| ---------------------- |
| HAProxy |
| Configuration Manual |
| ---------------------- |
| version 1.3.14 |
| willy tarreau |
| 2007/12/24 |
| |
| |
| This document covers the configuration language as implemented in the version |
| specified above. It does not provide any hint, example or advice. For such |
| documentation, please refer to the Reference Manual or the Architecture Manual. |
| |
| |
| HAProxy's configuration process involves 3 major sources of parameters : |
| |
| - the arguments from the command-line, which always take precedence |
| - the "global" section, which sets process-wide parameters |
| - the proxies sections which can take form of "defaults", "listen", |
| "frontend" and "backend". |
| |
| The configuration file syntax consists in lines beginning with a keyword |
| referenced in this manual, optionally followed by one or several parameters |
| delimited by spaces. If spaces have to be entered in strings, then they must be |
| preceeded by a backslash ('\') to be escaped. Backslashes also have to be |
| escaped by doubling them. |
| |
| Some parameters involve values representating 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 |
| |
| |
| 1. 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 |
| - chroot |
| - daemon |
| - gid |
| - group |
| - log |
| - nbproc |
| - pidfile |
| - uid |
| - ulimit-n |
| - user |
| - stats |
| |
| * Performance tuning |
| - maxconn |
| - noepoll |
| - nokqueue |
| - nopoll |
| - nosepoll |
| - tune.maxpollevents |
| - spread-checks |
| |
| * Debugging |
| - debug |
| - quiet |
| |
| |
| 1.1) Process management and security |
| ------------------------------------ |
| |
| chroot <jail dir> |
| 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 unwritable to anyone. |
| |
| daemon |
| 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. |
| |
| gid <number> |
| Changes the process' 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. |
| See also "group" and "uid". |
| |
| group <group name> |
| Similar to "gid" but uses the GID of group name <group name> from /etc/group. |
| See also "gid" and "user". |
| |
| log <address> <facility> [max level] |
| Adds a global syslog server. Up to two global servers can be defined. They |
| will receive logs for startups 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 an 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 |
| writeable). |
| |
| <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 |
| |
| An optional level 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. 8 levels are known : |
| |
| emerg alert crit err warning notice info debug |
| |
| nbproc <number> |
| 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. USING MULTIPLE PROCESSES |
| IS HARDER TO DEBUG AND IS REALLY DISCOURAGED. See also "daemon". |
| |
| pidfile <pidfile> |
| Writes pids of all daemons into file <pidfile>. This option is equivalent to |
| the "-p" command line argument. The file must be accessible to the user |
| starting the process. See also "daemon". |
| |
| stats socket <path> [{uid | user} <uid>] [{gid | group} <gid>] [mode <mode>] |
| Creates a UNIX socket in stream mode at location <path>. Any previously |
| existing socket will be backed up then replaced. Connections to this socket |
| will get a CSV-formated output of the process statistics in response to the |
| "show stat" command followed by a line feed. On platforms which support it, |
| it is possible to restrict access to this socket by specifying numerical IDs |
| after "uid" and "gid", or valid user and group names after the "user" and |
| "group" keywords. It is also possible to restrict permissions on the socket |
| by passing an octal value after the "mode" keyword (same syntax as chmod). |
| Depending on the platform, the permissions on the socket will be inherited |
| from the directory which hosts it, or from the user the process is started |
| with. |
| |
| stats timeout <timeout, in milliseconds> |
| 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 }. |
| |
| stats maxconn <connections> |
| By default, the stats socket is limited to 10 concurrent connections. It is |
| possible to change this value with "stats maxconn". |
| |
| uid <number> |
| Changes the process' 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". |
| |
| ulimit-n <number> |
| 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. |
| |
| user <user name> |
| Similar to "uid" but uses the UID of user name <user name> from /etc/passwd. |
| See also "uid" and "group". |
| |
| |
| 1.2) Performance tuning |
| ----------------------- |
| |
| maxconn <number> |
| 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". |
| |
| noepoll |
| 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 "nosepoll", and "nopoll". |
| |
