| ------------------------ |
| HAProxy Management Guide |
| ------------------------ |
| version 1.8 |
| |
| |
| This document describes how to start, stop, manage, and troubleshoot HAProxy, |
| as well as some known limitations and traps to avoid. It does not describe how |
| to configure it (for this please read configuration.txt). |
| |
| Note to documentation contributors : |
| This document is formatted with 80 columns per line, with even number of |
| spaces for indentation and without tabs. Please follow these rules strictly |
| so that it remains easily printable everywhere. If you add sections, please |
| update the summary below for easier searching. |
| |
| |
| Summary |
| ------- |
| |
| 1. Prerequisites |
| 2. Quick reminder about HAProxy's architecture |
| 3. Starting HAProxy |
| 4. Stopping and restarting HAProxy |
| 5. File-descriptor limitations |
| 6. Memory management |
| 7. CPU usage |
| 8. Logging |
| 9. Statistics and monitoring |
| 9.1. CSV format |
| 9.2. Typed output format |
| 9.3. Unix Socket commands |
| 10. Tricks for easier configuration management |
| 11. Well-known traps to avoid |
| 12. Debugging and performance issues |
| 13. Security considerations |
| |
| |
| 1. Prerequisites |
| ---------------- |
| |
| In this document it is assumed that the reader has sufficient administration |
| skills on a UNIX-like operating system, uses the shell on a daily basis and is |
| familiar with troubleshooting utilities such as strace and tcpdump. |
| |
| |
| 2. Quick reminder about HAProxy's architecture |
| ---------------------------------------------- |
| |
| HAProxy is a single-threaded, event-driven, non-blocking daemon. This means is |
| uses event multiplexing to schedule all of its activities instead of relying on |
| the system to schedule between multiple activities. Most of the time it runs as |
| a single process, so the output of "ps aux" on a system will report only one |
| "haproxy" process, unless a soft reload is in progress and an older process is |
| finishing its job in parallel to the new one. It is thus always easy to trace |
| its activity using the strace utility. |
| |
| HAProxy is designed to isolate itself into a chroot jail during startup, where |
| it cannot perform any file-system access at all. This is also true for the |
| libraries it depends on (eg: libc, libssl, etc). The immediate effect is that |
| a running process will not be able to reload a configuration file to apply |
| changes, instead a new process will be started using the updated configuration |
| file. Some other less obvious effects are that some timezone files or resolver |
| files the libc might attempt to access at run time will not be found, though |
| this should generally not happen as they're not needed after startup. A nice |
| consequence of this principle is that the HAProxy process is totally stateless, |
| and no cleanup is needed after it's killed, so any killing method that works |
| will do the right thing. |
| |
| HAProxy doesn't write log files, but it relies on the standard syslog protocol |
| to send logs to a remote server (which is often located on the same system). |
| |
| HAProxy uses its internal clock to enforce timeouts, that is derived from the |
| system's time but where unexpected drift is corrected. This is done by limiting |
| the time spent waiting in poll() for an event, and measuring the time it really |
| took. In practice it never waits more than one second. This explains why, when |
| running strace over a completely idle process, periodic calls to poll() (or any |
| of its variants) surrounded by two gettimeofday() calls are noticed. They are |
| normal, completely harmless and so cheap that the load they imply is totally |
| undetectable at the system scale, so there's nothing abnormal there. Example : |
| |
| 16:35:40.002320 gettimeofday({1442759740, 2605}, NULL) = 0 |
| 16:35:40.002942 epoll_wait(0, {}, 200, 1000) = 0 |
| 16:35:41.007542 gettimeofday({1442759741, 7641}, NULL) = 0 |
| 16:35:41.007998 gettimeofday({1442759741, 8114}, NULL) = 0 |
| 16:35:41.008391 epoll_wait(0, {}, 200, 1000) = 0 |
| 16:35:42.011313 gettimeofday({1442759742, 11411}, NULL) = 0 |
| |
| HAProxy is a TCP proxy, not a router. It deals with established connections that |
| have been validated by the kernel, and not with packets of any form nor with |
| sockets in other states (eg: no SYN_RECV nor TIME_WAIT), though their existence |
| may prevent it from binding a port. It relies on the system to accept incoming |
| connections and to initiate outgoing connections. An immediate effect of this is |
| that there is no relation between packets observed on the two sides of a |
| forwarded connection, which can be of different size, numbers and even family. |
| Since a connection may only be accepted from a socket in LISTEN state, all the |
| sockets it is listening to are necessarily visible using the "netstat" utility |
| to show listening sockets. Example : |
| |
| # netstat -ltnp |
| Active Internet connections (only servers) |
| Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name |
| tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1629/sshd |
| tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 2847/haproxy |
| tcp 0 0 0.0.0.0:443 0.0.0.0:* LISTEN 2847/haproxy |
| |
| |
| 3. Starting HAProxy |
| ------------------- |
| |
| HAProxy is started by invoking the "haproxy" program with a number of arguments |
| passed on the command line. The actual syntax is : |
| |
| $ haproxy [<options>]* |
| |
| where [<options>]* is any number of options. An option always starts with '-' |
| followed by one of more letters, and possibly followed by one or multiple extra |
| arguments. Without any option, HAProxy displays the help page with a reminder |
| about supported options. Available options may vary slightly based on the |
| operating system. A fair number of these options overlap with an equivalent one |
| if the "global" section. In this case, the command line always has precedence |
| over the configuration file, so that the command line can be used to quickly |
| enforce some settings without touching the configuration files. The current |
| list of options is : |
| |
| -- <cfgfile>* : all the arguments following "--" are paths to configuration |
| file/directory to be loaded and processed in the declaration order. It is |
| mostly useful when relying on the shell to load many files that are |
| numerically ordered. See also "-f". The difference between "--" and "-f" is |
| that one "-f" must be placed before each file name, while a single "--" is |
| needed before all file names. Both options can be used together, the |
| command line ordering still applies. When more than one file is specified, |
| each file must start on a section boundary, so the first keyword of each |
| file must be one of "global", "defaults", "peers", "listen", "frontend", |
| "backend", and so on. A file cannot contain just a server list for example. |
| |
| -f <cfgfile|cfgdir> : adds <cfgfile> to the list of configuration files to be |
| loaded. If <cfgdir> is a directory, all the files (and only files) it |
| contains are added in lexical order (using LC_COLLATE=C) to the list of |
| configuration files to be loaded ; only files with ".cfg" extension are |
| added, only non hidden files (not prefixed with ".") are added. |
| Configuration files are loaded and processed in their declaration order. |
| This option may be specified multiple times to load multiple files. See |
| also "--". The difference between "--" and "-f" is that one "-f" must be |
| placed before each file name, while a single "--" is needed before all file |
| names. Both options can be used together, the command line ordering still |
| applies. When more than one file is specified, each file must start on a |
| section boundary, so the first keyword of each file must be one of |
| "global", "defaults", "peers", "listen", "frontend", "backend", and so on. |
| A file cannot contain just a server list for example. |
| |
| -C <dir> : changes to directory <dir> before loading configuration |
| files. This is useful when using relative paths. Warning when using |
| wildcards after "--" which are in fact replaced by the shell before |
| starting haproxy. |
| |
| -D : start as a daemon. The process detaches from the current terminal after |
| forking, and errors are not reported anymore in the terminal. It is |
| equivalent to the "daemon" keyword in the "global" section of the |
| configuration. It is recommended to always force it in any init script so |
| that a faulty configuration doesn't prevent the system from booting. |
| |
| -Ds : work in systemd mode. Only used by the systemd wrapper. |
| |
| -L <name> : change the local peer name to <name>, which defaults to the local |
| hostname. This is used only with peers replication. |
| |
| -N <limit> : sets the default per-proxy maxconn to <limit> instead of the |
| builtin default value (usually 2000). Only useful for debugging. |
| |
| -V : enable verbose mode (disables quiet mode). Reverts the effect of "-q" or |
| "quiet". |
| |
| -c : only performs a check of the configuration files and exits before trying |
| to bind. The exit status is zero if everything is OK, or non-zero if an |
| error is encountered. |
| |
| -d : enable debug mode. This disables daemon mode, forces the process to stay |
| in foreground and to show incoming and outgoing events. It is equivalent to |
| the "global" section's "debug" keyword. It must never be used in an init |
| script. |
| |
| -dG : disable use of getaddrinfo() to resolve host names into addresses. It |
| can be used when suspecting that getaddrinfo() doesn't work as expected. |
| This option was made available because many bogus implementations of |
| getaddrinfo() exist on various systems and cause anomalies that are |
| difficult to troubleshoot. |
| |
| -dM[<byte>] : forces memory poisoning, which means that each and every |
| memory region allocated with malloc() or pool_alloc2() will be filled with |
| <byte> before being passed to the caller. When <byte> is not specified, it |
| defaults to 0x50 ('P'). While this slightly slows down operations, it is |
| useful to reliably trigger issues resulting from missing initializations in |
| the code that cause random crashes. Note that -dM0 has the effect of |
| turning any malloc() into a calloc(). In any case if a bug appears or |
| disappears when using this option it means there is a bug in haproxy, so |
| please report it. |
| |
| -dS : disable use of the splice() system call. It is equivalent to the |
| "global" section's "nosplice" keyword. This may be used when splice() is |
| suspected to behave improperly or to cause performance issues, or when |
| using strace to see the forwarded data (which do not appear when using |
| splice()). |
| |
| -dV : disable SSL verify on the server side. It is equivalent to having |
| "ssl-server-verify none" in the "global" section. This is useful when |
| trying to reproduce production issues out of the production |
| environment. Never use this in an init script as it degrades SSL security |
| to the servers. |
| |
| -db : disable background mode and multi-process mode. The process remains in |
| foreground. It is mainly used during development or during small tests, as |
| Ctrl-C is enough to stop the process. Never use it in an init script. |
| |
| -de : disable the use of the "epoll" poller. It is equivalent to the "global" |
| section's keyword "noepoll". It is mostly useful when suspecting a bug |
| related to this poller. On systems supporting epoll, the fallback will |
| generally be the "poll" poller. |
| |
| -dk : disable the use of the "kqueue" poller. It is equivalent to the |
| "global" section's keyword "nokqueue". It is mostly useful when suspecting |
| a bug related to this poller. On systems supporting kqueue, the fallback |
| will generally be the "poll" poller. |
| |
| -dp : disable the use of the "poll" poller. It is equivalent to the "global" |
| section's keyword "nopoll". It is mostly useful when suspecting a bug |
| related to this poller. On systems supporting poll, the fallback will |
| generally be the "select" poller, which cannot be disabled and is limited |
| to 1024 file descriptors. |
| |
| -dr : ignore server address resolution failures. It is very common when |
| validating a configuration out of production not to have access to the same |
| resolvers and to fail on server address resolution, making it difficult to |
| test a configuration. This option simply appends the "none" method to the |
| list of address resolution methods for all servers, ensuring that even if |
| the libc fails to resolve an address, the startup sequence is not |
| interrupted. |
| |
| -m <limit> : limit the total allocatable memory to <limit> megabytes across |
| all processes. This may cause some connection refusals or some slowdowns |
| depending on the amount of memory needed for normal operations. This is |
| mostly used to force the processes to work in a constrained resource usage |
| scenario. It is important to note that the memory is not shared between |
| processes, so in a multi-process scenario, this value is first divided by |
| global.nbproc before forking. |
| |
| -n <limit> : limits the per-process connection limit to <limit>. This is |
| equivalent to the global section's keyword "maxconn". It has precedence |
| over this keyword. This may be used to quickly force lower limits to avoid |
| a service outage on systems where resource limits are too low. |
| |
| -p <file> : write all processes' pids into <file> during startup. This is |
| equivalent to the "global" section's keyword "pidfile". The file is opened |
| before entering the chroot jail, and after doing the chdir() implied by |
| "-C". Each pid appears on its own line. |
| |
| -q : set "quiet" mode. This disables some messages during the configuration |
| parsing and during startup. It can be used in combination with "-c" to |
| just check if a configuration file is valid or not. |
| |
| -sf <pid>* : send the "finish" signal (SIGUSR1) to older processes after boot |
| completion to ask them to finish what they are doing and to leave. <pid> |
| is a list of pids to signal (one per argument). The list ends on any |
| option starting with a "-". It is not a problem if the list of pids is |
| empty, so that it can be built on the fly based on the result of a command |
| like "pidof" or "pgrep". |
| |
| -st <pid>* : send the "terminate" signal (SIGTERM) to older processes after |
| boot completion to terminate them immediately without finishing what they |
| were doing. <pid> is a list of pids to signal (one per argument). The list |
| is ends on any option starting with a "-". It is not a problem if the list |
| of pids is empty, so that it can be built on the fly based on the result of |
| a command like "pidof" or "pgrep". |
| |
| -v : report the version and build date. |
| |
| -vv : display the version, build options, libraries versions and usable |
| pollers. This output is systematically requested when filing a bug report. |
| |
| A safe way to start HAProxy from an init file consists in forcing the daemon |
| mode, storing existing pids to a pid file and using this pid file to notify |
| older processes to finish before leaving : |
| |
| haproxy -f /etc/haproxy.cfg \ |
| -D -p /var/run/haproxy.pid -sf $(cat /var/run/haproxy.pid) |
| |
| When the configuration is split into a few specific files (eg: tcp vs http), |
| it is recommended to use the "-f" option : |
| |
| haproxy -f /etc/haproxy/global.cfg -f /etc/haproxy/stats.cfg \ |
| -f /etc/haproxy/default-tcp.cfg -f /etc/haproxy/tcp.cfg \ |
| -f /etc/haproxy/default-http.cfg -f /etc/haproxy/http.cfg \ |
| -D -p /var/run/haproxy.pid -sf $(cat /var/run/haproxy.pid) |
| |
| When an unknown number of files is expected, such as customer-specific files, |
| it is recommended to assign them a name starting with a fixed-size sequence |
| number and to use "--" to load them, possibly after loading some defaults : |
| |
| haproxy -f /etc/haproxy/global.cfg -f /etc/haproxy/stats.cfg \ |
| -f /etc/haproxy/default-tcp.cfg -f /etc/haproxy/tcp.cfg \ |
| -f /etc/haproxy/default-http.cfg -f /etc/haproxy/http.cfg \ |
| -D -p /var/run/haproxy.pid -sf $(cat /var/run/haproxy.pid) \ |
| -f /etc/haproxy/default-customers.cfg -- /etc/haproxy/customers/* |
| |
| Sometimes a failure to start may happen for whatever reason. Then it is |
| important to verify if the version of HAProxy you are invoking is the expected |
| version and if it supports the features you are expecting (eg: SSL, PCRE, |
| compression, Lua, etc). This can be verified using "haproxy -vv". Some |
| important information such as certain build options, the target system and |
| the versions of the libraries being used are reported there. It is also what |
| you will systematically be asked for when posting a bug report : |
| |
| $ haproxy -vv |
| HA-Proxy version 1.6-dev7-a088d3-4 2015/10/08 |
| Copyright 2000-2015 Willy Tarreau <willy@haproxy.org> |
| |
| Build options : |
| TARGET = linux2628 |
| CPU = generic |
| CC = gcc |
