mirror of
http://git.haproxy.org/git/haproxy.git/
synced 2024-12-11 22:15:14 +00:00
2007 lines
83 KiB
Plaintext
2007 lines
83 KiB
Plaintext
-------------------
|
|
H A - P r o x y
|
|
Reference Manual
|
|
-------------------
|
|
version 1.2.7
|
|
willy tarreau
|
|
2005/10/09
|
|
|
|
============
|
|
| Abstract |
|
|
============
|
|
|
|
HA-Proxy is a TCP/HTTP reverse proxy which is particularly suited for high
|
|
availability environments. Indeed, it can :
|
|
- route HTTP requests depending on statically assigned cookies ;
|
|
- spread the load among several servers while assuring server persistence
|
|
through the use of HTTP cookies ;
|
|
- switch to backup servers in the event a main one fails ;
|
|
- accept connections to special ports dedicated to service monitoring ;
|
|
- stop accepting connections without breaking existing ones ;
|
|
- add/modify/delete HTTP headers both ways ;
|
|
- block requests matching a particular pattern ;
|
|
|
|
It needs very little resource. Its event-driven architecture allows it to easily
|
|
handle thousands of simultaneous connections on hundreds of instances without
|
|
risking the system's stability.
|
|
|
|
====================
|
|
| Start parameters |
|
|
====================
|
|
|
|
There are only a few command line options :
|
|
|
|
-f <configuration file>
|
|
-n <high limit for the total number of simultaneous connections>
|
|
-N <high limit for the per-proxy number of simultaneous connections>
|
|
-d starts in foregreound with debugging mode enabled
|
|
-D starts in daemon mode
|
|
-q disable messages on output
|
|
-V displays messages on output even when -q or 'quiet' are specified.
|
|
-c only checks config file and exits with code 0 if no error was found, or
|
|
exits with code 1 if a syntax error was found.
|
|
-p <pidfile> asks the process to write down each of its children's
|
|
pids to this file in daemon mode.
|
|
-s shows statistics (only if compiled in)
|
|
-l shows even more statistics (implies '-s')
|
|
-de disables use of epoll()
|
|
-dp disables use of poll()
|
|
|
|
|
|
The maximal number of connections per proxy is used as the default parameter for
|
|
each instance for which the 'maxconn' paramter is not set in the 'listen' section.
|
|
|
|
The maximal number of total connections limits the number of connections used by
|
|
the whole process if the 'maxconn' parameter is not set in the 'global' section.
|
|
|
|
The debugging mode has the same effect as the 'debug' option in the 'global'
|
|
section. When the proxy runs in this mode, it dumps every connections,
|
|
disconnections, timestamps, and HTTP headers to stdout. This should NEVER
|
|
be used in an init script since it will prevent the system from starting up.
|
|
|
|
Statistics are only available if compiled in with the 'STATTIME' option. It's
|
|
only used during code optimization phases.
|
|
|
|
======================
|
|
| Configuration file |
|
|
======================
|
|
|
|
Structure
|
|
=========
|
|
|
|
The configuration file parser ignores empty lines, spaces, tabs. Anything
|
|
between a sharp ('#') not following a backslash ('\'), and the end of a line
|
|
constitutes a comment and is ignored too.
|
|
|
|
The configuration file is segmented in sections. A section begins whenever
|
|
one of these 3 keywords are encountered :
|
|
|
|
- 'global'
|
|
- 'listen'
|
|
- 'defaults'
|
|
|
|
Every parameter refer to the section beginning at the last one of these 3
|
|
keywords.
|
|
|
|
|
|
1) Global parameters
|
|
====================
|
|
|
|
Global parameters affect the whole process behaviour. They are all set in the
|
|
'global' section. There may be several 'global' sections if needed, but their
|
|
parameters will only be merged. Allowed parameters in 'global' section include
|
|
the following ones :
|
|
|
|
- log <address> <facility> [max_level]
|
|
- maxconn <number>
|
|
- uid <user id>
|
|
- gid <group id>
|
|
- chroot <directory>
|
|
- nbproc <number>
|
|
- daemon
|
|
- debug
|
|
- noepoll
|
|
- nopoll
|
|
- quiet
|
|
- pidfile <file>
|
|
- ulimit-n <number>
|
|
- stats
|
|
|
|
|
|
1.1) Event logging
|
|
------------------
|
|
Most events are logged : start, stop, servers going up and down, connections and
|
|
errors. Each event generates a syslog message which can be sent to up to 2
|
|
servers. The syntax is :
|
|
|
|
log <ip_address> <facility> [max_level]
|
|
|
|
Connections are logged at level "info". Services initialization and servers
|
|
going up are logged at level "notice", termination signals are logged at
|
|
"warning", and definitive service termination, as well as loss of servers are
|
|
logged at level "alert". The optional parameter <max_level> specifies above
|
|
what level messages should be sent. Level can take one of these 8 values :
|
|
|
|
emerg, alert, crit, err, warning, notice, info, debug
|
|
|
|
For backwards compatibility with versions 1.1.16 and earlier, the default level
|
|
value is "debug" if not specified.
|
|
|
|
Permitted facilities are :
|
|
kern, user, mail, daemon, auth, syslog, lpr, news,
|
|
uucp, cron, auth2, ftp, ntp, audit, alert, cron2,
|
|
local0, local1, local2, local3, local4, local5, local6, local7
|
|
|
|
According to RFC3164, messages are truncated to 1024 bytes before being emitted.
|
|
|
|
Example :
|
|
---------
|
|
global
|
|
log 192.168.2.200 local3
|
|
log 127.0.0.1 local4 notice
|
|
|
|
|
|
1.2) limiting the number of connections
|
|
---------------------------------------
|
|
It is possible and recommended to limit the global number of per-process
|
|
connections using the 'maxconn' global keyword. Since one connection includes
|
|
both a client and a server, it means that the max number of TCP sessions will
|
|
be about the double of this number. It's important to understand this when
|
|
trying to find best values for 'ulimit -n' before starting the proxy. To
|
|
anticipate the number of sockets needed, all these parameters must be counted :
|
|
|
|
- 1 socket per incoming connection
|
|
- 1 socket per outgoing connection
|
|
- 1 socket per address/port/proxy tuple.
|
|
- 1 socket per server being health-checked
|
|
- 1 socket for all logs
|
|
|
|
In simple configurations where each proxy only listens one one address/port,
|
|
set the limit of file descriptors (ulimit -n) to
|
|
(2 * maxconn + nbproxies + nbservers + 1). Starting with versions 1.1.32/1.2.6,
|
|
it is now possible to set the limit in the configuration using the 'ulimit-n'
|
|
global keyword, provided the proxy is started as root. This puts an end to the
|
|
recurrent problem of ensuring that the system limits are adapted to the proxy
|
|
values. Note that these limits are per-process.
|
|
|
|
Example :
|
|
---------
|
|
global
|
|
maxconn 32000
|
|
ulimit-n 65536
|
|
|
|
|
|
1.3) Drop of priviledges
|
|
------------------------
|
|
In order to reduce the risk and consequences of attacks, in the event where a
|
|
yet non-identified vulnerability would be successfully exploited, it's possible
|
|
to lower the process priviledges and even isolate it in a riskless directory.
|
|
|
|
In the 'global' section, the 'uid' parameter sets a numerical user identifier
|
|
which the process will switch to after binding its listening sockets. The value
|
|
'0', which normally represents the super-user, here indicates that the UID must
|
|
not change during startup. It's the default behaviour. The 'gid' parameter does
|
|
the same for the group identifier. It's particularly advised against use of
|
|
generic accounts such as 'nobody' because it has the same consequences as using
|
|
'root' if other services use them.
|
|
|
|
The 'chroot' parameter makes the process isolate itself in an empty directory
|
|
just before switching its UID. This type of isolation (chroot) can sometimes
|
|
be worked around on certain OS (Linux, Solaris), provided that the attacker
|
|
has gained 'root' priviledges and has the ability to use or create a directory.
|
|
For this reason, it's capital to use a dedicated directory and not to share one
|
|
between several services of different nature. To make isolation more resistant,
|
|
it's recommended to use an empty directory without any right, and to change the
|
|
UID of the process so that it cannot do anything there.
|
|
|
|
Note: in the event where such a vulnerability would be exploited, it's most
|
|
likely that first attempts would kill the process due to 'Segmentation Fault',
|
|
'Bus Error' or 'Illegal Instruction' signals. Eventhough it's true that
|
|
isolating the server reduces the risks of intrusion, it's sometimes useful to
|
|
find why a process dies, via the analysis of a 'core' file, although very rare
|
|
(the last bug of this sort was fixed in 1.1.9). For security reasons, most
|
|
systems disable the generation of core file when a process changes its UID. So
|
|
the two workarounds are either to start the process from a restricted user
|
|
account, which will not be able to chroot itself, or start it as root and not
|
|
change the UID. In both cases the core will be either in the start or the chroot
|
|
directories. Do not forget to allow core dumps prior to start the process :
|
|
|
|
# ulimit -c unlimited
|
|
|
|
Example :
|
|
---------
|
|
|
|
global
|
|
uid 30000
|
|
gid 30000
|
|
chroot /var/chroot/haproxy
|
|
|
|
|
|
1.4) Startup modes
|
|
------------------
|
|
The service can start in several different :
|
|
- foreground / background
|
|
- quiet / normal / debug
|
|
|
|
The default mode is normal, foreground, which means that the program doesn't
|
|
return once started. NEVER EVER use this mode in a system startup script, or
|
|
the system won't boot. It needs to be started in background, so that it
|
|
returns immediately after forking. That's accomplished by the 'daemon' option
|
|
in the 'global' section, which is the equivalent of the '-D' command line
|
|
argument.
|
|
|
|
Moreover, certain alert messages are still sent to the standard output even
|
|
in 'daemon' mode. To make them disappear, simply add the 'quiet' option in the
|
|
'global' section. This option has no command-line equivalent.
|
|
|
|
Last, the 'debug' mode, enabled with the 'debug' option in the 'global' section,
|
|
and which is equivalent of the '-d' option, allows deep TCP/HTTP analysis, with
|
|
timestamped display of each connection, disconnection, and HTTP headers for both
|
|
ways. This mode is incompatible with 'daemon' and 'quiet' modes for obvious
|
|
reasons.
|
|
|
|
|
|
1.5) Increasing the overall processing power
|
|
--------------------------------------------
|
|
On multi-processor systems, it may seem to be a shame to use only one processor,
|
|
eventhough the load needed to saturate a recent processor is far above common
|
|
usage. Anyway, for very specific needs, the proxy can start several processes
|
|
between which the operating system will spread the incoming connections. The
|
|
number of processes is controlled by the 'nbproc' parameter in the 'global'
|
|
section. It defaults to 1, and obviously works only in 'daemon' mode. One
|
|
typical usage of this parameter has been to workaround the default per-process
|
|
file-descriptor limit that Solaris imposes to user processes.
|
|
|
|
Example :
|
|
---------
|
|
|
|
global
|
|
daemon
|
|
quiet
|
|
nbproc 2
|
|
|
|
|
|
1.6) Helping process management
|
|
-------------------------------
|
|
Haproxy now supports the notion of pidfile. If the '-p' command line argument,
|
|
or the 'pidfile' global option is followed with a file name, this file will be
|
|
removed, then filled with all children's pids, one per line (only in daemon
|
|
mode). This file is NOT within the chroot, which allows to work with a readonly
|
|
chroot. It will be owned by the user starting the process, and will have
|
|
permissions 0644.