| nokqueue |
| 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". |
| |
| 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 "nosepoll", and "nopoll" and |
| "nokqueue". |
| |
| nosepoll |
| Disables the use of the "speculative epoll" event polling system on Linux. It |
| is equivalent to the command-line argument "-ds". The next polling system |
| used will generally be "epoll". See also "nosepoll", and "nopoll". |
| |
| tune.maxpollevents <number> |
| 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. |
| |
| spread-checks <0..50, in percent> |
| Sometimes it is desirable to avoid sending 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. |
| |
| |
| 1.3) Debugging |
| --------------- |
| |
| debug |
| Enables debug mode which dumps to stdout all exchanges, and disables forking |
| into background. It is the equivalent of the command-line argument "-d". It |
| should never be used in a production configuration since it may prevent full |
| system startup. |
| |
| quiet |
| Do not display any message during startup. It is equivalent to the command- |
| line argument "-q". |
| |
| |
| 2) Proxies |
| ---------- |
| |
| Proxy configuration can be located in a set of sections : |
| - defaults <name> |
| - frontend <name> |
| - backend <name> |
| - listen <name> |
| |
| A "defaults" section sets default parameters for all other sections following |
| its declaration. Those default parameters are reset by the next "defaults" |
| section. See below for the list of parameters which can be set in a "defaults" |
| section. The name is optional but its use is encouraged for better readability. |
| |
| 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. |
| |
| 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 |
| bidirectionnal 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. |
| |
| |
| 2.1) Quick reminder about HTTP |
| ------------------------------ |
| |
| When a proxy 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. |
| |
| |
| 2.1.1) The HTTP transaction model |
| --------------------------------- |
| |
| The HTTP protocol is transaction-driven. This means that each request will lead |
| to one and only one response. Traditionnally, a TCP connection is established |
| from the client to the server, a request is sent by the client on 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. HAProxy currently does not support the HTTP keep-alive mode, |
| but knows how to transform it to the close mode. |
| |
| A last 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. |
| |
| Right now, HAProxy only supports the first mode (HTTP close) if it needs to |
| process the request. This means that for each request, there will be one TCP |
| connection. If keep-alive or pipelining are required, HAProxy will still |
| support them, but will only see the first request and the first response of |
| each transaction. While this is generally problematic with regards to logs, |
| content switching or filtering, it most often causes no problem for persistence |
| with cookie insertion. |
| |
| |
| 2.1.2) 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 |
| |
| |
| 2.1.2.1) 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. |
| |
| |
| 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 2.1.2, lines 4 and 5 |
| define a total of 3 values for the 'Accept:' header. |
| |
| Contrary to a common mis-conception, header names are not case-sensitive, and |
| their values are not either if they refer to other header names (such as the |
| 'Connection:' header). |
| |
| 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 accusate an |
| application of being buggy if it does unusual, valid things. |
| |
| Important note: |
| As suggested by RFC2616, 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. |
| |
| |
| 2.1.3) 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 |
| |
| |
| 2.1.3.1) 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 : |
| - 2xx = OK, content is following (eg: 200, 206) |
| - 3xx = OK, no content following (eg: 302, 304) |
| - 4xx = error caused by the client (eg: 401, 403, 404) |
| - 5xx = error caused by the server (eg: 500, 502, 503) |
| |
| Please refer to RFC2616 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 practise to respect the well-established |
| messages. It can be composed of one or multiple words, such as "OK", "Found", |
| or "Authentication Required". |
| |
| |
| 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 2.1.2.2 for more |
| details. |
| |
| |
| 2.2) 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 functionnally |
| limited, and there are new recommended keywords to replace them. |
| |
| |
| keyword defaults frontend listen backend |
| ----------------------+----------+----------+---------+--------- |
