
ssl_f_notbefore : string
Returns the start date presented by the frontend as a formatted string
YYMMDDhhmmss[Z] when the incoming connection was made over an SSL/TLS
transport layer.
When the incoming connection was made over an SSL/TLS transport layer,
returns the full distinguished name of the subject of the certificate
presented by the frontend when no <entry> is specified, or the value of the
first given entry found from the beginning of the DN. If a positive/negative
occurrence number is specified as the optional second argument, it returns
the value of the nth given entry value from the beginning/end of the DN.
For instance, "ssl_f_s_dn(OU,2)" the second organization unit, and
"ssl_f_s_dn(CN)" retrieves the common name.
The <format> parameter allows you to receive the DN suitable for
consumption by different protocols. Currently supported is rfc2253 for
LDAP v3.
If you'd like to modify the format only you can specify an empty string
and zero for the first two parameters. Example: ssl_f_s_dn(,0,rfc2253)
ssl_f_serial : binary
Returns the serial of the certificate presented by the frontend when the
incoming connection was made over an SSL/TLS transport layer. When used for
an ACL, the value(s) to match against can be passed in hexadecimal form.
ssl_f_sha1 : binary
Returns the SHA-1 fingerprint of the certificate presented by the frontend
when the incoming connection was made over an SSL/TLS transport layer. This
can be used to know which certificate was chosen using SNI.
ssl_f_sig_alg : string
Returns the name of the algorithm used to sign the certificate presented by
the frontend when the incoming connection was made over an SSL/TLS transport
layer.
ssl_f_version : integer
Returns the version of the certificate presented by the frontend when the
incoming connection was made over an SSL/TLS transport layer.
ssl_fc : boolean
Returns true when the front connection was made via an SSL/TLS transport
layer and is locally deciphered. This means it has matched a socket declared
with a "bind" line having the "ssl" option.
Example :
# This passes "X-Proto: https" to servers when client connects over SSL
listen http-https
bind :80
bind :443 ssl crt /etc/haproxy.pem
http-request add-header X-Proto https if { ssl_fc }
ssl_fc_alg_keysize : integer
Returns the symmetric cipher key size supported in bits when the incoming
connection was made over an SSL/TLS transport layer.
ssl_fc_alpn : string
This extracts the Application Layer Protocol Negotiation field from an
incoming connection made via a TLS transport layer and locally deciphered by
HAProxy. The result is a string containing the protocol name advertised by
the client. The SSL library must have been built with support for TLS
extensions enabled (check haproxy -vv). Note that the TLS ALPN extension is
not advertised unless the "alpn" keyword on the "bind" line specifies a
protocol list. Also, nothing forces the client to pick a protocol from this
list, any other one may be requested. The TLS ALPN extension is meant to
replace the TLS NPN extension. See also "ssl_fc_npn".
ssl_fc_cipher : string
Returns the name of the used cipher when the incoming connection was made
over an SSL/TLS transport layer.
ssl_fc_cipherlist_bin : binary
Returns the binary form of the client hello cipher list. The maximum returned
value length is according with the value of
"tune.ssl.capture-cipherlist-size".
ssl_fc_cipherlist_hex : string
Returns the binary form of the client hello cipher list encoded as
hexadecimal. The maximum returned value length is according with the value of
"tune.ssl.capture-cipherlist-size".
ssl_fc_cipherlist_str : string
Returns the decoded text form of the client hello cipher list. The maximum
number of ciphers returned is according with the value of
"tune.ssl.capture-cipherlist-size". Note that this sample-fetch is only
available with OpenSSL >= 1.0.2. If the function is not enabled, this
sample-fetch returns the hash like "ssl_fc_cipherlist_xxh".
ssl_fc_cipherlist_xxh : integer
Returns a xxh64 of the cipher list. This hash can be return only is the value
"tune.ssl.capture-cipherlist-size" is set greater than 0, however the hash
take in account all the data of the cipher list.
ssl_fc_client_random : binary
Returns the client random of the front connection when the incoming connection
was made over an SSL/TLS transport layer. It is useful to to decrypt traffic
sent using ephemeral ciphers. This requires OpenSSL >= 1.1.0, or BoringSSL.
ssl_fc_client_early_traffic_secret : string
Return the CLIENT_EARLY_TRAFFIC_SECRET as an hexadecimal string for the
front connection when the incoming connection was made over a TLS 1.3
transport layer.
Require OpenSSL >= 1.1.1. This is one of the keys dumped by the OpenSSL
keylog callback to generate the SSLKEYLOGFILE. The SSL Key logging must be
activated with "tune.ssl.keylog on" in the global section. See also
"tune.ssl.keylog"
Return the CLIENT_HANDSHAKE_TRAFFIC_SECRET as an hexadecimal string for the
front connection when the incoming connection was made over a TLS 1.3
transport layer.
Require OpenSSL >= 1.1.1. This is one of the keys dumped by the OpenSSL
keylog callback to generate the SSLKEYLOGFILE. The SSL Key logging must be
activated with "tune.ssl.keylog on" in the global section. See also
"tune.ssl.keylog"
ssl_fc_client_traffic_secret_0 : string
Return the CLIENT_TRAFFIC_SECRET_0 as an hexadecimal string for the
front connection when the incoming connection was made over a TLS 1.3
transport layer.
Require OpenSSL >= 1.1.1. This is one of the keys dumped by the OpenSSL
keylog callback to generate the SSLKEYLOGFILE. The SSL Key logging must be
activated with "tune.ssl.keylog on" in the global section. See also
"tune.ssl.keylog"
ssl_fc_exporter_secret : string
Return the EXPORTER_SECRET as an hexadecimal string for the
front connection when the incoming connection was made over a TLS 1.3
transport layer.
Require OpenSSL >= 1.1.1. This is one of the keys dumped by the OpenSSL
keylog callback to generate the SSLKEYLOGFILE. The SSL Key logging must be
activated with "tune.ssl.keylog on" in the global section. See also
"tune.ssl.keylog"
ssl_fc_early_exporter_secret : string
Return the EARLY_EXPORTER_SECRET as an hexadecimal string for the
front connection when the incoming connection was made over an TLS 1.3
transport layer.
Require OpenSSL >= 1.1.1. This is one of the keys dumped by the OpenSSL
keylog callback to generate the SSLKEYLOGFILE. The SSL Key logging must be
activated with "tune.ssl.keylog on" in the global section. See also
"tune.ssl.keylog"
ssl_fc_has_crt : boolean
Returns true if a client certificate is present in an incoming connection over
SSL/TLS transport layer. Useful if 'verify' statement is set to 'optional'.
Note: on SSL session resumption with Session ID or TLS ticket, client
certificate is not present in the current connection but may be retrieved
from the cache or the ticket. So prefer "ssl_c_used" if you want to check if
current SSL session uses a client certificate.
ssl_fc_has_early : boolean
Returns true if early data were sent, and the handshake didn't happen yet. As
it has security implications, it is useful to be able to refuse those, or
wait until the handshake happened.
ssl_fc_has_sni : boolean
This checks for the presence of a Server Name Indication TLS extension (SNI)
in an incoming connection was made over an SSL/TLS transport layer. Returns
true when the incoming connection presents a TLS SNI field. This requires
that the SSL library is built with support for TLS extensions enabled (check
haproxy -vv).
ssl_fc_is_resumed : boolean
Returns true if the SSL/TLS session has been resumed through the use of
SSL session cache or TLS tickets on an incoming connection over an SSL/TLS
transport layer.
ssl_fc_npn : string
This extracts the Next Protocol Negotiation field from an incoming connection
made via a TLS transport layer and locally deciphered by HAProxy. The result
is a string containing the protocol name advertised by the client. The SSL
library must have been built with support for TLS extensions enabled (check
haproxy -vv). Note that the TLS NPN extension is not advertised unless the
"npn" keyword on the "bind" line specifies a protocol list. Also, nothing
forces the client to pick a protocol from this list, any other one may be
requested. Please note that the TLS NPN extension was replaced with ALPN.
ssl_fc_protocol : string
Returns the name of the used protocol when the incoming connection was made
over an SSL/TLS transport layer.
ssl_fc_unique_id : binary
When the incoming connection was made over an SSL/TLS transport layer,
returns the TLS unique ID as defined in RFC5929 section 3. The unique id
can be encoded to base64 using the converter: "ssl_fc_unique_id,base64".
Return the SERVER_HANDSHAKE_TRAFFIC_SECRET as an hexadecimal string for the
front connection when the incoming connection was made over a TLS 1.3
transport layer.
Require OpenSSL >= 1.1.1. This is one of the keys dumped by the OpenSSL
keylog callback to generate the SSLKEYLOGFILE. The SSL Key logging must be
activated with "tune.ssl.keylog on" in the global section. See also
"tune.ssl.keylog"
ssl_fc_server_traffic_secret_0 : string
Return the SERVER_TRAFFIC_SECRET_0 as an hexadecimal string for the
front connection when the incoming connection was made over an TLS 1.3
transport layer.
Require OpenSSL >= 1.1.1. This is one of the keys dumped by the OpenSSL
keylog callback to generate the SSLKEYLOGFILE. The SSL Key logging must be
activated with "tune.ssl.keylog on" in the global section. See also
"tune.ssl.keylog"
ssl_fc_server_random : binary
Returns the server random of the front connection when the incoming connection
was made over an SSL/TLS transport layer. It is useful to to decrypt traffic
sent using ephemeral ciphers. This requires OpenSSL >= 1.1.0, or BoringSSL.
ssl_fc_session_id : binary
Returns the SSL ID of the front connection when the incoming connection was
made over an SSL/TLS transport layer. It is useful to stick a given client to
a server. It is important to note that some browsers refresh their session ID
every few minutes.
ssl_fc_session_key : binary
Returns the SSL session master key of the front connection when the incoming
connection was made over an SSL/TLS transport layer. It is useful to decrypt
traffic sent using ephemeral ciphers. This requires OpenSSL >= 1.1.0, or
BoringSSL.
ssl_fc_sni : string
This extracts the Server Name Indication TLS extension (SNI) field from an
incoming connection made via an SSL/TLS transport layer and locally
deciphered by HAProxy. The result (when present) typically is a string
matching the HTTPS host name (253 chars or less). The SSL library must have
been built with support for TLS extensions enabled (check haproxy -vv).
This fetch is different from "req.ssl_sni" above in that it applies to the
connection being deciphered by HAProxy and not to SSL contents being blindly
forwarded. See also "ssl_fc_sni_end" and "ssl_fc_sni_reg" below. This
requires that the SSL library is built with support for TLS extensions
enabled (check haproxy -vv).
CAUTION! Except under very specific conditions, it is normally not correct to
use this field as a substitute for the HTTP "Host" header field. For example,
when forwarding an HTTPS connection to a server, the SNI field must be set
from the HTTP Host header field using "req.hdr(host)" and not from the front
SNI value. The reason is that SNI is solely used to select the certificate
the server side will present, and that clients are then allowed to send
requests with different Host values as long as they match the names in the
certificate. As such, "ssl_fc_sni" should normally not be used as an argument
to the "sni" server keyword, unless the backend works in TCP mode.
ACL derivatives :
ssl_fc_sni_end : suffix match
ssl_fc_sni_reg : regex match
ssl_fc_use_keysize : integer
Returns the symmetric cipher key size used in bits when the incoming
connection was made over an SSL/TLS transport layer.
ssl_s_der : binary
Returns the DER formatted certificate presented by the server when the
outgoing connection was made over an SSL/TLS transport layer. When used for
an ACL, the value(s) to match against can be passed in hexadecimal form.
ssl_s_chain_der : binary
Returns the DER formatted chain certificate presented by the server when the
outgoing connection was made over an SSL/TLS transport layer. When used for
an ACL, the value(s) to match against can be passed in hexadecimal form. One
can parse the result with any lib accepting ASN.1 DER data. It currently
does not support resumed sessions.
ssl_s_key_alg : string
Returns the name of the algorithm used to generate the key of the certificate
presented by the server when the outgoing connection was made over an
SSL/TLS transport layer.
ssl_s_notafter : string
Returns the end date presented by the server as a formatted string
YYMMDDhhmmss[Z] when the outgoing connection was made over an SSL/TLS
transport layer.
ssl_s_notbefore : string
Returns the start date presented by the server as a formatted string
YYMMDDhhmmss[Z] when the outgoing connection was made over an SSL/TLS
transport layer.
When the outgoing connection was made over an SSL/TLS transport layer,
returns the full distinguished name of the issuer of the certificate
presented by the server when no <entry> is specified, or the value of the
first given entry found from the beginning of the DN. If a positive/negative
occurrence number is specified as the optional second argument, it returns
the value of the nth given entry value from the beginning/end of the DN.
For instance, "ssl_s_i_dn(OU,2)" the second organization unit, and
"ssl_s_i_dn(CN)" retrieves the common name.
The <format> parameter allows you to receive the DN suitable for
consumption by different protocols. Currently supported is rfc2253 for
LDAP v3.
If you'd like to modify the format only you can specify an empty string
and zero for the first two parameters. Example: ssl_s_i_dn(,0,rfc2253)
When the outgoing connection was made over an SSL/TLS transport layer,
returns the full distinguished name of the subject of the certificate
presented by the server when no <entry> is specified, or the value of the
first given entry found from the beginning of the DN. If a positive/negative
occurrence number is specified as the optional second argument, it returns
the value of the nth given entry value from the beginning/end of the DN.
For instance, "ssl_s_s_dn(OU,2)" the second organization unit, and
"ssl_s_s_dn(CN)" retrieves the common name.
The <format> parameter allows you to receive the DN suitable for
consumption by different protocols. Currently supported is rfc2253 for
LDAP v3.
If you'd like to modify the format only you can specify an empty string
and zero for the first two parameters. Example: ssl_s_s_dn(,0,rfc2253)
ssl_s_serial : binary
Returns the serial of the certificate presented by the server when the
outgoing connection was made over an SSL/TLS transport layer. When used for
an ACL, the value(s) to match against can be passed in hexadecimal form.
ssl_s_sha1 : binary
Returns the SHA-1 fingerprint of the certificate presented by the server
when the outgoing connection was made over an SSL/TLS transport layer. This
can be used to know which certificate was chosen using SNI.
ssl_s_sig_alg : string
Returns the name of the algorithm used to sign the certificate presented by
the server when the outgoing connection was made over an SSL/TLS transport
layer.
ssl_s_version : integer
Returns the version of the certificate presented by the server when the
outgoing connection was made over an SSL/TLS transport layer.
7.3.5. Fetching samples from buffer contents (Layer 6)
Fetching samples from buffer contents is a bit different from the previous
sample fetches above because the sampled data are ephemeral. These data can
only be used when they're available and will be lost when they're forwarded.
For this reason, samples fetched from buffer contents during a request cannot
be used in a response for example. Even while the data are being fetched, they
can change. Sometimes it is necessary to set some delays or combine multiple
sample fetch methods to ensure that the expected data are complete and usable,
for example through TCP request content inspection. Please see the "tcp-request
content" keyword for more detailed information on the subject.
Warning : Following sample fetches are ignored if used from HTTP proxies. They
only deal with raw contents found in the buffers. On their side,
HTTP proxies use structured content. Thus raw representation of
these data are meaningless. A warning is emitted if an ACL relies on
one of the following sample fetches. But it is not possible to detect
all invalid usage (for instance inside a log-format string or a
sample expression). So be careful.
This is an alias for "req.payload" when used in the context of a request (e.g.
"stick on", "stick match"), and for "res.payload" when used in the context of
a response such as in "stick store response".
This is an alias for "req.payload_lv" when used in the context of a request
(e.g. "stick on", "stick match"), and for "res.payload_lv" when used in the
context of a response such as in "stick store response".
req.len : integer
Returns an integer value corresponding to the number of bytes present in the
request buffer. This is mostly used in ACL. It is important to understand
that this test does not return false as long as the buffer is changing. This
means that a check with equality to zero will almost always immediately match
at the beginning of the session, while a test for more data will wait for
that data to come in and return false only when HAProxy is certain that no
more data will come in. This test was designed to be used with TCP request
content inspection.
This extracts a binary block of <length> bytes and starting at byte <offset>
in the request buffer. As a special case, if the <length> argument is zero,
the the whole buffer from <offset> to the end is extracted. This can be used
with ACLs in order to check for the presence of some content in a buffer at
any location.
ACL derivatives :
req.payload(<offset>,<length>) : hex binary match
This extracts a binary block whose size is specified at <offset1> for <length>
bytes, and which starts at <offset2> if specified or just after the length in
the request buffer. The <offset2> parameter also supports relative offsets if
prepended with a '+' or '-' sign.
ACL derivatives :
req.payload_lv(<offset1>,<length>[,<offset2>]) : hex binary match
Example :
please consult the example from the "stick store-response" keyword.
req.proto_http : boolean
Returns true when data in the request buffer look like HTTP and correctly
parses as such. It is the same parser as the common HTTP request parser which
is used so there should be no surprises. The test does not match until the
request is complete, failed or timed out. This test may be used to report the
protocol in TCP logs, but the biggest use is to block TCP request analysis
until a complete HTTP request is present in the buffer, for example to track
a header.
