1418 lines
55 KiB
Plaintext
1418 lines
55 KiB
Plaintext
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H A - P r o x y
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---------------
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version 1.1.27
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willy tarreau
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2003/10/27
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============
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| Abstract |
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============
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HA-Proxy is a TCP/HTTP reverse proxy which is particularly suited for high
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availability environments. Indeed, it can :
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- route HTTP requests depending on statically assigned cookies ;
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- spread the load among several servers while assuring server persistence
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through the use of HTTP cookies ;
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- switch to backup servers in the event a main one fails ;
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- accept connections to special ports dedicated to service monitoring ;
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- stop accepting connections without breaking existing ones ;
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- add/modify/delete HTTP headers both ways ;
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- block requests matching a particular pattern ;
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It needs very little resource. Its event-driven architecture allows it to easily
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handle thousands of simultaneous connections on hundreds of instances without
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risking the system's stability.
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====================
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| Start parameters |
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====================
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There are only a few command line options :
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-f <configuration file>
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-n <high limit for the total number of simultaneous connections>
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-N <high limit for the per-proxy number of simultaneous connections>
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-d starts in foregreound with debugging mode enabled
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-D starts in daemon mode
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-p <pidfile> asks the process to write down each of its children's
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pids to this file in daemon mode.
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-s shows statistics (only if compiled in)
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-l shows even more statistics (implies '-s')
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The maximal number of connections per proxy is used as the default parameter for
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each instance for which the 'maxconn' paramter is not set in the 'listen' section.
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The maximal number of total connections limits the number of connections used by
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the whole process if the 'maxconn' parameter is not set in the 'global' section.
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The debugging mode has the same effect as the 'debug' option in the 'global'
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section. When the proxy runs in this mode, it dumps every connections,
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disconnections, timestamps, and HTTP headers to stdout. This should NEVER
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be used in an init script since it will prevent the system from starting up.
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Statistics are only available if compiled in with the 'STATTIME' option. It's
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only used during code optimization phases.
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======================
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| Configuration file |
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======================
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Structure
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=========
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The configuration file parser ignores empty lines, spaces, tabs. Anything
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between a sharp ('#') not following a backslash ('\'), and the end of a line
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constitutes a comment and is ignored too.
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The configuration file is segmented in sections. A section begins whenever
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one of these 3 keywords are encountered :
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- 'global'
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- 'listen'
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- 'defaults'
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Every parameter refer to the section beginning at the last one of these 3
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keywords.
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1) Global parameters
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====================
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Global parameters affect the whole process behaviour. They are all set in the
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'global' section. There may be several 'global' sections if needed, but their
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parameters will only be merged. Allowed parameters in 'global' section include
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the following ones :
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- log <address> <facility> [max_level]
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- maxconn <number>
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- uid <user id>
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- gid <group id>
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- chroot <directory>
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- nbproc <number>
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- daemon
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- debug
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- quiet
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- pidfile <file>
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1.1) Event logging
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------------------
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Most events are logged : start, stop, servers going up and down, connections and
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errors. Each event generates a syslog message which can be sent to up to 2
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servers. The syntax is :
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log <ip_address> <facility> [max_level]
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Connections are logged at level "info". Services initialization and servers
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going up are logged at level "notice", termination signals are logged at
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"warning", and definitive service termination, as well as loss of servers are
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logged at level "alert". The optional parameter <max_level> specifies above
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what level messages should be sent. Level can take one of these 8 values :
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emerg, alert, crit, err, warning, notice, info, debug
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For backwards compatibility with versions 1.1.16 and earlier, the default level
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value is "debug" if not specified.
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Permitted facilities are :
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kern, user, mail, daemon, auth, syslog, lpr, news,
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uucp, cron, auth2, ftp, ntp, audit, alert, cron2,
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local0, local1, local2, local3, local4, local5, local6, local7
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According to RFC3164, messages are truncated to 1024 bytes before being emitted.
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Example :
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---------
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global
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log 192.168.2.200 local3
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log 127.0.0.1 local4 notice
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1.2) limiting the number of connections
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---------------------------------------
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It is possible and recommended to limit the global number of per-process
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connections. Since one connection includes both a client and a server, it
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means that the max number of TCP sessions will be about the double of this
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number. It's important to understand this when trying to find best values
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for 'ulimit -n' before starting the proxy. To anticipate the number of
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sockets needed, all these parameters must be counted :
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- 1 socket per incoming connection
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- 1 socket per outgoing connection
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- 1 socket per address/port/proxy tuple.
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- 1 socket per server being health-checked
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- 1 socket for all logs
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In simple configurations where each proxy only listens one one address/port,
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set the limit of file descriptors (ulimit -n) to
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(2 * maxconn + nbproxies + nbservers + 1). In a future release, haproxy may
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be able to set this value itself.
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1.3) Drop of priviledges
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------------------------
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In order to reduce the risk and consequences of attacks, in the event where a
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yet non-identified vulnerability would be successfully exploited, it's possible
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to lower the process priviledges and even isolate it in a riskless directory.
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In the 'global' section, the 'uid' parameter sets a numerical user identifier
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which the process will switch to after binding its listening sockets. The value
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'0', which normally represents the super-user, here indicates that the UID must
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not change during startup. It's the default behaviour. The 'gid' parameter does
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the same for the group identifier. It's particularly advised against use of
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generic accounts such as 'nobody' because it has the same consequences as using
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'root' if other services use them.
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The 'chroot' parameter makes the process isolate itself in an empty directory
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just before switching its UID. This type of isolation (chroot) can sometimes
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be worked around on certain OS (Linux, Solaris), provided that the attacker
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has gained 'root' priviledges and has the ability to use or create a directory.
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For this reason, it's capital to use a dedicated directory and not to share one
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between several services of different nature. To make isolation more resistant,
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it's recommended to use an empty directory without any right, and to change the
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UID of the process so that it cannot do anything there.
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Note: in the event where such a vulnerability would be exploited, it's most
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likely that first attempts would kill the process due to 'Segmentation Fault',
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'Bus Error' or 'Illegal Instruction' signals. Eventhough it's true that
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isolating the server reduces the risks of intrusion, it's sometimes useful to
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find why a process dies, via the analysis of a 'core' file, although very rare
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(the last bug of this sort was fixed in 1.1.9). For security reasons, most
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systems disable the generation of core file when a process changes its UID. So
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the two workarounds are either to start the process from a restricted user
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account, which will not be able to chroot itself, or start it as root and not
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change the UID. In both cases the core will be either in the start or the chroot
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directories. Do not forget to allow core dumps prior to start the process :
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# ulimit -c unlimited
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Example :
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---------
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global
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uid 30000
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gid 30000
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chroot /var/chroot/haproxy
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1.4) Startup modes
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------------------
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The service can start in several different :
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- foreground / background
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- quiet / normal / debug
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The default mode is normal, foreground, which means that the program doesn't
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return once started. NEVER EVER use this mode in a system startup script, or
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the system won't boot. It needs to be started in background, so that it
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returns immediately after forking. That's accomplished by the 'daemon' option
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in the 'global' section, which is the equivalent of the '-D' command line
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argument.