| acl - X X X |
| appsession - - X X |
| balance X - X X |
| bind - X X - |
| block - X X X |
| capture cookie - X X - |
| capture request header - X X - |
| capture response header - X X - |
| clitimeout X X X - (deprecated) |
| contimeout X - X X (deprecated) |
| cookie X - X X |
| default_backend - X X - |
| disabled X X X X |
| dispatch - - X X |
| enabled X X X X |
| errorfile X X X X |
| errorloc X X X X |
| errorloc302 X X X X |
| errorloc303 X X X X |
| fullconn X - X X |
| grace - X X X |
| http-check disable-on-404 X - X X |
| log X X X X |
| maxconn X X X - |
| mode X X X X |
| monitor fail - X X - |
| monitor-net X X X - |
| monitor-uri X X X - |
| option abortonclose X - X X |
| option allbackups X - X X |
| option checkcache X - X X |
| option clitcpka X X X - |
| option contstats X X X - |
| option dontlognull X X X - |
| option forceclose X - X X |
| option forwardfor X X X X |
| option httpchk X - X X |
| option httpclose X X X X |
| option httplog X X X X |
| option logasap X X X - |
| option nolinger X X X X |
| option http_proxy X X X X |
| option persist X - X X |
| option redispatch X - X X |
| option smtpchk X - X X |
| option srvtcpka X - X X |
| option ssl-hello-chk X - X X |
| option tcpka X X X X |
| option tcplog X X X X |
| option tcpsplice X X X X |
| option transparent X X X - |
| redisp X - X X |
| redispatch X - X X |
| reqadd - X X X |
| reqallow - X X X |
| reqdel - X X X |
| reqdeny - X X X |
| reqiallow - X X X |
| reqidel - X X X |
| reqideny - X X X |
| reqipass - X X X |
| reqirep - X X X |
| reqisetbe - X X X |
| reqitarpit - X X X |
| reqpass - X X X |
| reqrep - X X X |
| reqsetbe - X X X |
| reqtarpit - X X X |
| retries X - X X |
| rspadd - X X X |
| rspdel - X X X |
| rspdeny - X X X |
| rspidel - X X X |
| rspideny - X X X |
| rspirep - X X X |
| rsprep - X X X |
| server - - X X |
| source X - X X |
| srvtimeout X - X X (deprecated) |
| stats auth X - X X |
| stats enable X - X X |
| stats realm X - X X |
| stats refresh X - X X |
| stats scope X - X X |
| stats uri X - X X |
| stats hide-version X - X X |
| timeout appsession X - X X |
| timeout client X X X - |
| timeout clitimeout X X X - (deprecated) |
| timeout connect X - X X |
| timeout contimeout X - X X (deprecated) |
| timeout queue X - X X |
| timeout server X - X X |
| timeout srvtimeout X - X X (deprecated) |
| timeout tarpit X X X - |
| transparent X X X - |
| use_backend - X X - |
| usesrc X - X X |
| ----------------------+----------+----------+---------+--------- |
| keyword defaults frontend listen backend |
| |
| |
| 2.2.1) Alphabetically sorted keywords reference |
| ----------------------------------------------- |
| |
| This section provides a description of each keyword and its usage. |
| |
| |
| acl <aclname> <criterion> [flags] [operator] <value> ... |
| 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 2.3 about ACL usage. |
| |
| |
| appsession <cookie> len <length> timeout <holdtime> |
| Define session stickiness on an existing application cookie. |
| May be used in sections : defaults | frontend | listen | backend |
| no | no | yes | yes |
| Arguments : |
| <cookie> this is the name of the cookie used by the application and which |
| HAProxy will have to learn for each new session. |
| |
| <length> this is the number of characters that will be memorized and |
| checked in each cookie value. |
| |
| <holdtime> this is the time after which the cookie will be removed from |
| memory if unused. If no unit is specified, this time is in |
| milliseconds. |
| |
| When an application cookie is defined in a backend, HAProxy will check when |
| the server sets such a cookie, and will store its value in a table, and |
| associate it with the server's identifier. Up to <length> characters from |
| the value will be retained. On each connection, haproxy will look for this |
| cookie both in the "Cookie:" headers, and as a URL parameter in the query |
| string. If a known value is found, the client will be directed to the server |
| associated with this value. Otherwise, the load balancing algorithm is |
| applied. Cookies are automatically removed from memory when they have been |
| unused for a duration longer than <holdtime>. |
| |
| The definition of an application cookie is limited to one per backend. |
| |
| Example : |
| appsession JSESSIONID len 52 timeout 3h |
| |
| See also : "cookie", "capture cookie" and "balance". |
| |
| |
| balance <algorithm> [ <arguments> ] |
| 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. |
| |
| 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 stickyness |
| to clients which refuse session cookies. This algorithm is |
| static, which means that changing a server's weight on the |
| fly will have no effect. |
| |