|
|
|
|
Example :
|
|
---------
|
|
|
|
global
|
|
daemon
|
|
quiet
|
|
nbproc 2
|
|
pidfile /var/run/haproxy-private.pid
|
|
|
|
# to stop only those processes among others :
|
|
# kill $(</var/run/haproxy-private.pid)
|
|
|
|
|
|
1.7) Polling mechanisms
|
|
-----------------------
|
|
Starting from version 1.2.5, haproxy supports the poll() and epoll() polling
|
|
mechanisms. On systems where select() is limited by FD_SETSIZE (like Solaris),
|
|
poll() can be an interesting alternative. Performance tests show that Solaris'
|
|
poll() performance does not decay as fast as the numbers of sockets increase,
|
|
making it a safe solution for high loads. However, Solaris already uses poll()
|
|
to emulate select(), so as long as the number of sockets has no reason to go
|
|
higher than FD_SETSIZE, poll() should not provide any better performance. On
|
|
Linux systems with the epoll() patch (or any 2.6 version), haproxy will use
|
|
epoll() which is extremely fast and non dependant on the number of sockets.
|
|
Tests have shown constant performance from 1 to 20000 simultaneous sessions.
|
|
|
|
Haproxy will use epoll() when available, and will fall back to poll(), then to
|
|
select(). However, if for any reason you need to disable epoll() or poll() (eg.
|
|
because of a bug or just to compare performance), two new global options have
|
|
been created for this matter : 'noepoll' and 'nopoll'.
|
|
|
|
Example :
|
|
---------
|
|
|
|
global
|
|
# use only select()
|
|
noepoll
|
|
nopoll
|
|
|
|
Note :
|
|
------
|
|
For the sake of configuration file portability, these options are accepted but
|
|
ignored if the poll() or epoll() mechanisms have not been enabled at compile
|
|
time.
|
|
|
|
To make debugging easier, the '-de' runtime argument disables epoll support and
|
|
the '-dp' argument disables poll support. They are respectively equivalent to
|
|
'noepoll' and 'nopoll'.
|
|
|
|
|
|
2) Declaration of a listening service
|
|
=====================================
|
|
|
|
Service sections start with the 'listen' keyword :
|
|
|
|
listen <instance_name> [ <IP_address>:<port_range>[,...] ]
|
|
|
|
- <instance_name> is the name of the instance. This name will be reported in
|
|
logs, so it is good to have it reflect the proxied service. No unicity test
|
|
is done on this name, and it's not mandatory for it to be unique, but highly
|
|
recommended.
|
|
|
|
- <IP_address> is the IP address the proxy binds to. Empty address, '*' and
|
|
'0.0.0.0' all mean that the proxy listens to all valid addresses on the
|
|
system.
|
|
|
|
- <port_range> is either a unique port, or a port range for which the proxy will
|
|
accept connections for the IP address specified above. This range can be :
|
|
- a numerical port (ex: '80')
|
|
- a dash-delimited ports range explicitly stating the lower and upper bounds
|
|
(ex: '2000-2100') which are included in the range.
|
|
|
|
Particular care must be taken against port ranges, because every <addr:port>
|
|
couple consumes one socket (=a file descriptor), so it's easy to eat lots of
|
|
descriptors with a simple range. The <addr:port> couple must be used only once
|
|
among all instances running on a same system. Please note that attaching to
|
|
ports lower than 1024 need particular priviledges to start the program, which
|
|
are independant of the 'uid' parameter.
|
|
|
|
- the <IP_address>:<port_range> couple may be repeated indefinitely to require
|
|
the proxy to listen to other addresses and/or ports. To achieve this, simply
|
|
separate them with a coma.
|
|
|
|
Examples :
|
|
---------
|
|
listen http_proxy :80
|
|
listen x11_proxy 127.0.0.1:6000-6009
|
|
listen smtp_proxy 127.0.0.1:25,127.0.0.1:587
|
|
listen ldap_proxy :389,:663
|
|
|
|
In the event that all addresses do not fit line width, it's preferable to
|
|
detach secondary addresses on other lines with the 'bind' keyword. If this
|
|
keyword is used, it's not even necessary to specify the first address on the
|
|
'listen' line, which sometimes makes multiple configuration handling easier :
|
|
|
|
bind [ <IP_address>:<port_range>[,...] ]
|
|
|
|
Examples :
|
|
----------
|
|
listen http_proxy
|
|
bind :80,:443
|
|
bind 10.0.0.1:10080,10.0.0.1:10443
|
|
|
|
|
|
2.1) Inhibiting a service
|
|
-------------------------
|
|
A service may be disabled for maintenance reasons, without needing to comment
|
|
out the whole section, simply by specifying the 'disabled' keyword in the
|
|
section to be disabled :
|
|
|
|
listen smtp_proxy 0.0.0.0:25
|
|
disabled
|
|
|
|
Note: the 'enabled' keyword allows to enable a service which has been disabled
|
|
previously by a default configuration.
|
|
|
|
|
|
2.2) Modes of operation
|
|
-----------------------
|
|
A service can work in 3 different distinct modes :
|
|
- TCP
|
|
- HTTP
|
|
- monitoring
|
|
|
|
TCP mode
|
|
--------
|
|
In this mode, the service relays TCP connections as soon as they're established,
|
|
towards one or several servers. No processing is done on the stream. It's only
|
|
an association of source(addr:port) -> destination(addr:port). To use this mode,
|
|
you must specify 'mode tcp' in the 'listen' section. This is the default mode.
|
|
|
|
Example :
|
|
---------
|
|
listen smtp_proxy 0.0.0.0:25
|
|
mode tcp
|
|
|
|
HTTP mode
|
|
---------
|
|
In this mode, the service relays TCP connections towards one or several servers,
|
|
when it has enough informations to decide, which normally means that all HTTP
|
|
headers have been read. Some of them may be scanned for a cookie or a pattern
|
|
matching a regex. To use this mode, specify 'mode http' in the 'listen' section.
|
|
|
|
Example :
|
|
---------
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
|
|
Health-checking mode
|
|
--------------------
|
|
This mode provides a way for external components to check the proxy's health.
|
|
It is meant to be used with intelligent load-balancers which can use send/expect
|
|
scripts to check for all of their servers' availability. This one simply accepts
|
|
the connection, returns the word 'OK' and closes it. If the 'option httpchk' is
|
|
set, then the reply will be 'HTTP/1.0 200 OK' with no data, so that it can be
|
|
tested from a tool which supports HTTP health-checks. To enable it, simply
|
|
specify 'health' as the working mode :
|
|
|
|
Example :
|
|
---------
|
|
# simple response : 'OK'
|
|
listen health_check 0.0.0.0:60000
|
|
mode health
|
|
|
|
# HTTP response : 'HTTP/1.0 200 OK'
|
|
listen http_health_check 0.0.0.0:60001
|
|
mode health
|
|
option httpchk
|
|
|
|
Monitoring
|
|
----------
|
|
Versions 1.1.32 and 1.2.6 provide a new solution to check the proxy's
|
|
availability without perturbating the service. The 'monitor-net' keyword was
|
|
created to specify a network of equipments which CANNOT use the service for
|
|
anything but health-checks. This is particularly suited to TCP proxies, because
|
|
it prevents the proxy from relaying the monitor's connection to the remote
|
|
server.
|
|
|
|
When used with TCP, the connection is accepted then closed and nothing is
|
|
logged. This is enough for a front-end load-balancer to detect the service as
|
|
available.
|
|
|
|
When used with HTTP, the connection is accepted, nothing is logged, the
|
|
following response is sent, then the session is closed : "HTTP/1.0 200 OK".
|
|
This is normally enough for any front-end HTTP load-balancer to detect the
|
|
service as available too, both with TCP and HTTP checks.
|
|
|
|
Proxies using the "monitor-net" keyword can remove the "option dontlognull", as
|
|
it will make them log empty connections from hosts outside the monitoring
|
|
network.
|
|
|
|
Example :
|
|
---------
|
|
|
|
listen tse-proxy
|
|
bind :3389,:1494,:5900 # TSE, ICA and VNC at once.
|
|
mode tcp
|
|
balance roundrobin
|
|
server tse-farm 192.168.1.10
|
|
monitor-net 192.168.1.252/31 # L4 load-balancers on .252 and .253
|
|
|
|
|
|
2.3) Limiting the number of simultaneous connections
|
|
----------------------------------------------------
|
|
The 'maxconn' parameter allows a proxy to refuse connections above a certain
|
|
amount of simultaneous ones. When the limit is reached, it simply stops
|
|
listening, but the system may still be accepting them because of the back log
|
|
queue. These connections will be processed later when other ones have freed
|
|
some slots. This provides a serialization effect which helps very fragile
|
|
servers resist to high loads. Se further for system limitations.
|
|
|
|
Example :
|
|
---------
|
|
listen tiny_server 0.0.0.0:80
|
|
maxconn 10
|
|
|
|
|
|
2.4) Soft stop
|
|
--------------
|
|
It is possible to stop services without breaking existing connections by the
|
|
sending of the SIGUSR1 signal to the process. All services are then put into
|
|
soft-stop state, which means that they will refuse to accept new connections,
|
|
except for those which have a non-zero value in the 'grace' parameter, in which
|
|
case they will still accept connections for the specified amount of time, in
|
|
milliseconds. This makes it possible to tell a load-balancer that the service
|
|
is failing, while still doing the job during the time it needs to detect it.
|
|
|
|
Note: active connections are never killed. In the worst case, the user will have
|
|
to wait for all of them to close or to time-out, or simply kill the process
|
|
normally (SIGTERM). The default 'grace' value is '0'.
|
|
|
|
Example :
|
|
---------
|
|
# enter soft stop after 'killall -USR1 haproxy'
|
|
# the service will still run 10 seconds after the signal
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
grace 10000
|
|
|
|
# this port is dedicated to a load-balancer, and must fail immediately
|
|
listen health_check 0.0.0.0:60000
|
|
mode health
|
|
grace 0
|
|
|
|
|
|
As of version 1.2.8, a new soft-reconfiguration mechanism has been introduced.
|
|
It is now possible to "pause" all the proxies by sending a SIGTTOU signal to
|
|
the processes. This will disable the listening socket without breaking existing
|
|
connections. After that, sending a SIGTTIN signal to those processes enables
|
|
the listening sockets again. This is very useful to try to load a new
|
|
configuration or even a new version of haproxy without breaking existing
|
|
connections. If the load succeeds, then simply send a SIGUSR1 which will make
|
|
the previous proxies exit immediately once their sessions are closed ; and if
|
|
the load fails, then simply send a SIGTTIN to restore the service immediately.
|
|
Please note that the 'grace' parameter is ignored for SIGTTOU, as well as for
|
|
SIGUSR1 when the process was in the pause mode. Please also note that it would
|
|
be useful to save the pidfile before starting a new instance.
|
|
|
|
|
|
2.5) Connections expiration time
|
|
--------------------------------
|
|
It is possible (and recommended) to configure several time-outs on TCP
|
|
connections. Three independant timers are adjustable with values specified
|
|
in milliseconds. A session will be terminated if either one of these timers
|
|
expire.