Example:
# track request counts per "base" (concatenation of Host+URL)
tcp-request inspect-delay 10s
tcp-request content reject if !HTTP
tcp-request content track-sc0 base table req-rate
When the request buffer looks like the RDP protocol, extracts the RDP cookie
<name>, or any cookie if unspecified. The parser only checks for the first
cookie, as illustrated in the RDP protocol specification. The cookie name is
case insensitive. Generally the "MSTS" cookie name will be used, as it can
contain the user name of the client connecting to the server if properly
configured on the client. The "MSTSHASH" cookie is often used as well for
session stickiness to servers.
This differs from "balance rdp-cookie" in that any balancing algorithm may be
used and thus the distribution of clients to backend servers is not linked to
a hash of the RDP cookie. It is envisaged that using a balancing algorithm
such as "balance roundrobin" or "balance leastconn" will lead to a more even
distribution of clients to backend servers than the hash used by "balance
rdp-cookie".
ACL derivatives :
req.rdp_cookie([<name>]) : exact string match
Example :
listen tse-farm
bind 0.0.0.0:3389
# wait up to 5s for an RDP cookie in the request
tcp-request inspect-delay 5s
tcp-request content accept if RDP_COOKIE
# apply RDP cookie persistence
persist rdp-cookie
# Persist based on the mstshash cookie
# This is only useful makes sense if
# balance rdp-cookie is not used
stick-table type string size 204800
stick on req.rdp_cookie(mstshash)
server srv1 1.1.1.1:3389
server srv1 1.1.1.2:3389
Tries to parse the request buffer as RDP protocol, then returns an integer
corresponding to the number of RDP cookies found. If an optional cookie name
is passed, only cookies matching this name are considered. This is mostly
used in ACL.
ACL derivatives :
req.rdp_cookie_cnt([<name>]) : integer match
req.ssl_alpn : string
Returns a string containing the values of the Application-Layer Protocol
Negotiation (ALPN) TLS extension (RFC7301), sent by the client within the SSL
ClientHello message. Note that this only applies to raw contents found in the
request buffer and not to the contents deciphered via an SSL data layer, so
this will not work with "bind" lines having the "ssl" option. This is useful
in ACL to make a routing decision based upon the ALPN preferences of a TLS
client, like in the example below. See also "ssl_fc_alpn".
Examples :
# Wait for a client hello for at most 5 seconds
tcp-request inspect-delay 5s
tcp-request content accept if { req.ssl_hello_type 1 }
use_backend bk_acme if { req.ssl_alpn acme-tls/1 }
default_backend bk_default
req.ssl_ec_ext : boolean
Returns a boolean identifying if client sent the Supported Elliptic Curves
Extension as defined in RFC4492, section 5.1. within the SSL ClientHello
message. This can be used to present ECC compatible clients with EC
certificate and to use RSA for all others, on the same IP address. Note that
this only applies to raw contents found in the request buffer and not to
contents deciphered via an SSL data layer, so this will not work with "bind"
lines having the "ssl" option.
req.ssl_hello_type : integer
Returns an integer value containing the type of the SSL hello message found
in the request buffer if the buffer contains data that parse as a complete
SSL (v3 or superior) client hello message. Note that this only applies to raw
contents found in the request buffer and not to contents deciphered via an
SSL data layer, so this will not work with "bind" lines having the "ssl"
option. This is mostly used in ACL to detect presence of an SSL hello message
that is supposed to contain an SSL session ID usable for stickiness.
req.ssl_sni : string
Returns a string containing the value of the Server Name TLS extension sent
by a client in a TLS stream passing through the request buffer if the buffer
contains data that parse as a complete SSL (v3 or superior) client hello
message. Note that this only applies to raw contents found in the request
buffer and not to contents deciphered via an SSL data layer, so this will not
work with "bind" lines having the "ssl" option. This will only work for actual
implicit TLS based protocols like HTTPS (443), IMAPS (993), SMTPS (465),
however it will not work for explicit TLS based protocols, like SMTP (25/587)
or IMAP (143). SNI normally contains the name of the host the client tries to
connect to (for recent browsers). SNI is useful for allowing or denying access
to certain hosts when SSL/TLS is used by the client. This test was designed to
be used with TCP request content inspection. If content switching is needed,
it is recommended to first wait for a complete client hello (type 1), like in
the example below. See also "ssl_fc_sni".
ACL derivatives :
req.ssl_sni : exact string match
Examples :
# Wait for a client hello for at most 5 seconds
tcp-request inspect-delay 5s
tcp-request content accept if { req.ssl_hello_type 1 }
use_backend bk_allow if { req.ssl_sni -f allowed_sites }
default_backend bk_sorry_page
req.ssl_st_ext : integer
Returns 0 if the client didn't send a SessionTicket TLS Extension (RFC5077)
Returns 1 if the client sent SessionTicket TLS Extension
Returns 2 if the client also sent non-zero length TLS SessionTicket
Note that this only applies to raw contents found in the request buffer and
not to contents deciphered via an SSL data layer, so this will not work with
"bind" lines having the "ssl" option. This can for example be used to detect
whether the client sent a SessionTicket or not and stick it accordingly, if
no SessionTicket then stick on SessionID or don't stick as there's no server
side state is there when SessionTickets are in use.
req.ssl_ver : integer
Returns an integer value containing the version of the SSL/TLS protocol of a
stream present in the request buffer. Both SSLv2 hello messages and SSLv3
messages are supported. TLSv1 is announced as SSL version 3.1. The value is
composed of the major version multiplied by 65536, added to the minor
version. Note that this only applies to raw contents found in the request
buffer and not to contents deciphered via an SSL data layer, so this will not
work with "bind" lines having the "ssl" option. The ACL version of the test
matches against a decimal notation in the form MAJOR.MINOR (e.g. 3.1). This
fetch is mostly used in ACL.
ACL derivatives :
req.ssl_ver : decimal match
res.len : integer
Returns an integer value corresponding to the number of bytes present in the
response buffer. This is mostly used in ACL. It is important to understand
that this test does not return false as long as the buffer is changing. This
means that a check with equality to zero will almost always immediately match
at the beginning of the session, while a test for more data will wait for
that data to come in and return false only when HAProxy is certain that no
more data will come in. This test was designed to be used with TCP response
content inspection. But it may also be used in tcp-check based expect rules.
This extracts a binary block of <length> bytes and starting at byte <offset>
in the response buffer. As a special case, if the <length> argument is zero,
the whole buffer from <offset> to the end is extracted. This can be used
with ACLs in order to check for the presence of some content in a buffer at
any location. It may also be used in tcp-check based expect rules.
This extracts a binary block whose size is specified at <offset1> for <length>
bytes, and which starts at <offset2> if specified or just after the length in
the response buffer. The <offset2> parameter also supports relative offsets
if prepended with a '+' or '-' sign. It may also be used in tcp-check based
expect rules.
Example :
please consult the example from the "stick store-response" keyword.
res.ssl_hello_type : integer
Returns an integer value containing the type of the SSL hello message found
in the response buffer if the buffer contains data that parses as a complete
SSL (v3 or superior) hello message. Note that this only applies to raw
contents found in the response buffer and not to contents deciphered via an
SSL data layer, so this will not work with "server" lines having the "ssl"
option. This is mostly used in ACL to detect presence of an SSL hello message
that is supposed to contain an SSL session ID usable for stickiness.
wait_end : boolean
This fetch either returns true when the inspection period is over, or does
not fetch. It is only used in ACLs, in conjunction with content analysis to
avoid returning a wrong verdict early. It may also be used to delay some
actions, such as a delayed reject for some special addresses. Since it either
stops the rules evaluation or immediately returns true, it is recommended to
use this acl as the last one in a rule. Please note that the default ACL
"WAIT_END" is always usable without prior declaration. This test was designed
to be used with TCP request content inspection.
Examples :
# delay every incoming request by 2 seconds
tcp-request inspect-delay 2s
tcp-request content accept if WAIT_END
# don't immediately tell bad guys they are rejected
tcp-request inspect-delay 10s
acl goodguys src 10.0.0.0/24
acl badguys src 10.0.1.0/24
tcp-request content accept if goodguys
tcp-request content reject if badguys WAIT_END
tcp-request content reject
7.3.6. Fetching HTTP samples (Layer 7)
It is possible to fetch samples from HTTP contents, requests and responses.
This application layer is also called layer 7. It is only possible to fetch the
data in this section when a full HTTP request or response has been parsed from
its respective request or response buffer. This is always the case with all
HTTP specific rules and for sections running with "mode http". When using TCP
content inspection, it may be necessary to support an inspection delay in order
to let the request or response come in first. These fetches may require a bit
more CPU resources than the layer 4 ones, but not much since the request and
response are indexed.
Note : Regarding HTTP processing from the tcp-request content rules, everything
will work as expected from an HTTP proxy. However, from a TCP proxy,
without an HTTP upgrade, it will only work for HTTP/1 content. For
HTTP/2 content, only the preface is visible. Thus, it is only possible
to rely to "req.proto_http", "req.ver" and eventually "method" sample
fetches. All other L7 sample fetches will fail. After an HTTP upgrade,
they will work in the same manner than from an HTTP proxy.
base : string
This returns the concatenation of the first Host header and the path part of
the request, which starts at the first slash and ends before the question
mark. It can be useful in virtual hosted environments to detect URL abuses as
well as to improve shared caches efficiency. Using this with a limited size
stick table also allows one to collect statistics about most commonly
requested objects by host/path. With ACLs it can allow simple content
switching rules involving the host and the path at the same time, such as
"www.example.com/favicon.ico". See also "path" and "uri".
ACL derivatives :
base : exact string match
base_beg : prefix match
base_dir : subdir match
base_dom : domain match
base_end : suffix match
base_len : length match
base_reg : regex match
base_sub : substring match
base32 : integer
This returns a 32-bit hash of the value returned by the "base" fetch method
above. This is useful to track per-URL activity on high traffic sites without
having to store all URLs. Instead a shorter hash is stored, saving a lot of
memory. The output type is an unsigned integer. The hash function used is
SDBM with full avalanche on the output. Technically, base32 is exactly equal
to "base,sdbm(1)".
base32+src : binary
This returns the concatenation of the base32 fetch above and the src fetch
below. The resulting type is of type binary, with a size of 8 or 20 bytes
depending on the source address family. This can be used to track per-IP,
per-URL counters.
baseq : string
This returns the concatenation of the first Host header and the path part of
the request with the query-string, which starts at the first slash. Using this
instead of "base" allows one to properly identify the target resource, for
statistics or caching use cases. See also "path", "pathq" and "base".
This extracts the content of the header captured by the "capture request
header", idx is the position of the capture keyword in the configuration.
See also: "capture request header".
capture.req.method : string
This extracts the METHOD of an HTTP request. It can be used in both request
and response. Unlike "method", it can be used in both request and response
because it's allocated.
capture.req.uri : string
This extracts the request's URI, which starts at the first slash and ends
before the first space in the request (without the host part). Unlike "path"
and "url", it can be used in both request and response because it's
allocated.
capture.req.ver : string
This extracts the request's HTTP version and returns either "HTTP/1.0" or
"HTTP/1.1". Unlike "req.ver", it can be used in both request, response, and
logs because it relies on a persistent flag.
This extracts the content of the header captured by the "capture response
header", idx is the position of the capture keyword in the configuration.
The first entry is an index of 0.
See also: "capture response header"
capture.res.ver : string
This extracts the response's HTTP version and returns either "HTTP/1.0" or
"HTTP/1.1". Unlike "res.ver", it can be used in logs because it relies on a
persistent flag.
req.body : binary
This returns the HTTP request's available body as a block of data. It is
recommended to use "option http-buffer-request" to be sure to wait, as much
as possible, for the request's body.
This fetch assumes that the body of the POST request is url-encoded. The user
can check if the "content-type" contains the value
"application/x-www-form-urlencoded". This extracts the first occurrence of the
parameter <name> in the body, which ends before '&'. The parameter name is
case-sensitive. If no name is given, any parameter will match, and the first
one will be returned. The result is a string corresponding to the value of the
parameter <name> as presented in the request body (no URL decoding is
performed). Note that the ACL version of this fetch iterates over multiple
parameters and will iteratively report all parameters values if no name is
given.
req.body_len : integer
This returns the length of the HTTP request's available body in bytes. It may
be lower than the advertised length if the body is larger than the buffer. It
is recommended to use "option http-buffer-request" to be sure to wait, as
much as possible, for the request's body.
req.body_size : integer
This returns the advertised length of the HTTP request's body in bytes. It
will represent the advertised Content-Length header, or the size of the
available data in case of chunked encoding.
This extracts the last occurrence of the cookie name <name> on a "Cookie"
header line from the request, and returns its value as string. If no name is
specified, the first cookie value is returned. When used with ACLs, all
matching cookies are evaluated. Spaces around the name and the value are
ignored as requested by the Cookie header specification (RFC6265). The cookie
name is case-sensitive. Empty cookies are valid, so an empty cookie may very
well return an empty value if it is present. Use the "found" match to detect
presence. Use the res.cook() variant for response cookies sent by the server.
ACL derivatives :
req.cook([<name>]) : exact string match
req.cook_beg([<name>]) : prefix match
req.cook_dir([<name>]) : subdir match
req.cook_dom([<name>]) : domain match
req.cook_end([<name>]) : suffix match
req.cook_len([<name>]) : length match
req.cook_reg([<name>]) : regex match
req.cook_sub([<name>]) : substring match
Returns an integer value representing the number of occurrences of the cookie
<name> in the request, or all cookies if <name> is not specified.
This extracts the last occurrence of the cookie name <name> on a "Cookie"
header line from the request, and converts its value to an integer which is
returned. If no name is specified, the first cookie value is returned. When
used in ACLs, all matching names are iterated over until a value matches.
This extracts the last occurrence of the cookie name <name> on a "Cookie"
header line from the request, or a "Set-Cookie" header from the response, and
returns its value as a string. A typical use is to get multiple clients
sharing a same profile use the same server. This can be similar to what
"appsession" did with the "request-learn" statement, but with support for
multi-peer synchronization and state keeping across restarts. If no name is
specified, the first cookie value is returned. This fetch should not be used
anymore and should be replaced by req.cook() or res.cook() instead as it
ambiguously uses the direction based on the context where it is used.
This is equivalent to req.hdr() when used on requests, and to res.hdr() when
used on responses. Please refer to these respective fetches for more details.
In case of doubt about the fetch direction, please use the explicit ones.
Note that contrary to the hdr() sample fetch method, the hdr_* ACL keywords
unambiguously apply to the request headers.
This returns the full value of the last occurrence of header <name> in an
HTTP request. It differs from req.hdr() in that any commas present in the
value are returned and are not used as delimiters. This is sometimes useful
with headers such as User-Agent.
When used from an ACL, all occurrences are iterated over until a match is
found.
Optionally, a specific occurrence might be specified as a position number.
Positive values indicate a position from the first occurrence, with 1 being
the first one. Negative values indicate positions relative to the last one,
with -1 being the last one.
Returns an integer value representing the number of occurrences of request
header field name <name>, or the total number of header fields if <name> is
not specified. Like req.fhdr() it differs from res.hdr_cnt() by not splitting
headers at commas.
This returns the last comma-separated value of the header <name> in an HTTP
request. The fetch considers any comma as a delimiter for distinct values.
This is useful if you need to process headers that are defined to be a list
of values, such as Accept, or X-Forwarded-For. If full-line headers are
desired instead, use req.fhdr(). Please carefully check RFC 7231 to know how
certain headers are supposed to be parsed. Also, some of them are case
insensitive (e.g. Connection).
When used from an ACL, all occurrences are iterated over until a match is
found.
Optionally, a specific occurrence might be specified as a position number.
Positive values indicate a position from the first occurrence, with 1 being
the first one. Negative values indicate positions relative to the last one,
with -1 being the last one.
A typical use is with the X-Forwarded-For header once converted to IP,
associated with an IP stick-table.
ACL derivatives :
hdr([<name>[,<occ>]]) : exact string match
hdr_beg([<name>[,<occ>]]) : prefix match
hdr_dir([<name>[,<occ>]]) : subdir match
hdr_dom([<name>[,<occ>]]) : domain match
hdr_end([<name>[,<occ>]]) : suffix match
hdr_len([<name>[,<occ>]]) : length match
hdr_reg([<name>[,<occ>]]) : regex match
hdr_sub([<name>[,<occ>]]) : substring match
Returns an integer value representing the number of occurrences of request
header field name <name>, or the total number of header field values if
<name> is not specified. Like req.hdr() it counts each comma separated
part of the header's value. If counting of full-line headers is desired,
then req.fhdr_cnt() should be used instead.
With ACLs, it can be used to detect presence, absence or abuse of a specific
header, as well as to block request smuggling attacks by rejecting requests
which contain more than one of certain headers.
Refer to req.hdr() for more information on header matching.
This extracts the last occurrence of header <name> in an HTTP request,
converts it to an IPv4 or IPv6 address and returns this address. When used
with ACLs, all occurrences are checked, and if <name> is omitted, every value
of every header is checked. The parser strictly adheres to the format
described in RFC7239, with the extension that IPv4 addresses may optionally
be followed by a colon (':') and a valid decimal port number (0 to 65535),
which will be silently dropped. All other forms will not match and will
cause the address to be ignored.