| uri The left part of the URI (before the question mark) is hashed |
| and divided by the total weight of the running servers. The |
| result designates which server will receive the request. This |
| ensures that a 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, which means |
| that changing a server's weight on the fly will have no |
| effect. |
| |
| url_param The URL parameter specified in argument will be looked up in |
| the query string of each HTTP request. If it 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, which |
| means that changing a server's weight on the fly will have no |
| effect. |
| |
| <arguments> is an optional list of arguments which may be needed by some |
| algorithms. Right now, only the "url_param" algorithm supports |
| a mandatory argument. |
| |
| The definition of the load balancing algorithm is mandatory for a backend |
| and limited to one per backend. |
| |
| Examples : |
| balance roundrobin |
| balance url_param userid |
| |
| See also : "dispatch", "cookie", "appsession", "transparent" and "http_proxy". |
| |
| |
| bind [<address>]:<port> [, ...] |
| 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". |
| |
| <port> is the TCP port number the proxy will listen on. The port is |
| mandatory. Note that in the case of an IPv6 address, the port is |
| always the number after the last colon (':'). |
| |
| 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 |
| |
| See also : "source". |
| |
| |
| block { if | unless } <condition> |
| Block a layer 7 request if/unless a condition is matched |
| May be used in sections : defaults | frontend | listen | backend |
| no | yes | yes | yes |
| |
| The HTTP request will be blocked very early in the layer 7 processing |
| if/unless <condition> is matched. A 403 error will be returned if the request |
| is blocked. The condition has to reference ACLs (see section 2.3). This is |
| typically used to deny access to certain sensible resources if some |
| conditions are met or not met. There is no fixed limit to the number of |
| "block" statements per instance. |
| |
| 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 |
| block if invalid_src || local_dst |
| |
| See section 2.3 about ACL usage. |
| |
| |
| capture cookie <name> len <length> |
| 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 (eg: ASPSESSIONXXXXX). |
| |
| <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 |
| configured in the souces by default to 64 characters. It is not possible to |
| specify a capture in a "defaults" section. |
| |
| Example: |
| capture cookie ASPSESSION len 32 |
| |
| See also : "capture request header", "capture response header" as well as |
| section 2.4 about logging. |
| |
| |
| capture request header <name> len <length> |
| Capture and log the first 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 practise 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>. |
| |
| Only the first value of the first 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. 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 differenciate between real users and robots, and "X-Forwarded-For" |
| in proxied environments to find where the request came from. |
| |
| There is no limit to the number of captured request headers, but each capture |
| is limited to 64 characters. 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 Referrer len 15 |
| |
| See also : "capture cookie", "capture response header" as well as section 2.4 |
| about logging. |
| |
| |
| capture response header <name> len <length> |
| Capture and log the first 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 practise 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>. |
| |
| Only the first value of the first 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. 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, but each |
| capture is limited to 64 characters. 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 |
| |
| See also : "capture cookie", "capture request header" as well as section 2.4 |
| about logging. |
| |
| |
| clitimeout <timeout> |
| 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 is 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. 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 practise to cover one or several TCP packet |
| losses by specifying timeouts that are slightly above multiples of 3 seconds |
| (eg: 4 or 5 seconds). |
| |
| 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 results in accumulation of expired sessions in |
| the system if the system's timeouts are not configured either. |
| |
| This parameter is provided for compatibility but is currently deprecated. |
| Please use "timeout client" instead. |
| |
| See also : "timeout client", "timeout server", "srvtimeout". |
| |
| |