|
|
|
|
- the time we accept to wait for data from the client, or for the client to
|
|
accept data : 'clitimeout' :
|
|
|
|
# client time-out set to 2mn30.
|
|
clitimeout 150000
|
|
|
|
- the time we accept to wait for data from the server, or for the server to
|
|
accept data : 'srvtimeout' :
|
|
|
|
# server time-out set to 30s.
|
|
srvtimeout 30000
|
|
|
|
- the time we accept to wait for a connection to establish on a server :
|
|
'contimeout' :
|
|
|
|
# we give up if the connection does not complete within 4 seconds
|
|
contimeout 4000
|
|
|
|
Notes :
|
|
-------
|
|
- 'contimeout' and 'srvtimeout' have no sense on 'health' mode servers ;
|
|
- under high loads, or with a saturated or defective network, it's possible
|
|
that some packets get lost. Since the first TCP retransmit only happens
|
|
after 3 seconds, a time-out equal to, or lower than 3 seconds cannot
|
|
compensate for a packet loss. A 4 seconds time-out seems a reasonable
|
|
minimum which will considerably reduce connection failures.
|
|
|
|
|
|
2.6) Attempts to reconnect
|
|
--------------------------
|
|
After a connection failure to a server, it is possible to retry, potentially
|
|
on another server. This is useful if health-checks are too rare and you don't
|
|
want the clients to see the failures. The number of attempts to reconnect is
|
|
set by the 'retries' paramter.
|
|
|
|
Example :
|
|
---------
|
|
# we can retry 3 times max after a failure
|
|
retries 3
|
|
|
|
|
|
2.7) Address of the dispatch server (deprecated)
|
|
------------------------------------------------
|
|
The server which will be sent all new connections is defined by the 'dispatch'
|
|
parameter, in the form <address>:<port>. It generally is dedicated to unknown
|
|
connections and will assign them a cookie, in case of HTTP persistence mode,
|
|
or simply is a single server in case of generic TCP proxy. This old mode is only
|
|
provided for backwards compatibility, but doesn't allow to check remote servers
|
|
state, and has a rather limited usage. All new setups should switch to 'balance'
|
|
mode. The principle of the dispatcher is to be able to perform the load
|
|
balancing itself, but work only on new clients so that the server doesn't need
|
|
to be a big machine.
|
|
|
|
Example :
|
|
---------
|
|
# all new connections go there
|
|
dispatch 192.168.1.2:80
|
|
|
|
Note :
|
|
------
|
|
This parameter has no sense for 'health' servers, and is incompatible with
|
|
'balance' mode.
|
|
|
|
|
|
2.8) Outgoing source address
|
|
----------------------------
|
|
It is often necessary to bind to a particular address when connecting to some
|
|
remote hosts. This is done via the 'source' parameter which is a per-proxy
|
|
parameter. A newer version may allow to fix different sources to reach different
|
|
servers. The syntax is 'source <address>[:<port>]', where <address> is a valid
|
|
local address (or '0.0.0.0' or '*' or empty to let the system choose), and
|
|
<port> is an optional parameter allowing the user to force the source port for
|
|
very specific needs. If the port is not specified or is '0', the system will
|
|
choose a free port. Note that as of version 1.1.18, the servers health checks
|
|
are also performed from the same source.
|
|
|
|
Examples :
|
|
----------
|
|
listen http_proxy *:80
|
|
# all connections take 192.168.1.200 as source address
|
|
source 192.168.1.200:0
|
|
|
|
listen rlogin_proxy *:513
|
|
# use address 192.168.1.200 and the reserved port 900 (needs to be root)
|
|
source 192.168.1.200:900
|
|
|
|
|
|
2.9) Setting the cookie name
|
|
----------------------------
|
|
In HTTP mode, it is possible to look for a particular cookie which will contain
|
|
a server identifier which should handle the connection. The cookie name is set
|
|
via the 'cookie' parameter.
|
|
|
|
Example :
|
|
---------
|
|
listen http_proxy :80
|
|
mode http
|
|
cookie SERVERID
|
|
|
|
It is possible to change the cookie behaviour to get a smarter persistence,
|
|
depending on applications. It is notably possible to delete or modify a cookie
|
|
emitted by a server, insert a cookie identifying the server in an HTTP response
|
|
and even add a header to tell upstream caches not to cache this response.
|
|
|
|
Examples :
|
|
----------
|
|
|
|
To remove the cookie for direct accesses (ie when the server matches the one
|
|
which was specified in the client cookie) :
|
|
|
|
cookie SERVERID indirect
|
|
|
|
To replace the cookie value with the one assigned to the server if any (no
|
|
cookie will be created if the server does not provide one, nor if the
|
|
configuration does not provide one). This lets the application put the cookie
|
|
exactly on certain pages (eg: successful authentication) :
|
|
|
|
cookie SERVERID rewrite
|
|
|
|
To create a new cookie and assign the server identifier to it (in this case, all
|
|
servers should be associated with a valid cookie, since no cookie will simply
|
|
delete the cookie from the client's browser) :
|
|
|
|
cookie SERVERID insert
|
|
|
|
To reuse an existing application cookie and prefix it with the server's
|
|
identifier, and remove it in the request, use the 'prefix' option. This allows
|
|
to insert a haproxy in front of an application without risking to break clients
|
|
which does not support more than one cookie :
|
|
|
|
cookie JSESSIONID prefix
|
|
|
|
To insert a cookie and ensure that no upstream cache will store it, add the
|
|
'nocache' option :
|
|
|
|
cookie SERVERID insert nocache
|
|
|
|
To insert a cookie only after a POST request, add 'postonly' after 'insert'.
|
|
This has the advantage that there's no risk of caching, and that all pages
|
|
seen before the POST one can still be cached :
|
|
|
|
cookie SERVERID insert postonly
|
|
|
|
Notes :
|
|
-----------
|
|
- it is possible to combine 'insert' with 'indirect' or 'rewrite' to adapt to
|
|
applications which already generate the cookie with an invalid content.
|
|
|
|
- in the case where 'insert' and 'indirect' are both specified, the cookie is
|
|
never transmitted to the server, since it wouldn't understand it. This is the
|
|
most application-transparent mode.
|
|
|
|
- it is particularly recommended to use 'nocache' in 'insert' mode if any
|
|
upstream HTTP/1.0 cache is susceptible to cache the result, because this may
|
|
lead to many clients going to the same server, or even worse, some clients
|
|
having their server changed while retrieving a page from the cache.
|
|
|
|
- the 'prefix' mode normally does not need 'indirect', 'nocache', nor
|
|
'postonly', because just as in the 'rewrite' mode, it relies on the
|
|
application to know when a cookie can be emitted. However, since it has to
|
|
fix the cookie name in every subsequent requests, you must ensure that the
|
|
proxy will be used without any "HTTP keep-alive". Use option "httpclose" if
|
|
unsure.
|
|
|
|
- when the application is well known and controlled, the best method is to
|
|
only add the persistence cookie on a POST form because it's up to the
|
|
application to select which page it wants the upstream servers to cache. In
|
|
this case, you would use 'insert postonly indirect'.
|
|
|
|
|
|
2.10) Associating a cookie value with a server
|
|
----------------------------------------------
|
|
In HTTP mode, it's possible to associate a cookie value to each server. This
|
|
was initially used in combination with 'dispatch' mode to handle direct accesses
|
|
but it is now the standard way of doing the load balancing. The syntax is :
|
|
|
|
server <identifier> <address>:<port> cookie <value>
|
|
|
|
- <identifier> is any name which can be used to identify the server in the logs.
|
|
- <address>:<port> specifies where the server is bound.
|
|
- <value> is the value to put in or to read from the cookie.
|
|
|
|
Example : the 'SERVERID' cookie can be either 'server01' or 'server02'
|
|
---------
|
|
listen http_proxy :80
|
|
mode http
|
|
cookie SERVERID
|
|
dispatch 192.168.1.100:80
|
|
server web1 192.168.1.1:80 cookie server01
|
|
server web2 192.168.1.2:80 cookie server02
|
|
|
|
Warning : the syntax has changed since version 1.0 !
|
|
---------
|
|
|
|
|
|
2.11) Application Cookies
|
|
-------------------------
|
|
Since 1.2.4 it is possible to catch the cookie that comes from an
|
|
application server in order to apply "application session stickyness".
|
|
The server's response is searched for 'appsession' cookie, the first
|
|
'len' bytes are used for matching and it is stored for a period of
|
|
'timeout'.
|
|
The syntax is:
|
|
|
|
appsession <SESSIONCOOKIE> len <MATCHLENGTH> timeout <HOLDTIME>
|
|
|
|
- <SESSIONCOOKIE> is the cookie, the server uses for it's session-handling
|
|
- <MATCHLENGTH> how many bytes/characters should be used for matching equal
|
|
sessions
|
|
- <HOLDTIME> after this inactivaty time, in ms, the cookie will be deleted
|
|
from the sessionstore
|
|
|
|
The appsession is only per 'listen' section possible.
|
|
|
|
Example :
|
|
---------
|
|
listen http_proxy :80
|
|
mode http
|
|
appsession JSESSIONID len 52 timeout 300000
|
|
.
|
|
.
|
|
|
|
|
|
3) Autonomous load balancer
|
|
===========================
|
|
|
|
The proxy can perform the load-balancing itself, both in TCP and in HTTP modes.
|
|
This is the most interesting mode which obsoletes the old 'dispatch' mode
|
|
described above. It has advantages such as server health monitoring, multiple
|
|
port binding and port mapping. To use this mode, the 'balance' keyword is used,
|
|
followed by the selected algorithm. As of version 1.1.23, only 'roundrobin' is
|
|
available, which is also the default value if unspecified. In this mode, there
|
|
will be no dispatch address, but the proxy needs at least one server.
|
|
|
|
Example : same as the last one, with internal load balancer
|
|
---------
|
|
|
|
listen http_proxy :80
|
|
mode http
|
|
cookie SERVERID
|
|
balance roundrobin
|
|
server web1 192.168.1.1:80 cookie server01
|
|
server web2 192.168.1.2:80 cookie server02
|
|
|
|
|
|
Since version 1.1.22, it is possible to automatically determine on which port
|
|
the server will get the connection, depending on the port the client connected
|
|
to. Indeed, there now are 4 possible combinations for the server's <port> field:
|
|
|
|
- unspecified or '0' :
|
|
the connection will be sent to the same port as the one on which the proxy
|
|
received the client connection itself.
|
|
|
|
- numerical value (the only one supported in versions earlier than 1.1.22) :
|
|
the connection will always be sent to the specified port.
|
|
|
|
- '+' followed by a numerical value :
|
|
the connection will be sent to the same port as the one on which the proxy
|
|
received the connection, plus this value.
|
|
|
|
- '-' followed by a numerical value :
|
|
the connection will be sent to the same port as the one on which the proxy
|
|
received the connection, minus this value.