| CFLAGS = -pg -O0 -g -fno-strict-aliasing -Wdeclaration-after-statement \ |
| -DBUFSIZE=8030 -DMAXREWRITE=1030 -DSO_MARK=36 -DTCP_REPAIR=19 |
| OPTIONS = USE_ZLIB=1 USE_DLMALLOC=1 USE_OPENSSL=1 USE_LUA=1 USE_PCRE=1 |
| |
| Default settings : |
| maxconn = 2000, bufsize = 8030, maxrewrite = 1030, maxpollevents = 200 |
| |
| Encrypted password support via crypt(3): yes |
| Built with zlib version : 1.2.6 |
| Compression algorithms supported : identity("identity"), deflate("deflate"), \ |
| raw-deflate("deflate"), gzip("gzip") |
| Built with OpenSSL version : OpenSSL 1.0.1o 12 Jun 2015 |
| Running on OpenSSL version : OpenSSL 1.0.1o 12 Jun 2015 |
| OpenSSL library supports TLS extensions : yes |
| OpenSSL library supports SNI : yes |
| OpenSSL library supports prefer-server-ciphers : yes |
| Built with PCRE version : 8.12 2011-01-15 |
| PCRE library supports JIT : no (USE_PCRE_JIT not set) |
| Built with Lua version : Lua 5.3.1 |
| Built with transparent proxy support using: IP_TRANSPARENT IP_FREEBIND |
| |
| Available polling systems : |
| epoll : pref=300, test result OK |
| poll : pref=200, test result OK |
| select : pref=150, test result OK |
| Total: 3 (3 usable), will use epoll. |
| |
| The relevant information that many non-developer users can verify here are : |
| - the version : 1.6-dev7-a088d3-4 above means the code is currently at commit |
| ID "a088d3" which is the 4th one after after official version "1.6-dev7". |
| Version 1.6-dev7 would show as "1.6-dev7-8c1ad7". What matters here is in |
| fact "1.6-dev7". This is the 7th development version of what will become |
| version 1.6 in the future. A development version not suitable for use in |
| production (unless you know exactly what you are doing). A stable version |
| will show as a 3-numbers version, such as "1.5.14-16f863", indicating the |
| 14th level of fix on top of version 1.5. This is a production-ready version. |
| |
| - the release date : 2015/10/08. It is represented in the universal |
| year/month/day format. Here this means August 8th, 2015. Given that stable |
| releases are issued every few months (1-2 months at the beginning, sometimes |
| 6 months once the product becomes very stable), if you're seeing an old date |
| here, it means you're probably affected by a number of bugs or security |
| issues that have since been fixed and that it might be worth checking on the |
| official site. |
| |
| - build options : they are relevant to people who build their packages |
| themselves, they can explain why things are not behaving as expected. For |
| example the development version above was built for Linux 2.6.28 or later, |
| targeting a generic CPU (no CPU-specific optimizations), and lacks any |
| code optimization (-O0) so it will perform poorly in terms of performance. |
| |
| - libraries versions : zlib version is reported as found in the library |
| itself. In general zlib is considered a very stable product and upgrades |
| are almost never needed. OpenSSL reports two versions, the version used at |
| build time and the one being used, as found on the system. These ones may |
| differ by the last letter but never by the numbers. The build date is also |
| reported because most OpenSSL bugs are security issues and need to be taken |
| seriously, so this library absolutely needs to be kept up to date. Seeing a |
| 4-months old version here is highly suspicious and indeed an update was |
| missed. PCRE provides very fast regular expressions and is highly |
| recommended. Certain of its extensions such as JIT are not present in all |
| versions and still young so some people prefer not to build with them, |
| which is why the build status is reported as well. Regarding the Lua |
| scripting language, HAProxy expects version 5.3 which is very young since |
| it was released a little time before HAProxy 1.6. It is important to check |
| on the Lua web site if some fixes are proposed for this branch. |
| |
| - Available polling systems will affect the process's scalability when |
| dealing with more than about one thousand of concurrent connections. These |
| ones are only available when the correct system was indicated in the TARGET |
| variable during the build. The "epoll" mechanism is highly recommended on |
| Linux, and the kqueue mechanism is highly recommended on BSD. Lacking them |
| will result in poll() or even select() being used, causing a high CPU usage |
| when dealing with a lot of connections. |
| |
| |
| 4. Stopping and restarting HAProxy |
| ---------------------------------- |
| |
| HAProxy supports a graceful and a hard stop. The hard stop is simple, when the |
| SIGTERM signal is sent to the haproxy process, it immediately quits and all |
| established connections are closed. The graceful stop is triggered when the |
| SIGUSR1 signal is sent to the haproxy process. It consists in only unbinding |
| from listening ports, but continue to process existing connections until they |
| close. Once the last connection is closed, the process leaves. |
| |
| The hard stop method is used for the "stop" or "restart" actions of the service |
| management script. The graceful stop is used for the "reload" action which |
| tries to seamlessly reload a new configuration in a new process. |
| |
| Both of these signals may be sent by the new haproxy process itself during a |
| reload or restart, so that they are sent at the latest possible moment and only |
| if absolutely required. This is what is performed by the "-st" (hard) and "-sf" |
| (graceful) options respectively. |
| |
| To understand better how these signals are used, it is important to understand |
| the whole restart mechanism. |
| |
| First, an existing haproxy process is running. The administrator uses a system |
| specific command such as "/etc/init.d/haproxy reload" to indicate he wants to |
| take the new configuration file into effect. What happens then is the following. |
| First, the service script (/etc/init.d/haproxy or equivalent) will verify that |
| the configuration file parses correctly using "haproxy -c". After that it will |
| try to start haproxy with this configuration file, using "-st" or "-sf". |
| |
| Then HAProxy tries to bind to all listening ports. If some fatal errors happen |
| (eg: address not present on the system, permission denied), the process quits |
| with an error. If a socket binding fails because a port is already in use, then |
| the process will first send a SIGTTOU signal to all the pids specified in the |
| "-st" or "-sf" pid list. This is what is called the "pause" signal. It instructs |
| all existing haproxy processes to temporarily stop listening to their ports so |
| that the new process can try to bind again. During this time, the old process |
| continues to process existing connections. If the binding still fails (because |
| for example a port is shared with another daemon), then the new process sends a |
| SIGTTIN signal to the old processes to instruct them to resume operations just |
| as if nothing happened. The old processes will then restart listening to the |
| ports and continue to accept connections. Not that this mechanism is system |
| dependent and some operating systems may not support it in multi-process mode. |
| |
| If the new process manages to bind correctly to all ports, then it sends either |
| the SIGTERM (hard stop in case of "-st") or the SIGUSR1 (graceful stop in case |
| of "-sf") to all processes to notify them that it is now in charge of operations |
| and that the old processes will have to leave, either immediately or once they |
| have finished their job. |
| |
| It is important to note that during this timeframe, there are two small windows |
| of a few milliseconds each where it is possible that a few connection failures |
| will be noticed during high loads. Typically observed failure rates are around |
| 1 failure during a reload operation every 10000 new connections per second, |
| which means that a heavily loaded site running at 30000 new connections per |
| second may see about 3 failed connection upon every reload. The two situations |
| where this happens are : |
| |
| - if the new process fails to bind due to the presence of the old process, |
| it will first have to go through the SIGTTOU+SIGTTIN sequence, which |
| typically lasts about one millisecond for a few tens of frontends, and |
| during which some ports will not be bound to the old process and not yet |
| bound to the new one. HAProxy works around this on systems that support the |
| SO_REUSEPORT socket options, as it allows the new process to bind without |
| first asking the old one to unbind. Most BSD systems have been supporting |
| this almost forever. Linux has been supporting this in version 2.0 and |
| dropped it around 2.2, but some patches were floating around by then. It |
| was reintroduced in kernel 3.9, so if you are observing a connection |
| failure rate above the one mentioned above, please ensure that your kernel |
| is 3.9 or newer, or that relevant patches were backported to your kernel |
| (less likely). |
| |
| - when the old processes close the listening ports, the kernel may not always |
| redistribute any pending connection that was remaining in the socket's |
| backlog. Under high loads, a SYN packet may happen just before the socket |
| is closed, and will lead to an RST packet being sent to the client. In some |
| critical environments where even one drop is not acceptable, these ones are |
| sometimes dealt with using firewall rules to block SYN packets during the |
| reload, forcing the client to retransmit. This is totally system-dependent, |
| as some systems might be able to visit other listening queues and avoid |
| this RST. A second case concerns the ACK from the client on a local socket |
| that was in SYN_RECV state just before the close. This ACK will lead to an |
| RST packet while the haproxy process is still not aware of it. This one is |
| harder to get rid of, though the firewall filtering rules mentioned above |
| will work well if applied one second or so before restarting the process. |
| |
| For the vast majority of users, such drops will never ever happen since they |
| don't have enough load to trigger the race conditions. And for most high traffic |
| users, the failure rate is still fairly within the noise margin provided that at |
| least SO_REUSEPORT is properly supported on their systems. |
| |
| |
| 5. File-descriptor limitations |
| ------------------------------ |
| |
| In order to ensure that all incoming connections will successfully be served, |
| HAProxy computes at load time the total number of file descriptors that will be |
| needed during the process's life. A regular Unix process is generally granted |
| 1024 file descriptors by default, and a privileged process can raise this limit |
| itself. This is one reason for starting HAProxy as root and letting it adjust |
| the limit. The default limit of 1024 file descriptors roughly allow about 500 |
| concurrent connections to be processed. The computation is based on the global |
| maxconn parameter which limits the total number of connections per process, the |
| number of listeners, the number of servers which have a health check enabled, |
| the agent checks, the peers, the loggers and possibly a few other technical |
| requirements. A simple rough estimate of this number consists in simply |
| doubling the maxconn value and adding a few tens to get the approximate number |
| of file descriptors needed. |
| |
| Originally HAProxy did not know how to compute this value, and it was necessary |
| to pass the value using the "ulimit-n" setting in the global section. This |
| explains why even today a lot of configurations are seen with this setting |
| present. Unfortunately it was often miscalculated resulting in connection |
| failures when approaching maxconn instead of throttling incoming connection |
| while waiting for the needed resources. For this reason it is important to |
| remove any vestigial "ulimit-n" setting that can remain from very old versions. |
| |
| Raising the number of file descriptors to accept even moderate loads is |
| mandatory but comes with some OS-specific adjustments. First, the select() |
| polling system is limited to 1024 file descriptors. In fact on Linux it used |
| to be capable of handling more but since certain OS ship with excessively |
| restrictive SELinux policies forbidding the use of select() with more than |
| 1024 file descriptors, HAProxy now refuses to start in this case in order to |
| avoid any issue at run time. On all supported operating systems, poll() is |
| available and will not suffer from this limitation. It is automatically picked |
| so there is nothing to do to get a working configuration. But poll's becomes |
| very slow when the number of file descriptors increases. While HAProxy does its |
| best to limit this performance impact (eg: via the use of the internal file |
| descriptor cache and batched processing), a good rule of thumb is that using |
| poll() with more than a thousand concurrent connections will use a lot of CPU. |
| |
| For Linux systems base on kernels 2.6 and above, the epoll() system call will |
| be used. It's a much more scalable mechanism relying on callbacks in the kernel |
| that guarantee a constant wake up time regardless of the number of registered |
| monitored file descriptors. It is automatically used where detected, provided |
| that HAProxy had been built for one of the Linux flavors. Its presence and |
| support can be verified using "haproxy -vv". |
| |
| For BSD systems which support it, kqueue() is available as an alternative. It |
| is much faster than poll() and even slightly faster than epoll() thanks to its |
| batched handling of changes. At least FreeBSD and OpenBSD support it. Just like |
| with Linux's epoll(), its support and availability are reported in the output |
| of "haproxy -vv". |
| |
| Having a good poller is one thing, but it is mandatory that the process can |
| reach the limits. When HAProxy starts, it immediately sets the new process's |
| file descriptor limits and verifies if it succeeds. In case of failure, it |
| reports it before forking so that the administrator can see the problem. As |
| long as the process is started by as root, there should be no reason for this |
| setting to fail. However, it can fail if the process is started by an |
| unprivileged user. If there is a compelling reason for *not* starting haproxy |
| as root (eg: started by end users, or by a per-application account), then the |
| file descriptor limit can be raised by the system administrator for this |
| specific user. The effectiveness of the setting can be verified by issuing |
| "ulimit -n" from the user's command line. It should reflect the new limit. |
| |
| Warning: when an unprivileged user's limits are changed in this user's account, |
| it is fairly common that these values are only considered when the user logs in |
| and not at all in some scripts run at system boot time nor in crontabs. This is |
| totally dependent on the operating system, keep in mind to check "ulimit -n" |
| before starting haproxy when running this way. The general advice is never to |
| start haproxy as an unprivileged user for production purposes. Another good |
| reason is that it prevents haproxy from enabling some security protections. |
| |
| Once it is certain that the system will allow the haproxy process to use the |
| requested number of file descriptors, two new system-specific limits may be |
| encountered. The first one is the system-wide file descriptor limit, which is |
| the total number of file descriptors opened on the system, covering all |
| processes. When this limit is reached, accept() or socket() will typically |
| return ENFILE. The second one is the per-process hard limit on the number of |
| file descriptors, it prevents setrlimit() from being set higher. Both are very |
| dependent on the operating system. On Linux, the system limit is set at boot |
| based on the amount of memory. It can be changed with the "fs.file-max" sysctl. |
| And the per-process hard limit is set to 1048576 by default, but it can be |
| changed using the "fs.nr_open" sysctl. |
| |
| File descriptor limitations may be observed on a running process when they are |
| set too low. The strace utility will report that accept() and socket() return |
| "-1 EMFILE" when the process's limits have been reached. In this case, simply |
| raising the "ulimit-n" value (or removing it) will solve the problem. If these |
| system calls return "-1 ENFILE" then it means that the kernel's limits have |
| been reached and that something must be done on a system-wide parameter. These |
| trouble must absolutely be addressed, as they result in high CPU usage (when |
| accept() fails) and failed connections that are generally visible to the user. |
| One solution also consists in lowering the global maxconn value to enforce |
| serialization, and possibly to disable HTTP keep-alive to force connections |
| to be released and reused faster. |
| |
| |
| 6. Memory management |
| -------------------- |
| |