| contimeout <timeout> |
| 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 is 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 practise to |
| cover one or several TCP packet losses by specifying timeouts that are |
| slightly above multiples of 3 seconds (eg: 4 or 5 seconds). By default, the |
| connect timeout also presets the queue timeout to the same value if this one |
| has not been specified. Historically, the contimeout was also used to set the |
| tarpit timeout in a listen section, which is not possible in a pure frontend. |
| |
| 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 results in accumulation of failed sessions in |
| the system if the system's timeouts are not configured either. |
| |
| This parameter is provided for backwards compatibility but is currently |
| deprecated. Please use "timeout connect", "timeout queue" or "timeout tarpit" |
| instead. |
| |
| See also : "timeout connect", "timeout queue", "timeout tarpit", |
| "timeout server", "contimeout". |
| |
| |
| cookie <name> [ rewrite|insert|prefix ] [ indirect ] [ nocache ] [ postonly ] |
| 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 (eg: |
| 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 only |
| works in HTTP close mode. Unless the application behaviour 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 the responses. If the server emits a |
| cookie with the same name, it will be replaced anyway. 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. Due to |
| caching effects, it is generally wise to add the "indirect" and |
| "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 requires the HTTP close mode. The "prefix" keyword is |
| not compatible with "rewrite" and "insert". |
| |
| indirect When this option is specified in insert mode, cookies will only |
| be added when the server was not reached after a direct access, |
| which means that only when a server is elected after applying a |
| load-balancing algorithm, or after a redispatch, then the cookie |
| will be inserted. If the client has all the required information |
| to connect to the same server next time, no further cookie will |
| be inserted. In all cases, when the "indirect" option is used in |
| insert mode, the cookie is always removed from the requests |
| transmitted to the server. The persistence mechanism then becomes |
| totally transparent from the application point of view. |
| |
| 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. |
| |
| 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 |
| |
| See also : "appsession", "balance source", "capture cookie", "server". |
| |
| |
| default_backend <backend> |
| 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. |
| |
| The "default_backend" keyword is also supported in TCP mode frontends to |
| facilitate the ordering of configurations in frontends and backends, |
| eventhough it does not make much more sense in case of TCP due to the fact |
| that use_backend currently does not work in TCP mode. |
| |
| Example : |
| |
| use_backend dynamic if url_dyn |
| use_backend static if url_css url_img extension_img |
| default_backend dynamic |
| |
| |
| disabled |
| 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" |
| |
| |
| enabled |
| 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" |
| |
| |
| errorfile <code> <file> |
| 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 400, 403, 408, 500, 502, 503, and 504. |
| |
| <file> designates a file containing the full HTTP response. It is |
| recommended to follow the common practise of appending ".http" to |
| the filename so that people do not confuse the response with HTML |
| error pages. |
| |
| 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. |
| |
| The files are returned verbatim on the TCP socket. This allows any trick such |
| as redirections to another URL or site, as well as tricks to clean cookies, |
| force enable or disable caching, etc... The package provides default error |
| files returning the same contents as default errors. |
| |
| 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 developping those files consists in associating them to the |
| 403 status code and interrogating a blocked URL. |
| |
| See also : "errorloc", "errorloc302", "errorloc303" |
| |
| |
| http-check disable-on-404 |
| Enable a maintenance mode upon HTTP/404 response to health-checks |
| May be used in sections : defaults | frontend | listen | backend |
| no | 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. |
| |
| |
| monitor fail [if | unless] <condition> |
| Add a condition to report a failure to a monitor 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 |
| combinated 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. |
| |
| Example: |
| frontend www |