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Moreover, certain alert messages are still sent to the standard output even
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in 'daemon' mode. To make them disappear, simply add the 'quiet' option in the
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'global' section. This option has no command-line equivalent.
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Last, the 'debug' mode, enabled with the 'debug' option in the 'global' section,
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and which is equivalent of the '-d' option, allows deep TCP/HTTP analysis, with
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timestamped display of each connection, disconnection, and HTTP headers for both
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ways. This mode is incompatible with 'daemon' and 'quiet' modes for obvious
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reasons.
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1.5) Increasing the overall processing power
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--------------------------------------------
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On multi-processor systems, it may seem to be a shame to use only one processor,
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eventhough the load needed to saturate a recent processor are far above common
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usage. Anyway, for very specific needs, the proxy can start several processes
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between which the operating system will spread the incoming connections. The
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number of processes is controlled by the 'nbproc' parameter in the 'global'
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section. It defaults to 1, and obviously works only in 'daemon' mode.
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Example :
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---------
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global
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daemon
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quiet
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nbproc 2
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1.6) Helping process management
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-------------------------------
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Haproxy now supports the notion of pidfile. If the '-p' command line argument,
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or the 'pidfile' global option is followed with a file name, this file will be
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removed, then filled with all children's pids, one per line (only in daemon
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mode). This file is NOT within the chroot, which allows to work with a readonly
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chroot. It will be owned by the user starting the process, and will have
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permissions 0644.
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Example :
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---------
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global
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daemon
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quiet
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nbproc 2
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pidfile /var/run/haproxy-private.pid
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# to stop only those processes among others :
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# kill $(</var/run/haproxy-private.pid)
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2) Declaration of a listening service
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=====================================
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Service sections start with the 'listen' keyword :
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listen <instance_name> [ <IP_address>:<port_range>[,...] ]
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- <instance_name> is the name of the instance. This name will be reported in
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logs, so it is good to have it reflect the proxied service. No unicity test
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is done on this name, and it's not mandatory for it to be unique, but highly
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recommended.
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- <IP_address> is the IP address the proxy binds to. Empty address, '*' and
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'0.0.0.0' all mean that the proxy listens to all valid addresses on the
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system.
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- <port_range> is either a unique port, or a port range for which the proxy will
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accept connections for the IP address specified above. This range can be :
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- a numerical port (ex: '80')
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- a dash-delimited ports range explicitly stating the lower and upper bounds
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(ex: '2000-2100') which are included in the range.
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Particular care must be taken against port ranges, because every <addr:port>
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couple consumes one socket (=a file descriptor), so it's easy to eat lots of
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descriptors with a simple range. The <addr:port> couple must be used only once
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among all instances running on a same system. Please note that attaching to
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ports lower than 1024 need particular priviledges to start the program, which
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are independant of the 'uid' parameter.
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- the <IP_address>:<port_range> couple may be repeated indefinitely to require
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the proxy to listen to other addresses and/or ports. To achieve this, simply
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separate them with a coma.
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Examples :
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---------
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listen http_proxy :80
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listen x11_proxy 127.0.0.1:6000-6009
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listen smtp_proxy 127.0.0.1:25,127.0.0.1:587
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listen ldap_proxy :389,:663
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In the event that all addresses do not fit line width, it's preferable to
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detach secondary addresses on other lines with the 'bind' keyword. If this
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keyword is used, it's not even necessary to specify the first address on the
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'listen' line, which sometimes makes multiple configuration handling easier :
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bind [ <IP_address>:<port_range>[,...] ]
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Examples :
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----------
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listen http_proxy
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bind :80,:443
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bind 10.0.0.1:10080,10.0.0.1:10443
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2.1) Inhibiting a service
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-------------------------
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A service may be disabled for maintenance reasons, without needing to comment
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out the whole section, simply by specifying the 'disabled' keyword in the
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section to be disabled :
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listen smtp_proxy 0.0.0.0:25
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disabled
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Note: the 'enabled' keyword allows to enable a service which has been disabled
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previously by a default configuration.
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2.2) Modes of operation
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-----------------------
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A service can work in 3 different distinct modes :
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- TCP
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- HTTP
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- monitoring
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TCP mode
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--------
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In this mode, the service relays TCP connections as soon as they're established,
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towards one or several servers. No processing is done on the stream. It's only
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an association of source(addr:port) -> destination(addr:port). To use this mode,
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you must specify 'mode tcp' in the 'listen' section. This is the default mode.
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Example :
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---------
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listen smtp_proxy 0.0.0.0:25
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mode tcp
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HTTP mode
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---------
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In this mode, the service relays TCP connections towards one or several servers,
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when it has enough informations to decide, which normally means that all HTTP
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headers have been read. Some of them may be scanned for a cookie or a pattern
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matching a regex. To use this mode, specify 'mode http' in the 'listen' section.
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Example :
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---------
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listen http_proxy 0.0.0.0:80
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mode http
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Health-checking mode
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--------------------
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This mode provides a way for external components to check the proxy's health.
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It is meant to be used with intelligent load-balancers which can use send/expect
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scripts to check for all of their servers' availability. This one simply accepts
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the connection, returns the word 'OK' and closes it. If the 'option httpchk' is
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set, then the reply will be 'HTTP/1.0 200 OK' with no data, so that it can be
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tested from a tool which supports HTTP health-checks. To enable it, simply
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specify 'health' as the working mode :
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Example :
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---------
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# simple response : 'OK'
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listen health_check 0.0.0.0:60000
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mode health
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# HTTP response : 'HTTP/1.0 200 OK'
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listen http_health_check 0.0.0.0:60001
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mode health
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option httpchk
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2.3) Limiting the number of simultaneous connections
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----------------------------------------------------
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The 'maxconn' parameter allows a proxy to refuse connections above a certain
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amount of simultaneous ones. When the limit is reached, it simply stops
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listening, but the system may still be accepting them because of the back log
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queue. These connections will be processed further when other ones have freed
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some slots. This provides a serialization effect which helps very fragile
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servers resist to high loads. Se further for system limitations.
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Example :
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---------
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listen tiny_server 0.0.0.0:80
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maxconn 10
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2.4) Soft stop
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--------------
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It is possible to stop services without breaking existing connections by the
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sending of the SIG_USR1 signal to the process. All services are then put into
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soft-stop state, which means that they will refuse to accept new connections,
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except for those which have a non-zero value in the 'grace' parameter, in which
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case they will still accept connections for the specified amount of time, in
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milliseconds. This allows to tell a load-balancer that the service is failing,
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while still doing the job during the time it needs to detect it.
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Note: active connections are never killed. In the worst case, the user will have
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to wait for all of them to close or to time-out, or simply kill the process
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normally (SIG_TERM). The default 'grace' value is '0'.