The <occ> parameter is processed as with req.hdr().
A typical use is with the X-Forwarded-For and X-Client-IP headers.
This extracts the last occurrence of header <name> in an HTTP request, and
converts it to an integer value. When used with ACLs, all occurrences are
checked, and if <name> is omitted, every value of every header is checked.
The <occ> parameter is processed as with req.hdr().
A typical use is with the X-Forwarded-For header.
req.hdrs : string
Returns the current request headers as string including the last empty line
separating headers from the request body. The last empty line can be used to
detect a truncated header block. This sample fetch is useful for some SPOE
headers analyzers and for advanced logging.
req.hdrs_bin : binary
Returns the current request headers contained in preparsed binary form. This
is useful for offloading some processing with SPOE. Each string is described
by a length followed by the number of bytes indicated in the length. The
length is represented using the variable integer encoding detailed in the
SPOE documentation. The end of the list is marked by a couple of empty header
names and values (length of 0 for both).
*(<str:header-name><str:header-value>)<empty string><empty string>
int: refer to the SPOE documentation for the encoding
str: <int:length><bytes>
Returns a boolean indicating whether the authentication data received from
the client match a username & password stored in the specified userlist. This
fetch function is not really useful outside of ACLs. Currently only http
basic auth is supported.
Returns the client-provided token found in the authorization data when the
Bearer scheme is used (to send JSON Web Tokens for instance). No check is
performed on the data sent by the client.
If a specific <header> is supplied, it will parse this header instead of the
Authorization one.
Returns a string corresponding to the user name found in the authentication
data received from the client if both the user name and password are valid
according to the specified userlist. The main purpose is to use it in ACLs
where it is then checked whether the user belongs to any group within a list.
This fetch function is not really useful outside of ACLs. Currently only http
basic auth is supported.
ACL derivatives :
http_auth_group(<userlist>) : group ...
Returns true when the user extracted from the request and whose password is
valid according to the specified userlist belongs to at least one of the
groups.
http_auth_pass : string
Returns the user's password found in the authentication data received from
the client, as supplied in the Authorization header. Not checks are
performed by this sample fetch. Only Basic authentication is supported.
http_auth_type : string
Returns the authentication method found in the authentication data received from
the client, as supplied in the Authorization header. Not checks are
performed by this sample fetch. Only Basic authentication is supported.
http_auth_user : string
Returns the user name found in the authentication data received from the
client, as supplied in the Authorization header. Not checks are performed by
this sample fetch. Only Basic authentication is supported.
http_first_req : boolean
Returns true when the request being processed is the first one of the
connection. This can be used to add or remove headers that may be missing
from some requests when a request is not the first one, or to help grouping
requests in the logs.
method : integer + string
Returns an integer value corresponding to the method in the HTTP request. For
example, "GET" equals 1 (check sources to establish the matching). Value 9
means "other method" and may be converted to a string extracted from the
stream. This should not be used directly as a sample, this is only meant to
be used from ACLs, which transparently convert methods from patterns to these
integer + string values. Some predefined ACL already check for most common
methods.
ACL derivatives :
method : case insensitive method match
Example :
# only accept GET and HEAD requests
acl valid_method method GET HEAD
http-request deny if ! valid_method
path : string
This extracts the request's URL path, which starts at the first slash and
ends before the question mark (without the host part). A typical use is with
prefetch-capable caches, and with portals which need to aggregate multiple
information from databases and keep them in caches. Note that with outgoing
caches, it would be wiser to use "url" instead. With ACLs, it's typically
used to match exact file names (e.g. "/login.php"), or directory parts using
the derivative forms. See also the "url" and "base" fetch methods. Please
note that any fragment reference in the URI ('#' after the path) is strictly
forbidden by the HTTP standard and will be rejected. However, if the frontend
receiving the request has "option accept-invalid-http-request", then this
fragment part will be accepted and will also appear in the path.
ACL derivatives :
path : exact string match
path_beg : prefix match
path_dir : subdir match
path_dom : domain match
path_end : suffix match
path_len : length match
path_reg : regex match
path_sub : substring match
pathq : string
This extracts the request's URL path with the query-string, which starts at
the first slash. This sample fetch is pretty handy to always retrieve a
relative URI, excluding the scheme and the authority part, if any. Indeed,
while it is the common representation for an HTTP/1.1 request target, in
HTTP/2, an absolute URI is often used. This sample fetch will return the same
result in both cases. Please note that any fragment reference in the URI ('#'
after the path) is strictly forbidden by the HTTP standard and will be
rejected. However, if the frontend receiving the request has "option
accept-invalid-http-request", then this fragment part will be accepted and
will also appear in the path.
query : string
This extracts the request's query string, which starts after the first
question mark. If no question mark is present, this fetch returns nothing. If
a question mark is present but nothing follows, it returns an empty string.
This means it's possible to easily know whether a query string is present
using the "found" matching method. This fetch is the complement of "path"
which stops before the question mark.
This builds a string made from the concatenation of all header names as they
appear in the request when the rule is evaluated. The default delimiter is
the comma (',') but it may be overridden as an optional argument <delim>. In
this case, only the first character of <delim> is considered.
req.ver : string
Returns the version string from the HTTP request, for example "1.1". This can
be useful for logs, but is mostly there for ACL. Some predefined ACL already
check for versions 1.0 and 1.1.
ACL derivatives :
req.ver : exact string match
res.body : binary
This returns the HTTP response's available body as a block of data. Unlike
the request side, there is no directive to wait for the response's body. This
sample fetch is really useful (and usable) in the health-check context.
It may be used in tcp-check based expect rules.
res.body_len : integer
This returns the length of the HTTP response available body in bytes. Unlike
the request side, there is no directive to wait for the response's body. This
sample fetch is really useful (and usable) in the health-check context.
It may be used in tcp-check based expect rules.
res.body_size : integer
This returns the advertised length of the HTTP response body in bytes. It
will represent the advertised Content-Length header, or the size of the
available data in case of chunked encoding. Unlike the request side, there is
no directive to wait for the response body. This sample fetch is really
useful (and usable) in the health-check context.
It may be used in tcp-check based expect rules.
res.cache_hit : boolean
Returns the boolean "true" value if the response has been built out of an
HTTP cache entry, otherwise returns boolean "false".
res.cache_name : string
Returns a string containing the name of the HTTP cache that was used to
build the HTTP response if res.cache_hit is true, otherwise returns an
empty string.
res.comp : boolean
Returns the boolean "true" value if the response has been compressed by
HAProxy, otherwise returns boolean "false". This may be used to add
information in the logs.
res.comp_algo : string
Returns a string containing the name of the algorithm used if the response
was compressed by HAProxy, for example : "deflate". This may be used to add
some information in the logs.
This extracts the last occurrence of the cookie name <name> on a "Set-Cookie"
header line from the response, and returns its value as string. If no name is
specified, the first cookie value is returned.
It may be used in tcp-check based expect rules.
ACL derivatives :
res.scook([<name>] : exact string match
Returns an integer value representing the number of occurrences of the cookie
<name> in the response, or all cookies if <name> is not specified. This is
mostly useful when combined with ACLs to detect suspicious responses.
It may be used in tcp-check based expect rules.
This extracts the last occurrence of the cookie name <name> on a "Set-Cookie"
header line from the response, and converts its value to an integer which is
returned. If no name is specified, the first cookie value is returned.
It may be used in tcp-check based expect rules.
This fetch works like the req.fhdr() fetch with the difference that it acts
on the headers within an HTTP response.
Like req.fhdr() the res.fhdr() fetch returns full values. If the header is
defined to be a list you should use res.hdr().
This fetch is sometimes useful with headers such as Date or Expires.
It may be used in tcp-check based expect rules.
This fetch works like the req.fhdr_cnt() fetch with the difference that it
acts on the headers within an HTTP response.
Like req.fhdr_cnt() the res.fhdr_cnt() fetch acts on full values. If the
header is defined to be a list you should use res.hdr_cnt().
It may be used in tcp-check based expect rules.
This fetch works like the req.hdr() fetch with the difference that it acts
on the headers within an HTTP response.
Like req.hdr() the res.hdr() fetch considers the comma to be a delimiter. If
this is not desired res.fhdr() should be used.
It may be used in tcp-check based expect rules.
ACL derivatives :
res.hdr([<name>[,<occ>]]) : exact string match
res.hdr_beg([<name>[,<occ>]]) : prefix match
res.hdr_dir([<name>[,<occ>]]) : subdir match
res.hdr_dom([<name>[,<occ>]]) : domain match
res.hdr_end([<name>[,<occ>]]) : suffix match
res.hdr_len([<name>[,<occ>]]) : length match
res.hdr_reg([<name>[,<occ>]]) : regex match
res.hdr_sub([<name>[,<occ>]]) : substring match
This fetch works like the req.hdr_cnt() fetch with the difference that it
acts on the headers within an HTTP response.
Like req.hdr_cnt() the res.hdr_cnt() fetch considers the comma to be a
delimiter. If this is not desired res.fhdr_cnt() should be used.
It may be used in tcp-check based expect rules.
This fetch works like the req.hdr_ip() fetch with the difference that it
acts on the headers within an HTTP response.
This can be useful to learn some data into a stick table.
It may be used in tcp-check based expect rules.
This builds a string made from the concatenation of all header names as they
appear in the response when the rule is evaluated. The default delimiter is
the comma (',') but it may be overridden as an optional argument <delim>. In
this case, only the first character of <delim> is considered.
It may be used in tcp-check based expect rules.
This fetch works like the req.hdr_val() fetch with the difference that it
acts on the headers within an HTTP response.
This can be useful to learn some data into a stick table.
It may be used in tcp-check based expect rules.
res.hdrs : string
Returns the current response headers as string including the last empty line
separating headers from the request body. The last empty line can be used to
detect a truncated header block. This sample fetch is useful for some SPOE
headers analyzers and for advanced logging.
It may also be used in tcp-check based expect rules.
res.hdrs_bin : binary
Returns the current response headers contained in preparsed binary form. This
is useful for offloading some processing with SPOE. It may be used in
tcp-check based expect rules. Each string is described by a length followed
by the number of bytes indicated in the length. The length is represented
using the variable integer encoding detailed in the SPOE documentation. The
end of the list is marked by a couple of empty header names and values
(length of 0 for both).
*(<str:header-name><str:header-value>)<empty string><empty string>
int: refer to the SPOE documentation for the encoding
str: <int:length><bytes>
res.ver : string
Returns the version string from the HTTP response, for example "1.1". This
can be useful for logs, but is mostly there for ACL.
It may be used in tcp-check based expect rules.
ACL derivatives :
resp.ver : exact string match
This extracts the last occurrence of the cookie name <name> on a "Set-Cookie"
header line from the response and uses the corresponding value to match. This
can be comparable to what "appsession" did with default options, but with
support for multi-peer synchronization and state keeping across restarts.
This fetch function is deprecated and has been superseded by the "res.cook"
fetch. This keyword will disappear soon.
status : integer
Returns an integer containing the HTTP status code in the HTTP response, for
example, 302. It is mostly used within ACLs and integer ranges, for example,
to remove any Location header if the response is not a 3xx.
It may be used in tcp-check based expect rules.
unique-id : string
Returns the unique-id attached to the request. The directive
"unique-id-format" must be set. If it is not set, the unique-id sample fetch
fails. Note that the unique-id is usually used with HTTP requests, however this
sample fetch can be used with other protocols. Obviously, if it is used with
other protocols than HTTP, the unique-id-format directive must not contain
HTTP parts. See: unique-id-format and unique-id-header
url : string
This extracts the request's URL as presented in the request. A typical use is
with prefetch-capable caches, and with portals which need to aggregate
multiple information from databases and keep them in caches. With ACLs, using
"path" is preferred over using "url", because clients may send a full URL as
is normally done with proxies. The only real use is to match "*" which does
not match in "path", and for which there is already a predefined ACL. See
also "path" and "base". Please note that any fragment reference in the URI
('#' after the path) is strictly forbidden by the HTTP standard and will be
rejected. However, if the frontend receiving the request has "option
accept-invalid-http-request", then this fragment part will be accepted and
will also appear in the url.
ACL derivatives :
url : exact string match
url_beg : prefix match
url_dir : subdir match
url_dom : domain match
url_end : suffix match
url_len : length match
url_reg : regex match
url_sub : substring match
url_ip : ip
This extracts the IP address from the request's URL when the host part is
presented as an IP address. Its use is very limited. For instance, a
monitoring system might use this field as an alternative for the source IP in
order to test what path a given source address would follow, or to force an
entry in a table for a given source address. With ACLs it can be used to
restrict access to certain systems through a proxy, for example when combined
with option "http_proxy".
url_port : integer
This extracts the port part from the request's URL. Note that if the port is
not specified in the request, port 80 is assumed. With ACLs it can be used to
restrict access to certain systems through a proxy, for example when combined
with option "http_proxy".
This extracts the first occurrence of the parameter <name> in the query
string, which begins after either '?' or <delim>, and which ends before '&',
';' or <delim>. The parameter name is case-sensitive. If no name is given,
any parameter will match, and the first one will be returned. The result is
a string corresponding to the value of the parameter <name> as presented in
the request (no URL decoding is performed). This can be used for session
stickiness based on a client ID, to extract an application cookie passed as a
URL parameter, or in ACLs to apply some checks. Note that the ACL version of
this fetch iterates over multiple parameters and will iteratively report all
parameters values if no name is given
ACL derivatives :
urlp(<name>[,<delim>]) : exact string match
urlp_beg(<name>[,<delim>]) : prefix match
urlp_dir(<name>[,<delim>]) : subdir match
urlp_dom(<name>[,<delim>]) : domain match
urlp_end(<name>[,<delim>]) : suffix match
urlp_len(<name>[,<delim>]) : length match
urlp_reg(<name>[,<delim>]) : regex match
urlp_sub(<name>[,<delim>]) : substring match
Example :
# match http://example.com/foo?PHPSESSIONID=some_id
stick on urlp(PHPSESSIONID)
# match http://example.com/foo;JSESSIONID=some_id
stick on urlp(JSESSIONID,;)
See "urlp" above. This one extracts the URL parameter <name> in the request
and converts it to an integer value. This can be used for session stickiness
based on a user ID for example, or with ACLs to match a page number or price.
url32 : integer
This returns a 32-bit hash of the value obtained by concatenating the first
Host header and the whole URL including parameters (not only the path part of
the request, as in the "base32" fetch above). This is useful to track per-URL
activity. A shorter hash is stored, saving a lot of memory. The output type
is an unsigned integer.
url32+src : binary
7.3.7. Fetching samples for developers
This set of sample fetch methods is reserved to developers and must never be
used on a production environment, except on developer demand, for debugging
purposes. Moreover, no special care will be taken on backwards compatibility.
There is no warranty the following sample fetches will never change, be renamed
or simply removed. So be really careful if you should use one of them. To avoid
any ambiguity, these sample fetches are placed in the dedicated scope "internal",
for instance "internal.strm.is_htx".
internal.htx.data : integer
Returns the size in bytes used by data in the HTX message associated to a
channel. The channel is chosen depending on the sample direction.
internal.htx.free : integer
Returns the free space (size - used) in bytes in the HTX message associated
to a channel. The channel is chosen depending on the sample direction.
internal.htx.free_data : integer
Returns the free space for the data in bytes in the HTX message associated to
a channel. The channel is chosen depending on the sample direction.
internal.htx.has_eom : boolean
Returns true if the HTX message associated to a channel contains the
end-of-message flag (EOM). Otherwise, it returns false. The channel is chosen
depending on the sample direction.
internal.htx.nbblks : integer
Returns the number of blocks present in the HTX message associated to a
channel. The channel is chosen depending on the sample direction.
internal.htx.size : integer
Returns the total size in bytes of the HTX message associated to a
channel. The channel is chosen depending on the sample direction.
internal.htx.used : integer
Returns the total size used in bytes (data + metadata) in the HTX message
associated to a channel. The channel is chosen depending on the sample
direction.
Returns the size of the block at the position <idx> in the HTX message
associated to a channel or 0 if it does not exist. The channel is chosen
depending on the sample direction. <idx> may be any positive integer or one
of the special value :
* head : The oldest inserted block
* tail : The newest inserted block
* first : The first block where to (re)start the analysis
Returns the type of the block at the position <idx> in the HTX message
associated to a channel or "HTX_BLK_UNUSED" if it does not exist. The channel
is chosen depending on the sample direction. <idx> may be any positive
integer or one of the special value :
* head : The oldest inserted block
* tail : The newest inserted block
* first : The first block where to (re)start the analysis
Returns the value of the DATA block at the position <idx> in the HTX message
associated to a channel or an empty string if it does not exist or if it is
not a DATA block. The channel is chosen depending on the sample direction.