| acl site_dead nbsrv(dynamic) lt 2 |
| acl site_dead nbsrv(static) lt 2 |
| monitor-uri /site_alive |
| monitor fail if site_dead |
| |
| |
| option contstats |
| 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 continuously, |
| during a whole session. Recounting touches a hotpath directly so |
| it is not enabled by default, as it has small performance impact (~0.5%). |
| |
| |
| timeout client <timeout> |
| timeout clitimeout <timeout> (deprecated) |
| 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 is 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. 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 practise to cover one or several TCP packet |
| losses by specifying timeouts that are slightly above multiples of 3 seconds |
| (eg: 4 or 5 seconds). |
| |
| 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 results in accumulation of expired sessions in |
| the system if the system's timeouts are not configured either. |
| |
| This parameter replaces the old, deprecated "clitimeout". It is recommended |
| to use it to write new configurations. The form "timeout clitimeout" is |
| provided only by backwards compatibility but its use is strongly discouraged. |
| |
| See also : "clitimeout", "timeout server". |
| |
| |
| timeout connect <timeout> |
| timeout contimeout <timeout> (deprecated) |
| 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 is 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 practise to |
| cover one or several TCP packet losses by specifying timeouts that are |
| slightly above multiples of 3 seconds (eg: 4 or 5 seconds). By default, the |
| connect timeout also presets the queue timeout to the same value if this one |
| has 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 results in accumulation of failed sessions in |
| the system if the system's timeouts are not configured either. |
| |
| This parameter replaces the old, deprecated "contimeout". It is recommended |
| to use it to write new configurations. The form "timeout contimeout" is |
| provided only by backwards compatibility but its use is strongly discouraged. |
| |
| See also : "timeout queue", "timeout server", "contimeout". |
| |
| |
| 2.3) Using ACLs |
| --------------- |
| |
| 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 : |
| |
| - define test criteria with sets of values |
| - perform actions only if a set of tests is valid |
| |
| The actions generally consist in blocking the request, or selecting a backend. |
| |
| 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. 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 following ACL flags are currently supported : |
| |
| -i : ignore case during matching. |
| -- : force end of flags. Useful when a string looks like one of the flags. |
| |
| Supported types of values are : |
| |
| - integers or integer ranges |
| - strings |
| - regular expressions |
| - IP addresses and networks |
| |
| |
| 2.3.1) Matching integers |
| ------------------------ |
| |
| Matching integers is special in that ranges and operators are permitted. 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. |
| |
| 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 hdr_val(content-length) lt 0 |
| |
| |
| 2.3.2) Matching strings |
| ----------------------- |
| |
| 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 "--". |
| |
| |
| 2.3.3) 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 "--". |
| |
| |
| 2.3.4) Matching IPv4 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 practise 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. |
| |
| |
| 2.3.5) Available matching criteria |
| ---------------------------------- |
| |
| 2.3.5.1) Matching at Layer 4 and below |
| -------------------------------------- |
| |
| A first set of criteria applies to information which does not require any |
| analysis of the request or response contents. Those generally include TCP/IP |
| addresses and ports, as well as internal values independant on the stream. |
| |
| always_false |
| This one never matches. All values and flags are ignored. It may be used as |
| a temporary replacement for another one when adjusting configurations. |
| |
| always_true |
| This one always matches. All values and flags are ignored. It may be used as |
| a temporary replacement for another one when adjusting configurations. |
| |
| src <ip_address> |
| Applies to the client's IPv4 address. It is usually used to limit access to |
| certain resources such as statistics. Note that it is the TCP-level source |
| address which is used, and not the address of a client behind a proxy. |
| |
| src_port <integer> |
| Applies to the client's TCP source port. This has a very limited usage. |
| |
| dst <ip_address> |
| Applies to the local IPv4 address the client connected to. It can be used to |