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Example :
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---------
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# enter soft stop after 'killall -USR1 haproxy'
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# the service will still run 10 seconds after the signal
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listen http_proxy 0.0.0.0:80
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mode http
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grace 10000
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# this port is dedicated to a load-balancer, and must fail immediately
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listen health_check 0.0.0.0:60000
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mode health
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grace 0
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2.5) Connections expiration time
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--------------------------------
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It is possible (and recommended) to configure several time-outs on TCP
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connections. Three independant timers are adjustable with values specified
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in milliseconds. A session will be terminated if either one of these timers
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expire.
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- the time we accept to wait for data from the client, or for the client to
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accept data : 'clitimeout' :
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# client time-out set to 2mn30.
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clitimeout 150000
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- the time we accept to wait for data from the server, or for the server to
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accept data : 'srvtimeout' :
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# server time-out set to 30s.
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srvtimeout 30000
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- the time we accept to wait for a connection to establish on a server :
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'contimeout' :
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# we give up if the connection does not complete within 4 seconds
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contimeout 4000
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Notes :
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-------
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- 'contimeout' and 'srvtimeout' have no sense on 'health' mode servers ;
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- under high loads, or with a saturated or defective network, it's possible
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that some packets get lost. Since the first TCP retransmit only happens
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after 3 seconds, a time-out equal to, or lower than 3 seconds cannot
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compensate for a packet loss. A 4 seconds time-out seems a reasonable
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minimum which will considerably reduce connection failures.
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2.6) Attempts to reconnect
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--------------------------
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After a connection failure to a server, it is possible to retry, potentially
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on another server. This is useful if health-checks are too rare and you don't
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want the clients to see the failures. The number of attempts to reconnect is
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set by the 'retries' paramter.
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Example :
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---------
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# we can retry 3 times max after a failure
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retries 3
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2.7) Address of the dispatch server (deprecated)
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------------------------------------------------
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The server which will be sent all new connections is defined by the 'dispatch'
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parameter, in the form <address>:<port>. It generally is dedicated to unknown
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connections and will assign them a cookie, in case of HTTP persistence mode,
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or simply is a single server in case of generic TCP proxy. This old mode is only
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provided for backwards compatibility, but doesn't allow to check remote servers
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state, and has a rather limited usage. All new setups should switch to 'balance'
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mode. The principle of the dispatcher is to be able to perform the load
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balancing itself, but work only on new clients so that the server doesn't need
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to be a big machine.
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Example :
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---------
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# all new connections go there
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dispatch 192.168.1.2:80
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Note :
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------
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This parameter has no sense for 'health' servers, and is incompatible with
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'balance' mode.
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2.8) Outgoing source address
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----------------------------
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It is often necessary to bind to a particular address when connecting to some
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remote hosts. This is done via the 'source' parameter which is a per-proxy
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parameter. A newer version may allow to fix different sources to reach different
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servers. The syntax is 'source <address>[:<port>]', where <address> is a valid
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local address (or '0.0.0.0' or '*' or empty to let the system choose), and
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<port> is an optional parameter allowing the user to force the source port for
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very specific needs. If the port is not specified or is '0', the system will
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choose a free port. Note that as of version 1.1.18, the servers health checks
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are also performed from the same source.
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|
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Examples :
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----------
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listen http_proxy *:80
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# all connections take 192.168.1.200 as source address
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source 192.168.1.200:0
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listen rlogin_proxy *:513
|
|
# use address 192.168.1.200 and the reserved port 900 (needs to be root)
|
|
source 192.168.1.200:900
|
|
|
|
|
|
2.9) Setting the cookie name
|
|
----------------------------
|
|
In HTTP mode, it is possible to look for a particular cookie which will contain
|
|
a server identifier which should handle the connection. The cookie name is set
|
|
via the 'cookie' parameter.
|
|
|
|
Example :
|
|
---------
|
|
listen http_proxy :80
|
|
mode http
|
|
cookie SERVERID
|
|
|
|
It is possible to change the cookie behaviour to get a smarter persistence,
|
|
depending on applications. It is notably possible to delete or modify a cookie
|
|
emitted by a server, insert a cookie identifying the server in an HTTP response
|
|
and even add a header to tell upstream caches not to cache this response.
|
|
|
|
Examples :
|
|
----------
|
|
|
|
To remove the cookie for direct accesses (ie when the server matches the one
|
|
which was specified in the client cookie) :
|
|
|
|
cookie SERVERID indirect
|
|
|
|
To replace the cookie value with the one assigned to the server if any (no
|
|
cookie will be created if the server does not provide one, nor if the
|
|
configuration does not provide one). This lets the application put the cookie
|
|
exactly on certain pages (eg: successful authentication) :
|
|
|
|
cookie SERVERID rewrite
|
|
|
|
To create a new cookie and assign the server identifier to it (in this case, all
|
|
servers should be associated with a valid cookie, since no cookie will simply
|
|
delete the cookie from the client's browser) :
|
|
|
|
cookie SERVERID insert
|
|
|
|
To insert a cookie and ensure that no upstream cache will store it, add the
|
|
'nocache' option :
|
|
|
|
cookie SERVERID insert nocache
|
|
|
|
To insert a cookie only after a POST request, add 'postonly' after 'insert'.
|
|
This has the advantage that there's no risk of caching, and that all pages
|
|
seen before the POST one can still be cached :
|
|
|
|
cookie SERVERID insert postonly
|
|
|
|
Notes :
|
|
-----------
|
|
- it is possible to combine 'insert' with 'indirect' or 'rewrite' to adapt to
|
|
applications which already generate the cookie with an invalid content.
|
|
|
|
- in the case where 'insert' and 'indirect' are both specified, the cookie is
|
|
never transmitted to the server, since it wouldn't understand it. This is
|
|
the most application-transparent mode.
|
|
|
|
- it is particularly recommended to use 'nocache' in 'insert' mode if any
|
|
upstream HTTP/1.0 cache is susceptible to cache the result, because this may
|
|
lead to many clients going to the same server, or even worse, some clients
|
|
having their server changed while retrieving a page from the cache.
|
|
|
|
- when the application is well known and controlled, the best method is to
|
|
only add the persistence cookie on a POST form because it's up to the
|
|
application to select which page it wants the upstream servers to cache.
|
|
In this case, you would use 'insert postonly indirect'.
|
|
|
|
2.10) Associating a cookie value with a server
|
|
----------------------------------------------
|
|
In HTTP mode, it's possible to associate a cookie value to each server. This
|
|
was initially used in combination with 'dispatch' mode to handle direct accesses
|
|
but it is now the standard way of doing the load balancing. The syntax is :
|
|
|
|
server <identifier> <address>:<port> cookie <value>
|
|
|
|
- <identifier> is any name which can be used to identify the server in the logs.
|
|
- <address>:<port> specifies where the server is bound.
|
|
- <value> is the value to put in or to read from the cookie.
|
|
|
|
Example : the 'SERVERID' cookie can be either 'server01' or 'server02'
|
|
---------
|
|
listen http_proxy :80
|
|
mode http
|
|
cookie SERVERID
|
|
dispatch 192.168.1.100:80
|
|
server web1 192.168.1.1:80 cookie server01
|
|
server web2 192.168.1.2:80 cookie server02
|
|
|
|
Warning : the syntax has changed since version 1.0 !