| HAProxy uses a simple and fast pool-based memory management. Since it relies on |
| a small number of different object types, it's much more efficient to pick new |
| objects from a pool which already contains objects of the appropriate size than |
| to call malloc() for each different size. The pools are organized as a stack or |
| LIFO, so that newly allocated objects are taken from recently released objects |
| still hot in the CPU caches. Pools of similar sizes are merged together, in |
| order to limit memory fragmentation. |
| |
| By default, since the focus is set on performance, each released object is put |
| back into the pool it came from, and allocated objects are never freed since |
| they are expected to be reused very soon. |
| |
| On the CLI, it is possible to check how memory is being used in pools thanks to |
| the "show pools" command : |
| |
| > show pools |
| Dumping pools usage. Use SIGQUIT to flush them. |
| - Pool pipe (32 bytes) : 5 allocated (160 bytes), 5 used, 3 users [SHARED] |
| - Pool hlua_com (48 bytes) : 0 allocated (0 bytes), 0 used, 1 users [SHARED] |
| - Pool vars (64 bytes) : 0 allocated (0 bytes), 0 used, 2 users [SHARED] |
| - Pool task (112 bytes) : 5 allocated (560 bytes), 5 used, 1 users [SHARED] |
| - Pool session (128 bytes) : 1 allocated (128 bytes), 1 used, 2 users [SHARED] |
| - Pool http_txn (272 bytes) : 0 allocated (0 bytes), 0 used, 1 users [SHARED] |
| - Pool connection (352 bytes) : 2 allocated (704 bytes), 2 used, 1 users [SHARED] |
| - Pool hdr_idx (416 bytes) : 0 allocated (0 bytes), 0 used, 1 users [SHARED] |
| - Pool stream (864 bytes) : 1 allocated (864 bytes), 1 used, 1 users [SHARED] |
| - Pool requri (1024 bytes) : 0 allocated (0 bytes), 0 used, 1 users [SHARED] |
| - Pool buffer (8064 bytes) : 3 allocated (24192 bytes), 2 used, 1 users [SHARED] |
| Total: 11 pools, 26608 bytes allocated, 18544 used. |
| |
| The pool name is only indicative, it's the name of the first object type using |
| this pool. The size in parenthesis is the object size for objects in this pool. |
| Object sizes are always rounded up to the closest multiple of 16 bytes. The |
| number of objects currently allocated and the equivalent number of bytes is |
| reported so that it is easy to know which pool is responsible for the highest |
| memory usage. The number of objects currently in use is reported as well in the |
| "used" field. The difference between "allocated" and "used" corresponds to the |
| objects that have been freed and are available for immediate use. |
| |
| It is possible to limit the amount of memory allocated per process using the |
| "-m" command line option, followed by a number of megabytes. It covers all of |
| the process's addressable space, so that includes memory used by some libraries |
| as well as the stack, but it is a reliable limit when building a resource |
| constrained system. It works the same way as "ulimit -v" on systems which have |
| it, or "ulimit -d" for the other ones. |
| |
| If a memory allocation fails due to the memory limit being reached or because |
| the system doesn't have any enough memory, then haproxy will first start to |
| free all available objects from all pools before attempting to allocate memory |
| again. This mechanism of releasing unused memory can be triggered by sending |
| the signal SIGQUIT to the haproxy process. When doing so, the pools state prior |
| to the flush will also be reported to stderr when the process runs in |
| foreground. |
| |
| During a reload operation, the process switched to the graceful stop state also |
| automatically performs some flushes after releasing any connection so that all |
| possible memory is released to save it for the new process. |
| |
| |
| 7. CPU usage |
| ------------ |
| |
| HAProxy normally spends most of its time in the system and a smaller part in |
| userland. A finely tuned 3.5 GHz CPU can sustain a rate about 80000 end-to-end |
| connection setups and closes per second at 100% CPU on a single core. When one |
| core is saturated, typical figures are : |
| - 95% system, 5% user for long TCP connections or large HTTP objects |
| - 85% system and 15% user for short TCP connections or small HTTP objects in |
| close mode |
| - 70% system and 30% user for small HTTP objects in keep-alive mode |
| |
| The amount of rules processing and regular expressions will increase the user |
| land part. The presence of firewall rules, connection tracking, complex routing |
| tables in the system will instead increase the system part. |
| |
| On most systems, the CPU time observed during network transfers can be cut in 4 |
| parts : |
| - the interrupt part, which concerns all the processing performed upon I/O |
| receipt, before the target process is even known. Typically Rx packets are |
| accounted for in interrupt. On some systems such as Linux where interrupt |
| processing may be deferred to a dedicated thread, it can appear as softirq, |
| and the thread is called ksoftirqd/0 (for CPU 0). The CPU taking care of |
| this load is generally defined by the hardware settings, though in the case |
| of softirq it is often possible to remap the processing to another CPU. |
| This interrupt part will often be perceived as parasitic since it's not |
| associated with any process, but it actually is some processing being done |
| to prepare the work for the process. |
| |
| - the system part, which concerns all the processing done using kernel code |
| called from userland. System calls are accounted as system for example. All |
| synchronously delivered Tx packets will be accounted for as system time. If |
| some packets have to be deferred due to queues filling up, they may then be |
| processed in interrupt context later (eg: upon receipt of an ACK opening a |
| TCP window). |
| |
| - the user part, which exclusively runs application code in userland. HAProxy |
| runs exclusively in this part, though it makes heavy use of system calls. |
| Rules processing, regular expressions, compression, encryption all add to |
| the user portion of CPU consumption. |
| |
| - the idle part, which is what the CPU does when there is nothing to do. For |
| example HAProxy waits for an incoming connection, or waits for some data to |
| leave, meaning the system is waiting for an ACK from the client to push |
| these data. |
| |
| In practice regarding HAProxy's activity, it is in general reasonably accurate |
| (but totally inexact) to consider that interrupt/softirq are caused by Rx |
| processing in kernel drivers, that user-land is caused by layer 7 processing |
| in HAProxy, and that system time is caused by network processing on the Tx |
| path. |
| |
| Since HAProxy runs around an event loop, it waits for new events using poll() |
| (or any alternative) and processes all these events as fast as possible before |
| going back to poll() waiting for new events. It measures the time spent waiting |
| in poll() compared to the time spent doing processing events. The ratio of |
| polling time vs total time is called the "idle" time, it's the amount of time |
| spent waiting for something to happen. This ratio is reported in the stats page |
| on the "idle" line, or "Idle_pct" on the CLI. When it's close to 100%, it means |
| the load is extremely low. When it's close to 0%, it means that there is |
| constantly some activity. While it cannot be very accurate on an overloaded |
| system due to other processes possibly preempting the CPU from the haproxy |
| process, it still provides a good estimate about how HAProxy considers it is |
| working : if the load is low and the idle ratio is low as well, it may indicate |
| that HAProxy has a lot of work to do, possibly due to very expensive rules that |
| have to be processed. Conversely, if HAProxy indicates the idle is close to |
| 100% while things are slow, it means that it cannot do anything to speed things |
| up because it is already waiting for incoming data to process. In the example |
| below, haproxy is completely idle : |
| |
| $ echo "show info" | socat - /var/run/haproxy.sock | grep ^Idle |
| Idle_pct: 100 |
| |
| When the idle ratio starts to become very low, it is important to tune the |
| system and place processes and interrupts correctly to save the most possible |
| CPU resources for all tasks. If a firewall is present, it may be worth trying |
| to disable it or to tune it to ensure it is not responsible for a large part |
| of the performance limitation. It's worth noting that unloading a stateful |
| firewall generally reduces both the amount of interrupt/softirq and of system |
| usage since such firewalls act both on the Rx and the Tx paths. On Linux, |
| unloading the nf_conntrack and ip_conntrack modules will show whether there is |
| anything to gain. If so, then the module runs with default settings and you'll |
| have to figure how to tune it for better performance. In general this consists |
| in considerably increasing the hash table size. On FreeBSD, "pfctl -d" will |
| disable the "pf" firewall and its stateful engine at the same time. |
| |
| If it is observed that a lot of time is spent in interrupt/softirq, it is |
| important to ensure that they don't run on the same CPU. Most systems tend to |
| pin the tasks on the CPU where they receive the network traffic because for |
| certain workloads it improves things. But with heavily network-bound workloads |
| it is the opposite as the haproxy process will have to fight against its kernel |
| counterpart. Pinning haproxy to one CPU core and the interrupts to another one, |
| all sharing the same L3 cache tends to sensibly increase network performance |
| because in practice the amount of work for haproxy and the network stack are |
| quite close, so they can almost fill an entire CPU each. On Linux this is done |
| using taskset (for haproxy) or using cpu-map (from the haproxy config), and the |
| interrupts are assigned under /proc/irq. Many network interfaces support |
| multiple queues and multiple interrupts. In general it helps to spread them |
| across a small number of CPU cores provided they all share the same L3 cache. |
| Please always stop irq_balance which always does the worst possible thing on |
| such workloads. |
| |
| For CPU-bound workloads consisting in a lot of SSL traffic or a lot of |
| compression, it may be worth using multiple processes dedicated to certain |
| tasks, though there is no universal rule here and experimentation will have to |
| be performed. |
| |
| In order to increase the CPU capacity, it is possible to make HAProxy run as |
| several processes, using the "nbproc" directive in the global section. There |
| are some limitations though : |
| - health checks are run per process, so the target servers will get as many |
| checks as there are running processes ; |
| - maxconn values and queues are per-process so the correct value must be set |
| to avoid overloading the servers ; |
| - outgoing connections should avoid using port ranges to avoid conflicts |
| - stick-tables are per process and are not shared between processes ; |
| - each peers section may only run on a single process at a time ; |
| - the CLI operations will only act on a single process at a time. |
| |
| With this in mind, it appears that the easiest setup often consists in having |
| one first layer running on multiple processes and in charge for the heavy |
| processing, passing the traffic to a second layer running in a single process. |
| This mechanism is suited to SSL and compression which are the two CPU-heavy |
| features. Instances can easily be chained over UNIX sockets (which are cheaper |
| than TCP sockets and which do not waste ports), and the proxy protocol which is |
| useful to pass client information to the next stage. When doing so, it is |
| generally a good idea to bind all the single-process tasks to process number 1 |
| and extra tasks to next processes, as this will make it easier to generate |
| similar configurations for different machines. |
| |
| On Linux versions 3.9 and above, running HAProxy in multi-process mode is much |
| more efficient when each process uses a distinct listening socket on the same |
| IP:port ; this will make the kernel evenly distribute the load across all |
| processes instead of waking them all up. Please check the "process" option of |
| the "bind" keyword lines in the configuration manual for more information. |
| |
| |
| 8. Logging |
| ---------- |
| |
| For logging, HAProxy always relies on a syslog server since it does not perform |
| any file-system access. The standard way of using it is to send logs over UDP |
| to the log server (by default on port 514). Very commonly this is configured to |
| 127.0.0.1 where the local syslog daemon is running, but it's also used over the |
| network to log to a central server. The central server provides additional |
| benefits especially in active-active scenarios where it is desirable to keep |
| the logs merged in arrival order. HAProxy may also make use of a UNIX socket to |
| send its logs to the local syslog daemon, but it is not recommended at all, |
| because if the syslog server is restarted while haproxy runs, the socket will |
| be replaced and new logs will be lost. Since HAProxy will be isolated inside a |
| chroot jail, it will not have the ability to reconnect to the new socket. It |
| has also been observed in field that the log buffers in use on UNIX sockets are |
| very small and lead to lost messages even at very light loads. But this can be |
| fine for testing however. |
| |
| It is recommended to add the following directive to the "global" section to |
| make HAProxy log to the local daemon using facility "local0" : |
| |
| log 127.0.0.1:514 local0 |
| |
| and then to add the following one to each "defaults" section or to each frontend |
| and backend section : |
| |
| log global |
| |
| This way, all logs will be centralized through the global definition of where |
| the log server is. |
| |
| Some syslog daemons do not listen to UDP traffic by default, so depending on |
| the daemon being used, the syntax to enable this will vary : |
| |
| - on sysklogd, you need to pass argument "-r" on the daemon's command line |
| so that it listens to a UDP socket for "remote" logs ; note that there is |
| no way to limit it to address 127.0.0.1 so it will also receive logs from |
| remote systems ; |
| |
| - on rsyslogd, the following lines must be added to the configuration file : |
| |
| $ModLoad imudp |
| $UDPServerAddress * |
| $UDPServerRun 514 |
| |
| - on syslog-ng, a new source can be created the following way, it then needs |
| to be added as a valid source in one of the "log" directives : |
| |
| source s_udp { |
| udp(ip(127.0.0.1) port(514)); |
| }; |
| |
| Please consult your syslog daemon's manual for more information. If no logs are |
| seen in the system's log files, please consider the following tests : |
| |
| - restart haproxy. Each frontend and backend logs one line indicating it's |
| starting. If these logs are received, it means logs are working. |
| |
| - run "strace -tt -s100 -etrace=sendmsg -p <haproxy's pid>" and perform some |
| activity that you expect to be logged. You should see the log messages |
| being sent using sendmsg() there. If they don't appear, restart using |
| strace on top of haproxy. If you still see no logs, it definitely means |
| that something is wrong in your configuration. |
| |
| - run tcpdump to watch for port 514, for example on the loopback interface if |
| the traffic is being sent locally : "tcpdump -As0 -ni lo port 514". If the |
| packets are seen there, it's the proof they're sent then the syslogd daemon |
| needs to be troubleshooted. |
| |
| While traffic logs are sent from the frontends (where the incoming connections |
| are accepted), backends also need to be able to send logs in order to report a |
| server state change consecutive to a health check. Please consult HAProxy's |
| configuration manual for more information regarding all possible log settings. |
| |
| It is convenient to chose a facility that is not used by other daemons. HAProxy |
| examples often suggest "local0" for traffic logs and "local1" for admin logs |
| because they're never seen in field. A single facility would be enough as well. |
| Having separate logs is convenient for log analysis, but it's also important to |
| remember that logs may sometimes convey confidential information, and as such |
| they must not be mixed with other logs that may accidentally be handed out to |
| unauthorized people. |
| |
| For in-field troubleshooting without impacting the server's capacity too much, |
| it is recommended to make use of the "halog" utility provided with HAProxy. |
| This is sort of a grep-like utility designed to process HAProxy log files at |
| a very fast data rate. Typical figures range between 1 and 2 GB of logs per |
| second. It is capable of extracting only certain logs (eg: search for some |
| classes of HTTP status codes, connection termination status, search by response |
| time ranges, look for errors only), count lines, limit the output to a number |