| switch to a different backend for some alternative addresses. |
| |
| dst_port <integer> |
| Applies to the local port the client connected to. It can be used to switch |
| to a different backend for some alternative ports. |
| |
| dst_conn <integer> |
| Applies to the number of currently established connections on the frontend, |
| including the one being evaluated. 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 farm is considered saturated. |
| |
| nbsrv <integer> |
| nbsrv(backend) <integer> |
| Returns true when the number of usable servers of either the current backend |
| or the named backend matches the values or ranges specified. This is 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". |
| |
| |
| 2.3.5.2) Matching at Layer 7 |
| ---------------------------- |
| |
| A second set of criteria applies to information which can be found at the |
| application layer (layer 7). Those require that a full HTTP request has been |
| read, and are only evaluated then. They may require slightly more CPU resources |
| than the layer 4 ones, but not much since the request and response are indexed. |
| |
| method <string> |
| Applies to the method in the HTTP request, eg: "GET". Some predefined ACL |
| already check for most common methods. |
| |
| req_ver <string> |
| Applies to the version string in the HTTP request, eg: "1.0". Some predefined |
| ACL already check for versions 1.0 and 1.1. |
| |
| path <string> |
| Returns true when the path part of the request, which starts at the first |
| slash and ends before the question mark, equals one of the strings. It may be |
| used to match known files, such as /favicon.ico. |
| |
| path_beg <string> |
| Returns true when the path begins with one of the strings. This can be used |
| to send certain directory names to alternative backends. |
| |
| path_end <string> |
| Returns true when the path ends with one of the strings. This may be used to |
| control file name extension. |
| |
| path_sub <string> |
| Returns true when the path contains one of the strings. It can be used to |
| detect particular patterns in paths, such as "../" for example. See also |
| "path_dir". |
| |
| path_dir <string> |
| Returns true when one of the strings is found isolated or delimited with |
| slashes in the path. This is used to perform filename or directory name |
| matching without the risk of wrong match due to colliding prefixes. See also |
| "url_dir" and "path_sub". |
| |
| path_dom <string> |
| Returns true when one of the strings is found isolated or delimited with dots |
| in the path. This may be used to perform domain name matching in proxy |
| requests. See also "path_sub" and "url_dom". |
| |
| path_reg <regex> |
| Returns true when the path matches one of the regular expressions. It can be |
| used any time, but it is important to remember that regex matching is slower |
| than other methods. See also "url_reg" and all "path_" criteria. |
| |
| url <string> |
| Applies to the whole URL passed in the request. The only real use is to match |
| "*", for which there already is a predefined ACL. |
| |
| url_beg <string> |
| Returns true when the URL begins with one of the strings. This can be used to |
| check whether a URL begins with a slash or with a protocol scheme. |
| |
| url_end <string> |
| Returns true when the URL ends with one of the strings. It has very limited |
| use. "path_end" should be used instead for filename matching. |
| |
| url_sub <string> |
| Returns true when the URL contains one of the strings. It can be used to |
| detect particular patterns in query strings for example. See also "path_sub". |
| |
| url_dir <string> |
| Returns true when one of the strings is found isolated or delimited with |
| slashes in the URL. This is used to perform filename or directory name |
| matching without the risk of wrong match due to colliding prefixes. See also |
| "path_dir" and "url_sub". |
| |
| url_dom <string> |
| Returns true when one of the strings is found isolated or delimited with dots |
| in the URL. This is used to perform domain name matching without the risk of |
| wrong match due to colliding prefixes. See also "url_sub". |
| |
| url_reg <regex> |
| Returns true when the URL matches one of the regular expressions. It can be |
| used any time, but it is important to remember that regex matching is slower |
| than other methods. See also "path_reg" and all "url_" criteria. |
| |
| url_ip <ip_address> |
| Applies to the IP address specified in the absolute URI in an HTTP request. |
| It can be used to prevent access to certain resources such as local network. |
| It is useful with option 'http_proxy'. |
| |
| url_port <integer> |
| Applies to the port specified in the absolute URI in an HTTP request. It can |