|
|
|
|
Examples :
|
|
----------
|
|
|
|
# same as previous example
|
|
|
|
listen http_proxy :80
|
|
mode http
|
|
cookie SERVERID
|
|
balance roundrobin
|
|
server web1 192.168.1.1 cookie server01
|
|
server web2 192.168.1.2 cookie server02
|
|
|
|
# simultaneous relaying of ports 80, 81 and 8080-8089
|
|
|
|
listen http_proxy :80,:81,:8080-8089
|
|
mode http
|
|
cookie SERVERID
|
|
balance roundrobin
|
|
server web1 192.168.1.1 cookie server01
|
|
server web2 192.168.1.2 cookie server02
|
|
|
|
# relaying of TCP ports 25, 389 and 663 to ports 1025, 1389 and 1663
|
|
|
|
listen http_proxy :25,:389,:663
|
|
mode tcp
|
|
balance roundrobin
|
|
server srv1 192.168.1.1:+1000
|
|
server srv2 192.168.1.2:+1000
|
|
|
|
|
|
3.1) Server monitoring
|
|
----------------------
|
|
It is possible to check the servers status by trying to establish TCP
|
|
connections or even sending HTTP requests to them. A server which fails to
|
|
reply to health checks as expected will not be used by the load balancing
|
|
algorithms. To enable monitoring, add the 'check' keyword on a server line.
|
|
It is possible to specify the interval between tests (in milliseconds) with
|
|
the 'inter' parameter, the number of failures supported before declaring that
|
|
the server has fallen down with the 'fall' parameter, and the number of valid
|
|
checks needed for the server to fully get up with the 'rise' parameter. Since
|
|
version 1.1.22, it is also possible to send checks to a different port
|
|
(mandatory when none is specified) with the 'port' parameter. The default
|
|
values are the following ones :
|
|
|
|
- inter : 2000
|
|
- rise : 2
|
|
- fall : 3
|
|
- port : default server port
|
|
|
|
The default mode consists in establishing TCP connections only. But in certain
|
|
types of application failures, it is often that the server continues to accept
|
|
connections because the system does it itself while the application is running
|
|
an endless loop, or is completely stuck. So in version 1.1.16 were introduced
|
|
HTTP health checks which only performed simple lightweight requests and analysed
|
|
the response. Now, as of version 1.1.23, it is possible to change the HTTP
|
|
method, the URI, and the HTTP version string (which even allows to send headers
|
|
with a dirty trick). To enable HTTP health-checks, use 'option httpchk'.
|
|
|
|
By default, requests use the 'OPTIONS' method because it's very light and easy
|
|
to filter from logs, and does it on '/'. Only HTTP responses 2xx and 3xx are
|
|
considered valid ones, and only if they come before the time to send a new
|
|
request is reached ('inter' parameter). If some servers block this type of
|
|
request, 3 other forms help to forge a request :
|
|
|
|
- option httpchk -> OPTIONS / HTTP/1.0
|
|
- option httpchk URI -> OPTIONS <URI> HTTP/1.0
|
|
- option httpchk METH URI -> <METH> <URI> HTTP/1.0
|
|
- option httpchk METH URI VER -> <METH> <URI> <VER>
|
|
|
|
See examples below.
|
|
|
|
Since version 1.1.17, it is possible to specify backup servers. These servers
|
|
are only sollicited when no other server is available. This may only be useful
|
|
to serve a maintenance page, or define one active and one backup server (seldom
|
|
used in TCP mode). To make a server a backup one, simply add the 'backup' option
|
|
on its line. These servers also support cookies, so if a cookie is specified for
|
|
a backup server, clients assigned to this server will stick to it even when the
|
|
other ones come back. Conversely, if no cookie is assigned to such a server,
|
|
the clients will get their cookies removed (empty cookie = removal), and will
|
|
be balanced against other servers once they come back. Please note that there
|
|
is no load-balancing among backup servers. If there are several backup servers,
|
|
the second one will only be used when the first one dies, and so on.
|
|
|
|
Since version 1.1.17, it is also possible to visually check the status of all
|
|
servers at once. For this, you just have to send a SIGHUP signal to the proxy.
|
|
The servers status will be dumped into the logs at the 'notice' level, as well
|
|
as on <stderr> if not closed. For this reason, it's always a good idea to have
|
|
one local log server at the 'notice' level.
|
|
|
|
Since version 1.1.28 and 1.2.1, if an instance loses all its servers, an
|
|
emergency message will be sent in the logs to inform the administator that an
|
|
immediate action must be taken.
|
|
|
|
Since version 1.1.30 and 1.2.3, several servers can share the same cookie
|
|
value. This is particularly useful in backup mode, to select alternate paths
|
|
for a given server for example, to provide soft-stop, or to direct the clients
|
|
to a temporary page during an application restart. The principle is that when
|
|
a server is dead, the proxy will first look for another server which shares the
|
|
same cookie value for every client which presents the cookie. If there is no
|
|
standard server for this cookie, it will then look for a backup server which
|
|
shares the same name. Please consult the architecture guide for more information.
|
|
|
|
Examples :
|
|
----------
|
|
# same setup as in paragraph 3) with TCP monitoring
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
cookie SERVERID
|
|
balance roundrobin
|
|
server web1 192.168.1.1:80 cookie server01 check
|
|
server web2 192.168.1.2:80 cookie server02 check inter 500 rise 1 fall 2
|
|
|
|
# same with HTTP monitoring via 'OPTIONS / HTTP/1.0'
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
cookie SERVERID
|
|
balance roundrobin
|
|
option httpchk
|
|
server web1 192.168.1.1:80 cookie server01 check
|
|
server web2 192.168.1.2:80 cookie server02 check inter 500 rise 1 fall 2
|
|
|
|
# same with HTTP monitoring via 'OPTIONS /index.html HTTP/1.0'
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
cookie SERVERID
|
|
balance roundrobin
|
|
option httpchk /index.html
|
|
server web1 192.168.1.1:80 cookie server01 check
|
|
server web2 192.168.1.2:80 cookie server02 check inter 500 rise 1 fall 2
|
|
|
|
# same with HTTP monitoring via 'HEAD /index.jsp? HTTP/1.1\r\nHost: www'
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
cookie SERVERID
|
|
balance roundrobin
|
|
option httpchk HEAD /index.jsp? HTTP/1.1\r\nHost:\ www
|
|
server web1 192.168.1.1:80 cookie server01 check
|
|
server web2 192.168.1.2:80 cookie server02 check inter 500 rise 1 fall 2
|
|
|
|
# Load-balancing with 'prefixed cookie' persistence, and soft-stop using an
|
|
# alternate port 81 on the server for health-checks.
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
cookie JSESSIONID prefix
|
|
balance roundrobin
|
|
option httpchk HEAD /index.jsp? HTTP/1.1\r\nHost:\ www
|
|
server web1-norm 192.168.1.1:80 cookie s1 check port 81
|
|
server web2-norm 192.168.1.2:80 cookie s2 check port 81
|
|
server web1-stop 192.168.1.1:80 cookie s1 check port 80 backup
|
|
server web2-stop 192.168.1.2:80 cookie s2 check port 80 backup
|
|
|
|
# automatic insertion of a cookie in the server's response, and automatic
|
|
# deletion of the cookie in the client request, while asking upstream caches
|
|
# not to cache replies.
|
|
listen web_appl 0.0.0.0:80
|
|
mode http
|
|
cookie SERVERID insert nocache indirect
|
|
balance roundrobin
|
|
server web1 192.168.1.1:80 cookie server01 check
|
|
server web2 192.168.1.2:80 cookie server02 check
|
|
|
|
# same with off-site application backup and local error pages server
|
|
listen web_appl 0.0.0.0:80
|
|
mode http
|
|
cookie SERVERID insert nocache indirect
|
|
balance roundrobin
|
|
server web1 192.168.1.1:80 cookie server01 check
|
|
server web2 192.168.1.2:80 cookie server02 check
|
|
server web-backup 192.168.2.1:80 cookie server03 check backup
|
|
server web-excuse 192.168.3.1:80 check backup
|
|
|
|
# SMTP+TLS relaying with health-checks and backup servers
|
|
|
|
listen http_proxy :25,:587
|
|
mode tcp
|
|
balance roundrobin
|
|
server srv1 192.168.1.1 check port 25 inter 30000 rise 1 fall 2
|
|
server srv2 192.168.1.2 backup
|
|
|
|
|
|
3.2) Redistribute connections in case of failure
|
|
------------------------------------------------
|
|
In HTTP mode, if a server designated by a cookie does not respond, the clients
|
|
may definitely stick to it because they cannot flush the cookie, so they will
|
|
not be able to access the service anymore. Specifying 'redispatch' will allow
|
|
the proxy to break their persistence and redistribute them to working servers.
|
|
|
|
Example :
|
|
---------
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
cookie SERVERID
|
|
dispatch 192.168.1.100:80
|
|
server web1 192.168.1.1:80 cookie server01
|
|
server web2 192.168.1.2:80 cookie server02
|
|
redispatch # send back to dispatch in case of connection failure
|
|
|
|
Up to, and including version 1.1.16, this parameter only applied to connection
|
|
failures. Since version 1.1.17, it also applies to servers which have been
|
|
detected as failed by the health check mechanism. Indeed, a server may be broken
|
|
but still accepting connections, which would not solve every case. But it is
|
|
possible to conserve the old behaviour, that is, make a client insist on trying
|
|
to connect to a server even if it is said to be down, by setting the 'persist'
|
|
option :
|
|
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
option persist
|
|
cookie SERVERID
|
|
dispatch 192.168.1.100:80
|
|
server web1 192.168.1.1:80 cookie server01
|
|
server web2 192.168.1.2:80 cookie server02
|
|
redispatch # send back to dispatch in case of connection failure
|
|
|
|
|
|
4) Additionnal features
|
|
=======================
|
|
|
|
Other features are available. They are transparent mode, event logging and
|
|
header rewriting/filtering.
|
|
|
|
|
|
4.1) Network features
|
|
---------------------
|
|
4.1.1) Transparent mode
|
|
-----------------------
|
|
In HTTP mode, the 'transparent' keyword allows to intercept sessions which are
|
|
routed through the system hosting the proxy. This mode was implemented as a
|
|
replacement for the 'dispatch' mode, since connections without cookie will be
|
|
sent to the original address while known cookies will be sent to the servers.
|
|
This mode implies that the system can redirect sessions to a local port.
|
|
|
|
Example :
|
|
---------
|
|
listen http_proxy 0.0.0.0:65000
|
|
mode http
|
|
transparent
|
|
cookie SERVERID
|
|
server server01 192.168.1.1:80
|
|
server server02 192.168.1.2:80
|
|
|
|
# iptables -t nat -A PREROUTING -i eth0 -p tcp -d 192.168.1.100 \
|
|
--dport 80 -j REDIRECT --to-ports 65000
|
|
|
|
Note :
|
|
------
|
|
If the port is left unspecified on the server, the port the client connected to
|
|
will be used. This allows to relay a full port range without using transparent
|
|
mode nor thousands of file descriptors, provided that the system can redirect
|
|
sessions to local ports.
|
|
|
|
Example :
|
|
---------
|
|
# redirect all ports to local port 65000, then forward to the server on the
|
|
# original port.
|
|
listen http_proxy 0.0.0.0:65000
|
|
mode tcp
|
|
server server01 192.168.1.1 check port 60000
|
|
server server02 192.168.1.2 check port 60000
|
|
|
|
# iptables -t nat -A PREROUTING -i eth0 -p tcp -d 192.168.1.100 \
|
|
-j REDIRECT --to-ports 65000
|
|
|
|
4.1.2) Per-server source address binding
|
|
----------------------------------------
|
|
As of versions 1.1.30 and 1.2.3, it is possible to specify a particular source
|
|
to reach each server. This is useful when reaching backup servers from a
|
|
different LAN, or to use an alternate path to reach the same server. It is also
|
|
usable to provide source load-balancing for outgoing connections. Obviously,
|
|
the same source address is used to send health-checks.