| of lines, and perform some more advanced statistics such as sorting servers |
| by response time or error counts, sorting URLs by time or count, sorting client |
| addresses by access count, and so on. It is pretty convenient to quickly spot |
| anomalies such as a bot looping on the site, and block them. |
| |
| |
| 9. Statistics and monitoring |
| ---------------------------- |
| |
| It is possible to query HAProxy about its status. The most commonly used |
| mechanism is the HTTP statistics page. This page also exposes an alternative |
| CSV output format for monitoring tools. The same format is provided on the |
| Unix socket. |
| |
| |
| 9.1. CSV format |
| --------------- |
| |
| The statistics may be consulted either from the unix socket or from the HTTP |
| page. Both means provide a CSV format whose fields follow. The first line |
| begins with a sharp ('#') and has one word per comma-delimited field which |
| represents the title of the column. All other lines starting at the second one |
| use a classical CSV format using a comma as the delimiter, and the double quote |
| ('"') as an optional text delimiter, but only if the enclosed text is ambiguous |
| (if it contains a quote or a comma). The double-quote character ('"') in the |
| text is doubled ('""'), which is the format that most tools recognize. Please |
| do not insert any column before these ones in order not to break tools which |
| use hard-coded column positions. |
| |
| In brackets after each field name are the types which may have a value for |
| that field. The types are L (Listeners), F (Frontends), B (Backends), and |
| S (Servers). |
| |
| 0. pxname [LFBS]: proxy name |
| 1. svname [LFBS]: service name (FRONTEND for frontend, BACKEND for backend, |
| any name for server/listener) |
| 2. qcur [..BS]: current queued requests. For the backend this reports the |
| number queued without a server assigned. |
| 3. qmax [..BS]: max value of qcur |
| 4. scur [LFBS]: current sessions |
| 5. smax [LFBS]: max sessions |
| 6. slim [LFBS]: configured session limit |
| 7. stot [LFBS]: cumulative number of sessions |
| 8. bin [LFBS]: bytes in |
| 9. bout [LFBS]: bytes out |
| 10. dreq [LFB.]: requests denied because of security concerns. |
| - For tcp this is because of a matched tcp-request content rule. |
| - For http this is because of a matched http-request or tarpit rule. |
| 11. dresp [LFBS]: responses denied because of security concerns. |
| - For http this is because of a matched http-request rule, or |
| "option checkcache". |
| 12. ereq [LF..]: request errors. Some of the possible causes are: |
| - early termination from the client, before the request has been sent. |
| - read error from the client |
| - client timeout |
| - client closed connection |
| - various bad requests from the client. |
| - request was tarpitted. |
| 13. econ [..BS]: number of requests that encountered an error trying to |
| connect to a backend server. The backend stat is the sum of the stat |
| for all servers of that backend, plus any connection errors not |
| associated with a particular server (such as the backend having no |
| active servers). |
| 14. eresp [..BS]: response errors. srv_abrt will be counted here also. |
| Some other errors are: |
| - write error on the client socket (won't be counted for the server stat) |
| - failure applying filters to the response. |
| 15. wretr [..BS]: number of times a connection to a server was retried. |
| 16. wredis [..BS]: number of times a request was redispatched to another |
| server. The server value counts the number of times that server was |
| switched away from. |
| 17. status [LFBS]: status (UP/DOWN/NOLB/MAINT/MAINT(via)/MAINT(resolution)...) |
| 18. weight [..BS]: total weight (backend), server weight (server) |
| 19. act [..BS]: number of active servers (backend), server is active (server) |
| 20. bck [..BS]: number of backup servers (backend), server is backup (server) |
| 21. chkfail [...S]: number of failed checks. (Only counts checks failed when |
| the server is up.) |
| 22. chkdown [..BS]: number of UP->DOWN transitions. The backend counter counts |
| transitions to the whole backend being down, rather than the sum of the |
| counters for each server. |
| 23. lastchg [..BS]: number of seconds since the last UP<->DOWN transition |
| 24. downtime [..BS]: total downtime (in seconds). The value for the backend |
| is the downtime for the whole backend, not the sum of the server downtime. |
| 25. qlimit [...S]: configured maxqueue for the server, or nothing in the |
| value is 0 (default, meaning no limit) |
| 26. pid [LFBS]: process id (0 for first instance, 1 for second, ...) |
| 27. iid [LFBS]: unique proxy id |
| 28. sid [L..S]: server id (unique inside a proxy) |
| 29. throttle [...S]: current throttle percentage for the server, when |
| slowstart is active, or no value if not in slowstart. |
| 30. lbtot [..BS]: total number of times a server was selected, either for new |
| sessions, or when re-dispatching. The server counter is the number |
| of times that server was selected. |
| 31. tracked [...S]: id of proxy/server if tracking is enabled. |
| 32. type [LFBS]: (0=frontend, 1=backend, 2=server, 3=socket/listener) |
| 33. rate [.FBS]: number of sessions per second over last elapsed second |
| 34. rate_lim [.F..]: configured limit on new sessions per second |
| 35. rate_max [.FBS]: max number of new sessions per second |
| 36. check_status [...S]: status of last health check, one of: |
| UNK -> unknown |
| INI -> initializing |
| SOCKERR -> socket error |
| L4OK -> check passed on layer 4, no upper layers testing enabled |
| L4TOUT -> layer 1-4 timeout |
| L4CON -> layer 1-4 connection problem, for example |
| "Connection refused" (tcp rst) or "No route to host" (icmp) |
| L6OK -> check passed on layer 6 |
| L6TOUT -> layer 6 (SSL) timeout |
| L6RSP -> layer 6 invalid response - protocol error |
| L7OK -> check passed on layer 7 |
| L7OKC -> check conditionally passed on layer 7, for example 404 with |
| disable-on-404 |
| L7TOUT -> layer 7 (HTTP/SMTP) timeout |
| L7RSP -> layer 7 invalid response - protocol error |
| L7STS -> layer 7 response error, for example HTTP 5xx |
| 37. check_code [...S]: layer5-7 code, if available |
| 38. check_duration [...S]: time in ms took to finish last health check |
| 39. hrsp_1xx [.FBS]: http responses with 1xx code |
| 40. hrsp_2xx [.FBS]: http responses with 2xx code |
| 41. hrsp_3xx [.FBS]: http responses with 3xx code |
| 42. hrsp_4xx [.FBS]: http responses with 4xx code |
| 43. hrsp_5xx [.FBS]: http responses with 5xx code |
| 44. hrsp_other [.FBS]: http responses with other codes (protocol error) |
| 45. hanafail [...S]: failed health checks details |
| 46. req_rate [.F..]: HTTP requests per second over last elapsed second |
| 47. req_rate_max [.F..]: max number of HTTP requests per second observed |
| 48. req_tot [.FB.]: total number of HTTP requests received |
| 49. cli_abrt [..BS]: number of data transfers aborted by the client |
| 50. srv_abrt [..BS]: number of data transfers aborted by the server |
| (inc. in eresp) |
| 51. comp_in [.FB.]: number of HTTP response bytes fed to the compressor |
| 52. comp_out [.FB.]: number of HTTP response bytes emitted by the compressor |
| 53. comp_byp [.FB.]: number of bytes that bypassed the HTTP compressor |
| (CPU/BW limit) |
| 54. comp_rsp [.FB.]: number of HTTP responses that were compressed |
| 55. lastsess [..BS]: number of seconds since last session assigned to |
| server/backend |
| 56. last_chk [...S]: last health check contents or textual error |
| 57. last_agt [...S]: last agent check contents or textual error |
| 58. qtime [..BS]: the average queue time in ms over the 1024 last requests |
| 59. ctime [..BS]: the average connect time in ms over the 1024 last requests |
| 60. rtime [..BS]: the average response time in ms over the 1024 last requests |
| (0 for TCP) |
| 61. ttime [..BS]: the average total session time in ms over the 1024 last |
| requests |
| 62. agent_status [...S]: status of last agent check, one of: |
| UNK -> unknown |
| INI -> initializing |
| SOCKERR -> socket error |
| L4OK -> check passed on layer 4, no upper layers testing enabled |
| L4TOUT -> layer 1-4 timeout |
| L4CON -> layer 1-4 connection problem, for example |
| "Connection refused" (tcp rst) or "No route to host" (icmp) |
| L7OK -> agent reported "up" |
| L7STS -> agent reported "fail", "stop", or "down" |
| 63. agent_code [...S]: numeric code reported by agent if any (unused for now) |
| 64. agent_duration [...S]: time in ms taken to finish last check |
| 65. check_desc [...S]: short human-readable description of check_status |
| 66. agent_desc [...S]: short human-readable description of agent_status |
| 67. check_rise [...S]: server's "rise" parameter used by checks |
| 68. check_fall [...S]: server's "fall" parameter used by checks |
| 69. check_health [...S]: server's health check value between 0 and rise+fall-1 |
| 70. agent_rise [...S]: agent's "rise" parameter, normally 1 |
| 71. agent_fall [...S]: agent's "fall" parameter, normally 1 |
| 72. agent_health [...S]: agent's health parameter, between 0 and rise+fall-1 |
| 73. addr [L..S]: address:port or "unix". IPv6 has brackets around the address. |
| 74: cookie [..BS]: server's cookie value or backend's cookie name |
| 75: mode [LFBS]: proxy mode (tcp, http, health, unknown) |
| 76: algo [..B.]: load balancing algorithm |
| 77: conn_rate [.F..]: number of connections over the last elapsed second |
| 78: conn_rate_max [.F..]: highest known conn_rate |
| 79: conn_tot [.F..]: cumulative number of connections |
| 80: intercepted [.FB.]: cum. number of intercepted requests (monitor, stats) |
| 81: dcon [LF..]: requests denied by "tcp-request connection" rules |
| 82: dses [LF..]: requests denied by "tcp-request session" rules |
| |
| |
| 9.2) Typed output format |
| ------------------------ |
| |
| Both "show info" and "show stat" support a mode where each output value comes |
| with its type and sufficient information to know how the value is supposed to |
| be aggregated between processes and how it evolves. |
| |
| In all cases, the output consists in having a single value per line with all |
| the information split into fields delimited by colons (':'). |
| |
| The first column designates the object or metric being dumped. Its format is |
| specific to the command producing this output and will not be described in this |
| section. Usually it will consist in a series of identifiers and field names. |
| |
| The second column contains 3 characters respectively indicating the origin, the |
| nature and the scope of the value being reported. The first character (the |
| origin) indicates where the value was extracted from. Possible characters are : |
| |
| M The value is a metric. It is valid at one instant any may change depending |
| on its nature . |
| |
| S The value is a status. It represents a discrete value which by definition |
| cannot be aggregated. It may be the status of a server ("UP" or "DOWN"), |
| the PID of the process, etc. |
| |
| K The value is a sorting key. It represents an identifier which may be used |
| to group some values together because it is unique among its class. All |
| internal identifiers are keys. Some names can be listed as keys if they |
| are unique (eg: a frontend name is unique). In general keys come from the |
| configuration, even though some of them may automatically be assigned. For |
| most purposes keys may be considered as equivalent to configuration. |
| |
| C The value comes from the configuration. Certain configuration values make |
| sense on the output, for example a concurrent connection limit or a cookie |
| name. By definition these values are the same in all processes started |
| from the same configuration file. |
| |
| P The value comes from the product itself. There are very few such values, |
| most common use is to report the product name, version and release date. |
| These elements are also the same between all processes. |
| |
| The second character (the nature) indicates the nature of the information |
| carried by the field in order to let an aggregator decide on what operation to |
| use to aggregate multiple values. Possible characters are : |
| |
| A The value represents an age since a last event. This is a bit different |
| from the duration in that an age is automatically computed based on the |
| current date. A typical example is how long ago did the last session |
| happen on a server. Ages are generally aggregated by taking the minimum |
| value and do not need to be stored. |
| |
| a The value represents an already averaged value. The average response times |
| and server weights are of this nature. Averages can typically be averaged |
| between processes. |
| |
| C The value represents a cumulative counter. Such measures perpetually |
| increase until they wrap around. Some monitoring protocols need to tell |
| the difference between a counter and a gauge to report a different type. |
| In general counters may simply be summed since they represent events or |
| volumes. Examples of metrics of this nature are connection counts or byte |
| counts. |
| |
| D The value represents a duration for a status. There are a few usages of |
| this, most of them include the time taken by the last health check and |
| the time a server has spent down. Durations are generally not summed, |
| most of the time the maximum will be retained to compute an SLA. |
| |
| G The value represents a gauge. It's a measure at one instant. The memory |
| usage or the current number of active connections are of this nature. |
| Metrics of this type are typically summed during aggregation. |
| |
| L The value represents a limit (generally a configured one). By nature, |
| limits are harder to aggregate since they are specific to the point where |
| they were retrieved. In certain situations they may be summed or be kept |
| separate. |
| |
| M The value represents a maximum. In general it will apply to a gauge and |
| keep the highest known value. An example of such a metric could be the |
| maximum amount of concurrent connections that was encountered in the |
| product's life time. To correctly aggregate maxima, you are supposed to |
| output a range going from the maximum of all maxima and the sum of all |
| of them. There is indeed no way to know if they were encountered |
| simultaneously or not. |
| |
| m The value represents a minimum. In general it will apply to a gauge and |
| keep the lowest known value. An example of such a metric could be the |
| minimum amount of free memory pools that was encountered in the product's |
| life time. To correctly aggregate minima, you are supposed to output a |
| range going from the minimum of all minima and the sum of all of them. |
| There is indeed no way to know if they were encountered simultaneously |
| or not. |
| |
| N The value represents a name, so it is a string. It is used to report |
| proxy names, server names and cookie names. Names have configuration or |
| keys as their origin and are supposed to be the same among all processes. |
| |
| O The value represents a free text output. Outputs from various commands, |
| returns from health checks, node descriptions are of such nature. |
| |
| R The value represents an event rate. It's a measure at one instant. It is |
| quite similar to a gauge except that the recipient knows that this measure |
| moves slowly and may decide not to keep all values. An example of such a |
| metric is the measured amount of connections per second. Metrics of this |
| type are typically summed during aggregation. |
| |
| T The value represents a date or time. A field emitting the current date |
| would be of this type. The method to aggregate such information is left |
| as an implementation choice. For now no field uses this type. |
| |
| The third character (the scope) indicates what extent the value reflects. Some |
| elements may be per process while others may be per configuration or per system. |
| The distinction is important to know whether or not a single value should be |
| kept during aggregation or if values have to be aggregated. The following |
| characters are currently supported : |
| |
| C The value is valid for a whole cluster of nodes, which is the set of nodes |
| communicating over the peers protocol. An example could be the amount of |
| entries present in a stick table that is replicated with other peers. At |
| the moment no metric use this scope. |
| |
| P The value is valid only for the process reporting it. Most metrics use |
| this scope. |
| |
| S The value is valid for the whole service, which is the set of processes |
| started together from the same configuration file. All metrics originating |
| from the configuration use this scope. Some other metrics may use it as |
| well for some shared resources (eg: shared SSL cache statistics). |
| |
| s The value is valid for the whole system, such as the system's hostname, |
| current date or resource usage. At the moment this scope is not used by |
| any metric. |
| |
| Consumers of these information will generally have enough of these 3 characters |