|
|
---------
|
|
|
|
3) Autonomous load balancer
|
|
===========================
|
|
|
|
The proxy can perform the load-balancing itself, both in TCP and in HTTP modes.
|
|
This is the most interesting mode which obsoletes the old 'dispatch' mode
|
|
described above. It has advantages such as server health monitoring, multiple
|
|
port binding and port mapping. To use this mode, the 'balance' keyword is used,
|
|
followed by the selected algorithm. As of version 1.1.23, only 'roundrobin' is
|
|
available, which is also the default value if unspecified. In this mode, there
|
|
will be no dispatch address, but the proxy needs at least one server.
|
|
|
|
Example : same as the last one, with internal load balancer
|
|
---------
|
|
|
|
listen http_proxy :80
|
|
mode http
|
|
cookie SERVERID
|
|
balance roundrobin
|
|
server web1 192.168.1.1:80 cookie server01
|
|
server web2 192.168.1.2:80 cookie server02
|
|
|
|
|
|
Since version 1.1.22, it is possible to automatically determine on which port
|
|
the server will get the connection, depending on the port the client connected
|
|
to. Indeed, there now are 4 possible combinations for the server's <port> field:
|
|
|
|
- unspecified or '0' :
|
|
the connection will be sent to the same port as the one on which the proxy
|
|
received the client connection itself.
|
|
|
|
- numerical value (the only one supported in versions earlier than 1.1.22) :
|
|
the connection will always be sent to the specified port.
|
|
|
|
- '+' followed by a numerical value :
|
|
the connection will be sent to the same port as the one on which the proxy
|
|
received the connection, plus this value.
|
|
|
|
- '-' followed by a numerical value :
|
|
the connection will be sent to the same port as the one on which the proxy
|
|
received the connection, minus this value.
|
|
|
|
Examples :
|
|
----------
|
|
|
|
# same as previous example
|
|
|
|
listen http_proxy :80
|
|
mode http
|
|
cookie SERVERID
|
|
balance roundrobin
|
|
server web1 192.168.1.1 cookie server01
|
|
server web2 192.168.1.2 cookie server02
|
|
|
|
# simultaneous relaying of ports 80, 81 and 8080-8089
|
|
|
|
listen http_proxy :80,:81,:8080-8089
|
|
mode http
|
|
cookie SERVERID
|
|
balance roundrobin
|
|
server web1 192.168.1.1 cookie server01
|
|
server web2 192.168.1.2 cookie server02
|
|
|
|
# relaying of TCP ports 25, 389 and 663 to ports 1025, 1389 and 1663
|
|
|
|
listen http_proxy :25,:389,:663
|
|
mode tcp
|
|
balance roundrobin
|
|
server srv1 192.168.1.1:+1000
|
|
server srv2 192.168.1.2:+1000
|
|
|
|
|
|
3.1) Server monitoring
|
|
----------------------
|
|
|
|
It is possible to check the servers status by trying to establish TCP
|
|
connections or even sending HTTP requests to them. A server which fails to
|
|
reply to health checks as expected will not be used by the load balancing
|
|
algorithms. To enable monitoring, add the 'check' keyword on a server line.
|
|
It is possible to specify the interval between tests (in milliseconds) with
|
|
the 'inter' parameter, the number of failures supported before declaring that
|
|
the server has fallen down with the 'fall' parameter, and the number of valid
|
|
checks needed for the server to fully get up with the 'rise' parameter. Since
|
|
version 1.1.22, it is also possible to send checks to a different port
|
|
(mandatory when none is specified) with the 'port' parameter. The default
|
|
values are the following ones :
|
|
|
|
- inter : 2000
|
|
- rise : 2
|
|
- fall : 3
|
|
- port : default server port
|
|
|
|
The default mode consists in establishing TCP connections only. But in certain
|
|
types of application failures, it is often that the server continues to accept
|
|
connections because the system does it itself while the application is running
|
|
an endless loop, or is completely stuck. So in version 1.1.16 were introduced
|
|
HTTP health checks which only performed simple lightweight requests and analysed
|
|
the response. Now, as of version 1.1.23, it is possible to change the HTTP
|
|
method, the URI, and the HTTP version string (which even allows to send headers
|
|
with a dirty trick). To enable HTTP health-checks, use 'option httpchk'.
|
|
|
|
By default, requests use the 'OPTIONS' method because it's very light and easy
|
|
to filter from logs, and does it on '/'. Only HTTP responses 2xx and 3xx are
|
|
considered valid ones, and only if they come before the time to send a new
|
|
request is reached ('inter' parameter). If some servers block this type of
|
|
request, 3 other forms help to forge a request :
|
|
|
|
- option httpchk -> OPTIONS / HTTP/1.0
|
|
- option httpchk URI -> OPTIONS <URI> HTTP/1.0
|
|
- option httpchk METH URI -> <METH> <URI> HTTP/1.0
|
|
- option httpchk METH URI VER -> <METH> <URI> <VER>
|
|
|
|
See examples below.
|
|
|
|
Since version 1.1.17, it is possible to specify backup servers. These servers
|
|
are only sollicited when no other server is available. This may only be useful
|
|
to serve a maintenance page, or define one active and one backup server (seldom
|
|
used in TCP mode). To make a server a backup one, simply add the 'backup' option
|
|
on its line. These servers also support cookies, so if a cookie is specified for
|
|
a backup server, clients assigned to this server will stick to it even when the
|
|
other ones come back. Conversely, if no cookie is assigned to such a server,
|
|
the clients will get their cookies removed (empty cookie = removal), and will
|
|
be balanced against other servers once they come back. Please note that there
|
|
is no load-balancing among backup servers. If there are several backup servers,
|
|
the second one will only be used when the first one dies, and so on.
|
|
|
|
Since version 1.1.17, it is also possible to visually check the status of all
|
|
servers at once. For this, you just have to send a SIGHUP signal to the proxy.
|
|
The servers status will be dumped into the logs at the 'notice' level, as well
|
|
as on <stderr> if not closed. For this reason, it's always a good idea to have
|
|
one local log server at the 'notice' level.