|
|
|
|
Example :
|
|
---------
|
|
# use a particular source to reach both servers
|
|
listen http_proxy 0.0.0.0:65000
|
|
mode http
|
|
balance roundrobin
|
|
server server01 192.168.1.1:80 source 192.168.2.13
|
|
server server02 192.168.1.2:80 source 192.168.2.13
|
|
|
|
Example :
|
|
---------
|
|
# use a particular source to reach each servers
|
|
listen http_proxy 0.0.0.0:65000
|
|
mode http
|
|
balance roundrobin
|
|
server server01 192.168.1.1:80 source 192.168.1.1
|
|
server server02 192.168.2.1:80 source 192.168.2.1
|
|
|
|
Example :
|
|
---------
|
|
# provide source load-balancing to reach the same proxy through 2 WAN links
|
|
listen http_proxy 0.0.0.0:65000
|
|
mode http
|
|
balance roundrobin
|
|
server remote-proxy-way1 192.168.1.1:3128 source 192.168.2.1
|
|
server remote-proxy-way2 192.168.1.1:3128 source 192.168.3.1
|
|
|
|
Example :
|
|
---------
|
|
# force a TCP connection to bind to a specific port
|
|
listen http_proxy 0.0.0.0:2000
|
|
mode tcp
|
|
balance roundrobin
|
|
server srv1 192.168.1.1:80 source 192.168.2.1:20
|
|
server srv2 192.168.1.2:80 source 192.168.2.1:20
|
|
|
|
4.1.3) TCP keep-alive
|
|
---------------------
|
|
With version 1.2.7, it becomes possible to enable TCP keep-alives on both the
|
|
client and server sides. This makes it possible to prevent long sessions from
|
|
expiring on external layer 4 components such as firewalls and load-balancers.
|
|
It also allows the system to terminate dead sessions when no timeout has been
|
|
set (not recommanded). The proxy cannot set the keep-alive probes intervals nor
|
|
maximal count, consult your operating system manual for this. There are 3
|
|
options to enable TCP keep-alive :
|
|
|
|
option tcpka # enables keep-alive both on client and server side
|
|
option clitcpka # enables keep-alive only on client side
|
|
option srvtcpka # enables keep-alive only on server side
|
|
|
|
|
|
4.2) Event logging
|
|
------------------
|
|
|
|
HAProxy's strength certainly lies in its precise logs. It probably provides the
|
|
finest level of information available for such a product, which is very
|
|
important for troubleshooting complex environments. Standard log information
|
|
include client ports, TCP/HTTP state timers, precise session state at
|
|
termination and precise termination cause, information about decisions to
|
|
direct trafic to a server, and of course the ability to capture arbitrary
|
|
headers.
|
|
|
|
In order to improve administrators reactivity, it offers a great transparency
|
|
about encountered problems, both internal and external, and it is possible to
|
|
send logs to different sources at the same time with different level filters :
|
|
|
|
- global process-level logs (system errors, start/stop, etc..)
|
|
- per-listener system and internal errors (lack of resource, bugs, ...)
|
|
- per-listener external troubles (servers up/down, max connections)
|
|
- per-listener activity (client connections), either at the establishment or
|
|
at the termination.
|
|
|
|
The ability to distribute different levels of logs to different log servers
|
|
allow several production teams to interact and to fix their problems as soon
|
|
as possible. For example, the system team might monitor system-wide errors,
|
|
while the application team might be monitoring the up/down for their servers in
|
|
real time, and the security team might analyze the activity logs with one hour
|
|
delay.
|
|
|
|
4.2.1) Log levels
|
|
-----------------
|
|
TCP and HTTP connections can be logged with informations such as date, time,
|
|
source IP address, destination address, connection duration, response times,
|
|
HTTP request, the HTTP return code, number of bytes transmitted, the conditions
|
|
in which the session ended, and even exchanged cookies values, to track a
|
|
particular user's problems for example. All messages are sent to up to two
|
|
syslog servers. Consult section 1.1 for more info about log facilities. The
|
|
syntax follows :
|
|
|
|
log <address_1> <facility_1> [max_level_1]
|
|
log <address_2> <facility_2> [max_level_2]
|
|
or
|
|
log global
|
|
|
|
Note :
|
|
------
|
|
The particular syntax 'log global' means that the same log configuration as the
|
|
'global' section will be used.
|
|
|
|
Example :
|
|
---------
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
log 192.168.2.200 local3
|
|
log 192.168.2.201 local4
|
|
|
|
4.2.2) Log format
|
|
-----------------
|
|
By default, connections are logged at the TCP level, as soon as the session
|
|
establishes between the client and the proxy. By enabling the 'tcplog' option,
|
|
the proxy will wait until the session ends to generate an enhanced log
|
|
containing more information such as session duration and its state during the
|
|
disconnection.
|
|
|
|
Example of TCP logging :
|
|
------------------------
|
|
listen relais-tcp 0.0.0.0:8000
|
|
mode tcp
|
|
option tcplog
|
|
log 192.168.2.200 local3
|
|
|
|
>>> haproxy[18989]: 127.0.0.1:34550 [15/Oct/2003:15:24:28] relais-tcp Srv1 0/5007 0 -- 1/1
|
|
|
|
Field Format Example
|
|
|
|
1 process_name '[' pid ']:' haproxy[18989]:
|
|
2 client_ip ':' client_port 127.0.0.1:34550
|
|
3 '[' date ']' [15/Oct/2003:15:24:28]
|
|
4 listener_name relais-tcp
|
|
5 server_name Srv1
|
|
6 connect_time '/' total_time 0/5007
|
|
7 bytes_read 0
|
|
8 termination_state --
|
|
9 listener_conns '/' process_conns 1/1
|
|
|
|
|
|
Another option, 'httplog', provides more detailed information about HTTP
|
|
contents, such as the request and some cookies. In the event where an external
|
|
component would establish frequent connections to check the service, logs may be
|
|
full of useless lines. So it is possible not to log any session which didn't
|
|
transfer any data, by the setting of the 'dontlognull' option. This only has
|
|
effect on sessions which are established then closed.
|
|
|
|
Example of HTTP logging :
|
|
-------------------------
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
option httplog
|
|
option dontlognull
|
|
log 192.168.2.200 local3
|
|
|
|
>>> haproxy[674]: 127.0.0.1:33319 [15/Oct/2003:08:31:57] relais-http Srv1 9/7/147/723 200 243 - - ---- 3/3 "HEAD / HTTP/1.0"
|
|
|
|
More complete example
|
|
haproxy[18989]: 10.0.0.1:34552 [15/Oct/2003:15:26:31] relais-http Srv1 3183/-1/-1/11215 503 0 - - SC-- 202/205 {w.ods.org|Mozilla} {} "HEAD / HTTP/1.0"
|
|
|
|
Field Format Example
|
|
|
|
1 process_name '[' pid ']:' haproxy[18989]:
|
|
2 client_ip ':' client_port 10.0.0.1:34552
|
|
3 '[' date ']' [15/Oct/2003:15:26:31]
|
|
4 listener_name relais-http
|
|
5 server_name Srv1
|
|
6 Tq '/' Tc '/' Tr '/' Tt 3183/-1/-1/11215
|
|
7 HTTP_return_code 503
|
|
8 bytes_read 0
|
|
9 captured_request_cookie -
|
|
10 captured_response_cookie -
|
|
11 termination_state SC--
|
|
12 listener_conns '/' process_conns 202/205
|
|
13 '{' captured_request_headers '}' {w.ods.org|Mozilla}
|
|
14 '{' captured_response_headers '}' {}
|
|
15 '"' HTTP_request '"' "HEAD / HTTP/1.0"
|
|
|
|
Note for log parsers: the URI is ALWAYS the end of the line starting with the
|
|
first double quote '"'.
|
|
|
|
The problem when logging at end of connection is that you have no clue about
|
|
what is happening during very long sessions. To workaround this problem, a
|
|
new option 'logasap' has been introduced in 1.1.28/1.2.1. When specified, the
|
|
proxy will log as soon as possible, just before data transfer begins. This means
|
|
that in case of TCP, it will still log the connection status to the server, and
|
|
in case of HTTP, it will log just after processing the server headers. In this
|
|
case, the number of bytes reported is the number of header bytes sent to the
|
|
client.
|
|
|
|
In order to avoid confusion with normal logs, the total time field and the
|
|
number of bytes are prefixed with a '+' sign which mean that real numbers are
|
|
certainly bigger.
|
|
|
|
Example :
|
|
---------
|
|
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
option httplog
|
|
option dontlognull
|
|
option logasap
|
|
log 192.168.2.200 local3
|
|
|
|
>>> haproxy[674]: 127.0.0.1:33320 [15/Oct/2003:08:32:17] relais-http Srv1 9/7/14/+30 200 +243 - - ---- 3/3 "GET /image.iso HTTP/1.0"
|
|
|
|
4.2.3) Timing events
|
|
--------------------
|
|
Timers provide a great help in trouble shooting network problems. All values
|
|
are reported in milliseconds (ms). In HTTP mode, four control points are
|
|
reported under the form 'Tq/Tc/Tr/Tt' :
|
|
|
|
- Tq: total time to get the client request.
|
|
It's the time elapsed between the moment the client connection was accepted
|
|
and the moment the proxy received the last HTTP header. The value '-1'
|
|
indicates that the end of headers (empty line) has never been seen.
|
|
|
|
- Tc: total time to establish the TCP connection to the server.
|
|
It's the time elapsed between the moment the proxy sent the connection
|
|
request, and the moment it was acknowledged, or between the TCP SYN packet
|
|
and the matching SYN/ACK in return. The value '-1' means that the
|
|
connection never established.
|
|
|
|
- Tr: server response time. It's the time elapsed between the moment the
|
|
TCP connection was established to the server and the moment it send its
|
|
complete response header. It purely shows its request processing time,
|
|
without the network overhead due to the data transmission. The value '-1'
|
|
means that the last the response header (empty line) was never seen.
|
|
|
|
- Tt: total session duration time, between the moment the proxy accepted it
|
|
and the moment both ends were closed. The exception is when the 'logasap'
|
|
option is specified. In this case, it only equals (Tq+Tc+Tr), and is
|
|
prefixed with a '+' sign. From this field, we can deduce Td, the data
|
|
transmission time, by substracting other timers when valid :
|
|
|
|
Td = Tt - (Tq + Tc + Tr)
|
|
|
|
Timers with '-1' values have to be excluded from this equation.
|
|
|
|
In TCP mode ('option tcplog'), only Tc and Tt are reported.
|
|
|
|
These timers provide precious indications on trouble causes. Since the TCP
|
|
protocol defines retransmit delays of 3, 6, 12... seconds, we know for sure
|
|
that timers close to multiples of 3s are nearly always related to packets lost
|
|
due to network problems (wires or negociation). Moreover, if <Tt> is close to
|
|
a timeout value specified in the configuration, it often means that a session
|
|
has been aborted on time-out.