<idx> may be any positive integer or one of the special value :
* head : The oldest inserted block
* tail : The newest inserted block
* first : The first block where to (re)start the analysis
Returns the header name of the HEADER block at the position <idx> in the HTX
message associated to a channel or an empty string if it does not exist or if
it is not an HEADER block. The channel is chosen depending on the sample
direction. <idx> may be any positive integer or one of the special value :
* head : The oldest inserted block
* tail : The newest inserted block
* first : The first block where to (re)start the analysis
Returns the header value of the HEADER block at the position <idx> in the HTX
message associated to a channel or an empty string if it does not exist or if
it is not an HEADER block. The channel is chosen depending on the sample
direction. <idx> may be any positive integer or one of the special value :
* head : The oldest inserted block
* tail : The newest inserted block
* first : The first block where to (re)start the analysis
Returns the value of the REQ_SL or RES_SL block at the position <idx> in the
HTX message associated to a channel or an empty string if it does not exist
or if it is not a SL block. The channel is chosen depending on the sample
direction. <idx> may be any positive integer or one of the special value :
* head : The oldest inserted block
* tail : The newest inserted block
* first : The first block where to (re)start the analysis
internal.strm.is_htx : boolean
Returns true if the current stream is an HTX stream. It means the data in the
channels buffers are stored using the internal HTX representation. Otherwise,
it returns false.
7.4. Pre-defined ACLs
Some predefined ACLs are hard-coded so that they do not have to be declared in
every frontend which needs them. They all have their names in upper case in
order to avoid confusion. Their equivalence is provided below.
| ACL name | Equivalent to Usage | |
|---|---|---|
| FALSE | always_false | never match |
| HTTP | req.proto_http | match if request protocol is valid HTTP |
| HTTP_1.0 | req.ver 1.0 | match if HTTP request version is 1.0 |
| HTTP_1.1 | req.ver 1.1 | match if HTTP request version is 1.1 |
| HTTP_2.0 | req.ver 2.0 | match if HTTP request version is 2.0 |
| HTTP_CONTENT | req.hdr_val(content-length) gt 0 | match an existing content-length in the HTTP request |
| HTTP_URL_ABS | url_reg ^[^/:]*:// | match absolute URL with scheme |
| HTTP_URL_SLASH | url_beg / | match URL beginning with "/" |
| HTTP_URL_STAR | url * | match URL equal to "*" |
| LOCALHOST | src 127.0.0.1/8 | match connection from local host |
| METH_CONNECT | method CONNECT | match HTTP CONNECT method |
| METH_DELETE | method DELETE | match HTTP DELETE method |
| METH_GET | method GET HEAD | match HTTP GET or HEAD method |
| METH_HEAD | method HEAD | match HTTP HEAD method |
| METH_OPTIONS | method OPTIONS | match HTTP OPTIONS method |
| METH_POST | method POST | match HTTP POST method |
| METH_PUT | method PUT | match HTTP PUT method |
| METH_TRACE | method TRACE | match HTTP TRACE method |
| RDP_COOKIE | req.rdp_cookie_cnt gt 0 | match presence of an RDP cookie in the request buffer |
| REQ_CONTENT | req.len gt 0 | match data in the request buffer |
| TRUE | always_true | always match |
| WAIT_END | wait_end | wait for end of content analysis |
8. Logging
One of HAProxy's strong points certainly lies is its precise logs. It probably
provides the finest level of information available for such a product, which is
very important for troubleshooting complex environments. Standard information
provided in logs include client ports, TCP/HTTP state timers, precise session
state at termination and precise termination cause, information about decisions
to direct traffic to a server, and of course the ability to capture arbitrary
headers.
In order to improve administrators reactivity, it offers a great transparency
about encountered problems, both internal and external, and it is possible to
send logs to different sources at the same time with different level filters :
- global process-level logs (system errors, start/stop, etc..)
- per-instance system and internal errors (lack of resource, bugs, ...)
- per-instance external troubles (servers up/down, max connections)
- per-instance activity (client connections), either at the establishment or
at the termination.
- per-request control of log-level, e.g.
http-request set-log-level silent if sensitive_request
The ability to distribute different levels of logs to different log servers
allow several production teams to interact and to fix their problems as soon
as possible. For example, the system team might monitor system-wide errors,
while the application team might be monitoring the up/down for their servers in
real time, and the security team might analyze the activity logs with one hour
delay.
8.1. Log levels
TCP and HTTP connections can be logged with information such as the date, time,
source IP address, destination address, connection duration, response times,
HTTP request, HTTP return code, number of bytes transmitted, conditions
in which the session ended, and even exchanged cookies values. For example
track a particular user's problems. All messages may be sent to up to two
syslog servers. Check the "log" keyword in section 4.2 for more information
about log facilities.
8.2. Log formats
HAProxy supports 5 log formats. Several fields are common between these formats
and will be detailed in the following sections. A few of them may vary
slightly with the configuration, due to indicators specific to certain
options. The supported formats are as follows :
- the default format, which is very basic and very rarely used. It only
provides very basic information about the incoming connection at the moment
it is accepted : source IP:port, destination IP:port, and frontend-name.
This mode will eventually disappear so it will not be described to great
extents.
- the TCP format, which is more advanced. This format is enabled when "option
tcplog" is set on the frontend. HAProxy will then usually wait for the
connection to terminate before logging. This format provides much richer
information, such as timers, connection counts, queue size, etc... This
format is recommended for pure TCP proxies.
- the HTTP format, which is the most advanced for HTTP proxying. This format
is enabled when "option httplog" is set on the frontend. It provides the
same information as the TCP format with some HTTP-specific fields such as
the request, the status code, and captures of headers and cookies. This
format is recommended for HTTP proxies.
- the CLF HTTP format, which is equivalent to the HTTP format, but with the
fields arranged in the same order as the CLF format. In this mode, all
timers, captures, flags, etc... appear one per field after the end of the
common fields, in the same order they appear in the standard HTTP format.
- the custom log format, allows you to make your own log line.
Next sections will go deeper into details for each of these formats. Format
specification will be performed on a "field" basis. Unless stated otherwise, a
field is a portion of text delimited by any number of spaces. Since syslog
servers are susceptible of inserting fields at the beginning of a line, it is
always assumed that the first field is the one containing the process name and
identifier.
Note : Since log lines may be quite long, the log examples in sections below
might be broken into multiple lines. The example log lines will be
prefixed with 3 closing angle brackets ('>>>') and each time a log is
broken into multiple lines, each non-final line will end with a
backslash ('\') and the next line will start indented by two characters.
8.2.1. Default log format
This format is used when no specific option is set. The log is emitted as soon
as the connection is accepted. One should note that this currently is the only
format which logs the request's destination IP and ports.
Example :
listen www
mode http
log global
server srv1 127.0.0.1:8000
>>> Feb 6 12:12:09 localhost \
haproxy[14385]: Connect from 10.0.1.2:33312 to 10.0.3.31:8012 \
(www/HTTP)
Field Format Extract from the example above
1 process_name '[' pid ']:' haproxy[14385]:
2 'Connect from' Connect from
3 source_ip ':' source_port 10.0.1.2:33312
4 'to' to
5 destination_ip ':' destination_port 10.0.3.31:8012
6 '(' frontend_name '/' mode ')' (www/HTTP)
Detailed fields description :
- "source_ip" is the IP address of the client which initiated the connection.
- "source_port" is the TCP port of the client which initiated the connection.
- "destination_ip" is the IP address the client connected to.
- "destination_port" is the TCP port the client connected to.
- "frontend_name" is the name of the frontend (or listener) which received
and processed the connection.
- "mode is the mode the frontend is operating (TCP or HTTP).
In case of a UNIX socket, the source and destination addresses are marked as
"unix:" and the ports reflect the internal ID of the socket which accepted the
connection (the same ID as reported in the stats).
It is advised not to use this deprecated format for newer installations as it
will eventually disappear.
8.2.2. TCP log format
The TCP format is used when "option tcplog" is specified in the frontend, and
is the recommended format for pure TCP proxies. It provides a lot of precious
information for troubleshooting. Since this format includes timers and byte
counts, the log is normally emitted at the end of the session. It can be
emitted earlier if "option logasap" is specified, which makes sense in most
environments with long sessions such as remote terminals. Sessions which match
the "monitor" rules are never logged. It is also possible not to emit logs for
sessions for which no data were exchanged between the client and the server, by
specifying "option dontlognull" in the frontend. Successful connections will
not be logged if "option dontlog-normal" is specified in the frontend. A few
fields may slightly vary depending on some configuration options, those are
marked with a star ('*') after the field name below.
Example :
frontend fnt
mode tcp
option tcplog
log global
default_backend bck
backend bck
server srv1 127.0.0.1:8000
>>> Feb 6 12:12:56 localhost \
haproxy[14387]: 10.0.1.2:33313 [06/Feb/2009:12:12:51.443] fnt \
bck/srv1 0/0/5007 212 -- 0/0/0/0/3 0/0
Field Format Extract from the example above
1 process_name '[' pid ']:' haproxy[14387]:
2 client_ip ':' client_port 10.0.1.2:33313
3 '[' accept_date ']' [06/Feb/2009:12:12:51.443]
4 frontend_name fnt
5 backend_name '/' server_name bck/srv1
6 Tw '/' Tc '/' Tt* 0/0/5007
7 bytes_read* 212
8 termination_state --
9 actconn '/' feconn '/' beconn '/' srv_conn '/' retries* 0/0/0/0/3
10 srv_queue '/' backend_queue 0/0
Detailed fields description :
- "client_ip" is the IP address of the client which initiated the TCP
connection to HAProxy. If the connection was accepted on a UNIX socket
instead, the IP address would be replaced with the word "unix". Note that
when the connection is accepted on a socket configured with "accept-proxy"
and the PROXY protocol is correctly used, or with a "accept-netscaler-cip"
and the NetScaler Client IP insertion protocol is correctly used, then the
logs will reflect the forwarded connection's information.
- "client_port" is the TCP port of the client which initiated the connection.
If the connection was accepted on a UNIX socket instead, the port would be
replaced with the ID of the accepting socket, which is also reported in the
stats interface.
- "accept_date" is the exact date when the connection was received by HAProxy
(which might be very slightly different from the date observed on the
network if there was some queuing in the system's backlog). This is usually
the same date which may appear in any upstream firewall's log. When used in
HTTP mode, the accept_date field will be reset to the first moment the
connection is ready to receive a new request (end of previous response for
HTTP/1, immediately after previous request for HTTP/2).
- "frontend_name" is the name of the frontend (or listener) which received
and processed the connection.
- "backend_name" is the name of the backend (or listener) which was selected
to manage the connection to the server. This will be the same as the
frontend if no switching rule has been applied, which is common for TCP
applications.
- "server_name" is the name of the last server to which the connection was
sent, which might differ from the first one if there were connection errors
and a redispatch occurred. Note that this server belongs to the backend
which processed the request. If the connection was aborted before reaching
a server, "<NOSRV>" is indicated instead of a server name.
- "Tw" is the total time in milliseconds spent waiting in the various queues.
It can be "-1" if the connection was aborted before reaching the queue.
See "Timers" below for more details.
- "Tc" is the total time in milliseconds spent waiting for the connection to
establish to the final server, including retries. It can be "-1" if the
connection was aborted before a connection could be established. See
"Timers" below for more details.
- "Tt" is the total time in milliseconds elapsed between the accept and the
last close. It covers all possible processing. There is one exception, if
"option logasap" was specified, then the time counting stops at the moment
the log is emitted. In this case, a '+' sign is prepended before the value,
indicating that the final one will be larger. See "Timers" below for more
details.
- "bytes_read" is the total number of bytes transmitted from the server to
the client when the log is emitted. If "option logasap" is specified, the
this value will be prefixed with a '+' sign indicating that the final one
may be larger. Please note that this value is a 64-bit counter, so log
analysis tools must be able to handle it without overflowing.
- "termination_state" is the condition the session was in when the session
ended. This indicates the session state, which side caused the end of
session to happen, and for what reason (timeout, error, ...). The normal
flags should be "--", indicating the session was closed by either end with
no data remaining in buffers. See below "Session state at disconnection"
for more details.
- "actconn" is the total number of concurrent connections on the process when
the session was logged. It is useful to detect when some per-process system
limits have been reached. For instance, if actconn is close to 512 when
multiple connection errors occur, chances are high that the system limits
the process to use a maximum of 1024 file descriptors and that all of them
are used. See section 3 "Global parameters" to find how to tune the system.
- "feconn" is the total number of concurrent connections on the frontend when
the session was logged. It is useful to estimate the amount of resource
required to sustain high loads, and to detect when the frontend's "maxconn"
has been reached. Most often when this value increases by huge jumps, it is
because there is congestion on the backend servers, but sometimes it can be
caused by a denial of service attack.
- "beconn" is the total number of concurrent connections handled by the
backend when the session was logged. It includes the total number of
concurrent connections active on servers as well as the number of
connections pending in queues. It is useful to estimate the amount of
additional servers needed to support high loads for a given application.
Most often when this value increases by huge jumps, it is because there is
congestion on the backend servers, but sometimes it can be caused by a
denial of service attack.
- "srv_conn" is the total number of concurrent connections still active on
the server when the session was logged. It can never exceed the server's
configured "maxconn" parameter. If this value is very often close or equal
to the server's "maxconn", it means that traffic regulation is involved a
lot, meaning that either the server's maxconn value is too low, or that
there aren't enough servers to process the load with an optimal response
time. When only one of the server's "srv_conn" is high, it usually means
that this server has some trouble causing the connections to take longer to
be processed than on other servers.
- "retries" is the number of connection retries experienced by this session
when trying to connect to the server. It must normally be zero, unless a
server is being stopped at the same moment the connection was attempted.
Frequent retries generally indicate either a network problem between
HAProxy and the server, or a misconfigured system backlog on the server
preventing new connections from being queued. This field may optionally be
prefixed with a '+' sign, indicating that the session has experienced a
redispatch after the maximal retry count has been reached on the initial
server. In this case, the server name appearing in the log is the one the
connection was redispatched to, and not the first one, though both may
sometimes be the same in case of hashing for instance. So as a general rule
of thumb, when a '+' is present in front of the retry count, this count
should not be attributed to the logged server.
- "srv_queue" is the total number of requests which were processed before
this one in the server queue. It is zero when the request has not gone
through the server queue. It makes it possible to estimate the approximate
server's response time by dividing the time spent in queue by the number of
requests in the queue. It is worth noting that if a session experiences a
redispatch and passes through two server queues, their positions will be
cumulative. A request should not pass through both the server queue and the
backend queue unless a redispatch occurs.
- "backend_queue" is the total number of requests which were processed before
this one in the backend's global queue. It is zero when the request has not
gone through the global queue. It makes it possible to estimate the average
queue length, which easily translates into a number of missing servers when
divided by a server's "maxconn" parameter. It is worth noting that if a
session experiences a redispatch, it may pass twice in the backend's queue,
and then both positions will be cumulative. A request should not pass
through both the server queue and the backend queue unless a redispatch
occurs.
8.2.3. HTTP log format
The HTTP format is the most complete and the best suited for HTTP proxies. It
is enabled by when "option httplog" is specified in the frontend. It provides
the same level of information as the TCP format with additional features which
are specific to the HTTP protocol. Just like the TCP format, the log is usually
emitted at the end of the session, unless "option logasap" is specified, which
generally only makes sense for download sites. A session which matches the
"monitor" rules will never logged. It is also possible not to log sessions for
which no data were sent by the client by specifying "option dontlognull" in the
frontend. Successful connections will not be logged if "option dontlog-normal"
is specified in the frontend.
Most fields are shared with the TCP log, some being different. A few fields may
slightly vary depending on some configuration options. Those ones are marked
with a star ('*') after the field name below.
Example :
frontend http-in
mode http
option httplog
log global
default_backend bck
backend static
server srv1 127.0.0.1:8000
>>> Feb 6 12:14:14 localhost \
haproxy[14389]: 10.0.1.2:33317 [06/Feb/2009:12:14:14.655] http-in \
static/srv1 10/0/30/69/109 200 2750 - - ---- 1/1/1/1/0 0/0 {1wt.eu} \
{} "GET /index.html HTTP/1.1"
Field Format Extract from the example above
1 process_name '[' pid ']:' haproxy[14389]:
2 client_ip ':' client_port 10.0.1.2:33317
3 '[' request_date ']' [06/Feb/2009:12:14:14.655]
4 frontend_name http-in
5 backend_name '/' server_name static/srv1
6 TR '/' Tw '/' Tc '/' Tr '/' Ta* 10/0/30/69/109
7 status_code 200
8 bytes_read* 2750
9 captured_request_cookie -
10 captured_response_cookie -
11 termination_state ----
12 actconn '/' feconn '/' beconn '/' srv_conn '/' retries* 1/1/1/1/0
13 srv_queue '/' backend_queue 0/0
14 '{' captured_request_headers* '}' {haproxy.1wt.eu}
15 '{' captured_response_headers* '}' {}
16 '"' http_request '"' "GET /index.html HTTP/1.1"
Detailed fields description :
- "client_ip" is the IP address of the client which initiated the TCP
connection to HAProxy. If the connection was accepted on a UNIX socket
instead, the IP address would be replaced with the word "unix". Note that
when the connection is accepted on a socket configured with "accept-proxy"
and the PROXY protocol is correctly used, or with a "accept-netscaler-cip"
and the NetScaler Client IP insertion protocol is correctly used, then the
logs will reflect the forwarded connection's information.
- "client_port" is the TCP port of the client which initiated the connection.
If the connection was accepted on a UNIX socket instead, the port would be
replaced with the ID of the accepting socket, which is also reported in the
stats interface.