|
|
|
|
Examples :
|
|
----------
|
|
# same setup as in paragraph 3) with TCP monitoring
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
cookie SERVERID
|
|
balance roundrobin
|
|
server web1 192.168.1.1:80 cookie server01 check
|
|
server web2 192.168.1.2:80 cookie server02 check inter 500 rise 1 fall 2
|
|
|
|
# same with HTTP monitoring via 'OPTIONS / HTTP/1.0'
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
cookie SERVERID
|
|
balance roundrobin
|
|
option httpchk
|
|
server web1 192.168.1.1:80 cookie server01 check
|
|
server web2 192.168.1.2:80 cookie server02 check inter 500 rise 1 fall 2
|
|
|
|
# same with HTTP monitoring via 'OPTIONS /index.html HTTP/1.0'
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
cookie SERVERID
|
|
balance roundrobin
|
|
option httpchk /index.html
|
|
server web1 192.168.1.1:80 cookie server01 check
|
|
server web2 192.168.1.2:80 cookie server02 check inter 500 rise 1 fall 2
|
|
|
|
# same with HTTP monitoring via 'HEAD /index.jsp? HTTP/1.1\r\nHost: www'
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
cookie SERVERID
|
|
balance roundrobin
|
|
option httpchk HEAD /index.jsp? HTTP/1.1\r\nHost:\ www
|
|
server web1 192.168.1.1:80 cookie server01 check
|
|
server web2 192.168.1.2:80 cookie server02 check inter 500 rise 1 fall 2
|
|
|
|
# automatic insertion of a cookie in the server's response, and automatic
|
|
# deletion of the cookie in the client request, while asking upstream caches
|
|
# not to cache replies.
|
|
listen web_appl 0.0.0.0:80
|
|
mode http
|
|
cookie SERVERID insert nocache indirect
|
|
balance roundrobin
|
|
server web1 192.168.1.1:80 cookie server01 check
|
|
server web2 192.168.1.2:80 cookie server02 check
|
|
|
|
# same with off-site application backup and local error pages server
|
|
listen web_appl 0.0.0.0:80
|
|
mode http
|
|
cookie SERVERID insert nocache indirect
|
|
balance roundrobin
|
|
server web1 192.168.1.1:80 cookie server01 check
|
|
server web2 192.168.1.2:80 cookie server02 check
|
|
server web-backup 192.168.2.1:80 cookie server03 check backup
|
|
server web-excuse 192.168.3.1:80 check backup
|
|
|
|
# SMTP+TLS relaying with heakth-checks and backup servers
|
|
|
|
listen http_proxy :25,:587
|
|
mode tcp
|
|
balance roundrobin
|
|
server srv1 192.168.1.1 check port 25 inter 30000 rise 1 fall 2
|
|
server srv2 192.168.1.2 backup
|
|
|
|
|
|
3.2) Redistribute connections in case of failure
|
|
------------------------------------------------
|
|
In HTTP mode, if a server designated by a cookie does not respond, the clients
|
|
may definitely stick to it because they cannot flush the cookie, so they will
|
|
not be able to access the service anymore. Specifying 'redispatch' will allow
|
|
the proxy to break their persistence and redistribute them to working servers.
|
|
|
|
Example :
|
|
---------
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
cookie SERVERID
|
|
dispatch 192.168.1.100:80
|
|
server web1 192.168.1.1:80 cookie server01
|
|
server web2 192.168.1.2:80 cookie server02
|
|
redispatch # send back to dispatch in case of connection failure
|
|
|
|
Up to, and including version 1.1.16, this parameter only applied to connection
|
|
failures. Since version 1.1.17, it also applies to servers which have been
|
|
detected as failed by the health check mechanism. Indeed, a server may be broken
|
|
but still accepting connections, which would not solve every case. But it is
|
|
possible to conserve the old behaviour, that is, make a client insist on trying
|
|
to connect to a server even if it is said to be down, by setting the 'persist'
|
|
option :
|
|
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
option persist
|
|
cookie SERVERID
|
|
dispatch 192.168.1.100:80
|
|
server web1 192.168.1.1:80 cookie server01
|
|
server web2 192.168.1.2:80 cookie server02
|
|
redispatch # send back to dispatch in case of connection failure
|
|
|
|
|
|
4) Additionnal features
|
|
=======================
|
|
|
|
Other features are available. They are transparent mode, event logging and
|
|
header rewriting/filtering.
|
|
|
|
4.1) Transparent mode
|
|
---------------------
|
|
In HTTP mode, the 'transparent' keyword allows to intercept sessions which are
|
|
routed through the system hosting the proxy. This mode was implemented as a
|
|
replacement for the 'dispatch' mode, since connections without cookie will be
|
|
sent to the original address while known cookies will be sent to the servers.
|
|
This mode implies that the system can redirect sessions to a local port.
|
|
|
|
Example :
|
|
---------
|
|
listen http_proxy 0.0.0.0:65000
|
|
mode http
|
|
transparent
|
|
cookie SERVERID
|
|
server server01 192.168.1.1:80
|
|
server server02 192.168.1.2:80
|
|
|
|
# iptables -t nat -A PREROUTING -i eth0 -p tcp -d 192.168.1.100 \
|
|
--dport 80 -j REDIRECT --to-ports 65000
|
|
|
|
Note :
|
|
------
|
|
If the port is left unspecified on the server, the port the client connected to
|
|
will be used. This allows to relay a full port range without using transparent
|
|
mode nor thousands of file descriptors, provided that the system can redirect
|
|
sessions to local ports.
|
|
|
|
Example :
|
|
---------
|
|
# redirect all ports to local port 65000, then forward to the server on the
|
|
# original port.
|
|
listen http_proxy 0.0.0.0:65000
|
|
mode tcp
|
|
server server01 192.168.1.1 check port 60000
|
|
server server02 192.168.1.2 check port 60000
|
|
|
|
# iptables -t nat -A PREROUTING -i eth0 -p tcp -d 192.168.1.100 \
|
|
-j REDIRECT --to-ports 65000
|
|
|
|
|
|
4.2) Event logging
|
|
------------------
|
|
4.2.1) Log levels
|
|
-----------------
|
|
TCP and HTTP connections can be logged with informations such as date, time,
|
|
source IP address, destination address, connection duration, response times,
|
|
HTTP request, the HTTP return code, number of bytes transmitted, the conditions
|
|
in which the session ended, and even exchanged cookies values, to track a
|
|
particular user's problems for example. All messages are sent to up to two
|
|
syslog servers. Consult section 1.1 for more info about log facilities. The
|
|
syntax follows :
|
|
|
|
log <address_1> <facility_1> [max_level_1]
|
|
log <address_2> <facility_2> [max_level_2]
|
|
or
|
|
log global
|
|
|
|
Note :
|
|
------
|
|
The particular syntax 'log global' means that the same log configuration as the
|
|
'global' section will be used.
|
|
|
|
Example :
|
|
---------
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
log 192.168.2.200 local3
|
|
log 192.168.2.201 local4
|
|
|
|
4.2.2) Log format
|
|
-----------------
|
|
By default, connections are logged at the TCP level, as soon as the session
|
|
establishes between the client and the proxy. By enabling the 'tcplog' option,
|
|
the proxy will wait until the session ends to generate an enhanced log
|
|
containing more information such as session duration and its state during the
|
|
disconnection.
|
|
|
|
Another option, 'httplog', provides more detailed information about HTTP
|
|
contents, such as the request and some cookies. In the event where an external
|
|
component would establish frequent connections to check the service, logs may be
|
|
full of useless lines. So it is possible not to log any session which didn't
|
|
transfer any data, by the setting of the 'dontlognull' option. This only has
|
|
effect on sessions which are established then closed.
|
|
|
|
Example :
|
|
---------
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
option httplog
|
|
option dontlognull
|
|
log 192.168.2.200 local3
|
|
|
|
4.2.3) Timing events
|
|
--------------------
|
|
Timers provide a great help in trouble shooting network problems. All values
|
|
are reported in milliseconds (ms). In HTTP mode, four control points are
|
|
reported under the form 'Tq/Tc/Tr/Tt' :
|
|
|
|
- Tq: total time to get the client request.