|
|
|
|
Most common cases :
|
|
|
|
- If Tq is close to 3000, a packet has probably been lost between the client
|
|
and the proxy.
|
|
- If Tc is close to 3000, a packet has probably been lost between the server
|
|
and the proxy during the server connection phase. This one should always be
|
|
very low (less than a few tens).
|
|
- If Tr is nearly always lower than 3000 except some rare values which seem to
|
|
be the average majored by 3000, there are probably some packets lost between
|
|
the proxy and the server.
|
|
- If Tt is often slightly higher than a time-out, it's often because the
|
|
client and the server use HTTP keep-alive and the session is maintained
|
|
after the response ends. Se further for how to disable HTTP keep-alive.
|
|
|
|
Other cases ('xx' means any value to be ignored) :
|
|
-1/xx/xx/Tt : the client was not able to send its complete request in time,
|
|
or that it aborted it too early.
|
|
Tq/-1/xx/Tt : the connection could not establish on the server. Either it
|
|
refused it or it timed out after Tt-Tq ms.
|
|
Tq/Tc/-1/Tt : the server has accepted the connection but did not return a
|
|
complete response in time, or it closed its connexion
|
|
unexpectedly, after Tt-(Tq+Tc) ms.
|
|
|
|
4.2.4) Session state at disconnection
|
|
-------------------------------------
|
|
TCP and HTTP logs provide a session completion indicator in the
|
|
<termination_state> field, just before the number of active
|
|
connections. It is 2-characters long in TCP, and 4-characters long in
|
|
HTTP, each of which has a special meaning :
|
|
|
|
- On the first character, a code reporting the first event which caused the
|
|
session to terminate :
|
|
|
|
C : the TCP session was unexpectedly aborted by the client.
|
|
|
|
S : the TCP session was unexpectedly aborted by the server, or the
|
|
server explicitly refused it.
|
|
|
|
P : the session was prematurely aborted by the proxy, because of a
|
|
connection limit enforcement, because a DENY filter was matched,
|
|
or because of a security check which detected and blocked a
|
|
dangerous error in server response which might have caused
|
|
information leak (eg: cacheable cookie).
|
|
|
|
R : a resource on the proxy has been exhausted (memory, sockets, source
|
|
ports, ...). Usually, this appears during the connection phase, and
|
|
system logs should contain a copy of the precise error.
|
|
|
|
I : an internal error was identified by the proxy during a self-check.
|
|
This should NEVER happen, and you are encouraged to report any log
|
|
containing this, because this is a bug.
|
|
|
|
c : the client-side time-out expired first.
|
|
|
|
s : the server-side time-out expired first.
|
|
|
|
- : normal session completion.
|
|
|
|
- on the second character, the TCP/HTTP session state when it was closed :
|
|
|
|
R : waiting for complete REQUEST from the client (HTTP only). Nothing
|
|
was sent to any server.
|
|
|
|
C : waiting for CONNECTION to establish on the server. The server might
|
|
at most have noticed a connection attempt.
|
|
|
|
H : waiting for, receiving and processing server HEADERS (HTTP only).
|
|
|
|
D : the session was in the DATA phase.
|
|
|
|
L : the proxy was still transmitting LAST data to the client while the
|
|
server had already finished.
|
|
|
|
- : normal session completion after end of data transfer.
|
|
|
|
- the third character tells whether the persistence cookie was provided by
|
|
the client (only in HTTP mode) :
|
|
|
|
N : the client provided NO cookie. This is usually the case on new
|
|
connections.
|
|
|
|
I : the client provided an INVALID cookie matching no known
|
|
server. This might be caused by a recent configuration change,
|
|
mixed cookies between HTTP/HTTPS sites, or an attack.
|
|
|
|
D : the client provided a cookie designating a server which was DOWN,
|
|
so either the 'persist' option was used and the client was sent to
|
|
this server, or it was not set and the client was redispatched to
|
|
another server.
|
|
|
|
V : the client provided a valid cookie, and was sent to the associated
|
|
server.
|
|
|
|
- : does not apply (no cookie set in configuration).
|
|
|
|
- the last character reports what operations were performed on the persistence
|
|
cookie returned by the server (only in HTTP mode) :
|
|
|
|
N : NO cookie was provided by the server, and none was inserted either.
|
|
|
|
I : no cookie was provided by the server, and the proxy INSERTED one.
|
|
|
|
P : a cookie was PROVIDED by the server and transmitted as-is.
|
|
|
|
R : the cookie provided by the server was REWRITTEN by the proxy.
|
|
|
|
D : the cookie provided by the server was DELETED by the proxy.
|
|
|
|
- : does not apply (no cookie set in configuration).
|
|
|
|
The combination of the two first flags give a lot of information about what was
|
|
happening when the session terminated. It can be helpful to detect server
|
|
saturation, network troubles, local system resource starvation, attacks, etc...
|
|
|
|
The most common termination flags combinations are indicated here.
|
|
|
|
Flags Reason
|
|
CR The client aborted before sending a full request. Most probably the
|
|
request was done by hand using a telnet client, and aborted early.
|
|
|
|
cR The client timed out before sending a full request. This is sometimes
|
|
caused by too large TCP MSS values on the client side for PPPoE
|
|
networks which cannot transport full-sized packets, or by clients
|
|
sending requests by hand and not typing fast enough.
|
|
|
|
SC The server explicitly refused the connection (the proxy received a
|
|
TCP RST or an ICMP in return). Under some circumstances, it can
|
|
also be the network stack telling the proxy that the server is
|
|
unreachable (eg: no route, or no ARP response on local network).
|
|
|
|
sC The connection to the server did not complete during contimeout.
|
|
|
|
PC The proxy refused to establish a connection to the server because the
|
|
maxconn limit has been reached. The listener's maxconn parameter may
|
|
be increased in the proxy configuration, as well as the global
|
|
maxconn parameter.
|
|
|
|
RC A local resource has been exhausted (memory, sockets, source ports)
|
|
preventing the connection to the server from establishing. The error
|
|
logs will tell precisely what was missing. Anyway, this can only be
|
|
solved by system tuning.
|
|
|
|
cH The client timed out during a POST request. This is sometimes caused
|
|
by too large TCP MSS values for PPPoE networks which cannot transport
|
|
full-sized packets.
|
|
|
|
SH The server aborted before sending its full headers, or it crashed.
|
|
|
|
sH The server failed to reply during the srvtimeout delay, which
|
|
indicates too long transactions, probably caused by back-end
|
|
saturation. The only solutions are to fix the problem on the
|
|
application or to increase the 'srvtimeout' parameter to support
|
|
longer delays (at the risk of the client giving up anyway).
|
|
|
|
PR The proxy blocked the client's request, either because of an invalid
|
|
HTTP syntax, in which case it returned an HTTP 400 error to the
|
|
client, or because a deny filter matched, in which case it returned
|
|
an HTTP 403 error.
|
|
|
|
PH The proxy blocked the server's response, because it was invalid,
|
|
incomplete, dangerous (cache control), or matched a security filter.
|
|
In any case, an HTTP 502 error is sent to the client.
|
|
|
|
cD The client did not read any data for as long as the clitimeout delay.
|
|
This is often caused by network failures on the client side.
|
|
|
|
CD The client unexpectedly aborted during data transfer. This is either
|
|
caused by a browser crash, or by a keep-alive session between the
|
|
server and the client terminated first by the client.
|
|
|
|
sD The server did nothing during the srvtimeout delay. This is often
|
|
caused by too short timeouts on L4 equipements before the server
|
|
(firewalls, load-balancers, ...).
|
|
|
|
4.2.5) Non-printable characters
|
|
-------------------------------
|
|
As of version 1.1.29, non-printable characters are not sent as-is into log
|
|
files, but are converted to their two-digits hexadecimal representation,
|
|
prefixed by the character '#'. The only characters that can now be logged
|
|
without being escaped are between 32 and 126 (inclusive). Obviously, the
|
|
escape character '#' is also encoded to avoid any ambiguity. It is the same for
|
|
the character '"', as well as '{', '|' and '}' when logging headers.
|
|
|
|
4.2.6) Capturing HTTP headers and cookies
|
|
-----------------------------------------
|
|
Version 1.1.23 brought cookie capture, and 1.1.29 the header capture. All this
|
|
is performed using the 'capture' keyword.
|
|
|
|
Cookie capture makes it easy to track a complete user session. The syntax is :
|
|
|
|
capture cookie <cookie_prefix> len <capture_length>
|
|
|
|
This will enable cookie capture from both requests and responses. This way,
|
|
it's easy to detect when a user switches to a new session for example, because
|
|
the server will reassign it a new cookie.
|
|
|
|
The FIRST cookie whose name starts with <cookie_prefix> will be captured, and
|
|
logged as 'NAME=value', without exceeding <capture_length> characters (64 max).
|
|
When the cookie name is fixed and known, it's preferable to suffix '=' to it to
|
|
ensure that no other cookie will be logged.
|
|
|
|
Examples :
|
|
----------
|
|
# capture the first cookie whose name starts with "ASPSESSION"
|
|
capture cookie ASPSESSION len 32
|
|
|
|
# capture the first cookie whose name is exactly "vgnvisitor"
|
|
capture cookie vgnvisitor= len 32
|
|
|
|
In the logs, the field preceeding the completion indicator contains the cookie
|
|
value as sent by the server, preceeded by the cookie value as sent by the
|
|
client. Each of these field is replaced with '-' when no cookie was seen or
|
|
when the option is disabled.
|
|
|
|
Header captures have a different goal. They are useful to track unique request
|
|
identifiers set by a previous proxy, virtual host names, user-agents, POST
|
|
content-length, referrers, etc. In the response, one can search for information
|
|
about the response length, how the server asked the cache to behave, or an
|
|
object location during a redirection. As for cookie captures, it is both
|
|
possible to include request headers and response headers at the same time. The
|
|
syntax is :
|
|
|
|
capture request header <name> len <max length>
|
|
capture response header <name> len <max length>
|
|
|
|
Note: Header names are not case-sensitive.
|
|
|
|
Examples:
|
|
---------
|
|
# keep the name of the virtual server
|
|
capture request header Host len 20
|
|
# keep the amount of data uploaded during a POST
|
|
capture request header Content-Length len 10
|
|
|
|
# note the expected cache behaviour on the response
|
|
capture response header Cache-Control len 8
|
|
# note the URL location during a redirection
|
|
capture response header Location len 20
|
|
|
|
Non-existant headers are logged as empty strings, and if one header appears more
|
|
than once, only its last occurence will be kept. Request headers are grouped
|
|
within braces '{' and '}' in the same order as they were declared, and delimited
|
|
with a vertical bar '|' without any space. Response headers follow the same
|
|
representation, but are displayed after a space following the request headers
|
|
block. These blocks are displayed just before the HTTP request in the logs.