- "request_date" is the exact date when the first byte of the HTTP request
was received by HAProxy (log field %tr).
- "frontend_name" is the name of the frontend (or listener) which received
and processed the connection.
- "backend_name" is the name of the backend (or listener) which was selected
to manage the connection to the server. This will be the same as the
frontend if no switching rule has been applied.
- "server_name" is the name of the last server to which the connection was
sent, which might differ from the first one if there were connection errors
and a redispatch occurred. Note that this server belongs to the backend
which processed the request. If the request was aborted before reaching a
server, "<NOSRV>" is indicated instead of a server name. If the request was
intercepted by the stats subsystem, "<STATS>" is indicated instead.
- "TR" is the total time in milliseconds spent waiting for a full HTTP
request from the client (not counting body) after the first byte was
received. It can be "-1" if the connection was aborted before a complete
request could be received or a bad request was received. It should
always be very small because a request generally fits in one single packet.
Large times here generally indicate network issues between the client and
HAProxy or requests being typed by hand. See section 8.4 "Timing Events"
for more details.
- "Tw" is the total time in milliseconds spent waiting in the various queues.
It can be "-1" if the connection was aborted before reaching the queue.
See section 8.4 "Timing Events" for more details.
- "Tc" is the total time in milliseconds spent waiting for the connection to
establish to the final server, including retries. It can be "-1" if the
request was aborted before a connection could be established. See section
8.4 "Timing Events" for more details.
- "Tr" is the total time in milliseconds spent waiting for the server to send
a full HTTP response, not counting data. It can be "-1" if the request was
aborted before a complete response could be received. It generally matches
the server's processing time for the request, though it may be altered by
the amount of data sent by the client to the server. Large times here on
"GET" requests generally indicate an overloaded server. See section 8.4
"Timing Events" for more details.
- "Ta" is the time the request remained active in HAProxy, which is the total
time in milliseconds elapsed between the first byte of the request was
received and the last byte of response was sent. It covers all possible
processing except the handshake (see Th) and idle time (see Ti). There is
one exception, if "option logasap" was specified, then the time counting
stops at the moment the log is emitted. In this case, a '+' sign is
prepended before the value, indicating that the final one will be larger.
See section 8.4 "Timing Events" for more details.
- "status_code" is the HTTP status code returned to the client. This status
is generally set by the server, but it might also be set by HAProxy when
the server cannot be reached or when its response is blocked by HAProxy.
- "bytes_read" is the total number of bytes transmitted to the client when
the log is emitted. This does include HTTP headers. If "option logasap" is
specified, this value will be prefixed with a '+' sign indicating that
the final one may be larger. Please note that this value is a 64-bit
counter, so log analysis tools must be able to handle it without
overflowing.
- "captured_request_cookie" is an optional "name=value" entry indicating that
the client had this cookie in the request. The cookie name and its maximum
length are defined by the "capture cookie" statement in the frontend
configuration. The field is a single dash ('-') when the option is not
set. Only one cookie may be captured, it is generally used to track session
ID exchanges between a client and a server to detect session crossing
between clients due to application bugs. For more details, please consult
the section "Capturing HTTP headers and cookies" below.
- "captured_response_cookie" is an optional "name=value" entry indicating
that the server has returned a cookie with its response. The cookie name
and its maximum length are defined by the "capture cookie" statement in the
frontend configuration. The field is a single dash ('-') when the option is
not set. Only one cookie may be captured, it is generally used to track
session ID exchanges between a client and a server to detect session
crossing between clients due to application bugs. For more details, please
consult the section "Capturing HTTP headers and cookies" below.
- "termination_state" is the condition the session was in when the session
ended. This indicates the session state, which side caused the end of
session to happen, for what reason (timeout, error, ...), just like in TCP
logs, and information about persistence operations on cookies in the last
two characters. The normal flags should begin with "--", indicating the
session was closed by either end with no data remaining in buffers. See
below "Session state at disconnection" for more details.
- "actconn" is the total number of concurrent connections on the process when
the session was logged. It is useful to detect when some per-process system
limits have been reached. For instance, if actconn is close to 512 or 1024
when multiple connection errors occur, chances are high that the system
limits the process to use a maximum of 1024 file descriptors and that all
of them are used. See section 3 "Global parameters" to find how to tune the
system.
- "feconn" is the total number of concurrent connections on the frontend when
the session was logged. It is useful to estimate the amount of resource
required to sustain high loads, and to detect when the frontend's "maxconn"
has been reached. Most often when this value increases by huge jumps, it is
because there is congestion on the backend servers, but sometimes it can be
caused by a denial of service attack.
- "beconn" is the total number of concurrent connections handled by the
backend when the session was logged. It includes the total number of
concurrent connections active on servers as well as the number of
connections pending in queues. It is useful to estimate the amount of
additional servers needed to support high loads for a given application.
Most often when this value increases by huge jumps, it is because there is
congestion on the backend servers, but sometimes it can be caused by a
denial of service attack.
- "srv_conn" is the total number of concurrent connections still active on
the server when the session was logged. It can never exceed the server's
configured "maxconn" parameter. If this value is very often close or equal
to the server's "maxconn", it means that traffic regulation is involved a
lot, meaning that either the server's maxconn value is too low, or that
there aren't enough servers to process the load with an optimal response
time. When only one of the server's "srv_conn" is high, it usually means
that this server has some trouble causing the requests to take longer to be
processed than on other servers.
- "retries" is the number of connection retries experienced by this session
when trying to connect to the server. It must normally be zero, unless a
server is being stopped at the same moment the connection was attempted.
Frequent retries generally indicate either a network problem between
HAProxy and the server, or a misconfigured system backlog on the server
preventing new connections from being queued. This field may optionally be
prefixed with a '+' sign, indicating that the session has experienced a
redispatch after the maximal retry count has been reached on the initial
server. In this case, the server name appearing in the log is the one the
connection was redispatched to, and not the first one, though both may
sometimes be the same in case of hashing for instance. So as a general rule
of thumb, when a '+' is present in front of the retry count, this count
should not be attributed to the logged server.
- "srv_queue" is the total number of requests which were processed before
this one in the server queue. It is zero when the request has not gone
through the server queue. It makes it possible to estimate the approximate
server's response time by dividing the time spent in queue by the number of
requests in the queue. It is worth noting that if a session experiences a
redispatch and passes through two server queues, their positions will be
cumulative. A request should not pass through both the server queue and the
backend queue unless a redispatch occurs.
- "backend_queue" is the total number of requests which were processed before
this one in the backend's global queue. It is zero when the request has not
gone through the global queue. It makes it possible to estimate the average
queue length, which easily translates into a number of missing servers when
divided by a server's "maxconn" parameter. It is worth noting that if a
session experiences a redispatch, it may pass twice in the backend's queue,
and then both positions will be cumulative. A request should not pass
through both the server queue and the backend queue unless a redispatch
occurs.
- "captured_request_headers" is a list of headers captured in the request due
to the presence of the "capture request header" statement in the frontend.
Multiple headers can be captured, they will be delimited by a vertical bar
('|'). When no capture is enabled, the braces do not appear, causing a
shift of remaining fields. It is important to note that this field may
contain spaces, and that using it requires a smarter log parser than when
it's not used. Please consult the section "Capturing HTTP headers and
cookies" below for more details.
- "captured_response_headers" is a list of headers captured in the response
due to the presence of the "capture response header" statement in the
frontend. Multiple headers can be captured, they will be delimited by a
vertical bar ('|'). When no capture is enabled, the braces do not appear,
causing a shift of remaining fields. It is important to note that this
field may contain spaces, and that using it requires a smarter log parser
than when it's not used. Please consult the section "Capturing HTTP headers
and cookies" below for more details.
- "http_request" is the complete HTTP request line, including the method,
request and HTTP version string. Non-printable characters are encoded (see
below the section "Non-printable characters"). This is always the last
field, and it is always delimited by quotes and is the only one which can
contain quotes. If new fields are added to the log format, they will be
added before this field. This field might be truncated if the request is
huge and does not fit in the standard syslog buffer (1024 characters). This
is the reason why this field must always remain the last one.
8.2.4. Custom log format
The directive log-format allows you to customize the logs in http mode and tcp
mode. It takes a string as argument.
HAProxy understands some log format variables. % precedes log format variables.
Variables can take arguments using braces ('{}'), and multiple arguments are
separated by commas within the braces. Flags may be added or removed by
prefixing them with a '+' or '-' sign.
Special variable "%o" may be used to propagate its flags to all other
variables on the same format string. This is particularly handy with quoted
("Q") and escaped ("E") string formats.
If a variable is named between square brackets ('[' .. ']') then it is used
as a sample expression rule (see section 7.3). This it useful to add some
less common information such as the client's SSL certificate's DN, or to log
the key that would be used to store an entry into a stick table.
Note: spaces must be escaped. In configuration directives "log-format",
"log-format-sd" and "unique-id-format", spaces are considered as
delimiters and are merged. In order to emit a verbatim '%', it must be
preceded by another '%' resulting in '%%'.
Note: when using the RFC5424 syslog message format, the characters '"',
'\' and ']' inside PARAM-VALUE should be escaped with '\' as prefix (see
https://tools.ietf.org/html/rfc5424#section-6.3.3 for more details). In
such cases, the use of the flag "E" should be considered.
Flags are :
* Q: quote a string
* X: hexadecimal representation (IPs, Ports, %Ts, %rt, %pid)
* E: escape characters '"', '\' and ']' in a string with '\' as prefix
(intended purpose is for the RFC5424 structured-data log formats)
Example:
log-format %T\ %t\ Some\ Text
log-format %{+Q}o\ %t\ %s\ %{-Q}r
log-format-sd %{+Q,+E}o\ [exampleSDID@1234\ header=%[capture.req.hdr(0)]]
At the moment, the default HTTP format is defined this way :
log-format "%ci:%cp [%tr] %ft %b/%s %TR/%Tw/%Tc/%Tr/%Ta %ST %B %CC \
%CS %tsc %ac/%fc/%bc/%sc/%rc %sq/%bq %hr %hs %{+Q}r"
the default CLF format is defined this way :
log-format "%{+Q}o %{-Q}ci - - [%trg] %r %ST %B \"\" \"\" %cp \
%ms %ft %b %s %TR %Tw %Tc %Tr %Ta %tsc %ac %fc \
%bc %sc %rc %sq %bq %CC %CS %hrl %hsl"
and the default TCP format is defined this way :
log-format "%ci:%cp [%t] %ft %b/%s %Tw/%Tc/%Tt %B %ts \
%ac/%fc/%bc/%sc/%rc %sq/%bq"
Please refer to the table below for currently defined variables :
+---+------+-----------------------------------------------+-------------+
| R | var | field name (8.2.2 and 8.2.3 for description) | type |
+---+------+-----------------------------------------------+-------------+
| | %o | special variable, apply flags on all next var | |
+---+------+-----------------------------------------------+-------------+
| | %B | bytes_read (from server to client) | numeric |
| H | %CC | captured_request_cookie | string |
| H | %CS | captured_response_cookie | string |
| | %H | hostname | string |
| H | %HM | HTTP method (ex: POST) | string |
| H | %HP | HTTP request URI without query string | string |
| H | %HPO | HTTP path only (without host nor query string)| string |
| H | %HQ | HTTP request URI query string (ex: ?bar=baz) | string |
| H | %HU | HTTP request URI (ex: /foo?bar=baz) | string |
| H | %HV | HTTP version (ex: HTTP/1.0) | string |
| | %ID | unique-id | string |
| | %ST | status_code | numeric |
| | %T | gmt_date_time | date |
| H | %Ta | Active time of the request (from TR to end) | numeric |
| | %Tc | Tc | numeric |
| | %Td | Td = Tt - (Tq + Tw + Tc + Tr) | numeric |
| | %Tl | local_date_time | date |
| | %Th | connection handshake time (SSL, PROXY proto) | numeric |
| H | %Ti | idle time before the HTTP request | numeric |
| H | %Tq | Th + Ti + TR | numeric |
| H | %TR | time to receive the full request from 1st byte| numeric |
| H | %Tr | Tr (response time) | numeric |
| | %Ts | timestamp | numeric |
| | %Tt | Tt | numeric |
| | %Tu | Tu | numeric |
| | %Tw | Tw | numeric |
| | %U | bytes_uploaded (from client to server) | numeric |
| | %ac | actconn | numeric |
| | %b | backend_name | string |
| | %bc | beconn (backend concurrent connections) | numeric |
| | %bi | backend_source_ip (connecting address) | IP |
| | %bp | backend_source_port (connecting address) | numeric |
| | %bq | backend_queue | numeric |
| | %ci | client_ip (accepted address) | IP |
| | %cp | client_port (accepted address) | numeric |
| | %f | frontend_name | string |
| | %fc | feconn (frontend concurrent connections) | numeric |
| | %fi | frontend_ip (accepting address) | IP |
| | %fp | frontend_port (accepting address) | numeric |
| | %ft | frontend_name_transport ('~' suffix for SSL) | string |
| | %lc | frontend_log_counter | numeric |
| | %hr | captured_request_headers default style | string |
| | %hrl | captured_request_headers CLF style | string list |
| | %hs | captured_response_headers default style | string |
| | %hsl | captured_response_headers CLF style | string list |
| | %ms | accept date milliseconds (left-padded with 0) | numeric |
| | %pid | PID | numeric |
| H | %r | http_request | string |
| | %rc | retries | numeric |
| | %rt | request_counter (HTTP req or TCP session) | numeric |
| | %s | server_name | string |
| | %sc | srv_conn (server concurrent connections) | numeric |
| | %si | server_IP (target address) | IP |
| | %sp | server_port (target address) | numeric |
| | %sq | srv_queue | numeric |
| S | %sslc| ssl_ciphers (ex: AES-SHA) | string |
| S | %sslv| ssl_version (ex: TLSv1) | string |
| | %t | date_time (with millisecond resolution) | date |
| H | %tr | date_time of HTTP request | date |
| H | %trg | gmt_date_time of start of HTTP request | date |
| H | %trl | local_date_time of start of HTTP request | date |
| | %ts | termination_state | string |
| H | %tsc | termination_state with cookie status | string |
+---+------+-----------------------------------------------+-------------+
R = Restrictions : H = mode http only ; S = SSL only
8.2.5. Error log format
When an incoming connection fails due to an SSL handshake or an invalid PROXY
protocol header, HAProxy will log the event using a shorter, fixed line format.
By default, logs are emitted at the LOG_INFO level, unless the option
"log-separate-errors" is set in the backend, in which case the LOG_ERR level
will be used. Connections on which no data are exchanged (e.g. probes) are not
logged if the "dontlognull" option is set.
The format looks like this :
>>> Dec 3 18:27:14 localhost \
haproxy[6103]: 127.0.0.1:56059 [03/Dec/2012:17:35:10.380] frt/f1: \
Connection error during SSL handshake
Field Format Extract from the example above
1 process_name '[' pid ']:' haproxy[6103]:
2 client_ip ':' client_port 127.0.0.1:56059
3 '[' accept_date ']' [03/Dec/2012:17:35:10.380]
4 frontend_name "/" bind_name ":" frt/f1:
5 message Connection error during SSL handshake
These fields just provide minimal information to help debugging connection
failures.
8.3. Advanced logging options
Some advanced logging options are often looked for but are not easy to find out
just by looking at the various options. Here is an entry point for the few
options which can enable better logging. Please refer to the keywords reference
for more information about their usage.
8.3.1. Disabling logging of external tests
It is quite common to have some monitoring tools perform health checks on
HAProxy. Sometimes it will be a layer 3 load-balancer such as LVS or any
commercial load-balancer, and sometimes it will simply be a more complete
monitoring system such as Nagios. When the tests are very frequent, users often
ask how to disable logging for those checks. There are three possibilities :
- if connections come from everywhere and are just TCP probes, it is often
desired to simply disable logging of connections without data exchange, by
setting "option dontlognull" in the frontend. It also disables logging of
port scans, which may or may not be desired.
- it is possible to use the "http-request set-log-level silent" action using
a variety of conditions (source networks, paths, user-agents, etc).
- if the tests are performed on a known URI, use "monitor-uri" to declare
this URI as dedicated to monitoring. Any host sending this request will
only get the result of a health-check, and the request will not be logged.
8.3.2. Logging before waiting for the session to terminate
The problem with logging at end of connection is that you have no clue about
what is happening during very long sessions, such as remote terminal sessions
or large file downloads. This problem can be worked around by specifying
"option logasap" in the frontend. HAProxy will then log as soon as possible,
just before data transfer begins. This means that in case of TCP, it will still
log the connection status to the server, and in case of HTTP, it will log just
after processing the server headers. In this case, the number of bytes reported
is the number of header bytes sent to the client. In order to avoid confusion
with normal logs, the total time field and the number of bytes are prefixed
with a '+' sign which means that real numbers are certainly larger.
8.3.3. Raising log level upon errors
Sometimes it is more convenient to separate normal traffic from errors logs,
for instance in order to ease error monitoring from log files. When the option
"log-separate-errors" is used, connections which experience errors, timeouts,
retries, redispatches or HTTP status codes 5xx will see their syslog level
raised from "info" to "err". This will help a syslog daemon store the log in
a separate file. It is very important to keep the errors in the normal traffic
file too, so that log ordering is not altered. You should also be careful if
you already have configured your syslog daemon to store all logs higher than
"notice" in an "admin" file, because the "err" level is higher than "notice".