|
|
It's the time elapsed between the moment the client connection was accepted
|
|
and the moment the proxy received the last HTTP header. The value '-1'
|
|
indicates that the end of headers (empty line) has never been seen.
|
|
|
|
- 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, or between the TCP SYN packet
|
|
and the matching SYN/ACK in return. The value '-1' means that the
|
|
connection never established.
|
|
|
|
- Tr: server response time. It's the time elapsed between the moment the
|
|
TCP connection was established to the server and the moment it send its
|
|
complete response header. It purely shows its request processing time,
|
|
without the network overhead due to the data transmission. The value '-1'
|
|
means that the last the response header (empty line) was never seen.
|
|
|
|
- Tt: total session duration time, between the moment the proxy accepted it
|
|
and the moment both ends were closed. From this one, we can deduce Td,
|
|
the data transmission time, by substracting other timers when valid :
|
|
|
|
Td = Tt - (Tq + Tc + Tr)
|
|
|
|
Timers with '-1' values have to be excluded from this equation.
|
|
|
|
In TCP mode ('option tcplog'), only Tc and Tt are reported.
|
|
|
|
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 packets lost
|
|
due to network problems (wires or negociation). Moreover, if <Tt> is close to
|
|
a timeout value specified in the configuration, it often means that a session
|
|
has been aborted on time-out.
|
|
|
|
Most common cases :
|
|
|
|
- If Tq is close to 3000, a packet has probably been lost between the client
|
|
and the proxy.
|
|
- If Tc is close to 3000, a packet has probably been lost between the server
|
|
and the proxy during the server connection phase. This one should always be
|
|
very low (less than a few tens).
|
|
- 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 Tt is often slightly higher than a time-out, it's often because the
|
|
client and the server use HTTP keep-alive and the session is maintained
|
|
after the response ends. Se further for how to disable HTTP keep-alive.
|
|
|
|
Other cases ('xx' means any value to be ignored) :
|
|
-1/xx/xx/Tt : the client was not able to send its complete request in time,
|
|
or that it aborted it too early.
|
|
Tq/-1/xx/Tt : the connection could not establish on the server. Either it
|
|
refused it or it timed out after Tt-Tq ms.
|
|
Tq/Tc/-1/Tt : the server has accepted the connection but did not return a
|
|
complete response in time, or it closed its connexion
|
|
unexpectedly, after Tt-(Tq+Tc) ms.
|
|
|
|
4.2.4) Session state at disconnection
|
|
-------------------------------------
|
|
TCP and HTTP logs provide a session completion indicator. It's a 4-characters
|
|
(2 in TCP) field preceeding the HTTP request, and indicating :
|
|
- On the first character, a code reporting the first event which caused the
|
|
session to terminate :
|
|
|
|
C : the TCP session was aborted by the client.
|
|
S : the TCP session was aborted by the server, or the server refused it.
|
|
P : the session was abordted prematurely by the proxy, either because of
|
|
an internal error, or because a DENY filter was matched.
|
|
c : the client time-out expired first.
|
|
s : the server time-out expired first.
|
|
- : normal session completion.
|
|
|
|
- on the second character, the HTTP session state when it was closed :
|
|
|
|
R : waiting for complete REQUEST from the client
|
|
C : waiting for CONNECTION to establish on the server
|
|
H : waiting for complete HEADERS from the server
|
|
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.
|
|
- : 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.
|
|
I : the client provided an INVALID cookie matching no known server.
|
|
D : the client provided a cookie designating a server which was DOWN,
|
|
so either the 'persist' option 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.
|
|
- : 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.
|
|
P : a cookie was PROVIDED by the server and transmitted as-is.
|
|
I : no cookie was provided by the server, and one was INSERTED by the
|
|
proxy.
|
|
D : the cookie provided by the server was DELETED by the proxy.
|
|
R : the cookie provided by the server was REWRITTEN by the proxy.
|
|
- : does not apply (no cookie set in configuration).
|
|
|
|
The 'capture' keyword allows to capture and log informations exchanged between
|
|
clients and servers. As of version 1.1.23, only cookies can be captured, which
|
|
makes it easy to track a complete user session. The syntax is :
|
|
|
|
capture cookie <cookie_prefix> len <capture_length>
|
|
|
|
The FIRST cookie whose name starts with <cookie_prefix> will be captured, and
|
|
logged as 'NAME=value', without exceeding <capture_length> characters (64 max).
|
|
When the cookie name is fixed and known, it's preferable to suffix '=' to it to
|
|
ensure that no other cookie will be logged.
|
|
|
|
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
|
|
|
|
In the logs, the field preceeding the completion indicator contains the cookie
|
|
value as sent by the server, preceeded by the cookie value as sent by the
|
|
client. Each of these field is replaced with '-' when no cookie was seen.
|
|
|
|
4.2.5) Examples of logs
|
|
-----------------------
|
|
- haproxy[674]: 127.0.0.1:33319 [15/Oct/2003:08:31:57] relais-http Srv1 6559/7/147/6723 200 243 - - ---- "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[18113]: 127.0.0.1:34548 [15/Oct/2003:15:18:55] relais-http <NOSRV> -1/-1/-1/8490 -1 0 - - CR-- ""
|
|
=> 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 the server.
|
|
|
|
- haproxy[18113]: 127.0.0.1:34549 [15/Oct/2003:15:19:06] relais-http <NOSRV> -1/-1/-1/50001 408 0 - - cR-- ""
|
|
=> 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 the 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] relais-tcp Srv1 0/5007 0 cD
|
|
=> This is a 'tcplog' entry. Client-side time-out ('c----') occured after 5s.
|
|
|
|
- haproxy[18989]: 10.0.0.1:34552 [15/Oct/2003:15:26:31] relais-http Srv1 3183/-1/-1/11215 503 0 - - SC-- "HEAD / HTTP/1.0"
|
|
=> The request took 3s to complete (probably a network problem), and the
|
|
connection to the server failed ('SC--') after 4 attemps of 2 seconds
|
|
(config says 'retries 3'), then a 503 error code was sent to the client.
|
|
|
|
4.3) HTTP header manipulation
|
|
-----------------------------
|
|
In HTTP mode, it is possible to rewrite, add or delete some of the request and
|
|
response headers based on regular expressions. It is also possible to block a
|
|
request or a response if a particular header matches a regular expression,
|
|
which is enough to stops most elementary protocol attacks, and to protect
|
|
against information leak from the internal network. But there is a limitation
|
|
to this : since haproxy's HTTP engine knows nothing about keep-alive, only
|
|
headers passed during the first request of a TCP session will be seen. All
|
|
subsequent headers will be considered data only and not analyzed. Furthermore,
|
|
haproxy doesn't touch data contents, it stops at the end of headers.