|
|
|
|
Example :
|
|
|
|
Config:
|
|
|
|
capture request header Host len 20
|
|
capture request header Content-Length len 10
|
|
capture request header Referer len 20
|
|
capture response header Server len 20
|
|
capture response header Content-Length len 10
|
|
capture response header Cache-Control len 8
|
|
capture response header Via len 20
|
|
capture response header Location len 20
|
|
|
|
Log :
|
|
|
|
Aug 9 20:26:09 localhost haproxy[2022]: 127.0.0.1:34014 [09/Aug/2004:20:26:09] relais-http netcache 0/0/162/+162 200 +350 - - ---- {fr.adserver.yahoo.co||http://fr.f416.mail.} {|864|private||} "GET http://fr.adserver.yahoo.com/"
|
|
Aug 9 20:30:46 localhost haproxy[2022]: 127.0.0.1:34020 [09/Aug/2004:20:30:46] relais-http netcache 0/0/182/+182 200 +279 - - ---- {w.ods.org||} {Formilux/0.1.8|3495|||} "GET http://w.ods.org/sytadin.html HTTP/1.1"
|
|
Aug 9 20:30:46 localhost haproxy[2022]: 127.0.0.1:34028 [09/Aug/2004:20:30:46] relais-http netcache 0/2/126/+128 200 +223 - - ---- {www.infotrafic.com||http://w.ods.org/syt} {Apache/2.0.40 (Red H|9068|||} "GET http://www.infotrafic.com/images/live/cartesidf/grandes/idf_ne.png HTTP/1.1"
|
|
|
|
|
|
4.2.7) Examples of logs
|
|
-----------------------
|
|
- haproxy[674]: 127.0.0.1:33319 [15/Oct/2003:08:31:57] relais-http Srv1 6559/7/147/6723 200 243 - - ---- 3/5 "HEAD / HTTP/1.0"
|
|
=> long request (6.5s) entered by hand through 'telnet'. The server replied
|
|
in 147 ms, and the session ended normally ('----')
|
|
|
|
- haproxy[674]: 127.0.0.1:33320 [15/Oct/2003:08:32:17] relais-http Srv1 9/7/14/+30 200 +243 - - ---- 3/3 "GET /image.iso HTTP/1.0"
|
|
=> request for a long data transfer. The 'logasap' option was specified, so
|
|
the log was produced just before transfering data. The server replied in
|
|
14 ms, 243 bytes of headers were sent to the client, and total time from
|
|
accept to first data byte is 30 ms.
|
|
|
|
- haproxy[674]: 127.0.0.1:33320 [15/Oct/2003:08:32:17] relais-http Srv1 9/7/14/30 502 243 - - PH-- 2/3 "GET /cgi-bin/bug.cgi? HTTP/1.0"
|
|
=> the proxy blocked a server response either because of an 'rspdeny' or
|
|
'rspideny' filter, or because it blocked sensible information which risked
|
|
being cached. In this case, the response is replaced with a '502 bad
|
|
gateway'.
|
|
|
|
- haproxy[18113]: 127.0.0.1:34548 [15/Oct/2003:15:18:55] relais-http <NOSRV> -1/-1/-1/8490 -1 0 - - CR-- 2/2 ""
|
|
=> the client never completed its request and aborted itself ('C---') after
|
|
8.5s, while the proxy was waiting for the request headers ('-R--').
|
|
Nothing was sent to the server.
|
|
|
|
- haproxy[18113]: 127.0.0.1:34549 [15/Oct/2003:15:19:06] relais-http <NOSRV> -1/-1/-1/50001 408 0 - - cR-- 2/2 ""
|
|
=> The client never completed its request, which was aborted by the time-out
|
|
('c---') after 50s, while the proxy was waiting for the request headers ('-R--').
|
|
Nothing was sent to the server, but the proxy could send a 408 return code
|
|
to the client.
|
|
|
|
- haproxy[18989]: 127.0.0.1:34550 [15/Oct/2003:15:24:28] relais-tcp Srv1 0/5007 0 cD
|
|
=> This is a 'tcplog' entry. Client-side time-out ('c----') occured after 5s.
|
|
|
|
- haproxy[18989]: 10.0.0.1:34552 [15/Oct/2003:15:26:31] relais-http Srv1 3183/-1/-1/11215 503 0 - - SC-- 202/205 "HEAD / HTTP/1.0"
|
|
=> The request took 3s to complete (probably a network problem), and the
|
|
connection to the server failed ('SC--') after 4 attemps of 2 seconds
|
|
(config says 'retries 3'), then a 503 error code was sent to the client.
|
|
There were 202 connections on this proxy, and 205 on the global process.
|
|
It is possible that the server refused the connection because of too many
|
|
already established.
|
|
|
|
|
|
4.3) HTTP header manipulation
|
|
-----------------------------
|
|
In HTTP mode, it is possible to rewrite, add or delete some of the request and
|
|
response headers based on regular expressions. It is also possible to block a
|
|
request or a response if a particular header matches a regular expression,
|
|
which is enough to stops most elementary protocol attacks, and to protect
|
|
against information leak from the internal network. But there is a limitation
|
|
to this : since haproxy's HTTP engine knows nothing about keep-alive, only
|
|
headers passed during the first request of a TCP session will be seen. All
|
|
subsequent headers will be considered data only and not analyzed. Furthermore,
|
|
haproxy doesn't touch data contents, it stops at the end of headers.
|
|
|
|
The syntax is :
|
|
reqadd <string> to add a header to the request
|
|
reqrep <search> <replace> to modify the request
|
|
reqirep <search> <replace> same, but ignoring the case
|
|
reqdel <search> to delete a header in the request
|
|
reqidel <search> same, but ignoring the case
|
|
reqallow <search> definitely allow a request if a header matches <search>
|
|
reqiallow <search> same, but ignoring the case
|
|
reqdeny <search> denies a request if a header matches <search>
|
|
reqideny <search> same, but ignoring the case
|
|
reqpass <search> ignore a header matching <search>
|
|
reqipass <search> same, but ignoring the case
|
|
|
|
rspadd <string> to add a header to the response
|
|
rsprep <search> <replace> to modify the response
|
|
rspirep <search> <replace> same, but ignoring the case
|
|
rspdel <search> to delete the response
|
|
rspidel <search> same, but ignoring the case
|
|
rspdeny <search> replaces a response with a HTTP 502 if a header matches <search>
|
|
rspideny <search> same, but ignoring the case
|
|
|
|
|
|
<search> is a POSIX regular expression (regex) which supports grouping through
|
|
parenthesis (without the backslash). Spaces and other delimiters must be
|
|
prefixed with a backslash ('\') to avoid confusion with a field delimiter.
|
|
Other characters may be prefixed with a backslash to change their meaning :
|
|
|
|
\t for a tab
|
|
\r for a carriage return (CR)
|
|
\n for a new line (LF)
|
|
\ to mark a space and differentiate it from a delimiter
|
|
\# to mark a sharp and differentiate it from a comment
|
|
\\ to use a backslash in a regex
|
|
\\\\ to use a backslash in the text (*2 for regex, *2 for haproxy)
|
|
\xXX to write the ASCII hex code XX as in the C language
|
|
|
|
|
|
<replace> containst the string to be used to replace the largest portion of text
|
|
matching the regex. It can make use of the special characters above, and can
|
|
reference a substring delimited by parenthesis in the regex, by the group
|
|
numerical order from 1 to 9. In this case, you would write a backslah ('\')
|
|
immediately followed by one digit indicating the group position.
|
|
|
|
<string> represents the string which will systematically be added after the last
|
|
header line. It can also use special characters above.
|
|
|
|
Notes :
|
|
-------
|
|
- the first line is considered as a header, which makes it possible to rewrite
|
|
or filter HTTP requests URIs or response codes.
|
|
- 'reqrep' is the equivalent of 'cliexp' in version 1.0, and 'rsprep' is the
|
|
equivalent of 'srvexp' in 1.0. Those names are still supported but
|
|
deprecated.
|
|
- for performances reasons, the number of characters added to a request or to
|
|
a response is limited to 4096 since version 1.1.5 (it was 256 before). This
|
|
value is easy to modify in the code if needed (#define). If it is too short
|
|
on occasional uses, it is possible to gain some space by removing some
|
|
useless headers before adding new ones.
|
|
- a denied request will generate an "HTTP 403 forbidden" response, while a
|
|
denied response will generate an "HTTP 502 Bad gateway" response.
|
|
|
|
|
|
Examples :
|
|
----------
|
|
###### a few examples ######
|
|
|
|
# rewrite 'online.fr' instead of 'free.fr' for GET and POST requests
|
|
reqrep ^(GET\ .*)(.free.fr)(.*) \1.online.fr\3
|
|
reqrep ^(POST\ .*)(.free.fr)(.*) \1.online.fr\3
|
|
|
|
# force proxy connections to close
|
|
reqirep ^Proxy-Connection:.* Proxy-Connection:\ close
|
|
# rewrite locations
|
|
rspirep ^(Location:\ )([^:]*://[^/]*)(.*) \1\3
|
|
|
|
###### A full configuration being used on production ######
|
|
|
|
# Every header should end with a colon followed by one space.
|
|
reqideny ^[^:\ ]*[\ ]*$
|
|
|
|
# block Apache chunk exploit
|
|
reqideny ^Transfer-Encoding:[\ ]*chunked
|
|
reqideny ^Host:\ apache-
|
|
|
|
# block annoying worms that fill the logs...
|
|
reqideny ^[^:\ ]*\ .*(\.|%2e)(\.|%2e)(%2f|%5c|/|\\\\)
|
|
reqideny ^[^:\ ]*\ ([^\ ]*\ [^\ ]*\ |.*%00)
|
|
reqideny ^[^:\ ]*\ .*<script
|
|
reqideny ^[^:\ ]*\ .*/(root\.exe\?|cmd\.exe\?|default\.ida\?)
|
|
|
|
# allow other syntactically valid requests, and block any other method
|
|
reqipass ^(GET|POST|HEAD|OPTIONS)\ /.*\ HTTP/1\.[01]$
|
|
reqipass ^OPTIONS\ \\*\ HTTP/1\.[01]$
|
|
reqideny ^[^:\ ]*\
|
|
|
|
# force connection:close, thus disabling HTTP keep-alive
|
|
option httpclose
|
|
|
|
# change the server name
|
|
rspidel ^Server:\
|
|
rspadd Server:\ Formilux/0.1.8
|
|
|
|
|
|
Also, the 'forwardfor' option creates an HTTP 'X-Forwarded-For' header which
|
|
contains the client's IP address. This is useful to let the final web server
|
|
know what the client address was (eg for statistics on domains).
|
|
|
|
Last, the 'httpclose' option removes any 'Connection' header both ways, and
|
|
adds a 'Connection: close' header in each direction. This makes it easier to
|
|
disable HTTP keep-alive than the previous 4-rules block..
|
|
|
|
Example :
|
|
---------
|
|
listen http_proxy 0.0.0.0:80
|
|
mode http
|
|
log global
|
|
option httplog
|
|
option dontlognull
|
|
option forwardfor
|
|
option httpclose
|
|
|
|
|
|
4.4) Load balancing with persistence
|
|
------------------------------------
|
|
Combining cookie insertion with internal load balancing allows to transparently
|
|
bring persistence to applications. The principle is quite simple :
|
|
- assign a cookie value to each server
|
|
- enable the load balancing between servers
|
|
- insert a cookie into responses resulting from the balancing algorithm
|
|
(indirect accesses), end ensure that no upstream proxy will cache it.
|
|
- remove the cookie in the request headers so that the application never sees
|
|
it.