8.3.4. Disabling logging of successful connections
Although this may sound strange at first, some large sites have to deal with
multiple thousands of logs per second and are experiencing difficulties keeping
them intact for a long time or detecting errors within them. If the option
"dontlog-normal" is set on the frontend, all normal connections will not be
logged. In this regard, a normal connection is defined as one without any
error, timeout, retry nor redispatch. In HTTP, the status code is checked too,
and a response with a status 5xx is not considered normal and will be logged
too. Of course, doing is is really discouraged as it will remove most of the
useful information from the logs. Do this only if you have no other
alternative.
8.4. Timing events
Timers provide a great help in troubleshooting network problems. All values are
reported in milliseconds (ms). These timers should be used in conjunction with
the session termination flags. In TCP mode with "option tcplog" set on the
frontend, 3 control points are reported under the form "Tw/Tc/Tt", and in HTTP
mode, 5 control points are reported under the form "TR/Tw/Tc/Tr/Ta". In
addition, three other measures are provided, "Th", "Ti", and "Tq".
Timings events in HTTP mode:
first request 2nd request
|<-------------------------------->|<-------------- ...
t tr t tr ...
---|----|----|----|----|----|----|----|----|--
: Th Ti TR Tw Tc Tr Td : Ti ...
:<---- Tq ---->: :
:<-------------- Tt -------------->:
:<-- -----Tu--------------->:
:<--------- Ta --------->:
Timings events in TCP mode:
TCP session
|<----------------->|
t t
---|----|----|----|----|---
| Th Tw Tc Td |
|<------ Tt ------->|
- Th: total time to accept tcp connection and execute handshakes for low level
protocols. Currently, these protocols are proxy-protocol and SSL. This may
only happen once during the whole connection's lifetime. A large time here
may indicate that the client only pre-established the connection without
speaking, that it is experiencing network issues preventing it from
completing a handshake in a reasonable time (e.g. MTU issues), or that an
SSL handshake was very expensive to compute. Please note that this time is
reported only before the first request, so it is safe to average it over
all request to calculate the amortized value. The second and subsequent
request will always report zero here.
- Ti: is the idle time before the HTTP request (HTTP mode only). This timer
counts between the end of the handshakes and the first byte of the HTTP
request. When dealing with a second request in keep-alive mode, it starts
to count after the end of the transmission the previous response. When a
multiplexed protocol such as HTTP/2 is used, it starts to count immediately
after the previous request. Some browsers pre-establish connections to a
server in order to reduce the latency of a future request, and keep them
pending until they need it. This delay will be reported as the idle time. A
value of -1 indicates that nothing was received on the connection.
- TR: total time to get the client request (HTTP mode only). It's the time
elapsed between the first bytes received and the moment the proxy received
the empty line marking the end of the HTTP headers. The value "-1"
indicates that the end of headers has never been seen. This happens when
the client closes prematurely or times out. This time is usually very short
since most requests fit in a single packet. A large time may indicate a
request typed by hand during a test.
- Tq: total time to get the client request from the accept date or since the
emission of the last byte of the previous response (HTTP mode only). It's
exactly equal to Th + Ti + TR unless any of them is -1, in which case it
returns -1 as well. This timer used to be very useful before the arrival of
HTTP keep-alive and browsers' pre-connect feature. It's recommended to drop
it in favor of TR nowadays, as the idle time adds a lot of noise to the
reports.
- Tw: total time spent in the queues waiting for a connection slot. It
accounts for backend queue as well as the server queues, and depends on the
queue size, and the time needed for the server to complete previous
requests. The value "-1" means that the request was killed before reaching
the queue, which is generally what happens with invalid or denied requests.
- Tc: total time to establish the TCP connection to the server. It's the time
elapsed between the moment the proxy sent the connection request, and the
moment it was acknowledged by the server, or between the TCP SYN packet and
the matching SYN/ACK packet in return. The value "-1" means that the
connection never established.
- Tr: server response time (HTTP mode only). It's the time elapsed between
the moment the TCP connection was established to the server and the moment
the server sent its complete response headers. It purely shows its request
processing time, without the network overhead due to the data transmission.
It is worth noting that when the client has data to send to the server, for
instance during a POST request, the time already runs, and this can distort
apparent response time. For this reason, it's generally wise not to trust
too much this field for POST requests initiated from clients behind an
untrusted network. A value of "-1" here means that the last the response
header (empty line) was never seen, most likely because the server timeout
stroke before the server managed to process the request.
- Td: this is the total transfer time of the response payload till the last
byte sent to the client. In HTTP it starts after the last response header
(after Tr).
The data sent are not guaranteed to be received by the client, they can be
stuck in either the kernel or the network.
- Ta: total active time for the HTTP request, between the moment the proxy
received the first byte of the request header and the emission of the last
byte of the response body. The exception is when the "logasap" option is
specified. In this case, it only equals (TR+Tw+Tc+Tr), and is prefixed with
a '+' sign. From this field, we can deduce "Td", the data transmission time,
by subtracting other timers when valid :
Td = Ta - (TR + Tw + Tc + Tr)
Timers with "-1" values have to be excluded from this equation. Note that
"Ta" can never be negative.
- Tt: total session duration time, between the moment the proxy accepted it
and the moment both ends were closed. The exception is when the "logasap"
option is specified. In this case, it only equals (Th+Ti+TR+Tw+Tc+Tr), and
is prefixed with a '+' sign. From this field, we can deduce "Td", the data
transmission time, by subtracting other timers when valid :
Td = Tt - (Th + Ti + TR + Tw + Tc + Tr)
Timers with "-1" values have to be excluded from this equation. In TCP
mode, "Ti", "Tq" and "Tr" have to be excluded too. Note that "Tt" can never
be negative and that for HTTP, Tt is simply equal to (Th+Ti+Ta).
- Tu: total estimated time as seen from client, between the moment the proxy
accepted it and the moment both ends were closed, without idle time.
This is useful to roughly measure end-to-end time as a user would see it,
without idle time pollution from keep-alive time between requests. This
timer in only an estimation of time seen by user as it assumes network
latency is the same in both directions. The exception is when the "logasap"
option is specified. In this case, it only equals (Th+TR+Tw+Tc+Tr), and is
prefixed with a '+' sign.
These timers provide precious indications on trouble causes. Since the TCP
protocol defines retransmit delays of 3, 6, 12... seconds, we know for sure
that timers close to multiples of 3s are nearly always related to lost packets
due to network problems (wires, negotiation, congestion). Moreover, if "Ta" or
"Tt" is close to a timeout value specified in the configuration, it often means
that a session has been aborted on timeout.
Most common cases :
- If "Th" or "Ti" are close to 3000, a packet has probably been lost between
the client and the proxy. This is very rare on local networks but might
happen when clients are on far remote networks and send large requests. It
may happen that values larger than usual appear here without any network
cause. Sometimes, during an attack or just after a resource starvation has
ended, HAProxy may accept thousands of connections in a few milliseconds.
The time spent accepting these connections will inevitably slightly delay
processing of other connections, and it can happen that request times in the
order of a few tens of milliseconds are measured after a few thousands of
new connections have been accepted at once. Using one of the keep-alive
modes may display larger idle times since "Ti" measures the time spent
waiting for additional requests.
- If "Tc" is close to 3000, a packet has probably been lost between the
server and the proxy during the server connection phase. This value should
always be very low, such as 1 ms on local networks and less than a few tens
of ms on remote networks.
- If "Tr" is nearly always lower than 3000 except some rare values which seem
to be the average majored by 3000, there are probably some packets lost
between the proxy and the server.
- If "Ta" is large even for small byte counts, it generally is because
neither the client nor the server decides to close the connection while
HAProxy is running in tunnel mode and both have agreed on a keep-alive
connection mode. In order to solve this issue, it will be needed to specify
one of the HTTP options to manipulate keep-alive or close options on either
the frontend or the backend. Having the smallest possible 'Ta' or 'Tt' is
important when connection regulation is used with the "maxconn" option on
the servers, since no new connection will be sent to the server until
another one is released.
Other noticeable HTTP log cases ('xx' means any value to be ignored) :
TR/Tw/Tc/Tr/+Ta The "option logasap" is present on the frontend and the log
was emitted before the data phase. All the timers are valid
except "Ta" which is shorter than reality.
-1/xx/xx/xx/Ta The client was not able to send a complete request in time
or it aborted too early. Check the session termination flags
then "timeout http-request" and "timeout client" settings.
TR/-1/xx/xx/Ta It was not possible to process the request, maybe because
servers were out of order, because the request was invalid
or forbidden by ACL rules. Check the session termination
flags.
TR/Tw/-1/xx/Ta The connection could not establish on the server. Either it
actively refused it or it timed out after Ta-(TR+Tw) ms.
Check the session termination flags, then check the
"timeout connect" setting. Note that the tarpit action might
return similar-looking patterns, with "Tw" equal to the time
the client connection was maintained open.
TR/Tw/Tc/-1/Ta The server has accepted the connection but did not return
a complete response in time, or it closed its connection
unexpectedly after Ta-(TR+Tw+Tc) ms. Check the session
termination flags, then check the "timeout server" setting.
8.5. Session state at disconnection
TCP and HTTP logs provide a session termination indicator in the
"termination_state" field, just before the number of active connections. It is
2-characters long in TCP mode, and is extended to 4 characters in HTTP mode,
each of which has a special meaning :
- On the first character, a code reporting the first event which caused the
session to terminate :
C : the TCP session was unexpectedly aborted by the client.
S : the TCP session was unexpectedly aborted by the server, or the
server explicitly refused it.
P : the session was prematurely aborted by the proxy, because of a
connection limit enforcement, because a DENY filter was matched,
because of a security check which detected and blocked a dangerous
error in server response which might have caused information leak
(e.g. cacheable cookie).
L : the session was locally processed by HAProxy.
R : a resource on the proxy has been exhausted (memory, sockets, source
ports, ...). Usually, this appears during the connection phase, and
system logs should contain a copy of the precise error. If this
happens, it must be considered as a very serious anomaly which
should be fixed as soon as possible by any means.
I : an internal error was identified by the proxy during a self-check.
This should NEVER happen, and you are encouraged to report any log
containing this, because this would almost certainly be a bug. It
would be wise to preventively restart the process after such an
event too, in case it would be caused by memory corruption.
D : the session was killed by HAProxy because the server was detected
as down and was configured to kill all connections when going down.
U : the session was killed by HAProxy on this backup server because an
active server was detected as up and was configured to kill all
backup connections when going up.
K : the session was actively killed by an admin operating on HAProxy.
c : the client-side timeout expired while waiting for the client to
send or receive data.
s : the server-side timeout expired while waiting for the server to
send or receive data.
- : normal session completion, both the client and the server closed
with nothing left in the buffers.
- on the second character, the TCP or HTTP session state when it was closed :
R : the proxy was waiting for a complete, valid REQUEST from the client
(HTTP mode only). Nothing was sent to any server.
Q : the proxy was waiting in the QUEUE for a connection slot. This can
only happen when servers have a 'maxconn' parameter set. It can
also happen in the global queue after a redispatch consecutive to
a failed attempt to connect to a dying server. If no redispatch is
reported, then no connection attempt was made to any server.
C : the proxy was waiting for the CONNECTION to establish on the
server. The server might at most have noticed a connection attempt.
H : the proxy was waiting for complete, valid response HEADERS from the
server (HTTP only).
D : the session was in the DATA phase.
L : the proxy was still transmitting LAST data to the client while the
server had already finished. This one is very rare as it can only
happen when the client dies while receiving the last packets.
T : the request was tarpitted. It has been held open with the client
during the whole "timeout tarpit" duration or until the client
closed, both of which will be reported in the "Tw" timer.
- : normal session completion after end of data transfer.
- the third character tells whether the persistence cookie was provided by
the client (only in HTTP mode) :
N : the client provided NO cookie. This is usually the case for new
visitors, so counting the number of occurrences of this flag in the
logs generally indicate a valid trend for the site frequentation.
I : the client provided an INVALID cookie matching no known server.
This might be caused by a recent configuration change, mixed
cookies between HTTP/HTTPS sites, persistence conditionally
ignored, or an attack.
D : the client provided a cookie designating a server which was DOWN,
so either "option persist" was used and the client was sent to
this server, or it was not set and the client was redispatched to
another server.
V : the client provided a VALID cookie, and was sent to the associated
server.
E : the client provided a valid cookie, but with a last date which was
older than what is allowed by the "maxidle" cookie parameter, so
the cookie is consider EXPIRED and is ignored. The request will be
redispatched just as if there was no cookie.
O : the client provided a valid cookie, but with a first date which was
older than what is allowed by the "maxlife" cookie parameter, so
the cookie is consider too OLD and is ignored. The request will be
redispatched just as if there was no cookie.
U : a cookie was present but was not used to select the server because
some other server selection mechanism was used instead (typically a
"use-server" rule).
- : does not apply (no cookie set in configuration).
- the last character reports what operations were performed on the persistence
cookie returned by the server (only in HTTP mode) :
N : NO cookie was provided by the server, and none was inserted either.
I : no cookie was provided by the server, and the proxy INSERTED one.
Note that in "cookie insert" mode, if the server provides a cookie,
it will still be overwritten and reported as "I" here.
U : the proxy UPDATED the last date in the cookie that was presented by
the client. This can only happen in insert mode with "maxidle". It
happens every time there is activity at a different date than the
date indicated in the cookie. If any other change happens, such as
a redispatch, then the cookie will be marked as inserted instead.
P : a cookie was PROVIDED by the server and transmitted as-is.
R : the cookie provided by the server was REWRITTEN by the proxy, which
happens in "cookie rewrite" or "cookie prefix" modes.
D : the cookie provided by the server was DELETED by the proxy.
- : does not apply (no cookie set in configuration).
The combination of the two first flags gives a lot of information about what
was happening when the session terminated, and why it did terminate. It can be
helpful to detect server saturation, network troubles, local system resource
starvation, attacks, etc...
The most common termination flags combinations are indicated below. They are
alphabetically sorted, with the lowercase set just after the upper case for
easier finding and understanding.
Flags Reason
-- Normal termination.
CC The client aborted before the connection could be established to the
server. This can happen when HAProxy tries to connect to a recently
dead (or unchecked) server, and the client aborts while HAProxy is
waiting for the server to respond or for "timeout connect" to expire.
CD The client unexpectedly aborted during data transfer. This can be
caused by a browser crash, by an intermediate equipment between the
client and HAProxy which decided to actively break the connection,
by network routing issues between the client and HAProxy, or by a
keep-alive session between the server and the client terminated first
by the client.
cD The client did not send nor acknowledge any data for as long as the
"timeout client" delay. This is often caused by network failures on
the client side, or the client simply leaving the net uncleanly.
CH The client aborted while waiting for the server to start responding.
It might be the server taking too long to respond or the client
clicking the 'Stop' button too fast.
cH The "timeout client" stroke while waiting for client data during a
POST request. This is sometimes caused by too large TCP MSS values
for PPPoE networks which cannot transport full-sized packets. It can
also happen when client timeout is smaller than server timeout and
the server takes too long to respond.
CQ The client aborted while its session was queued, waiting for a server
with enough empty slots to accept it. It might be that either all the
servers were saturated or that the assigned server was taking too
long a time to respond.
CR The client aborted before sending a full HTTP request. Most likely
the request was typed by hand using a telnet client, and aborted
too early. The HTTP status code is likely a 400 here. Sometimes this
might also be caused by an IDS killing the connection between HAProxy
and the client. "option http-ignore-probes" can be used to ignore
connections without any data transfer.
cR The "timeout http-request" stroke before the client sent a full HTTP
request. This is sometimes caused by too large TCP MSS values on the
client side for PPPoE networks which cannot transport full-sized
packets, or by clients sending requests by hand and not typing fast
enough, or forgetting to enter the empty line at the end of the
request. The HTTP status code is likely a 408 here. Note: recently,
some browsers started to implement a "pre-connect" feature consisting
in speculatively connecting to some recently visited web sites just
in case the user would like to visit them. This results in many
connections being established to web sites, which end up in 408
Request Timeout if the timeout strikes first, or 400 Bad Request when
the browser decides to close them first. These ones pollute the log
and feed the error counters. Some versions of some browsers have even
been reported to display the error code. It is possible to work
around the undesirable effects of this behavior by adding "option
http-ignore-probes" in the frontend, resulting in connections with
zero data transfer to be totally ignored. This will definitely hide
the errors of people experiencing connectivity issues though.
CT The client aborted while its session was tarpitted. It is important to
check if this happens on valid requests, in order to be sure that no
wrong tarpit rules have been written. If a lot of them happen, it
might make sense to lower the "timeout tarpit" value to something
closer to the average reported "Tw" timer, in order not to consume
resources for just a few attackers.
LC The request was intercepted and locally handled by HAProxy. The
request was not sent to the server. It only happens with a redirect
because of a "redir" parameter on the server line.