|
|
|
|
The syntax is :
|
|
reqadd <string> to add a header to the request
|
|
reqrep <search> <replace> to modify the request
|
|
reqirep <search> <replace> same, but ignoring the case
|
|
reqdel <search> to delete a header in the request
|
|
reqidel <search> same, but ignoring the case
|
|
reqallow <search> definitely allow a request if a header matches <search>
|
|
reqiallow <search> same, but ignoring the case
|
|
reqdeny <search> denies a request if a header matches <search>
|
|
reqideny <search> same, but ignoring the case
|
|
reqpass <search> ignore a header matching <search>
|
|
reqipass <search> same, but ignoring the case
|
|
|
|
rspadd <string> to add a header to the response
|
|
rsprep <search> <replace> to modify the response
|
|
rspirep <search> <replace> same, but ignoring the case
|
|
rspdel <search> to delete the response
|
|
rspidel <search> same, but ignoring the case
|
|
|
|
|
|
<search> is a POSIX regular expression (regex) which supports grouping through
|
|
parenthesis (without the backslash). Spaces and other delimiters must be
|
|
prefixed with a backslash ('\') to avoid confusion with a field delimiter.
|
|
Other characters may be prefixed with a backslash to change their meaning :
|
|
|
|
\t for a tab
|
|
\r for a carriage return (CR)
|
|
\n for a new line (LF)
|
|
\ to mark a space and differentiate it from a delimiter
|
|
\# to mark a sharp and differentiate it from a comment
|
|
\\ to use a backslash in a regex
|
|
\\\\ to use a backslash in the text (*2 for regex, *2 for haproxy)
|
|
\xXX to write the ASCII hex code XX as in the C language
|
|
|
|
|
|
<replace> containst the string to be used to replace the largest portion of text
|
|
matching the regex. It can make use of the special characters above, and can
|
|
reference a substring delimited by parenthesis in the regex, by the group
|
|
numerical order from 1 to 9. In this case, you would write a backslah ('\')
|
|
immediately followed by one digit indicating the group position.
|
|
|
|
<string> represents the string which will systematically be added after the last
|
|
header line. It can also use special characters above.
|
|
|
|
Notes :
|
|
-------
|
|
- the first line is considered as a header, which makes it possible to rewrite
|
|
or filter HTTP requests URIs or response codes.
|
|
- 'reqrep' is the equivalent of 'cliexp' in version 1.0, and 'rsprep' is the
|
|
equivalent of 'srvexp' in 1.0. Those names are still supported but
|
|
deprecated.
|
|
- for performances reasons, the number of characters added to a request or to
|
|
a response is limited to 4096 since version 1.1.5 (it was 256 before). This
|
|
value is easy to modify in the code if needed (#define). If it is too short
|
|
on occasional uses, it is possible to gain some space by removing some
|
|
useless headers before adding new ones.
|
|
|
|
Examples :
|
|
----------
|
|
###### a few examples ######
|
|
|
|
# rewrite 'online.fr' instead of 'free.fr' for GET and POST requests
|
|
reqrep ^(GET\ .*)(.free.fr)(.*) \1.online.fr\3
|
|
reqrep ^(POST\ .*)(.free.fr)(.*) \1.online.fr\3
|
|
|
|
# force proxy connections to close
|
|
reqirep ^Proxy-Connection:.* Proxy-Connection:\ close
|
|
# rewrite locations
|
|
rspirep ^(Location:\ )([^:]*://[^/]*)(.*) \1\3
|
|
|
|
###### A full configuration being used on production ######
|
|
|
|
# Every header should end with a colon followed by one space.
|
|
reqideny ^[^:\ ]*[\ ]*$
|
|
|
|
# block Apache chunk exploit
|
|
reqideny ^Transfer-Encoding:[\ ]*chunked
|
|
reqideny ^Host:\ apache-
|
|
|
|
# block annoying worms that fill the logs...
|
|
reqideny ^[^:\ ]*\ .*(\.|%2e)(\.|%2e)(%2f|%5c|/|\\\\)
|
|
reqideny ^[^:\ ]*\ ([^\ ]*\ [^\ ]*\ |.*%00)
|
|
reqideny ^[^:\ ]*\ .*<script
|
|
reqideny ^[^:\ ]*\ .*/(root\.exe\?|cmd\.exe\?|default\.ida\?)
|
|
|
|
# allow other syntactically valid requests, and block any other method
|
|
reqipass ^(GET|POST|HEAD|OPTIONS)\ /.*\ HTTP/1\.[01]$
|
|
reqipass ^OPTIONS\ \\*\ HTTP/1\.[01]$
|
|
reqideny ^[^:\ ]*\
|
|
|
|
# force connection:close, thus disabling HTTP keep-alive
|
|
reqidel ^Connection:
|
|
rspidel ^Connection:
|
|
reqadd Connection:\ close
|
|
rspadd Connection:\ close
|
|
|
|
# change the server name
|
|
rspidel ^Server:\
|
|
rspadd Server:\ Formilux/0.1.8
|
|
|
|
|
|
Last, the 'forwardfor' option creates an HTTP 'X-Forwarded-For' header which
|
|
contains the client's IP address. This is useful to let the final web server
|
|
know what the client address was (eg for statistics on domains).
|
|
|
|
Example :
|
|
---------
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
log global
|
|
option httplog
|
|
option dontlognull
|
|
option forwardfor
|
|
|
|
4.4) Load balancing with persistence
|
|
------------------------------------
|
|
|
|
Combining cookie insertion with internal load balancing allows to transparently
|
|
bring persistence to applications. The principle is quite simple :
|
|
- assign a cookie value to each server
|
|
- enable the load balancing between servers
|
|
- insert a cookie into responses resulting from the balancing algorithm
|
|
(indirect accesses), end ensure that no upstream proxy will cache it.
|
|
- remove the cookie in the request headers so that the application never sees
|
|
it.
|
|
|
|
Example :
|
|
---------
|
|
listen application 0.0.0.0:80
|
|
mode http
|
|
cookie SERVERID insert nocache indirect
|
|
balance roundrobin
|
|
server 192.168.1.1:80 cookie server01 check
|
|
server 192.168.1.2:80 cookie server02 check
|
|
|
|
4.5) Customizing errors
|
|
-----------------------
|
|
|
|
Some situations can make haproxy return an HTTP error code to the client :
|
|
- invalid or too long request => HTTP 400
|
|
- request not completely sent in time => HTTP 408
|
|
- forbidden request (matches a deny filter) => HTTP 403
|
|
- internal error in haproxy => HTTP 500
|
|
- the server returned an invalid or incomplete response => HTTP 502
|
|
- no server was available to handle the request => HTTP 503
|
|
- the server failed to reply in time => HTTP 504
|
|
|
|
A succint error message taken from the RFC accompanies these return codes.
|
|
But depending on the clients knowledge, it may be better to return custom, user
|
|
friendly, error pages. This is made possible through the use of the 'errorloc'
|
|
command :
|
|
|
|
errorloc <HTTP_code> <location>
|
|
|
|
Instead of generating an HTTP error <HTTP_code> among those above, the proxy
|
|
will return a temporary redirection code (HTTP 302) towards the address
|
|
specified in <location>. This address may be either relative to the site or
|
|
absolute. Since this request will be handled by the client's browser, it's
|
|
mandatory that the returned address be reachable from the outside.