| to determine how to accurately report aggregated information across multiple |
| processes. |
| |
| After this column, the third column indicates the type of the field, among "s32" |
| (signed 32-bit integer), "s64" (signed 64-bit integer), "u32" (unsigned 32-bit |
| integer), "u64" (unsigned 64-bit integer), "str" (string). It is important to |
| know the type before parsing the value in order to properly read it. For example |
| a string containing only digits is still a string an not an integer (eg: an |
| error code extracted by a check). |
| |
| Then the fourth column is the value itself, encoded according to its type. |
| Strings are dumped as-is immediately after the colon without any leading space. |
| If a string contains a colon, it will appear normally. This means that the |
| output should not be exclusively split around colons or some check outputs |
| or server addresses might be truncated. |
| |
| |
| 9.3. Unix Socket commands |
| ------------------------- |
| |
| The stats socket is not enabled by default. In order to enable it, it is |
| necessary to add one line in the global section of the haproxy configuration. |
| A second line is recommended to set a larger timeout, always appreciated when |
| issuing commands by hand : |
| |
| global |
| stats socket /var/run/haproxy.sock mode 600 level admin |
| stats timeout 2m |
| |
| It is also possible to add multiple instances of the stats socket by repeating |
| the line, and make them listen to a TCP port instead of a UNIX socket. This is |
| never done by default because this is dangerous, but can be handy in some |
| situations : |
| |
| global |
| stats socket /var/run/haproxy.sock mode 600 level admin |
| stats socket ipv4@192.168.0.1:9999 level admin |
| stats timeout 2m |
| |
| To access the socket, an external utility such as "socat" is required. Socat is |
| a swiss-army knife to connect anything to anything. We use it to connect |
| terminals to the socket, or a couple of stdin/stdout pipes to it for scripts. |
| The two main syntaxes we'll use are the following : |
| |
| # socat /var/run/haproxy.sock stdio |
| # socat /var/run/haproxy.sock readline |
| |
| The first one is used with scripts. It is possible to send the output of a |
| script to haproxy, and pass haproxy's output to another script. That's useful |
| for retrieving counters or attack traces for example. |
| |
| The second one is only useful for issuing commands by hand. It has the benefit |
| that the terminal is handled by the readline library which supports line |
| editing and history, which is very convenient when issuing repeated commands |
| (eg: watch a counter). |
| |
| The socket supports two operation modes : |
| - interactive |
| - non-interactive |
| |
| The non-interactive mode is the default when socat connects to the socket. In |
| this mode, a single line may be sent. It is processed as a whole, responses are |
| sent back, and the connection closes after the end of the response. This is the |
| mode that scripts and monitoring tools use. It is possible to send multiple |
| commands in this mode, they need to be delimited by a semi-colon (';'). For |
| example : |
| |
| # echo "show info;show stat;show table" | socat /var/run/haproxy stdio |
| |
| If a command needs to use a semi-colon or a backslash (eg: in a value), it |
| must be preceeded by a backslash ('\'). |
| |
| The interactive mode displays a prompt ('>') and waits for commands to be |
| entered on the line, then processes them, and displays the prompt again to wait |
| for a new command. This mode is entered via the "prompt" command which must be |
| sent on the first line in non-interactive mode. The mode is a flip switch, if |
| "prompt" is sent in interactive mode, it is disabled and the connection closes |
| after processing the last command of the same line. |
| |
| For this reason, when debugging by hand, it's quite common to start with the |
| "prompt" command : |
| |
| # socat /var/run/haproxy readline |
| prompt |
| > show info |
| ... |
| > |
| |
| Since multiple commands may be issued at once, haproxy uses the empty line as a |
| delimiter to mark an end of output for each command, and takes care of ensuring |
| that no command can emit an empty line on output. A script can thus easily |
| parse the output even when multiple commands were pipelined on a single line. |
| |
| It is important to understand that when multiple haproxy processes are started |
| on the same sockets, any process may pick up the request and will output its |
| own stats. |
| |
| The list of commands currently supported on the stats socket is provided below. |
| If an unknown command is sent, haproxy displays the usage message which reminds |
| all supported commands. Some commands support a more complex syntax, generally |
| it will explain what part of the command is invalid when this happens. |
| |
| add acl <acl> <pattern> |
| Add an entry into the acl <acl>. <acl> is the #<id> or the <file> returned by |
| "show acl". This command does not verify if the entry already exists. This |
| command cannot be used if the reference <acl> is a file also used with a map. |
| In this case, you must use the command "add map" in place of "add acl". |
| |
| add map <map> <key> <value> |
| Add an entry into the map <map> to associate the value <value> to the key |
| <key>. This command does not verify if the entry already exists. It is |
| mainly used to fill a map after a clear operation. Note that if the reference |
| <map> is a file and is shared with a map, this map will contain also a new |
| pattern entry. |
| |
| clear counters |
| Clear the max values of the statistics counters in each proxy (frontend & |
| backend) and in each server. The accumulated counters are not affected. This |
| can be used to get clean counters after an incident, without having to |
| restart nor to clear traffic counters. This command is restricted and can |
| only be issued on sockets configured for levels "operator" or "admin". |
| |
| clear counters all |
| Clear all statistics counters in each proxy (frontend & backend) and in each |
| server. This has the same effect as restarting. This command is restricted |
| and can only be issued on sockets configured for level "admin". |
| |
| clear acl <acl> |
| Remove all entries from the acl <acl>. <acl> is the #<id> or the <file> |
| returned by "show acl". Note that if the reference <acl> is a file and is |
| shared with a map, this map will be also cleared. |
| |
| clear map <map> |
| Remove all entries from the map <map>. <map> is the #<id> or the <file> |
| returned by "show map". Note that if the reference <map> is a file and is |
| shared with a acl, this acl will be also cleared. |
| |
| clear table <table> [ data.<type> <operator> <value> ] | [ key <key> ] |
| Remove entries from the stick-table <table>. |
| |
| This is typically used to unblock some users complaining they have been |
| abusively denied access to a service, but this can also be used to clear some |
| stickiness entries matching a server that is going to be replaced (see "show |
| table" below for details). Note that sometimes, removal of an entry will be |
| refused because it is currently tracked by a session. Retrying a few seconds |
| later after the session ends is usual enough. |
| |
| In the case where no options arguments are given all entries will be removed. |
| |
| When the "data." form is used entries matching a filter applied using the |
| stored data (see "stick-table" in section 4.2) are removed. A stored data |
| type must be specified in <type>, and this data type must be stored in the |
| table otherwise an error is reported. The data is compared according to |
| <operator> with the 64-bit integer <value>. Operators are the same as with |
| the ACLs : |
| |
| - eq : match entries whose data is equal to this value |
| - ne : match entries whose data is not equal to this value |
| - le : match entries whose data is less than or equal to this value |
| - ge : match entries whose data is greater than or equal to this value |
| - lt : match entries whose data is less than this value |
| - gt : match entries whose data is greater than this value |
| |
| When the key form is used the entry <key> is removed. The key must be of the |
| same type as the table, which currently is limited to IPv4, IPv6, integer and |
| string. |
| |
| Example : |
| $ echo "show table http_proxy" | socat stdio /tmp/sock1 |
| >>> # table: http_proxy, type: ip, size:204800, used:2 |
| >>> 0x80e6a4c: key=127.0.0.1 use=0 exp=3594729 gpc0=0 conn_rate(30000)=1 \ |
| bytes_out_rate(60000)=187 |
| >>> 0x80e6a80: key=127.0.0.2 use=0 exp=3594740 gpc0=1 conn_rate(30000)=10 \ |
| bytes_out_rate(60000)=191 |
| |
| $ echo "clear table http_proxy key 127.0.0.1" | socat stdio /tmp/sock1 |
| |
| $ echo "show table http_proxy" | socat stdio /tmp/sock1 |
| >>> # table: http_proxy, type: ip, size:204800, used:1 |
| >>> 0x80e6a80: key=127.0.0.2 use=0 exp=3594740 gpc0=1 conn_rate(30000)=10 \ |
| bytes_out_rate(60000)=191 |
| $ echo "clear table http_proxy data.gpc0 eq 1" | socat stdio /tmp/sock1 |
| $ echo "show table http_proxy" | socat stdio /tmp/sock1 |
| >>> # table: http_proxy, type: ip, size:204800, used:1 |
| |
| del acl <acl> [<key>|#<ref>] |
| Delete all the acl entries from the acl <acl> corresponding to the key <key>. |
| <acl> is the #<id> or the <file> returned by "show acl". If the <ref> is used, |
| this command delete only the listed reference. The reference can be found with |
| listing the content of the acl. Note that if the reference <acl> is a file and |
| is shared with a map, the entry will be also deleted in the map. |
| |
| del map <map> [<key>|#<ref>] |
| Delete all the map entries from the map <map> corresponding to the key <key>. |
| <map> is the #<id> or the <file> returned by "show map". If the <ref> is used, |
| this command delete only the listed reference. The reference can be found with |
| listing the content of the map. Note that if the reference <map> is a file and |
| is shared with a acl, the entry will be also deleted in the map. |
| |
| disable agent <backend>/<server> |
| Mark the auxiliary agent check as temporarily stopped. |
| |
| In the case where an agent check is being run as a auxiliary check, due |
| to the agent-check parameter of a server directive, new checks are only |
| initialized when the agent is in the enabled. Thus, disable agent will |
| prevent any new agent checks from begin initiated until the agent |
| re-enabled using enable agent. |
| |
| When an agent is disabled the processing of an auxiliary agent check that |
| was initiated while the agent was set as enabled is as follows: All |
| results that would alter the weight, specifically "drain" or a weight |
| returned by the agent, are ignored. The processing of agent check is |
| otherwise unchanged. |
| |
| The motivation for this feature is to allow the weight changing effects |
| of the agent checks to be paused to allow the weight of a server to be |
| configured using set weight without being overridden by the agent. |
| |
| This command is restricted and can only be issued on sockets configured for |
| level "admin". |
| |
| disable frontend <frontend> |
| Mark the frontend as temporarily stopped. This corresponds to the mode which |
| is used during a soft restart : the frontend releases the port but can be |
| enabled again if needed. This should be used with care as some non-Linux OSes |
| are unable to enable it back. This is intended to be used in environments |
| where stopping a proxy is not even imaginable but a misconfigured proxy must |
| be fixed. That way it's possible to release the port and bind it into another |
| process to restore operations. The frontend will appear with status "STOP" |
| on the stats page. |
| |
| The frontend may be specified either by its name or by its numeric ID, |
| prefixed with a sharp ('#'). |
| |
| This command is restricted and can only be issued on sockets configured for |
| level "admin". |
| |
| disable health <backend>/<server> |
| Mark the primary health check as temporarily stopped. This will disable |
| sending of health checks, and the last health check result will be ignored. |
| The server will be in unchecked state and considered UP unless an auxiliary |
| agent check forces it down. |
| |
| This command is restricted and can only be issued on sockets configured for |
| level "admin". |
| |
| disable server <backend>/<server> |
| Mark the server DOWN for maintenance. In this mode, no more checks will be |
| performed on the server until it leaves maintenance. |
| If the server is tracked by other servers, those servers will be set to DOWN |
| during the maintenance. |
| |
| In the statistics page, a server DOWN for maintenance will appear with a |
| "MAINT" status, its tracking servers with the "MAINT(via)" one. |
| |
| Both the backend and the server may be specified either by their name or by |
| their numeric ID, prefixed with a sharp ('#'). |
| |
| This command is restricted and can only be issued on sockets configured for |
| level "admin". |
| |
| enable agent <backend>/<server> |
| Resume auxiliary agent check that was temporarily stopped. |
| |
| See "disable agent" for details of the effect of temporarily starting |
| and stopping an auxiliary agent. |
| |
| This command is restricted and can only be issued on sockets configured for |
| level "admin". |
| |
| enable frontend <frontend> |
| Resume a frontend which was temporarily stopped. It is possible that some of |
| the listening ports won't be able to bind anymore (eg: if another process |
| took them since the 'disable frontend' operation). If this happens, an error |
| is displayed. Some operating systems might not be able to resume a frontend |
| which was disabled. |
| |
| The frontend may be specified either by its name or by its numeric ID, |
| prefixed with a sharp ('#'). |
| |
| This command is restricted and can only be issued on sockets configured for |
| level "admin". |
| |
| enable health <backend>/<server> |
| Resume a primary health check that was temporarily stopped. This will enable |
| sending of health checks again. Please see "disable health" for details. |
| |
| This command is restricted and can only be issued on sockets configured for |
| level "admin". |
| |
| enable server <backend>/<server> |
| If the server was previously marked as DOWN for maintenance, this marks the |
| server UP and checks are re-enabled. |
| |
| Both the backend and the server may be specified either by their name or by |
| their numeric ID, prefixed with a sharp ('#'). |
| |
| This command is restricted and can only be issued on sockets configured for |
| level "admin". |
| |
| get map <map> <value> |
| get acl <acl> <value> |
| Lookup the value <value> in the map <map> or in the ACL <acl>. <map> or <acl> |
| are the #<id> or the <file> returned by "show map" or "show acl". This command |
| returns all the matching patterns associated with this map. This is useful for |
| debugging maps and ACLs. The output format is composed by one line par |
| matching type. Each line is composed by space-delimited series of words. |
| |
| The first two words are: |
| |
| <match method>: The match method applied. It can be "found", "bool", |
| "int", "ip", "bin", "len", "str", "beg", "sub", "dir", |
| "dom", "end" or "reg". |
| |
| <match result>: The result. Can be "match" or "no-match". |
| |
| The following words are returned only if the pattern matches an entry. |
| |
| <index type>: "tree" or "list". The internal lookup algorithm. |
| |
| <case>: "case-insensitive" or "case-sensitive". The |
| interpretation of the case. |
| |
| <entry matched>: match="<entry>". Return the matched pattern. It is |
| useful with regular expressions. |
| |
| The two last word are used to show the returned value and its type. With the |
| "acl" case, the pattern doesn't exist. |
| |
| return=nothing: No return because there are no "map". |
| return="<value>": The value returned in the string format. |
| return=cannot-display: The value cannot be converted as string. |
| |
| type="<type>": The type of the returned sample. |
| |
| get weight <backend>/<server> |
| Report the current weight and the initial weight of server <server> in |
| backend <backend> or an error if either doesn't exist. The initial weight is |
| the one that appears in the configuration file. Both are normally equal |
| unless the current weight has been changed. Both the backend and the server |
| may be specified either by their name or by their numeric ID, prefixed with a |
| sharp ('#'). |
| |
| help |
| Print the list of known keywords and their basic usage. The same help screen |
| is also displayed for unknown commands. |
| |
| prompt |
| Toggle the prompt at the beginning of the line and enter or leave interactive |
| mode. In interactive mode, the connection is not closed after a command |
| completes. Instead, the prompt will appear again, indicating the user that |
| the interpreter is waiting for a new command. The prompt consists in a right |
| angle bracket followed by a space "> ". This mode is particularly convenient |