LR The request was intercepted and locally handled by HAProxy. The
request was not sent to the server. Generally it means a redirect was
returned, an HTTP return statement was processed or the request was
handled by an applet (stats, cache, Prometheus exported, lua applet...).
LH The response was intercepted and locally handled by HAProxy. Generally
it means a redirect was returned or an HTTP return statement was
processed.
SC The server or an equipment between it and HAProxy explicitly refused
the TCP connection (the proxy received a TCP RST or an ICMP message
in return). Under some circumstances, it can also be the network
stack telling the proxy that the server is unreachable (e.g. no route,
or no ARP response on local network). When this happens in HTTP mode,
the status code is likely a 502 or 503 here.
sC The "timeout connect" stroke before a connection to the server could
complete. When this happens in HTTP mode, the status code is likely a
503 or 504 here.
SD The connection to the server died with an error during the data
transfer. This usually means that HAProxy has received an RST from
the server or an ICMP message from an intermediate equipment while
exchanging data with the server. This can be caused by a server crash
or by a network issue on an intermediate equipment.
sD The server did not send nor acknowledge any data for as long as the
"timeout server" setting during the data phase. This is often caused
by too short timeouts on L4 equipment before the server (firewalls,
load-balancers, ...), as well as keep-alive sessions maintained
between the client and the server expiring first on HAProxy.
SH The server aborted before sending its full HTTP response headers, or
it crashed while processing the request. Since a server aborting at
this moment is very rare, it would be wise to inspect its logs to
control whether it crashed and why. The logged request may indicate a
small set of faulty requests, demonstrating bugs in the application.
Sometimes this might also be caused by an IDS killing the connection
between HAProxy and the server.
sH The "timeout server" stroke before the server could return its
response headers. This is the most common anomaly, indicating too
long transactions, probably caused by server or database saturation.
The immediate workaround consists in increasing the "timeout server"
setting, but it is important to keep in mind that the user experience
will suffer from these long response times. The only long term
solution is to fix the application.
sQ The session spent too much time in queue and has been expired. See
the "timeout queue" and "timeout connect" settings to find out how to
fix this if it happens too often. If it often happens massively in
short periods, it may indicate general problems on the affected
servers due to I/O or database congestion, or saturation caused by
external attacks.
PC The proxy refused to establish a connection to the server because the
process's socket limit has been reached while attempting to connect.
The global "maxconn" parameter may be increased in the configuration
so that it does not happen anymore. This status is very rare and
might happen when the global "ulimit-n" parameter is forced by hand.
PD The proxy blocked an incorrectly formatted chunked encoded message in
a request or a response, after the server has emitted its headers. In
most cases, this will indicate an invalid message from the server to
the client. HAProxy supports chunk sizes of up to 2GB - 1 (2147483647
bytes). Any larger size will be considered as an error.
PH The proxy blocked the server's response, because it was invalid,
incomplete, dangerous (cache control), or matched a security filter.
In any case, an HTTP 502 error is sent to the client. One possible
cause for this error is an invalid syntax in an HTTP header name
containing unauthorized characters. It is also possible but quite
rare, that the proxy blocked a chunked-encoding request from the
client due to an invalid syntax, before the server responded. In this
case, an HTTP 400 error is sent to the client and reported in the
logs. Finally, it may be due to an HTTP header rewrite failure on the
response. In this case, an HTTP 500 error is sent (see
"tune.maxrewrite" and "http-response strict-mode" for more
inforomation).
PR The proxy blocked the client's HTTP request, either because of an
invalid HTTP syntax, in which case it returned an HTTP 400 error to
the client, or because a deny filter matched, in which case it
returned an HTTP 403 error. It may also be due to an HTTP header
rewrite failure on the request. In this case, an HTTP 500 error is
sent (see "tune.maxrewrite" and "http-request strict-mode" for more
inforomation).
PT The proxy blocked the client's request and has tarpitted its
connection before returning it a 500 server error. Nothing was sent
to the server. The connection was maintained open for as long as
reported by the "Tw" timer field.
RC A local resource has been exhausted (memory, sockets, source ports)
preventing the connection to the server from establishing. The error
logs will tell precisely what was missing. This is very rare and can
only be solved by proper system tuning.
The combination of the two last flags gives a lot of information about how
persistence was handled by the client, the server and by HAProxy. This is very
important to troubleshoot disconnections, when users complain they have to
re-authenticate. The commonly encountered flags are :
-- Persistence cookie is not enabled.
NN No cookie was provided by the client, none was inserted in the
response. For instance, this can be in insert mode with "postonly"
set on a GET request.
II A cookie designating an invalid server was provided by the client,
a valid one was inserted in the response. This typically happens when
a "server" entry is removed from the configuration, since its cookie
value can be presented by a client when no other server knows it.
NI No cookie was provided by the client, one was inserted in the
response. This typically happens for first requests from every user
in "insert" mode, which makes it an easy way to count real users.
VN A cookie was provided by the client, none was inserted in the
response. This happens for most responses for which the client has
already got a cookie.
VU A cookie was provided by the client, with a last visit date which is
not completely up-to-date, so an updated cookie was provided in
response. This can also happen if there was no date at all, or if
there was a date but the "maxidle" parameter was not set, so that the
cookie can be switched to unlimited time.
EI A cookie was provided by the client, with a last visit date which is
too old for the "maxidle" parameter, so the cookie was ignored and a
new cookie was inserted in the response.
OI A cookie was provided by the client, with a first visit date which is
too old for the "maxlife" parameter, so the cookie was ignored and a
new cookie was inserted in the response.
DI The server designated by the cookie was down, a new server was
selected and a new cookie was emitted in the response.
VI The server designated by the cookie was not marked dead but could not
be reached. A redispatch happened and selected another one, which was
then advertised in the response.
8.6. Non-printable characters
In order not to cause trouble to log analysis tools or terminals during log
consulting, non-printable characters are not sent as-is into log files, but are
converted to the two-digits hexadecimal representation of their ASCII code,
prefixed by the character '#'. The only characters that can be logged without
being escaped are comprised between 32 and 126 (inclusive). Obviously, the
escape character '#' itself is also encoded to avoid any ambiguity ("#23"). It
is the same for the character '"' which becomes "#22", as well as '{', '|' and
'}' when logging headers.
Note that the space character (' ') is not encoded in headers, which can cause
issues for tools relying on space count to locate fields. A typical header
containing spaces is "User-Agent".
Last, it has been observed that some syslog daemons such as syslog-ng escape
the quote ('"') with a backslash ('\'). The reverse operation can safely be
performed since no quote may appear anywhere else in the logs.
8.7. Capturing HTTP cookies
Cookie capture simplifies the tracking a complete user session. This can be
achieved using the "capture cookie" statement in the frontend. Please refer to
section 4.2 for more details. Only one cookie can be captured, and the same
cookie will simultaneously be checked in the request ("Cookie:" header) and in
the response ("Set-Cookie:" header). The respective values will be reported in
the HTTP logs at the "captured_request_cookie" and "captured_response_cookie"
locations (see section 8.2.3 about HTTP log format). When either cookie is
not seen, a dash ('-') replaces the value. This way, it's easy to detect when a
user switches to a new session for example, because the server will reassign it
a new cookie. It is also possible to detect if a server unexpectedly sets a
wrong cookie to a client, leading to session crossing.
Examples :
# capture the first cookie whose name starts with "ASPSESSION"
capture cookie ASPSESSION len 32
# capture the first cookie whose name is exactly "vgnvisitor"
capture cookie vgnvisitor= len 32
8.8. Capturing HTTP headers
Header captures are useful to track unique request identifiers set by an upper
proxy, virtual host names, user-agents, POST content-length, referrers, etc. In
the response, one can search for information about the response length, how the
server asked the cache to behave, or an object location during a redirection.
Header captures are performed using the "capture request header" and "capture
response header" statements in the frontend. Please consult their definition in
section 4.2 for more details.
It is possible to include both request headers and response headers at the same
time. Non-existent headers are logged as empty strings, and if one header
appears more than once, only its last occurrence will be logged. Request headers
are grouped within braces '{' and '}' in the same order as they were declared,
and delimited with a vertical bar '|' without any space. Response headers
follow the same representation, but are displayed after a space following the
request headers block. These blocks are displayed just before the HTTP request
in the logs.
As a special case, it is possible to specify an HTTP header capture in a TCP
frontend. The purpose is to enable logging of headers which will be parsed in
an HTTP backend if the request is then switched to this HTTP backend.
Example :
# This instance chains to the outgoing proxy
listen proxy-out
mode http
option httplog
option logasap
log global
server cache1 192.168.1.1:3128
# log the name of the virtual server
capture request header Host len 20
# log the amount of data uploaded during a POST
capture request header Content-Length len 10
# log the beginning of the referrer
capture request header Referer len 20
# server name (useful for outgoing proxies only)
capture response header Server len 20
# logging the content-length is useful with "option logasap"
capture response header Content-Length len 10
# log the expected cache behavior on the response
capture response header Cache-Control len 8
# the Via header will report the next proxy's name
capture response header Via len 20
# log the URL location during a redirection
capture response header Location len 20
>>> Aug 9 20:26:09 localhost \
haproxy[2022]: 127.0.0.1:34014 [09/Aug/2004:20:26:09] proxy-out \
proxy-out/cache1 0/0/0/162/+162 200 +350 - - ---- 0/0/0/0/0 0/0 \
{fr.adserver.yahoo.co||http://fr.f416.mail.} {|864|private||} \
"GET http://fr.adserver.yahoo.com/"
>>> Aug 9 20:30:46 localhost \
haproxy[2022]: 127.0.0.1:34020 [09/Aug/2004:20:30:46] proxy-out \
proxy-out/cache1 0/0/0/182/+182 200 +279 - - ---- 0/0/0/0/0 0/0 \
{w.ods.org||} {Formilux/0.1.8|3495|||} \
"GET http://trafic.1wt.eu/ HTTP/1.1"
>>> Aug 9 20:30:46 localhost \
haproxy[2022]: 127.0.0.1:34028 [09/Aug/2004:20:30:46] proxy-out \
proxy-out/cache1 0/0/2/126/+128 301 +223 - - ---- 0/0/0/0/0 0/0 \
{www.sytadin.equipement.gouv.fr||http://trafic.1wt.eu/} \
{Apache|230|||http://www.sytadin.} \
"GET http://www.sytadin.equipement.gouv.fr/ HTTP/1.1"
8.9. Examples of logs
These are real-world examples of logs accompanied with an explanation. Some of
them have been made up by hand. The syslog part has been removed for better
reading. Their sole purpose is to explain how to decipher them.
>>> haproxy[674]: 127.0.0.1:33318 [15/Oct/2003:08:31:57.130] px-http \
px-http/srv1 6559/0/7/147/6723 200 243 - - ---- 5/3/3/1/0 0/0 \
"HEAD / HTTP/1.0"
=> long request (6.5s) entered by hand through 'telnet'. The server replied
in 147 ms, and the session ended normally ('----')
>>> haproxy[674]: 127.0.0.1:33319 [15/Oct/2003:08:31:57.149] px-http \
px-http/srv1 6559/1230/7/147/6870 200 243 - - ---- 324/239/239/99/0 \
0/9 "HEAD / HTTP/1.0"
=> Idem, but the request was queued in the global queue behind 9 other
requests, and waited there for 1230 ms.
>>> haproxy[674]: 127.0.0.1:33320 [15/Oct/2003:08:32:17.654] px-http \
px-http/srv1 9/0/7/14/+30 200 +243 - - ---- 3/3/3/1/0 0/0 \
"GET /image.iso HTTP/1.0"
=> request for a long data transfer. The "logasap" option was specified, so
the log was produced just before transferring data. The server replied in
14 ms, 243 bytes of headers were sent to the client, and total time from
accept to first data byte is 30 ms.
>>> haproxy[674]: 127.0.0.1:33320 [15/Oct/2003:08:32:17.925] px-http \
px-http/srv1 9/0/7/14/30 502 243 - - PH-- 3/2/2/0/0 0/0 \
"GET /cgi-bin/bug.cgi? HTTP/1.0"
=> the proxy blocked a server response either because of an "http-response
deny" rule, or because the response was improperly formatted and not
HTTP-compliant, or because it blocked sensitive information which risked
being cached. In this case, the response is replaced with a "502 bad
gateway". The flags ("PH--") tell us that it was HAProxy who decided to
return the 502 and not the server.
>>> haproxy[18113]: 127.0.0.1:34548 [15/Oct/2003:15:18:55.798] px-http \
px-http/<NOSRV> -1/-1/-1/-1/8490 -1 0 - - CR-- 2/2/2/0/0 0/0 ""
=> the client never completed its request and aborted itself ("C---") after
8.5s, while the proxy was waiting for the request headers ("-R--").
Nothing was sent to any server.
>>> haproxy[18113]: 127.0.0.1:34549 [15/Oct/2003:15:19:06.103] px-http \
px-http/<NOSRV> -1/-1/-1/-1/50001 408 0 - - cR-- 2/2/2/0/0 0/0 ""
=> The client never completed its request, which was aborted by the
time-out ("c---") after 50s, while the proxy was waiting for the request
headers ("-R--"). Nothing was sent to any server, but the proxy could
send a 408 return code to the client.
>>> haproxy[18989]: 127.0.0.1:34550 [15/Oct/2003:15:24:28.312] px-tcp \
px-tcp/srv1 0/0/5007 0 cD 0/0/0/0/0 0/0
=> This log was produced with "option tcplog". The client timed out after
5 seconds ("c----").
>>> haproxy[18989]: 10.0.0.1:34552 [15/Oct/2003:15:26:31.462] px-http \
px-http/srv1 3183/-1/-1/-1/11215 503 0 - - SC-- 205/202/202/115/3 \
0/0 "HEAD / HTTP/1.0"
=> The request took 3s to complete (probably a network problem), and the
connection to the server failed ('SC--') after 4 attempts of 2 seconds
(config says 'retries 3'), and no redispatch (otherwise we would have
seen "/+3"). Status code 503 was returned to the client. There were 115
connections on this server, 202 connections on this proxy, and 205 on
the global process. It is possible that the server refused the
connection because of too many already established.
9. Supported filters
Here are listed officially supported filters with the list of parameters they
accept. Depending on compile options, some of these filters might be
unavailable. The list of available filters is reported in haproxy -vv.
See also : "filter"
9.1. Trace
Arguments:
<name> is an arbitrary name that will be reported in
messages. If no name is provided, "TRACE" is used.
<quiet> inhibits trace messages.
<random-forwarding> enables the random forwarding of parsed data. By
default, this filter forwards all previously parsed
data. With this parameter, it only forwards a random
amount of the parsed data.
<hexdump> dumps all forwarded data to the server and the client.
This filter can be used as a base to develop new filters. It defines all
callbacks and print a message on the standard error stream (stderr) with useful
information for all of them. It may be useful to debug the activity of other
filters or, quite simply, HAProxy's activity.
Using <random-parsing> and/or <random-forwarding> parameters is a good way to
tests the behavior of a filter that parses data exchanged between a client and
a server by adding some latencies in the processing.
9.2. HTTP compression
The HTTP compression has been moved in a filter in HAProxy 1.7. "compression"
keyword must still be used to enable and configure the HTTP compression. And
when no other filter is used, it is enough. When used with the cache or the
fcgi-app enabled, it is also enough. In this case, the compression is always
done after the response is stored in the cache. But it is mandatory to
explicitly use a filter line to enable the HTTP compression when at least one
filter other than the cache or the fcgi-app is used for the same
listener/frontend/backend. This is important to know the filters evaluation
order.
See also : "compression", section 9.4 about the cache filter and section 9.5 about the fcgi-app filter.
9.3. Stream Processing Offload Engine (SPOE)
Arguments :
<name> is the engine name that will be used to find the right scope in
the configuration file. If not provided, all the file will be
parsed.
<file> is the path of the engine configuration file. This file can
contain configuration of several engines. In this case, each
part must be placed in its own scope.
The Stream Processing Offload Engine (SPOE) is a filter communicating with
external components. It allows the offload of some specifics processing on the
streams in tiered applications. These external components and information
exchanged with them are configured in dedicated files, for the main part. It
also requires dedicated backends, defined in HAProxy configuration.
SPOE communicates with external components using an in-house binary protocol,
the Stream Processing Offload Protocol (SPOP).
For all information about the SPOE configuration and the SPOP specification, see
"doc/SPOE.txt".
9.4. Cache
Arguments :
<name> is name of the cache section this filter will use.
The cache uses a filter to store cacheable responses. The HTTP rules
"cache-store" and "cache-use" must be used to define how and when to use a
cache. By default the corresponding filter is implicitly defined. And when no
other filters than fcgi-app or compression are used, it is enough. In such
case, the compression filter is always evaluated after the cache filter. But it
is mandatory to explicitly use a filter line to use a cache when at least one
filter other than the compression or the fcgi-app is used for the same
listener/frontend/backend. This is important to know the filters evaluation
order.
See also : section 9.2 about the compression filter, section 9.5 about the fcgi-app filter and section 6 about cache.
9.5. Fcgi-app
Arguments :
<name> is name of the fcgi-app section this filter will use.