|
|
|
|
Example :
|
|
---------
|
|
listen application 0.0.0.0:80
|
|
mode http
|
|
cookie SERVERID insert nocache indirect
|
|
balance roundrobin
|
|
server srv1 192.168.1.1:80 cookie server01 check
|
|
server srv2 192.168.1.2:80 cookie server02 check
|
|
|
|
The other solution brought by versions 1.1.30 and 1.2.3 is to reuse a cookie
|
|
from the server, and prefix the server's name to it. In this case, don't forget
|
|
to force "httpclose" mode so that you can be assured that every subsequent
|
|
request will have its cookie fixed.
|
|
|
|
listen application 0.0.0.0:80
|
|
mode http
|
|
cookie JSESSIONID prefix
|
|
balance roundrobin
|
|
server srv1 192.168.1.1:80 cookie srv1 check
|
|
server srv2 192.168.1.2:80 cookie srv2 check
|
|
option httpclose
|
|
|
|
|
|
4.5) Protection against information leak from the servers
|
|
---------------------------------------------------------
|
|
In versions 1.1.28/1.2.1, a new option 'checkcache' was created. It carefully
|
|
checks 'Cache-control', 'Pragma' and 'Set-cookie' headers in server response
|
|
to check if there's a risk of caching a cookie on a client-side proxy. When this
|
|
option is enabled, the only responses which can be delivered to the client are :
|
|
- all those without 'Set-Cookie' header ;
|
|
- all those with a return code other than 200, 203, 206, 300, 301, 410,
|
|
provided that the server has not set a 'Cache-control: public' header ;
|
|
- all those that come from a POST request, provided that the server has not
|
|
set a 'Cache-Control: public' header ;
|
|
- those with a 'Pragma: no-cache' header
|
|
- those with a 'Cache-control: private' header
|
|
- those with a 'Cache-control: no-store' header
|
|
- those with a 'Cache-control: max-age=0' header
|
|
- those with a 'Cache-control: s-maxage=0' header
|
|
- those with a 'Cache-control: no-cache' header
|
|
- those with a 'Cache-control: no-cache="set-cookie"' header
|
|
- those with a 'Cache-control: no-cache="set-cookie,' header
|
|
(allowing other fields after set-cookie)
|
|
|
|
If a response doesn't respect these requirements, then it will be blocked just
|
|
as if it was from an 'rspdeny' filter, with an "HTTP 502 bad gateway". The
|
|
session state shows "PH--" meaning that the proxy blocked the response during
|
|
headers processing. Additionnaly, an alert will be sent in the logs so that
|
|
admins are told that there's something to be done.
|
|
|
|
|
|
4.6) Customizing errors
|
|
-----------------------
|
|
Some situations can make haproxy return an HTTP error code to the client :
|
|
- invalid or too long request => HTTP 400
|
|
- request not completely sent in time => HTTP 408
|
|
- forbidden request (matches a deny filter) => HTTP 403
|
|
- internal error in haproxy => HTTP 500
|
|
- the server returned an invalid or incomplete response => HTTP 502
|
|
- no server was available to handle the request => HTTP 503
|
|
- the server failed to reply in time => HTTP 504
|
|
|
|
A succint error message taken from the RFC accompanies these return codes.
|
|
But depending on the clients knowledge, it may be better to return custom, user
|
|
friendly, error pages. This is made possible through the use of the 'errorloc'
|
|
command :
|
|
|
|
errorloc <HTTP_code> <location>
|
|
|
|
Instead of generating an HTTP error <HTTP_code> among those above, the proxy
|
|
will return a temporary redirection code (HTTP 302) towards the address
|
|
specified in <location>. This address may be either relative to the site or
|
|
absolute. Since this request will be handled by the client's browser, it's
|
|
mandatory that the returned address be reachable from the outside.
|
|
|
|
Example :
|
|
---------
|
|
listen application 0.0.0.0:80
|
|
errorloc 400 /badrequest.html
|
|
errorloc 403 /forbidden.html
|
|
errorloc 408 /toolong.html
|
|
errorloc 500 http://haproxy.domain.net/bugreport.html
|
|
errorloc 502 http://192.168.114.58/error50x.html
|
|
errorloc 503 http://192.168.114.58/error50x.html
|
|
errorloc 504 http://192.168.114.58/error50x.html
|
|
|
|
Note: RFC2616 says that a client must reuse the same method to fetch the
|
|
Location returned by a 302, which causes problems with the POST method.
|
|
The return code 303 was designed explicitly to force the client to fetch the
|
|
Location URL with the GET method, but there are some browsers pre-dating
|
|
HTTP/1.1 which don't support it. Anyway, most browsers still behave with 302 as
|
|
if it was a 303. In order to allow the user to chose, versions 1.1.31 and 1.2.5
|
|
bring two new keywords to replace 'errorloc' : 'errorloc302' and 'errorloc303'.
|
|
|
|
They are preffered over errorloc (which still does 302). Consider using
|
|
errorloc303 everytime you know that your clients support HTTP 303 responses..
|
|
|
|
|
|
4.7) Modifying default values
|
|
-----------------------------
|
|
Version 1.1.22 introduced the notion of default values, which eliminates the
|
|
pain of often repeating common parameters between many instances, such as
|
|
logs, timeouts, modes, etc...
|
|
|
|
Default values are set in a 'defaults' section. Each of these section clears
|
|
all previously set default parameters, so there may be as many default
|
|
parameters as needed. Only the last one before a 'listen' section will be
|
|
used for this section. The 'defaults' section uses the same syntax as the
|
|
'listen' section, for the supported parameters. The 'defaults' keyword ignores
|
|
everything on its command line, so that fake instance names can be specified
|
|
there for better clarity.
|
|
|
|
In version 1.1.28/1.2.1, only those parameters can be preset in the 'default'
|
|
section :
|
|
- log (the first and second one)
|
|
- mode { tcp, http, health }
|
|
- balance { roundrobin }
|
|
- disabled (to disable every further instances)
|
|
- enabled (to enable every further instances, this is the default)
|
|
- contimeout, clitimeout, srvtimeout, grace, retries, maxconn
|
|
- option { redispatch, transparent, keepalive, forwardfor, logasap, httpclose,
|
|
checkcache, httplog, tcplog, dontlognull, persist, httpchk }
|
|
- redispatch, redisp, transparent, source { addr:port }
|
|
- cookie, capture
|
|
- errorloc
|
|
|
|
As of 1.1.24, it is not possible to put certain parameters in a 'defaults'
|
|
section, mainly regular expressions and server configurations :
|
|
- dispatch, server,
|
|
- req*, rsp*
|
|
|
|
Last, there's no way yet to change a boolean option from its assigned default
|
|
value. So if an 'option' statement is set in a 'defaults' section, the only
|
|
way to flush it is to redefine a new 'defaults' section without this 'option'.
|
|
|
|
Examples :
|
|
----------
|
|
defaults applications TCP
|
|
log global
|
|
mode tcp
|
|
balance roundrobin
|
|
clitimeout 180000
|
|
srvtimeout 180000
|
|
contimeout 4000
|
|
retries 3
|
|
redispatch
|
|
|
|
listen app_tcp1 10.0.0.1:6000-6063
|
|
server srv1 192.168.1.1 check port 6000 inter 10000
|
|
server srv2 192.168.1.2 backup
|
|
|
|
listen app_tcp2 10.0.0.2:6000-6063
|
|
server srv1 192.168.2.1 check port 6000 inter 10000
|
|
server srv2 192.168.2.2 backup
|
|
|
|
defaults applications HTTP
|
|
log global
|
|
mode http
|
|
option httplog
|
|
option forwardfor
|
|
option dontlognull
|
|
balance roundrobin
|
|
clitimeout 20000
|
|
srvtimeout 20000
|
|
contimeout 4000
|
|
retries 3
|
|
|
|
listen app_http1 10.0.0.1:80-81
|
|
cookie SERVERID postonly insert indirect
|
|
capture cookie userid= len 10
|
|
server srv1 192.168.1.1:+8000 cookie srv1 check port 8080 inter 1000
|
|
server srv1 192.168.1.2:+8000 cookie srv2 check port 8080 inter 1000
|
|
|
|
defaults
|
|
# this empty section voids all default parameters
|
|
|
|
=========================
|
|
| System-specific setup |
|
|
=========================
|
|
|
|
Linux 2.4
|
|
=========
|
|
|
|
-- cut here --
|
|
#!/bin/sh
|
|
# set this to about 256/4M (16384 for 256M machine)
|
|
MAXFILES=16384
|
|
echo $MAXFILES > /proc/sys/fs/file-max
|
|
ulimit -n $MAXFILES
|
|
|
|
if [ -e /proc/sys/net/ipv4/ip_conntrack_max ]; then
|
|
echo 65536 > /proc/sys/net/ipv4/ip_conntrack_max
|
|
fi
|
|
|
|
if [ -e /proc/sys/net/ipv4/netfilter/ip_ct_tcp_timeout_fin_wait ]; then
|
|
# 30 seconds for fin, 15 for time wait
|
|
echo 3000 > /proc/sys/net/ipv4/netfilter/ip_ct_tcp_timeout_fin_wait
|
|
echo 1500 > /proc/sys/net/ipv4/netfilter/ip_ct_tcp_timeout_time_wait
|
|
echo 0 > /proc/sys/net/ipv4/netfilter/ip_ct_tcp_log_invalid_scale
|
|
echo 0 > /proc/sys/net/ipv4/netfilter/ip_ct_tcp_log_out_of_window
|
|
fi
|
|
|
|
echo 1024 60999 > /proc/sys/net/ipv4/ip_local_port_range
|
|
echo 30 > /proc/sys/net/ipv4/tcp_fin_timeout
|
|
echo 4096 > /proc/sys/net/ipv4/tcp_max_syn_backlog
|
|
echo 262144 > /proc/sys/net/ipv4/tcp_max_tw_buckets
|
|
echo 262144 > /proc/sys/net/ipv4/tcp_max_orphans
|
|
echo 300 > /proc/sys/net/ipv4/tcp_keepalive_time
|
|
echo 1 > /proc/sys/net/ipv4/tcp_tw_recycle
|
|
echo 0 > /proc/sys/net/ipv4/tcp_timestamps
|
|
echo 0 > /proc/sys/net/ipv4/tcp_ecn
|
|
echo 1 > /proc/sys/net/ipv4/tcp_sack
|
|
echo 0 > /proc/sys/net/ipv4/tcp_dsack
|
|
|
|
# auto-tuned on 2.4
|
|
#echo 262143 > /proc/sys/net/core/rmem_max
|
|
#echo 262143 > /proc/sys/net/core/rmem_default
|
|
|
|
echo 16384 65536 524288 > /proc/sys/net/ipv4/tcp_rmem
|
|
echo 16384 349520 699040 > /proc/sys/net/ipv4/tcp_wmem
|
|
|
|
-- cut here --
|
|
|
|
|
|
FreeBSD
|
|
=======
|
|
|
|
A FreeBSD port of HA-Proxy is now available and maintained, thanks to
|
|
Clement Laforet <sheepkiller@cultdeadsheep.org>.
|
|
|
|
For more information :
|
|
http://www.freebsd.org/cgi/url.cgi?ports/net/haproxy/pkg-descr
|
|
http://www.freebsd.org/cgi/cvsweb.cgi/ports/net/haproxy/
|
|
http://www.freshports.org/net/haproxy
|
|
|
|
|
|
-- end --
|