| when one wants to periodically check information such as stats or errors. |
| It is also a good idea to enter interactive mode before issuing a "help" |
| command. |
| |
| quit |
| Close the connection when in interactive mode. |
| |
| set map <map> [<key>|#<ref>] <value> |
| Modify the value corresponding to each key <key> in a map <map>. <map> is the |
| #<id> or <file> returned by "show map". If the <ref> is used in place of |
| <key>, only the entry pointed by <ref> is changed. The new value is <value>. |
| |
| set maxconn frontend <frontend> <value> |
| Dynamically change the specified frontend's maxconn setting. Any positive |
| value is allowed including zero, but setting values larger than the global |
| maxconn does not make much sense. If the limit is increased and connections |
| were pending, they will immediately be accepted. If it is lowered to a value |
| below the current number of connections, new connections acceptation will be |
| delayed until the threshold is reached. The frontend might be specified by |
| either its name or its numeric ID prefixed with a sharp ('#'). |
| |
| set maxconn server <backend/server> <value> |
| Dynamically change the specified server's maxconn setting. Any positive |
| value is allowed including zero, but setting values larger than the global |
| maxconn does not make much sense. |
| |
| set maxconn global <maxconn> |
| Dynamically change the global maxconn setting within the range defined by the |
| initial global maxconn setting. If it is increased and connections were |
| pending, they will immediately be accepted. If it is lowered to a value below |
| the current number of connections, new connections acceptation will be |
| delayed until the threshold is reached. A value of zero restores the initial |
| setting. |
| |
| set rate-limit connections global <value> |
| Change the process-wide connection rate limit, which is set by the global |
| 'maxconnrate' setting. A value of zero disables the limitation. This limit |
| applies to all frontends and the change has an immediate effect. The value |
| is passed in number of connections per second. |
| |
| set rate-limit http-compression global <value> |
| Change the maximum input compression rate, which is set by the global |
| 'maxcomprate' setting. A value of zero disables the limitation. The value is |
| passed in number of kilobytes per second. The value is available in the "show |
| info" on the line "CompressBpsRateLim" in bytes. |
| |
| set rate-limit sessions global <value> |
| Change the process-wide session rate limit, which is set by the global |
| 'maxsessrate' setting. A value of zero disables the limitation. This limit |
| applies to all frontends and the change has an immediate effect. The value |
| is passed in number of sessions per second. |
| |
| set rate-limit ssl-sessions global <value> |
| Change the process-wide SSL session rate limit, which is set by the global |
| 'maxsslrate' setting. A value of zero disables the limitation. This limit |
| applies to all frontends and the change has an immediate effect. The value |
| is passed in number of sessions per second sent to the SSL stack. It applies |
| before the handshake in order to protect the stack against handshake abuses. |
| |
| set server <backend>/<server> addr <ip4 or ip6 address> [port <port>] |
| Replace the current IP address of a server by the one provided. |
| Optionnaly, the port can be changed using the 'port' parameter. |
| Note that changing the port also support switching from/to port mapping |
| (notation with +X or -Y), only if a port is configured for the health check. |
| |
| set server <backend>/<server> agent [ up | down ] |
| Force a server's agent to a new state. This can be useful to immediately |
| switch a server's state regardless of some slow agent checks for example. |
| Note that the change is propagated to tracking servers if any. |
| |
| set server <backend>/<server> health [ up | stopping | down ] |
| Force a server's health to a new state. This can be useful to immediately |
| switch a server's state regardless of some slow health checks for example. |
| Note that the change is propagated to tracking servers if any. |
| |
| set server <backend>/<server> check-port <port> |
| Change the port used for health checking to <port> |
| |
| set server <backend>/<server> state [ ready | drain | maint ] |
| Force a server's administrative state to a new state. This can be useful to |
| disable load balancing and/or any traffic to a server. Setting the state to |
| "ready" puts the server in normal mode, and the command is the equivalent of |
| the "enable server" command. Setting the state to "maint" disables any traffic |
| to the server as well as any health checks. This is the equivalent of the |
| "disable server" command. Setting the mode to "drain" only removes the server |
| from load balancing but still allows it to be checked and to accept new |
| persistent connections. Changes are propagated to tracking servers if any. |
| |
| set server <backend>/<server> weight <weight>[%] |
| Change a server's weight to the value passed in argument. This is the exact |
| equivalent of the "set weight" command below. |
| |
| set ssl ocsp-response <response> |
| This command is used to update an OCSP Response for a certificate (see "crt" |
| on "bind" lines). Same controls are performed as during the initial loading of |
| the response. The <response> must be passed as a base64 encoded string of the |
| DER encoded response from the OCSP server. |
| |
| Example: |
| openssl ocsp -issuer issuer.pem -cert server.pem \ |
| -host ocsp.issuer.com:80 -respout resp.der |
| echo "set ssl ocsp-response $(base64 -w 10000 resp.der)" | \ |
| socat stdio /var/run/haproxy.stat |
| |
| set ssl tls-key <id> <tlskey> |
| Set the next TLS key for the <id> listener to <tlskey>. This key becomes the |
| ultimate key, while the penultimate one is used for encryption (others just |
| decrypt). The oldest TLS key present is overwritten. <id> is either a numeric |
| #<id> or <file> returned by "show tls-keys". <tlskey> is a base64 encoded 48 |
| bit TLS ticket key (ex. openssl rand -base64 48). |
| |
| set table <table> key <key> [data.<data_type> <value>]* |
| Create or update a stick-table entry in the table. If the key is not present, |
| an entry is inserted. See stick-table in section 4.2 to find all possible |
| values for <data_type>. The most likely use consists in dynamically entering |
| entries for source IP addresses, with a flag in gpc0 to dynamically block an |
| IP address or affect its quality of service. It is possible to pass multiple |
| data_types in a single call. |
| |
| set timeout cli <delay> |
| Change the CLI interface timeout for current connection. This can be useful |
| during long debugging sessions where the user needs to constantly inspect |
| some indicators without being disconnected. The delay is passed in seconds. |
| |
| set weight <backend>/<server> <weight>[%] |
| Change a server's weight to the value passed in argument. If the value ends |
| with the '%' sign, then the new weight will be relative to the initially |
| configured weight. Absolute weights are permitted between 0 and 256. |
| Relative weights must be positive with the resulting absolute weight is |
| capped at 256. Servers which are part of a farm running a static |
| load-balancing algorithm have stricter limitations because the weight |
| cannot change once set. Thus for these servers, the only accepted values |
| are 0 and 100% (or 0 and the initial weight). Changes take effect |
| immediately, though certain LB algorithms require a certain amount of |
| requests to consider changes. A typical usage of this command is to |
| disable a server during an update by setting its weight to zero, then to |
| enable it again after the update by setting it back to 100%. This command |
| is restricted and can only be issued on sockets configured for level |
| "admin". Both the backend and the server may be specified either by their |
| name or by their numeric ID, prefixed with a sharp ('#'). |
| |
| show cli sockets |
| List CLI sockets. The output format is composed of 3 fields separated by |
| spaces. The first field is the socket address, it can be a unix socket, a |
| ipv4 address:port couple or a ipv6 one. Socket of other types won't be dump. |
| The second field describe the level of the socket: 'admin', 'user' or |
| 'operator'. The last field list the processes on which the socket is bound, |
| separated by commas, it can be numbers or 'all'. |
| |
| Example : |
| |
| $ echo 'show cli sockets' | socat stdio /tmp/sock1 |
| # socket lvl processes |
| /tmp/sock1 admin all |
| 127.0.0.1:9999 user 2,3,4 |
| 127.0.0.2:9969 user 2 |
| [::1]:9999 operator 2 |
| |
| show env [<name>] |
| Dump one or all environment variables known by the process. Without any |
| argument, all variables are dumped. With an argument, only the specified |
| variable is dumped if it exists. Otherwise "Variable not found" is emitted. |
| Variables are dumped in the same format as they are stored or returned by the |
| "env" utility, that is, "<name>=<value>". This can be handy when debugging |
| certain configuration files making heavy use of environment variables to |
| ensure that they contain the expected values. This command is restricted and |
| can only be issued on sockets configured for levels "operator" or "admin". |
| |
| show errors [<iid>|<proxy>] [request|response] |
| Dump last known request and response errors collected by frontends and |
| backends. If <iid> is specified, the limit the dump to errors concerning |
| either frontend or backend whose ID is <iid>. Proxy ID "-1" will cause |
| all instances to be dumped. If a proxy name is specified instead, its ID |
| will be used as the filter. If "request" or "response" is added after the |
| proxy name or ID, only request or response errors will be dumped. This |
| command is restricted and can only be issued on sockets configured for |
| levels "operator" or "admin". |
| |
| The errors which may be collected are the last request and response errors |
| caused by protocol violations, often due to invalid characters in header |
| names. The report precisely indicates what exact character violated the |
| protocol. Other important information such as the exact date the error was |
| detected, frontend and backend names, the server name (when known), the |
| internal session ID and the source address which has initiated the session |
| are reported too. |
| |
| All characters are returned, and non-printable characters are encoded. The |
| most common ones (\t = 9, \n = 10, \r = 13 and \e = 27) are encoded as one |
| letter following a backslash. The backslash itself is encoded as '\\' to |
| avoid confusion. Other non-printable characters are encoded '\xNN' where |
| NN is the two-digits hexadecimal representation of the character's ASCII |
| code. |
| |
| Lines are prefixed with the position of their first character, starting at 0 |
| for the beginning of the buffer. At most one input line is printed per line, |
| and large lines will be broken into multiple consecutive output lines so that |
| the output never goes beyond 79 characters wide. It is easy to detect if a |
| line was broken, because it will not end with '\n' and the next line's offset |
| will be followed by a '+' sign, indicating it is a continuation of previous |
| line. |
| |
| Example : |
| $ echo "show errors -1 response" | socat stdio /tmp/sock1 |
| >>> [04/Mar/2009:15:46:56.081] backend http-in (#2) : invalid response |
| src 127.0.0.1, session #54, frontend fe-eth0 (#1), server s2 (#1) |
| response length 213 bytes, error at position 23: |
| |
| 00000 HTTP/1.0 200 OK\r\n |
| 00017 header/bizarre:blah\r\n |
| 00038 Location: blah\r\n |
| 00054 Long-line: this is a very long line which should b |
| 00104+ e broken into multiple lines on the output buffer, |
| 00154+ otherwise it would be too large to print in a ter |
| 00204+ minal\r\n |
| 00211 \r\n |
| |
| In the example above, we see that the backend "http-in" which has internal |
| ID 2 has blocked an invalid response from its server s2 which has internal |
| ID 1. The request was on session 54 initiated by source 127.0.0.1 and |
| received by frontend fe-eth0 whose ID is 1. The total response length was |
| 213 bytes when the error was detected, and the error was at byte 23. This |
| is the slash ('/') in header name "header/bizarre", which is not a valid |
| HTTP character for a header name. |
| |
| show backend |
| Dump the list of backends available in the running process |
| |
| show info [typed] |
| Dump info about haproxy status on current process. If "typed" is passed as an |
| optional argument, field numbers, names and types are emitted as well so that |
| external monitoring products can easily retrieve, possibly aggregate, then |
| report information found in fields they don't know. Each field is dumped on |
| its own line. By default, the format contains only two columns delimited by a |
| colon (':'). The left one is the field name and the right one is the value. |
| It is very important to note that in typed output format, the dump for a |
| single object is contiguous so that there is no need for a consumer to store |
| everything at once. |
| |
| When using the typed output format, each line is made of 4 columns delimited |
| by colons (':'). The first column is a dot-delimited series of 3 elements. The |
| first element is the numeric position of the field in the list (starting at |
| zero). This position shall not change over time, but holes are to be expected, |
| depending on build options or if some fields are deleted in the future. The |
| second element is the field name as it appears in the default "show info" |
| output. The third element is the relative process number starting at 1. |
| |
| The rest of the line starting after the first colon follows the "typed output |
| format" described in the section above. In short, the second column (after the |
| first ':') indicates the origin, nature and scope of the variable. The third |
| column indicates the type of the field, among "s32", "s64", "u32", "u64" and |
| "str". Then the fourth column is the value itself, which the consumer knows |
| how to parse thanks to column 3 and how to process thanks to column 2. |
| |
| Thus the overall line format in typed mode is : |
| |
| <field_pos>.<field_name>.<process_num>:<tags>:<type>:<value> |
| |
| Example : |
| |
| > show info |
| Name: HAProxy |
| Version: 1.7-dev1-de52ea-146 |
| Release_date: 2016/03/11 |
| Nbproc: 1 |
| Process_num: 1 |
| Pid: 28105 |
| Uptime: 0d 0h00m04s |
| Uptime_sec: 4 |
| Memmax_MB: 0 |
| PoolAlloc_MB: 0 |
| PoolUsed_MB: 0 |
| PoolFailed: 0 |
| (...) |
| |
| > show info typed |
| 0.Name.1:POS:str:HAProxy |
| 1.Version.1:POS:str:1.7-dev1-de52ea-146 |
| 2.Release_date.1:POS:str:2016/03/11 |
| 3.Nbproc.1:CGS:u32:1 |
| 4.Process_num.1:KGP:u32:1 |
| 5.Pid.1:SGP:u32:28105 |
| 6.Uptime.1:MDP:str:0d 0h00m08s |
| 7.Uptime_sec.1:MDP:u32:8 |
| 8.Memmax_MB.1:CLP:u32:0 |
| 9.PoolAlloc_MB.1:MGP:u32:0 |
| 10.PoolUsed_MB.1:MGP:u32:0 |
| 11.PoolFailed.1:MCP:u32:0 |
| (...) |
| |
| In the typed format, the presence of the process ID at the end of the |
| first column makes it very easy to visually aggregate outputs from |
| multiple processes. |
| Example : |
| |
| $ ( echo show info typed | socat /var/run/haproxy.sock1 ; \ |
| echo show info typed | socat /var/run/haproxy.sock2 ) | \ |
| sort -t . -k 1,1n -k 2,2 -k 3,3n |
| 0.Name.1:POS:str:HAProxy |
| 0.Name.2:POS:str:HAProxy |
| 1.Version.1:POS:str:1.7-dev1-868ab3-148 |
| 1.Version.2:POS:str:1.7-dev1-868ab3-148 |
| 2.Release_date.1:POS:str:2016/03/11 |
| 2.Release_date.2:POS:str:2016/03/11 |
| 3.Nbproc.1:CGS:u32:2 |
| 3.Nbproc.2:CGS:u32:2 |
| 4.Process_num.1:KGP:u32:1 |
| 4.Process_num.2:KGP:u32:2 |
| 5.Pid.1:SGP:u32:30120 |
| 5.Pid.2:SGP:u32:30121 |
| 6.Uptime.1:MDP:str:0d 0h01m28s |
| 6.Uptime.2:MDP:str:0d 0h01m28s |
| (...) |
| |
| show map [<map>] |
| Dump info about map converters. Without argument, the list of all available |
| maps is returned. If a <map> is specified, its contents are dumped. <map> is |
| the #<id> or <file>. The first column is a unique identifier. It can be used |
| as reference for the operation "del map" and "set map". The second column is |
| the pattern and the third column is the sample if available. The data returned |
| are not directly a list of available maps, but are the list of all patterns |
| composing any map. Many of these patterns can be shared with ACL. |
| |
| show acl [<acl>] |
| Dump info about acl converters. Without argument, the list of all available |
| acls is returned. If a <acl> is specified, its contents are dumped. <acl> if |
| the #<id> or <file>. The dump format is the same than the map even for the |
| sample value. The data returned are not a list of available ACL, but are the |
| list of all patterns composing any ACL. Many of these patterns can be shared |
| with maps. |
| |
| show pools |
| Dump the status of internal memory pools. This is useful to track memory |
| usage when suspecting a memory leak for example. It does exactly the same |