| be used to prevent access to certain resources. It is useful with option |
| 'http_proxy'. Note that if the port is not specified in the request, port 80 |
| is assumed. |
| |
| hdr <string> |
| hdr(header) <string> |
| Note: all the "hdr*" matching criteria either apply to all headers, or to a |
| particular header whose name is passed between parenthesis and without any |
| space. The header name is not case-sensitive. The header matching complies |
| with RFC2616, and treats as separate headers all values delimited by commas. |
| |
| The "hdr" criteria returns true if any of the headers matching the criteria |
| match any of the strings. This can be used to check exact for values. For |
| instance, checking that "connection: close" is set : |
| |
| hdr(Connection) -i close |
| |
| hdr_beg <string> |
| hdr_beg(header) <string> |
| Returns true when one of the headers begins with one of the strings. See |
| "hdr" for more information on header matching. |
| |
| hdr_end <string> |
| hdr_end(header) <string> |
| Returns true when one of the headers ends with one of the strings. See "hdr" |
| for more information on header matching. |
| |
| hdr_sub <string> |
| hdr_sub(header) <string> |
| Returns true when one of the headers contains one of the strings. See "hdr" |
| for more information on header matching. |
| |
| hdr_dir <string> |
| hdr_dir(header) <string> |
| Returns true when one of the headers contains one of the strings either |
| isolated or delimited by slashes. This is used to perform filename or |
| directory name matching, and may be used with Referer. See "hdr" for more |
| information on header matching. |
| |
| hdr_dom <string> |
| hdr_dom(header) <string> |
| Returns true when one of the headers contains one of the strings either |
| isolated or delimited by dots. This is used to perform domain name matching, |
| and may be used with the Host header. See "hdr" for more information on |
| header matching. |
| |
| hdr_reg <regex> |
| hdr_reg(header) <regex> |
| Returns true when one of the headers matches of the regular expressions. It |
| can be used at any time, but it is important to remember that regex matching |
| is slower than other methods. See also other "hdr_" criteria, as well as |
| "hdr" for more information on header matching. |
| |
| hdr_val <integer> |
| hdr_val(header) <integer> |
| Returns true when one of the headers starts with a number which matches the |
| values or ranges specified. This may be used to limit content-length to |
| acceptable values for example. See "hdr" for more information on header |
| matching. |
| |
| hdr_cnt <integer> |
| hdr_cnt(header) <integer> |
| Returns true when the number of occurrence of the specified header matches |
| the values or ranges specified. It is important to remember that one header |
| line may count as several headers if it has several values. This is used to |
| detect presence, absence or abuse of a specific header, as well as to block |
| request smugling attacks by rejecting requests which contain more than one |
| of certain headers. See "hdr" for more information on header matching. |
| |
| |
| 2.3.6) 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. Please note that |
| only the first three ones are not layer 7 based. |
| |
| ACL name Equivalent to Usage |
| ---------------+-----------------------------+--------------------------------- |
| TRUE always_true 1 always match |
| FALSE always_false 0 never match |
| LOCALHOST src 127.0.0.1/8 match connection from local host |
| HTTP_1.0 req_ver 1.0 match HTTP version 1.0 |
| HTTP_1.1 req_ver 1.1 match HTTP version 1.1 |
| METH_CONNECT method CONNECT match HTTP CONNECT 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_TRACE method TRACE match HTTP TRACE method |
| HTTP_URL_ABS url_reg ^[^/:]*:// match absolute URL with scheme |
| HTTP_URL_SLASH url_beg / match URL begining with "/" |
| HTTP_URL_STAR url * match URL equal to "*" |
| HTTP_CONTENT hdr_val(content-length) gt 0 match an existing content-length |
| ---------------+-----------------------------+--------------------------------- |
| |
| |
| 2.3.7) 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 disjonctive 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 hdr_cnt(Content-length) eq 0 |
| block if HTTP_URL_STAR !METH_OPTIONS || METH_POST missing_cl |
| block if METH_GET HTTP_CONTENT |
| block 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 |
| |
| See below for the detailed help on the "block" and "use_backend" keywords. |
| |
| |
| 2.4) Server options |
| ------------------- |
| |
| slowstart <start_time_in_ms> |
| 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. |
| |
| |
| /* |
| * Local variables: |
| * fill-column: 79 |
| * End: |
| */ |