|
|
|
|
Example :
|
|
---------
|
|
listen application 0.0.0.0:80
|
|
errorloc 400 /badrequest.html
|
|
errorloc 403 /forbidden.html
|
|
errorloc 408 /toolong.html
|
|
errorloc 500 http://haproxy.domain.net/bugreport.html
|
|
errorloc 502 http://192.168.114.58/error50x.html
|
|
errorloc 503 http://192.168.114.58/error50x.html
|
|
errorloc 504 http://192.168.114.58/error50x.html
|
|
|
|
4.6) Modifying default values
|
|
-----------------------------
|
|
|
|
Version 1.1.22 introduced the notion of default values, which eliminates the
|
|
pain of often repeating common parameters between many instances, such as
|
|
logs, timeouts, modes, etc...
|
|
|
|
Default values are set in a 'defaults' section. Each of these section clears
|
|
all previously set default parameters, so there may be as many default
|
|
parameters as needed. Only the last one before a 'listen' section will be
|
|
used for this section. The 'defaults' section uses the same syntax as the
|
|
'listen' section, for the supported parameters. The 'defaults' keyword ignores
|
|
everything on its command line, so that fake instance names can be specified
|
|
there for better clarity.
|
|
|
|
In version 1.1.23, only those parameters can be preset in the 'default'
|
|
section :
|
|
- log (the first and second one)
|
|
- mode { tcp, http, health }
|
|
- balance { roundrobin }
|
|
- disabled (to disable every further instances)
|
|
- enabled (to enable every further instances, this is the default)
|
|
- contimeout, clitimeout, srvtimeout, grace, retries, maxconn
|
|
- option { redispatch, transparent, keepalive, forwardfor, httplog,
|
|
dontlognull, persist, httpchk }
|
|
- redispatch, redisp, transparent, source { addr:port }
|
|
- cookie, capture
|
|
- errorloc
|
|
|
|
As of 1.1.24, it is not possible to put certain parameters in a 'defaults'
|
|
section, mainly regular expressions and server configurations :
|
|
- dispatch, server,
|
|
- req*, rsp*
|
|
|
|
Last, there's no way yet to change a boolean option from its assigned default
|
|
value. So if an 'option' statement is set in a 'defaults' section, the only
|
|
way to flush it is to redefine a new 'defaults' section without this 'option'.
|
|
|
|
Examples :
|
|
----------
|
|
defaults applications TCP
|
|
log global
|
|
mode tcp
|
|
balance roundrobin
|
|
clitimeout 180000
|
|
srvtimeout 180000
|
|
contimeout 4000
|
|
retries 3
|
|
redispatch
|
|
|
|
listen app_tcp1 10.0.0.1:6000-6063
|
|
server srv1 192.168.1.1 check port 6000 inter 10000
|
|
server srv2 192.168.1.2 backup
|
|
|
|
listen app_tcp2 10.0.0.2:6000-6063
|
|
server srv1 192.168.2.1 check port 6000 inter 10000
|
|
server srv2 192.168.2.2 backup
|
|
|
|
defaults applications HTTP
|
|
log global
|
|
mode http
|
|
option httplog
|
|
option forwardfor
|
|
option dontlognull
|
|
balance roundrobin
|
|
clitimeout 20000
|
|
srvtimeout 20000
|
|
contimeout 4000
|
|
retries 3
|
|
|
|
listen app_http1 10.0.0.1:80-81
|
|
cookie SERVERID postonly insert indirect
|
|
capture cookie userid= len 10
|
|
server srv1 192.168.1.1:+8000 cookie srv1 check port 8080 inter 1000
|
|
server srv1 192.168.1.2:+8000 cookie srv2 check port 8080 inter 1000
|
|
|
|
defaults
|
|
# this empty section voids all default parameters
|
|
|
|
=========================
|
|
| System-specific setup |
|
|
=========================
|
|
|
|
Linux 2.4
|
|
=========
|
|
|
|
-- cut here --
|
|
#!/bin/sh
|
|
# set this to about 256/4M (16384 for 256M machine)
|
|
MAXFILES=16384
|
|
echo $MAXFILES > /proc/sys/fs/file-max
|
|
ulimit -n $MAXFILES
|
|
|
|
if [ -e /proc/sys/net/ipv4/ip_conntrack_max ]; then
|
|
echo 65536 > /proc/sys/net/ipv4/ip_conntrack_max
|
|
fi
|
|
|
|
if [ -e /proc/sys/net/ipv4/netfilter/ip_ct_tcp_timeout_fin_wait ]; then
|
|
# 30 seconds for fin, 15 for time wait
|
|
echo 3000 > /proc/sys/net/ipv4/netfilter/ip_ct_tcp_timeout_fin_wait
|
|
echo 1500 > /proc/sys/net/ipv4/netfilter/ip_ct_tcp_timeout_time_wait
|
|
echo 0 > /proc/sys/net/ipv4/netfilter/ip_ct_tcp_log_invalid_scale
|
|
echo 0 > /proc/sys/net/ipv4/netfilter/ip_ct_tcp_log_out_of_window
|
|
fi
|
|
|
|
echo 1024 60999 > /proc/sys/net/ipv4/ip_local_port_range
|
|
echo 30 > /proc/sys/net/ipv4/tcp_fin_timeout
|
|
echo 4096 > /proc/sys/net/ipv4/tcp_max_syn_backlog
|
|
echo 262144 > /proc/sys/net/ipv4/tcp_max_tw_buckets
|
|
echo 262144 > /proc/sys/net/ipv4/tcp_max_orphans
|
|
echo 300 > /proc/sys/net/ipv4/tcp_keepalive_time
|
|
echo 1 > /proc/sys/net/ipv4/tcp_tw_recycle
|
|
echo 0 > /proc/sys/net/ipv4/tcp_timestamps
|
|
echo 0 > /proc/sys/net/ipv4/tcp_ecn
|
|
echo 0 > /proc/sys/net/ipv4/tcp_sack
|
|
echo 0 > /proc/sys/net/ipv4/tcp_dsack
|
|
|
|
# auto-tuned on 2.4
|
|
#echo 262143 > /proc/sys/net/core/rmem_max
|
|
#echo 262143 > /proc/sys/net/core/rmem_default
|
|
|
|
echo 16384 65536 524288 > /proc/sys/net/ipv4/tcp_rmem
|
|
echo 16384 349520 699040 > /proc/sys/net/ipv4/tcp_wmem
|
|
|
|
-- cut here --
|
|
|
|
|
|
FreeBSD
|
|
=======
|
|
|
|
A FreeBSD port of HA-Proxy is now available and maintained, thanks to
|
|
Clement Laforet <sheepkiller@cultdeadsheep.org>.
|
|
|
|
For more information :
|
|
http://www.freebsd.org/cgi/url.cgi?ports/net/haproxy/pkg-descr
|
|
http://www.freebsd.org/cgi/cvsweb.cgi/ports/net/haproxy/
|
|
http://www.freshports.org/net/haproxy
|
|
|
|
|
|
-- end --
|