| as the SIGQUIT when running in foreground except that it does not flush |
| the pools. |
| |
| show servers state [<backend>] |
| Dump the state of the servers found in the running configuration. A backend |
| name or identifier may be provided to limit the output to this backend only. |
| |
| The dump has the following format: |
| - first line contains the format version (1 in this specification); |
| - second line contains the column headers, prefixed by a sharp ('#'); |
| - third line and next ones contain data; |
| - each line starting by a sharp ('#') is considered as a comment. |
| |
| Since multiple versions of the output may co-exist, below is the list of |
| fields and their order per file format version : |
| 1: |
| be_id: Backend unique id. |
| be_name: Backend label. |
| srv_id: Server unique id (in the backend). |
| srv_name: Server label. |
| srv_addr: Server IP address. |
| srv_op_state: Server operational state (UP/DOWN/...). |
| 0 = SRV_ST_STOPPED |
| The server is down. |
| 1 = SRV_ST_STARTING |
| The server is warming up (up but |
| throttled). |
| 2 = SRV_ST_RUNNING |
| The server is fully up. |
| 3 = SRV_ST_STOPPING |
| The server is up but soft-stopping |
| (eg: 404). |
| srv_admin_state: Server administrative state (MAINT/DRAIN/...). |
| The state is actually a mask of values : |
| 0x01 = SRV_ADMF_FMAINT |
| The server was explicitly forced into |
| maintenance. |
| 0x02 = SRV_ADMF_IMAINT |
| The server has inherited the maintenance |
| status from a tracked server. |
| 0x04 = SRV_ADMF_CMAINT |
| The server is in maintenance because of |
| the configuration. |
| 0x08 = SRV_ADMF_FDRAIN |
| The server was explicitly forced into |
| drain state. |
| 0x10 = SRV_ADMF_IDRAIN |
| The server has inherited the drain status |
| from a tracked server. |
| 0x20 = SRV_ADMF_RMAINT |
| The server is in maintenance because of an |
| IP address resolution failure. |
| srv_uweight: User visible server's weight. |
| srv_iweight: Server's initial weight. |
| srv_time_since_last_change: Time since last operational change. |
| srv_check_status: Last health check status. |
| srv_check_result: Last check result (FAILED/PASSED/...). |
| 0 = CHK_RES_UNKNOWN |
| Initialized to this by default. |
| 1 = CHK_RES_NEUTRAL |
| Valid check but no status information. |
| 2 = CHK_RES_FAILED |
| Check failed. |
| 3 = CHK_RES_PASSED |
| Check succeeded and server is fully up |
| again. |
| 4 = CHK_RES_CONDPASS |
| Check reports the server doesn't want new |
| sessions. |
| srv_check_health: Checks rise / fall current counter. |
| srv_check_state: State of the check (ENABLED/PAUSED/...). |
| The state is actually a mask of values : |
| 0x01 = CHK_ST_INPROGRESS |
| A check is currently running. |
| 0x02 = CHK_ST_CONFIGURED |
| This check is configured and may be |
| enabled. |
| 0x04 = CHK_ST_ENABLED |
| This check is currently administratively |
| enabled. |
| 0x08 = CHK_ST_PAUSED |
| Checks are paused because of maintenance |
| (health only). |
| srv_agent_state: State of the agent check (ENABLED/PAUSED/...). |
| This state uses the same mask values as |
| "srv_check_state", adding this specific one : |
| 0x10 = CHK_ST_AGENT |
| Check is an agent check (otherwise it's a |
| health check). |
| bk_f_forced_id: Flag to know if the backend ID is forced by |
| configuration. |
| srv_f_forced_id: Flag to know if the server's ID is forced by |
| configuration. |
| |
| show sess |
| Dump all known sessions. Avoid doing this on slow connections as this can |
| be huge. This command is restricted and can only be issued on sockets |
| configured for levels "operator" or "admin". |
| |
| show sess <id> |
| Display a lot of internal information about the specified session identifier. |
| This identifier is the first field at the beginning of the lines in the dumps |
| of "show sess" (it corresponds to the session pointer). Those information are |
| useless to most users but may be used by haproxy developers to troubleshoot a |
| complex bug. The output format is intentionally not documented so that it can |
| freely evolve depending on demands. You may find a description of all fields |
| returned in src/dumpstats.c |
| |
| The special id "all" dumps the states of all sessions, which must be avoided |
| as much as possible as it is highly CPU intensive and can take a lot of time. |
| |
| show stat [{<iid>|<proxy>} <type> <sid>] [typed] |
| Dump statistics using the CSV format, or using the extended typed output |
| format described in the section above if "typed" is passed after the other |
| arguments. By passing <id>, <type> and <sid>, it is possible to dump only |
| selected items : |
| - <iid> is a proxy ID, -1 to dump everything. Alternatively, a proxy name |
| <proxy> may be specified. In this case, this proxy's ID will be used as |
| the ID selector. |
| - <type> selects the type of dumpable objects : 1 for frontends, 2 for |
| backends, 4 for servers, -1 for everything. These values can be ORed, |
| for example: |
| 1 + 2 = 3 -> frontend + backend. |
| 1 + 2 + 4 = 7 -> frontend + backend + server. |
| - <sid> is a server ID, -1 to dump everything from the selected proxy. |
| |
| Example : |
| $ echo "show info;show stat" | socat stdio unix-connect:/tmp/sock1 |
| >>> Name: HAProxy |
| Version: 1.4-dev2-49 |
| Release_date: 2009/09/23 |
| Nbproc: 1 |
| Process_num: 1 |
| (...) |
| |
| # pxname,svname,qcur,qmax,scur,smax,slim,stot,bin,bout,dreq, (...) |
| stats,FRONTEND,,,0,0,1000,0,0,0,0,0,0,,,,,OPEN,,,,,,,,,1,1,0, (...) |
| stats,BACKEND,0,0,0,0,1000,0,0,0,0,0,,0,0,0,0,UP,0,0,0,,0,250,(...) |
| (...) |
| www1,BACKEND,0,0,0,0,1000,0,0,0,0,0,,0,0,0,0,UP,1,1,0,,0,250, (...) |
| |
| $ |
| |
| In this example, two commands have been issued at once. That way it's easy to |
| find which process the stats apply to in multi-process mode. This is not |
| needed in the typed output format as the process number is reported on each |
| line. Notice the empty line after the information output which marks the end |
| of the first block. A similar empty line appears at the end of the second |
| block (stats) so that the reader knows the output has not been truncated. |
| |
| When "typed" is specified, the output format is more suitable to monitoring |
| tools because it provides numeric positions and indicates the type of each |
| output field. Each value stands on its own line with process number, element |
| number, nature, origin and scope. This same format is available via the HTTP |
| stats by passing ";typed" after the URI. It is very important to note that in |
| typed output format, the dump for a single object is contiguous so that there |
| is no need for a consumer to store everything at once. |
| |
| When using the typed output format, each line is made of 4 columns delimited |
| by colons (':'). The first column is a dot-delimited series of 5 elements. The |
| first element is a letter indicating the type of the object being described. |
| At the moment the following object types are known : 'F' for a frontend, 'B' |
| for a backend, 'L' for a listener, and 'S' for a server. The second element |
| The second element is a positive integer representing the unique identifier of |
| the proxy the object belongs to. It is equivalent to the "iid" column of the |
| CSV output and matches the value in front of the optional "id" directive found |
| in the frontend or backend section. The third element is a positive integer |
| containing the unique object identifier inside the proxy, and corresponds to |
| the "sid" column of the CSV output. ID 0 is reported when dumping a frontend |
| or a backend. For a listener or a server, this corresponds to their respective |
| ID inside the proxy. The fourth element is the numeric position of the field |
| in the list (starting at zero). This position shall not change over time, but |
| holes are to be expected, depending on build options or if some fields are |
| deleted in the future. The fifth element is the field name as it appears in |
| the CSV output. The sixth element is a positive integer and is the relative |
| process number starting at 1. |
| |
| The rest of the line starting after the first colon follows the "typed output |
| format" described in the section above. In short, the second column (after the |
| first ':') indicates the origin, nature and scope of the variable. The third |
| column indicates the type of the field, among "s32", "s64", "u32", "u64" and |
| "str". Then the fourth column is the value itself, which the consumer knows |
| how to parse thanks to column 3 and how to process thanks to column 2. |
| |
| Thus the overall line format in typed mode is : |
| |
| <obj>.<px_id>.<id>.<fpos>.<fname>.<process_num>:<tags>:<type>:<value> |
| |
| Here's an example of typed output format : |
| |
| $ echo "show stat typed" | socat stdio unix-connect:/tmp/sock1 |
| F.2.0.0.pxname.1:MGP:str:private-frontend |
| F.2.0.1.svname.1:MGP:str:FRONTEND |
| F.2.0.8.bin.1:MGP:u64:0 |
| F.2.0.9.bout.1:MGP:u64:0 |
| F.2.0.40.hrsp_2xx.1:MGP:u64:0 |
| L.2.1.0.pxname.1:MGP:str:private-frontend |
| L.2.1.1.svname.1:MGP:str:sock-1 |
| L.2.1.17.status.1:MGP:str:OPEN |
| L.2.1.73.addr.1:MGP:str:0.0.0.0:8001 |
| S.3.13.60.rtime.1:MCP:u32:0 |
| S.3.13.61.ttime.1:MCP:u32:0 |
| S.3.13.62.agent_status.1:MGP:str:L4TOUT |
| S.3.13.64.agent_duration.1:MGP:u64:2001 |
| S.3.13.65.check_desc.1:MCP:str:Layer4 timeout |
| S.3.13.66.agent_desc.1:MCP:str:Layer4 timeout |
| S.3.13.67.check_rise.1:MCP:u32:2 |
| S.3.13.68.check_fall.1:MCP:u32:3 |
| S.3.13.69.check_health.1:SGP:u32:0 |
| S.3.13.70.agent_rise.1:MaP:u32:1 |
| S.3.13.71.agent_fall.1:SGP:u32:1 |
| S.3.13.72.agent_health.1:SGP:u32:1 |
| S.3.13.73.addr.1:MCP:str:1.255.255.255:8888 |
| S.3.13.75.mode.1:MAP:str:http |
| B.3.0.0.pxname.1:MGP:str:private-backend |
| B.3.0.1.svname.1:MGP:str:BACKEND |
| B.3.0.2.qcur.1:MGP:u32:0 |
| B.3.0.3.qmax.1:MGP:u32:0 |
| B.3.0.4.scur.1:MGP:u32:0 |
| B.3.0.5.smax.1:MGP:u32:0 |
| B.3.0.6.slim.1:MGP:u32:1000 |
| B.3.0.55.lastsess.1:MMP:s32:-1 |
| (...) |
| |
| In the typed format, the presence of the process ID at the end of the |
| first column makes it very easy to visually aggregate outputs from |
| multiple processes, as show in the example below where each line appears |
| for each process : |
| |
| $ ( echo show stat typed | socat /var/run/haproxy.sock1 - ; \ |
| echo show stat typed | socat /var/run/haproxy.sock2 - ) | \ |
| sort -t . -k 1,1 -k 2,2n -k 3,3n -k 4,4n -k 5,5 -k 6,6n |
| B.3.0.0.pxname.1:MGP:str:private-backend |
| B.3.0.0.pxname.2:MGP:str:private-backend |
| B.3.0.1.svname.1:MGP:str:BACKEND |
| B.3.0.1.svname.2:MGP:str:BACKEND |
| B.3.0.2.qcur.1:MGP:u32:0 |
| B.3.0.2.qcur.2:MGP:u32:0 |
| B.3.0.3.qmax.1:MGP:u32:0 |
| B.3.0.3.qmax.2:MGP:u32:0 |
| B.3.0.4.scur.1:MGP:u32:0 |
| B.3.0.4.scur.2:MGP:u32:0 |
| B.3.0.5.smax.1:MGP:u32:0 |
| B.3.0.5.smax.2:MGP:u32:0 |
| B.3.0.6.slim.1:MGP:u32:1000 |
| B.3.0.6.slim.2:MGP:u32:1000 |
| (...) |
| |
| show stat resolvers [<resolvers section id>] |
| Dump statistics for the given resolvers section, or all resolvers sections |
| if no section is supplied. |
| |
| For each name server, the following counters are reported: |
| sent: number of DNS requests sent to this server |
| valid: number of DNS valid responses received from this server |
| update: number of DNS responses used to update the server's IP address |
| cname: number of CNAME responses |
| cname_error: CNAME errors encountered with this server |
| any_err: number of empty response (IE: server does not support ANY type) |
| nx: non existent domain response received from this server |
| timeout: how many time this server did not answer in time |
| refused: number of requests refused by this server |
| other: any other DNS errors |
| invalid: invalid DNS response (from a protocol point of view) |
| too_big: too big response |
| outdated: number of response arrived too late (after an other name server) |
| |
| show table |
| Dump general information on all known stick-tables. Their name is returned |
| (the name of the proxy which holds them), their type (currently zero, always |
| IP), their size in maximum possible number of entries, and the number of |
| entries currently in use. |
| |
| Example : |
| $ echo "show table" | socat stdio /tmp/sock1 |
| >>> # table: front_pub, type: ip, size:204800, used:171454 |
| >>> # table: back_rdp, type: ip, size:204800, used:0 |
| |
| show table <name> [ data.<type> <operator> <value> ] | [ key <key> ] |
| Dump contents of stick-table <name>. In this mode, a first line of generic |
| information about the table is reported as with "show table", then all |
| entries are dumped. Since this can be quite heavy, it is possible to specify |
| a filter in order to specify what entries to display. |
| |
| When the "data." form is used the filter applies to the stored data (see |
| "stick-table" in section 4.2). A stored data type must be specified |
| in <type>, and this data type must be stored in the table otherwise an |
| error is reported. The data is compared according to <operator> with the |
| 64-bit integer <value>. Operators are the same as with the ACLs : |
| |
| - eq : match entries whose data is equal to this value |
| - ne : match entries whose data is not equal to this value |
| - le : match entries whose data is less than or equal to this value |
| - ge : match entries whose data is greater than or equal to this value |
| - lt : match entries whose data is less than this value |
| - gt : match entries whose data is greater than this value |
| |
| |
| When the key form is used the entry <key> is shown. The key must be of the |
| same type as the table, which currently is limited to IPv4, IPv6, integer, |
| and string. |
| |
| Example : |
| $ echo "show table http_proxy" | socat stdio /tmp/sock1 |
| >>> # table: http_proxy, type: ip, size:204800, used:2 |
| >>> 0x80e6a4c: key=127.0.0.1 use=0 exp=3594729 gpc0=0 conn_rate(30000)=1 \ |
| bytes_out_rate(60000)=187 |
| >>> 0x80e6a80: key=127.0.0.2 use=0 exp=3594740 gpc0=1 conn_rate(30000)=10 \ |
| bytes_out_rate(60000)=191 |
| |
| $ echo "show table http_proxy data.gpc0 gt 0" | socat stdio /tmp/sock1 |
| >>> # table: http_proxy, type: ip, size:204800, used:2 |
| >>> 0x80e6a80: key=127.0.0.2 use=0 exp=3594740 gpc0=1 conn_rate(30000)=10 \ |
| bytes_out_rate(60000)=191 |
| |
| $ echo "show table http_proxy data.conn_rate gt 5" | \ |
| socat stdio /tmp/sock1 |
| >>> # table: http_proxy, type: ip, size:204800, used:2 |
| >>> 0x80e6a80: key=127.0.0.2 use=0 exp=3594740 gpc0=1 conn_rate(30000)=10 \ |
| bytes_out_rate(60000)=191 |
| |
| $ echo "show table http_proxy key 127.0.0.2" | \ |
| socat stdio /tmp/sock1 |
| >>> # table: http_proxy, type: ip, size:204800, used:2 |
| >>> 0x80e6a80: key=127.0.0.2 use=0 exp=3594740 gpc0=1 conn_rate(30000)=10 \ |
| bytes_out_rate(60000)=191 |
| |
| When the data criterion applies to a dynamic value dependent on time such as |
| a bytes rate, the value is dynamically computed during the evaluation of the |
| entry in order to decide whether it has to be dumped or not. This means that |
| such a filter could match for some time then not match anymore because as |
| time goes, the average event rate drops. |
| |
| It is possible to use this to extract lists of IP addresses abusing the |
| service, in order to monitor them or even blacklist them in a firewall. |
| Example : |
| $ echo "show table http_proxy data.gpc0 gt 0" \ |
| | socat stdio /tmp/sock1 \ |
| | fgrep 'key=' | cut -d' ' -f2 | cut -d= -f2 > abusers-ip.txt |
| ( or | awk '/key/{ print a[split($2,a,"=")]; }' ) |
| |
| show tls-keys [id|*] |
| Dump all loaded TLS ticket keys references. The TLS ticket key reference ID |
| and the file from which the keys have been loaded is shown. Both of those |
| can be used to update the TLS keys using "set ssl tls-key". If an ID is |
| specified as parameter, it will dump the tickets, using * it will dump every |
| keys from every references. |
| |
| shutdown frontend <frontend> |
| Completely delete the specified frontend. All the ports it was bound to will |
| be released. It will not be possible to enable the frontend anymore after |
| this operation. This is intended to be used in environments where stopping a |
| proxy is not even imaginable but a misconfigured proxy must be fixed. That |
| way it's possible to release the port and bind it into another process to |
| restore operations. The frontend will not appear at all on the stats page |
| once it is terminated. |
| |
| The frontend may be specified either by its name or by its numeric ID, |
| prefixed with a sharp ('#'). |
| |
| This command is restricted and can only be issued on sockets configured for |
| level "admin". |
| |
| shutdown session <id> |
| Immediately terminate the session matching the specified session identifier. |
| This identifier is the first field at the beginning of the lines in the dumps |
| of "show sess" (it corresponds to the session pointer). This can be used to |
| terminate a long-running session without waiting for a timeout or when an |
| endless transfer is ongoing. Such terminated sessions are reported with a 'K' |
| flag in the logs. |
| |
| shutdown sessions server <backend>/<server> |