The FastCGI application uses a filter to evaluate all custom parameters on the
request path, and to process the headers on the response path. the <name> must
reference an existing fcgi-app section. The directive "use-fcgi-app" should be
used to define the application to use. By default the corresponding filter is
implicitly defined. And when no other filters than cache or compression are
used, it is enough. But it is mandatory to explicitly use a filter line to a
fcgi-app when at least one filter other than the compression or the cache is
used for the same backend. This is important to know the filters evaluation
order.
See also: "use-fcgi-app", section 9.2 about the compression filter, section 9.4 about the cache filter and section 10 about FastCGI application.
9.6. OpenTracing
The OpenTracing filter adds native support for using distributed tracing in
HAProxy. This is enabled by sending an OpenTracing compliant request to one
of the supported tracers such as Datadog, Jaeger, Lightstep and Zipkin tracers.
Please note: tracers are not listed by any preference, but alphabetically.
This feature is only enabled when HAProxy was built with USE_OT=1.
The OpenTracing filter activation is done explicitly by specifying it in the
HAProxy configuration. If this is not done, the OpenTracing filter in no way
participates in the work of HAProxy.
Arguments :
<id> is the OpenTracing filter id that will be used to find the
right scope in the configuration file. If no filter id is
specified, 'ot-filter' is used as default. If scope is not
specified in the configuration file, it applies to all defined
OpenTracing filters.
<file> is the path of the OpenTracing configuration file. The same
file can contain configurations for multiple OpenTracing
filters simultaneously. In that case we do not need to define
scope so the same configuration applies to all filters or each
filter must have its own scope defined.
More detailed documentation related to the operation, configuration and use
of the filter can be found in the addons/ot directory.
10. FastCGI applications
HAProxy is able to send HTTP requests to Responder FastCGI applications. This
feature was added in HAProxy 2.1. To do so, servers must be configured to use
the FastCGI protocol (using the keyword "proto fcgi" on the server line) and a
FastCGI application must be configured and used by the backend managing these
servers (using the keyword "use-fcgi-app" into the proxy section). Several
FastCGI applications may be defined, but only one can be used at a time by a
backend.
HAProxy implements all features of the FastCGI specification for Responder
application. Especially it is able to multiplex several requests on a simple
connection.
10.1. Setup
10.1.1. Fcgi-app section
Declare a FastCGI application named <name>. To be valid, at least the
document root must be defined.
Declare or complete an access list.
See "acl" keyword in section 4.2 and section 7 about ACL usage for
details. ACLs defined for a FastCGI application are private. They cannot be
used by any other application or by any proxy. In the same way, ACLs defined
in any other section are not usable by a FastCGI application. However,
Pre-defined ACLs are available.
docroot <path>
Define the document root on the remote host. <path> will be used to build
the default value of FastCGI parameters SCRIPT_FILENAME and
PATH_TRANSLATED. It is a mandatory setting.
Define the script name that will be appended after an URI that ends with a
slash ("/") to set the default value of the FastCGI parameter SCRIPT_NAME. It
is an optional setting.
Example :
index index.php
log-stderr <address> [len <length>] [format <format>]
[sample <ranges>:<sample_size>] <facility> [<level> [<minlevel>]]
Enable logging of STDERR messages reported by the FastCGI application.
See "log" keyword in section 4.2 for details. It is an optional setting. By
default STDERR messages are ignored.
Specify the name of a request header which will be passed to the FastCGI
application. It may optionally be followed by an ACL-based condition, in
which case it will only be evaluated if the condition is true.
Most request headers are already available to the FastCGI application,
prefixed with "HTTP_". Thus, this directive is only required to pass headers
that are purposefully omitted. Currently, the headers "Authorization",
"Proxy-Authorization" and hop-by-hop headers are omitted.
Note that the headers "Content-type" and "Content-length" are never passed to
the FastCGI application because they are already converted into parameters.
Define a regular expression to extract the script-name and the path-info from
the URL-decoded path. Thus, <regex> may have two captures: the first one to
capture the script name and the second one to capture the path-info. The
first one is mandatory, the second one is optional. This way, it is possible
to extract the script-name from the path ignoring the path-info. It is an
optional setting. If it is not defined, no matching is performed on the
path. and the FastCGI parameters PATH_INFO and PATH_TRANSLATED are not
filled.
For security reason, when this regular expression is defined, the newline and
the null characters are forbidden from the path, once URL-decoded. The reason
to such limitation is because otherwise the matching always fails (due to a
limitation one the way regular expression are executed in HAProxy). So if one
of these two characters is found in the URL-decoded path, an error is
returned to the client. The principle of least astonishment is applied here.
Example :
path-info ^(/.+\.php)(/.*)?$ # both script-name and path-info may be set
path-info ^(/.+\.php) # the path-info is ignored
Enable or disable the retrieve of variables about connection management.
HAProxy is able to send the record FCGI_GET_VALUES on connection
establishment to retrieve the value for following variables:
* FCGI_MAX_REQS The maximum number of concurrent requests this
application will accept.
* FCGI_MPXS_CONNS "0" if this application does not multiplex connections,
"1" otherwise.
Some FastCGI applications does not support this feature. Some others close
the connection immediately after sending their response. So, by default, this
option is disabled.
Note that the maximum number of concurrent requests accepted by a FastCGI
application is a connection variable. It only limits the number of streams
per connection. If the global load must be limited on the application, the
server parameters "maxconn" and "pool-max-conn" must be set. In addition, if
an application does not support connection multiplexing, the maximum number
of concurrent requests is automatically set to 1.
Instruct the FastCGI application to keep the connection open or not after
sending a response.
If disabled, the FastCGI application closes the connection after responding
to this request. By default, this option is enabled.
Define the maximum number of concurrent requests this application will
accept.
This option may be overwritten if the variable FCGI_MAX_REQS is retrieved
during connection establishment. Furthermore, if the application does not
support connection multiplexing, this option will be ignored. By default set
to 1.
Enable or disable the support of connection multiplexing.
This option may be overwritten if the variable FCGI_MPXS_CONNS is retrieved
during connection establishment. It is disabled by default.
Set a FastCGI parameter that should be passed to this application. Its
value, defined by <fmt> must follows the log-format rules (see section 8.2.4
"Custom Log format"). It may optionally be followed by an ACL-based
condition, in which case it will only be evaluated if the condition is true.
With this directive, it is possible to overwrite the value of default FastCGI
parameters. If the value is evaluated to an empty string, the rule is
ignored. These directives are evaluated in their declaration order.
Example :
# PHP only, required if PHP was built with --enable-force-cgi-redirect
set-param REDIRECT_STATUS 200
set-param PHP_AUTH_DIGEST %[req.hdr(Authorization)]
10.1.2. Proxy section
Define the FastCGI application to use for the backend.
Arguments :
<name> is the name of the FastCGI application to use.
This keyword is only available for HTTP proxies with the backend capability
and with at least one FastCGI server. However, FastCGI servers can be mixed
with HTTP servers. But except there is a good reason to do so, it is not
recommended (see section 10.3 about the limitations for details). Only one
application may be defined at a time per backend.
Note that, once a FastCGI application is referenced for a backend, depending
on the configuration some processing may be done even if the request is not
sent to a FastCGI server. Rules to set parameters or pass headers to an
application are evaluated.
10.1.3. Example
frontend front-http
mode http
bind *:80
bind *:
use_backend back-dynamic if { path_reg ^/.+\.php(/.*)?$ }
default_backend back-static
backend back-static
mode http
server www A.B.C.D:80
backend back-dynamic
mode http
use-fcgi-app php-fpm
server php-fpm A.B.C.D:9000 proto fcgi
fcgi-app php-fpm
log-stderr global
option keep-conn
docroot /var/www/my-app
index index.php
path-info ^(/.+\.php)(/.*)?$
10.2. Default parameters
A Responder FastCGI application has the same purpose as a CGI/1.1 program. In
the CGI/1.1 specification (RFC3875), several variables must be passed to the
script. So HAProxy set them and some others commonly used by FastCGI
applications. All these variables may be overwritten, with caution though.
+-------------------+-----------------------------------------------------+
| AUTH_TYPE | Identifies the mechanism, if any, used by HAProxy |
| | to authenticate the user. Concretely, only the |
| | BASIC authentication mechanism is supported. |
| | |
+-------------------+-----------------------------------------------------+
| CONTENT_LENGTH | Contains the size of the message-body attached to |
| | the request. It means only requests with a known |
| | size are considered as valid and sent to the |
| | application. |
| | |
+-------------------+-----------------------------------------------------+
| CONTENT_TYPE | Contains the type of the message-body attached to |
| | the request. It may not be set. |
| | |
+-------------------+-----------------------------------------------------+
| DOCUMENT_ROOT | Contains the document root on the remote host under |
| | which the script should be executed, as defined in |
| | the application's configuration. |
| | |
+-------------------+-----------------------------------------------------+
| GATEWAY_INTERFACE | Contains the dialect of CGI being used by HAProxy |
| | to communicate with the FastCGI application. |
| | Concretely, it is set to "CGI/1.1". |
| | |
+-------------------+-----------------------------------------------------+
| PATH_INFO | Contains the portion of the URI path hierarchy |
| | following the part that identifies the script |
| | itself. To be set, the directive "path-info" must |
| | be defined. |
| | |
+-------------------+-----------------------------------------------------+
| PATH_TRANSLATED | If PATH_INFO is set, it is its translated version. |
| | It is the concatenation of DOCUMENT_ROOT and |
| | PATH_INFO. If PATH_INFO is not set, this parameters |
| | is not set too. |
| | |
+-------------------+-----------------------------------------------------+
| QUERY_STRING | Contains the request's query string. It may not be |
| | set. |
| | |
+-------------------+-----------------------------------------------------+
| REMOTE_ADDR | Contains the network address of the client sending |
| | the request. |
| | |
+-------------------+-----------------------------------------------------+
| REMOTE_USER | Contains the user identification string supplied by |
| | client as part of user authentication. |
| | |
+-------------------+-----------------------------------------------------+
| REQUEST_METHOD | Contains the method which should be used by the |
| | script to process the request. |
| | |
+-------------------+-----------------------------------------------------+
| REQUEST_URI | Contains the request's URI. |
| | |
+-------------------+-----------------------------------------------------+
| SCRIPT_FILENAME | Contains the absolute pathname of the script. it is |
| | the concatenation of DOCUMENT_ROOT and SCRIPT_NAME. |
| | |
+-------------------+-----------------------------------------------------+
| SCRIPT_NAME | Contains the name of the script. If the directive |
| | "path-info" is defined, it is the first part of the |
| | URI path hierarchy, ending with the script name. |
| | Otherwise, it is the entire URI path. |
| | |
+-------------------+-----------------------------------------------------+
| SERVER_NAME | Contains the name of the server host to which the |
| | client request is directed. It is the value of the |
| | header "Host", if defined. Otherwise, the |
| | destination address of the connection on the client |
| | side. |
| | |
+-------------------+-----------------------------------------------------+
| SERVER_PORT | Contains the destination TCP port of the connection |
| | on the client side, which is the port the client |
| | connected to. |
| | |
+-------------------+-----------------------------------------------------+
| SERVER_PROTOCOL | Contains the request's protocol. |
| | |
+-------------------+-----------------------------------------------------+
| SERVER_SOFTWARE | Contains the string "HAProxy" followed by the |
| | current HAProxy version. |
| | |
+-------------------+-----------------------------------------------------+
| HTTPS | Set to a non-empty value ("on") if the script was |
| | queried through the HTTPS protocol. |
| | |
+-------------------+-----------------------------------------------------+
10.3. Limitations
The current implementation have some limitations. The first one is about the
way some request headers are hidden to the FastCGI applications. This happens
during the headers analysis, on the backend side, before the connection
establishment. At this stage, HAProxy know the backend is using a FastCGI
application but it don't know if the request will be routed to a FastCGI server
or not. But to hide request headers, it simply removes them from the HTX
message. So, if the request is finally routed to an HTTP server, it never see
these headers. For this reason, it is not recommended to mix FastCGI servers
and HTTP servers under the same backend.
Similarly, the rules "set-param" and "pass-header" are evaluated during the
request headers analysis. So the evaluation is always performed, even if the
requests is finally forwarded to an HTTP server.
About the rules "set-param", when a rule is applied, a pseudo header is added
into the HTX message. So, the same way than for HTTP header rewrites, it may
fail if the buffer is full. The rules "set-param" will compete with
"http-request" ones.
Finally, all FastCGI params and HTTP headers are sent into a unique record
FCGI_PARAM. Encoding of this record must be done in one pass, otherwise a
processing error is returned. It means the record FCGI_PARAM, once encoded,
must not exceeds the size of a buffer. However, there is no reserve to respect
here.
11. Address formats
Several statements as "bind, "server", "nameserver" and "log" requires an
address.
This address can be a host name, an IPv4 address, an IPv6 address, or '*'.
The '*' is equal to the special address "0.0.0.0" and can be used, in the case
of "bind" or "dgram-bind" to listen on all IPv4 of the system.The IPv6
equivalent is '::'.
Depending of the statement, a port or port range follows the IP address. This
is mandatory on 'bind' statement, optional on 'server'.
This address can also begin with a slash '/'. It is considered as the "unix"
family, and '/' and following characters must be present the path.
Default socket type or transport method "datagram" or "stream" depends on the
configuration statement showing the address. Indeed, 'bind' and 'server' will
use a "stream" socket type by default whereas 'log', 'nameserver' or
'dgram-bind' will use a "datagram".
Optionally, a prefix could be used to force the address family and/or the
socket type and the transport method.
11.1. Address family prefixes
'abns@<name>' following <name> is an abstract namespace (Linux only).
'fd@<n>' following address is a file descriptor <n> inherited from the
parent. The fd must be bound and may or may not already be
listening.
'ip@<address>[:port1[-port2]]' following <address> is considered as an IPv4 or
IPv6 address depending on the syntax. Depending
on the statement using this address, a port or
a port range may or must be specified.
'ipv4@<address>[:port1[-port2]]' following <address> is always considered as
an IPv4 address. Depending on the statement
using this address, a port or a port range
may or must be specified.
'ipv6@<address>[:port1[-port2]]' following <address> is always considered as
an IPv6 address. Depending on the statement
using this address, a port or a port range
may or must be specified.
'sockpair@<n>' following address is the file descriptor of a connected unix
socket or of a socketpair. During a connection, the initiator
creates a pair of connected sockets, and passes one of them
over the FD to the other end. The listener waits to receive
the FD from the unix socket and uses it as if it were the FD
of an accept(). Should be used carefully.
'unix@<path>' following string is considered as a UNIX socket <path>. this
prefix is useful to declare an UNIX socket path which don't
start by slash '/'.
11.2. Socket type prefixes
Previous "Address family prefixes" can also be prefixed to force the socket
type and the transport method. The default depends of the statement using
this address but in some cases the user may force it to a different one.
This is the case for "log" statement where the default is syslog over UDP
but we could force to use syslog over TCP.
Those prefixes were designed for internal purpose and users should
instead use aliases of the next section "11.3 Protocol prefixes".
If users need one those prefixes to perform what they expect because
they can not configure the same using the protocol prefixes, they should
report this to the maintainers.
'stream+<family>@<address>' forces socket type and transport method
to "stream"
'dgram+<family>@<address>' forces socket type and transport method
to "datagram".
11.3. Protocol prefixes
'tcp@<address>[:port1[-port2]]' following <address> is considered as an IPv4
or IPv6 address depending of the syntax but
socket type and transport method is forced to
"stream". Depending on the statement using
this address, a port or a port range can or
must be specified. It is considered as an alias
of 'stream+ip@'.
'tcp4@<address>[:port1[-port2]]' following <address> is always considered as
an IPv4 address but socket type and transport
method is forced to "stream". Depending on the
statement using this address, a port or port
range can or must be specified.
It is considered as an alias of 'stream+ipv4@'.
'tcp6@<address>[:port1[-port2]]' following <address> is always considered as
an IPv6 address but socket type and transport
method is forced to "stream". Depending on the
statement using this address, a port or port
range can or must be specified.
It is considered as an alias of 'stream+ipv4@'.
'udp@<address>[:port1[-port2]]' following <address> is considered as an IPv4
or IPv6 address depending of the syntax but
socket type and transport method is forced to
"datagram". Depending on the statement using
this address, a port or a port range can or
must be specified. It is considered as an alias
of 'dgram+ip@'.
'udp4@<address>[:port1[-port2]]' following <address> is always considered as
an IPv4 address but socket type and transport
method is forced to "datagram". Depending on
the statement using this address, a port or
port range can or must be specified.
It is considered as an alias of 'dgram+ipv4@'.
'udp6@<address>[:port1[-port2]]' following <address> is always considered as
an IPv6 address but socket type and transport
method is forced to "datagram". Depending on
the statement using this address, a port or
port range can or must be specified.
It is considered as an alias of 'dgram+ipv4@'.
'uxdg@<path>' following string is considered as a unix socket <path> but
transport method is forced to "datagram". It is considered as
an alias of 'dgram+unix@'.
'uxst@<path>' following string is considered as a unix socket <path> but
transport method is forced to "stream". It is considered as
an alias of 'stream+unix@'.
In future versions, other prefixes could be used to specify protocols like
QUIC which proposes stream transport based on socket of type "datagram".
HAPEE-LB 2.4r1 (1.0.0-294.1376) – Configuration Manual