| Immediately terminate all the sessions attached to the specified server. This |
| can be used to terminate long-running sessions after a server is put into |
| maintenance mode, for instance. Such terminated sessions are reported with a |
| 'K' flag in the logs. |
| |
| |
| 10. Tricks for easier configuration management |
| ---------------------------------------------- |
| |
| It is very common that two HAProxy nodes constituting a cluster share exactly |
| the same configuration modulo a few addresses. Instead of having to maintain a |
| duplicate configuration for each node, which will inevitably diverge, it is |
| possible to include environment variables in the configuration. Thus multiple |
| configuration may share the exact same file with only a few different system |
| wide environment variables. This started in version 1.5 where only addresses |
| were allowed to include environment variables, and 1.6 goes further by |
| supporting environment variables everywhere. The syntax is the same as in the |
| UNIX shell, a variable starts with a dollar sign ('$'), followed by an opening |
| curly brace ('{'), then the variable name followed by the closing brace ('}'). |
| Except for addresses, environment variables are only interpreted in arguments |
| surrounded with double quotes (this was necessary not to break existing setups |
| using regular expressions involving the dollar symbol). |
| |
| Environment variables also make it convenient to write configurations which are |
| expected to work on various sites where only the address changes. It can also |
| permit to remove passwords from some configs. Example below where the the file |
| "site1.env" file is sourced by the init script upon startup : |
| |
| $ cat site1.env |
| LISTEN=192.168.1.1 |
| CACHE_PFX=192.168.11 |
| SERVER_PFX=192.168.22 |
| LOGGER=192.168.33.1 |
| STATSLP=admin:pa$$w0rd |
| ABUSERS=/etc/haproxy/abuse.lst |
| TIMEOUT=10s |
| |
| $ cat haproxy.cfg |
| global |
| log "${LOGGER}:514" local0 |
| |
| defaults |
| mode http |
| timeout client "${TIMEOUT}" |
| timeout server "${TIMEOUT}" |
| timeout connect 5s |
| |
| frontend public |
| bind "${LISTEN}:80" |
| http-request reject if { src -f "${ABUSERS}" } |
| stats uri /stats |
| stats auth "${STATSLP}" |
| use_backend cache if { path_end .jpg .css .ico } |
| default_backend server |
| |
| backend cache |
| server cache1 "${CACHE_PFX}.1:18080" check |
| server cache2 "${CACHE_PFX}.2:18080" check |
| |
| backend server |
| server cache1 "${SERVER_PFX}.1:8080" check |
| server cache2 "${SERVER_PFX}.2:8080" check |
| |
| |
| 11. Well-known traps to avoid |
| ----------------------------- |
| |
| Once in a while, someone reports that after a system reboot, the haproxy |
| service wasn't started, and that once they start it by hand it works. Most |
| often, these people are running a clustered IP address mechanism such as |
| keepalived, to assign the service IP address to the master node only, and while |
| it used to work when they used to bind haproxy to address 0.0.0.0, it stopped |
| working after they bound it to the virtual IP address. What happens here is |
| that when the service starts, the virtual IP address is not yet owned by the |
| local node, so when HAProxy wants to bind to it, the system rejects this |
| because it is not a local IP address. The fix doesn't consist in delaying the |
| haproxy service startup (since it wouldn't stand a restart), but instead to |
| properly configure the system to allow binding to non-local addresses. This is |
| easily done on Linux by setting the net.ipv4.ip_nonlocal_bind sysctl to 1. This |
| is also needed in order to transparently intercept the IP traffic that passes |
| through HAProxy for a specific target address. |
| |
| Multi-process configurations involving source port ranges may apparently seem |
| to work but they will cause some random failures under high loads because more |
| than one process may try to use the same source port to connect to the same |
| server, which is not possible. The system will report an error and a retry will |
| happen, picking another port. A high value in the "retries" parameter may hide |
| the effect to a certain extent but this also comes with increased CPU usage and |
| processing time. Logs will also report a certain number of retries. For this |
| reason, port ranges should be avoided in multi-process configurations. |
| |
| Since HAProxy uses SO_REUSEPORT and supports having multiple independent |
| processes bound to the same IP:port, during troubleshooting it can happen that |
| an old process was not stopped before a new one was started. This provides |
| absurd test results which tend to indicate that any change to the configuration |
| is ignored. The reason is that in fact even the new process is restarted with a |
| new configuration, the old one also gets some incoming connections and |
| processes them, returning unexpected results. When in doubt, just stop the new |
| process and try again. If it still works, it very likely means that an old |
| process remains alive and has to be stopped. Linux's "netstat -lntp" is of good |
| help here. |
| |
| When adding entries to an ACL from the command line (eg: when blacklisting a |
| source address), it is important to keep in mind that these entries are not |
| synchronized to the file and that if someone reloads the configuration, these |
| updates will be lost. While this is often the desired effect (for blacklisting) |
| it may not necessarily match expectations when the change was made as a fix for |
| a problem. See the "add acl" action of the CLI interface. |
| |
| |
| 12. Debugging and performance issues |
| ------------------------------------ |
| |
| When HAProxy is started with the "-d" option, it will stay in the foreground |
| and will print one line per event, such as an incoming connection, the end of a |
| connection, and for each request or response header line seen. This debug |
| output is emitted before the contents are processed, so they don't consider the |
| local modifications. The main use is to show the request and response without |
| having to run a network sniffer. The output is less readable when multiple |
| connections are handled in parallel, though the "debug2ansi" and "debug2html" |
| scripts found in the examples/ directory definitely help here by coloring the |
| output. |
| |
| If a request or response is rejected because HAProxy finds it is malformed, the |
| best thing to do is to connect to the CLI and issue "show errors", which will |
| report the last captured faulty request and response for each frontend and |
| backend, with all the necessary information to indicate precisely the first |
| character of the input stream that was rejected. This is sometimes needed to |
| prove to customers or to developers that a bug is present in their code. In |
| this case it is often possible to relax the checks (but still keep the |
| captures) using "option accept-invalid-http-request" or its equivalent for |
| responses coming from the server "option accept-invalid-http-response". Please |
| see the configuration manual for more details. |
| |
| Example : |
| |
| > show errors |
| Total events captured on [13/Oct/2015:13:43:47.169] : 1 |
| |
| [13/Oct/2015:13:43:40.918] frontend HAProxyLocalStats (#2): invalid request |
| backend <NONE> (#-1), server <NONE> (#-1), event #0 |
| src 127.0.0.1:51981, session #0, session flags 0x00000080 |
| HTTP msg state 26, msg flags 0x00000000, tx flags 0x00000000 |
| HTTP chunk len 0 bytes, HTTP body len 0 bytes |
| buffer flags 0x00808002, out 0 bytes, total 31 bytes |
| pending 31 bytes, wrapping at 8040, error at position 13: |
| |
| 00000 GET /invalid request HTTP/1.1\r\n |
| |
| |
| The output of "show info" on the CLI provides a number of useful information |
| regarding the maximum connection rate ever reached, maximum SSL key rate ever |
| reached, and in general all information which can help to explain temporary |
| issues regarding CPU or memory usage. Example : |
| |
| > show info |
| Name: HAProxy |
| Version: 1.6-dev7-e32d18-17 |
| Release_date: 2015/10/12 |
| Nbproc: 1 |
| Process_num: 1 |
| Pid: 7949 |
| Uptime: 0d 0h02m39s |
| Uptime_sec: 159 |
| Memmax_MB: 0 |
| Ulimit-n: 120032 |
| Maxsock: 120032 |
| Maxconn: 60000 |
| Hard_maxconn: 60000 |
| CurrConns: 0 |
| CumConns: 3 |
| CumReq: 3 |
| MaxSslConns: 0 |
| CurrSslConns: 0 |
| CumSslConns: 0 |
| Maxpipes: 0 |
| PipesUsed: 0 |
| PipesFree: 0 |
| ConnRate: 0 |
| ConnRateLimit: 0 |
| MaxConnRate: 1 |
| SessRate: 0 |
| SessRateLimit: 0 |
| MaxSessRate: 1 |
| SslRate: 0 |
| SslRateLimit: 0 |
| MaxSslRate: 0 |
| SslFrontendKeyRate: 0 |
| SslFrontendMaxKeyRate: 0 |
| SslFrontendSessionReuse_pct: 0 |
| SslBackendKeyRate: 0 |
| SslBackendMaxKeyRate: 0 |
| SslCacheLookups: 0 |
| SslCacheMisses: 0 |
| CompressBpsIn: 0 |
| CompressBpsOut: 0 |
| CompressBpsRateLim: 0 |
| ZlibMemUsage: 0 |
| MaxZlibMemUsage: 0 |
| Tasks: 5 |
| Run_queue: 1 |
| Idle_pct: 100 |
| node: wtap |
| description: |
| |
| When an issue seems to randomly appear on a new version of HAProxy (eg: every |
| second request is aborted, occasional crash, etc), it is worth trying to enable |
| memory poisoning so that each call to malloc() is immediately followed by the |
| filling of the memory area with a configurable byte. By default this byte is |
| 0x50 (ASCII for 'P'), but any other byte can be used, including zero (which |
| will have the same effect as a calloc() and which may make issues disappear). |
| Memory poisoning is enabled on the command line using the "-dM" option. It |
| slightly hurts performance and is not recommended for use in production. If |
| an issue happens all the time with it or never happens when poisoning uses |
| byte zero, it clearly means you've found a bug and you definitely need to |
| report it. Otherwise if there's no clear change, the problem it is not related. |
| |
| When debugging some latency issues, it is important to use both strace and |
| tcpdump on the local machine, and another tcpdump on the remote system. The |
| reason for this is that there are delays everywhere in the processing chain and |
| it is important to know which one is causing latency to know where to act. In |
| practice, the local tcpdump will indicate when the input data come in. Strace |
| will indicate when haproxy receives these data (using recv/recvfrom). Warning, |
| openssl uses read()/write() syscalls instead of recv()/send(). Strace will also |
| show when haproxy sends the data, and tcpdump will show when the system sends |
| these data to the interface. Then the external tcpdump will show when the data |
| sent are really received (since the local one only shows when the packets are |
| queued). The benefit of sniffing on the local system is that strace and tcpdump |
| will use the same reference clock. Strace should be used with "-tts200" to get |
| complete timestamps and report large enough chunks of data to read them. |
| Tcpdump should be used with "-nvvttSs0" to report full packets, real sequence |
| numbers and complete timestamps. |
| |
| In practice, received data are almost always immediately received by haproxy |
| (unless the machine has a saturated CPU or these data are invalid and not |
| delivered). If these data are received but not sent, it generally is because |
| the output buffer is saturated (ie: recipient doesn't consume the data fast |
| enough). This can be confirmed by seeing that the polling doesn't notify of |
| the ability to write on the output file descriptor for some time (it's often |
| easier to spot in the strace output when the data finally leave and then roll |
| back to see when the write event was notified). It generally matches an ACK |
| received from the recipient, and detected by tcpdump. Once the data are sent, |
| they may spend some time in the system doing nothing. Here again, the TCP |
| congestion window may be limited and not allow these data to leave, waiting for |
| an ACK to open the window. If the traffic is idle and the data take 40 ms or |
| 200 ms to leave, it's a different issue (which is not an issue), it's the fact |
| that the Nagle algorithm prevents empty packets from leaving immediately, in |
| hope that they will be merged with subsequent data. HAProxy automatically |
| disables Nagle in pure TCP mode and in tunnels. However it definitely remains |
| enabled when forwarding an HTTP body (and this contributes to the performance |
| improvement there by reducing the number of packets). Some HTTP non-compliant |
| applications may be sensitive to the latency when delivering incomplete HTTP |
| response messages. In this case you will have to enable "option http-no-delay" |
| to disable Nagle in order to work around their design, keeping in mind that any |
| other proxy in the chain may similarly be impacted. If tcpdump reports that data |
| leave immediately but the other end doesn't see them quickly, it can mean there |
| is a congested WAN link, a congested LAN with flow control enabled and |
| preventing the data from leaving, or more commonly that HAProxy is in fact |
| running in a virtual machine and that for whatever reason the hypervisor has |
| decided that the data didn't need to be sent immediately. In virtualized |
| environments, latency issues are almost always caused by the virtualization |
| layer, so in order to save time, it's worth first comparing tcpdump in the VM |
| and on the external components. Any difference has to be credited to the |
| hypervisor and its accompanying drivers. |
| |
| When some TCP SACK segments are seen in tcpdump traces (using -vv), it always |
| means that the side sending them has got the proof of a lost packet. While not |
| seeing them doesn't mean there are no losses, seeing them definitely means the |
| network is lossy. Losses are normal on a network, but at a rate where SACKs are |
| not noticeable at the naked eye. If they appear a lot in the traces, it is |
| worth investigating exactly what happens and where the packets are lost. HTTP |
| doesn't cope well with TCP losses, which introduce huge latencies. |
| |
| The "netstat -i" command will report statistics per interface. An interface |
| where the Rx-Ovr counter grows indicates that the system doesn't have enough |
| resources to receive all incoming packets and that they're lost before being |
| processed by the network driver. Rx-Drp indicates that some received packets |
| were lost in the network stack because the application doesn't process them |
| fast enough. This can happen during some attacks as well. Tx-Drp means that |
| the output queues were full and packets had to be dropped. When using TCP it |
| should be very rare, but will possibly indicate a saturated outgoing link. |
| |
| |
| 13. Security considerations |
| --------------------------- |
| |
| HAProxy is designed to run with very limited privileges. The standard way to |
| use it is to isolate it into a chroot jail and to drop its privileges to a |
| non-root user without any permissions inside this jail so that if any future |
| vulnerability were to be discovered, its compromise would not affect the rest |
| of the system. |
| |
| In order to perform a chroot, it first needs to be started as a root user. It is |
| pointless to build hand-made chroots to start the process there, these ones are |
| painful to build, are never properly maintained and always contain way more |
| bugs than the main file-system. And in case of compromise, the intruder can use |
| the purposely built file-system. Unfortunately many administrators confuse |
| "start as root" and "run as root", resulting in the uid change to be done prior |
| to starting haproxy, and reducing the effective security restrictions. |
| |
| HAProxy will need to be started as root in order to : |
| - adjust the file descriptor limits |
| - bind to privileged port numbers |
| - bind to a specific network interface |
| - transparently listen to a foreign address |
| - isolate itself inside the chroot jail |
| - drop to another non-privileged UID |
| |
| HAProxy may require to be run as root in order to : |
| - bind to an interface for outgoing connections |
| - bind to privileged source ports for outgoing connections |
| - transparently bind to a foreign address for outgoing connections |
| |
| Most users will never need the "run as root" case. But the "start as root" |
| covers most usages. |
| |
| A safe configuration will have : |
| |
| - a chroot statement pointing to an empty location without any access |
| permissions. This can be prepared this way on the UNIX command line : |
| |
| # mkdir /var/empty && chmod 0 /var/empty || echo "Failed" |
| |
| and referenced like this in the HAProxy configuration's global section : |
| |
| chroot /var/empty |
| |
| - both a uid/user and gid/group statements in the global section : |
| |
| user haproxy |
| group haproxy |
| |
| - a stats socket whose mode, uid and gid are set to match the user and/or |
| group allowed to access the CLI so that nobody may access it : |
| |
| stats socket /var/run/haproxy.stat uid hatop gid hatop mode 600 |
| |