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                             HAProxy how-to
                               version 1.7
                             willy tarreau

1) How to build it

This is a development version, so it is expected to break from time to time,
to add and remove features without prior notification and it should not be used
in production. If you are not used to build from sources or if you are not used
to follow updates then it is recommended that instead you use the packages provided
by your software vendor or Linux distribution. Most of them are taking this task
seriously and are doing a good job at backporting important fixes. If for any
reason you'd prefer a different version than the one packaged for your system,
you want to be certain to have all the fixes or to get some commercial support,
other choices are available at :


To build haproxy, you will need :
  - GNU make. Neither Solaris nor OpenBSD's make work with the GNU Makefile.
    If you get many syntax errors when running "make", you may want to retry
    with "gmake" which is the name commonly used for GNU make on BSD systems.
  - GCC between 2.95 and 4.8. Others may work, but not tested.
  - GNU ld

Also, you might want to build with libpcre support, which will provide a very
efficient regex implementation and will also fix some badness on Solaris' one.

To build haproxy, you have to choose your target OS amongst the following ones
and assign it to the TARGET variable :

  - linux22     for Linux 2.2
  - linux24     for Linux 2.4 and above (default)
  - linux24e    for Linux 2.4 with support for a working epoll (> 0.21)
  - linux26     for Linux 2.6 and above
  - linux2628   for Linux 2.6.28, 3.x, and above (enables splice and tproxy)
  - solaris     for Solaris 8 or 10 (others untested)
  - freebsd     for FreeBSD 5 to 10 (others untested)
  - netbsd      for NetBSD
  - osx         for Mac OS/X
  - openbsd     for OpenBSD 3.1 and above
  - aix51       for AIX 5.1
  - aix52       for AIX 5.2
  - cygwin      for Cygwin
  - haiku       for Haiku
  - generic     for any other OS or version.
  - custom      to manually adjust every setting

You may also choose your CPU to benefit from some optimizations. This is
particularly important on UltraSparc machines. For this, you can assign
one of the following choices to the CPU variable :

  - i686 for intel PentiumPro, Pentium 2 and above, AMD Athlon
  - i586 for intel Pentium, AMD K6, VIA C3.
  - ultrasparc : Sun UltraSparc I/II/III/IV processor
  - native : use the build machine's specific processor optimizations. Use with
    extreme care, and never in virtualized environments (known to break).
  - generic : any other processor or no CPU-specific optimization. (default)

Alternatively, you may just set the CPU_CFLAGS value to the optimal GCC options
for your platform.

You may want to build specific target binaries which do not match your native
compiler's target. This is particularly true on 64-bit systems when you want
to build a 32-bit binary. Use the ARCH variable for this purpose. Right now
it only knows about a few x86 variants (i386,i486,i586,i686,x86_64), two
generic ones (32,64) and sets -m32/-m64 as well as -march=<arch> accordingly.

If your system supports PCRE (Perl Compatible Regular Expressions), then you
really should build with libpcre which is between 2 and 10 times faster than
other libc implementations. Regex are used for header processing (deletion,
rewriting, allow, deny). The only inconvenient of libpcre is that it is not
yet widely spread, so if you build for other systems, you might get into
trouble if they don't have the dynamic library. In this situation, you should
statically link libpcre into haproxy so that it will not be necessary to
install it on target systems. Available build options for PCRE are :

  - USE_PCRE=1 to use libpcre, in whatever form is available on your system
    (shared or static)

  - USE_STATIC_PCRE=1 to use a static version of libpcre even if the dynamic
    one is available. This will enhance portability.

  - with no option, use your OS libc's standard regex implementation (default).
    Warning! group references on Solaris seem broken. Use static-pcre whenever

If your system doesn't provide PCRE, you are encouraged to download it from and build it yourself, it's fast and easy.

Recent systems can resolve IPv6 host names using getaddrinfo(). This primitive
is not present in all libcs and does not work in all of them either. Support in
glibc was broken before 2.3. Some embedded libs may not properly work either,
thus, support is disabled by default, meaning that some host names which only
resolve as IPv6 addresses will not resolve and configs might emit an error
during parsing. If you know that your OS libc has reliable support for
getaddrinfo(), you can add USE_GETADDRINFO=1 on the make command line to enable
it. This is the recommended option for most Linux distro packagers since it's
working fine on all recent mainstream distros. It is automatically enabled on
Solaris 8 and above, as it's known to work.

It is possible to add native support for SSL using the GNU makefile, by passing
"USE_OPENSSL=1" on the make command line. The libssl and libcrypto will
automatically be linked with haproxy. Some systems also require libz, so if the
build fails due to missing symbols such as deflateInit(), then try again with

Your are strongly encouraged to always use an up-to-date version of OpenSSL, as
found on as vulnerabilities are occasionally found and
you don't want them on your systems. HAProxy is known to build correctly on all
currently supported branches (0.9.8, 1.0.0, 1.0.1 and 1.0.2 at the time of
writing). Branch 1.0.2 is recommended for the richest features.

To link OpenSSL statically against haproxy, build OpenSSL with the no-shared
keyword and install it to a local directory, so your system is not affected :

    $ export STATICLIBSSL=/tmp/staticlibssl
    $ ./config --prefix=$STATICLIBSSL no-shared
    $ make && make install_sw

When building haproxy, pass that path via SSL_INC and SSL_LIB to make and
include additional libs with ADDLIB if needed (in this case for example libdl):


It is also possible to include native support for zlib to benefit from HTTP
compression. For this, pass "USE_ZLIB=1" on the "make" command line and ensure
that zlib is present on the system. Alternatively it is possible to use libslz
for a faster, memory less, but slightly less efficient compression, by passing

Zlib is commonly found on most systems, otherwise updates can be retrieved from It is easy and fast to build. Libslz can be downloaded
from and is even easier to build.

By default, the DEBUG variable is set to '-g' to enable debug symbols. It is
not wise to disable it on uncommon systems, because it's often the only way to
get a complete core when you need one. Otherwise, you can set DEBUG to '-s' to
strip the binary.

For example, I use this to build for Solaris 8 :

    $ make TARGET=solaris CPU=ultrasparc USE_STATIC_PCRE=1

And I build it this way on OpenBSD or FreeBSD :

    $ gmake TARGET=freebsd USE_PCRE=1 USE_OPENSSL=1 USE_ZLIB=1

And on a classic Linux with SSL and ZLIB support (eg: Red Hat 5.x) :

    $ make TARGET=linux26 USE_PCRE=1 USE_OPENSSL=1 USE_ZLIB=1

And on a recent Linux >= 2.6.28 with SSL and ZLIB support :

    $ make TARGET=linux2628 USE_PCRE=1 USE_OPENSSL=1 USE_ZLIB=1

In order to build a 32-bit binary on an x86_64 Linux system with SSL support
without support for compression but when OpenSSL requires ZLIB anyway :

    $ make TARGET=linux26 ARCH=i386 USE_OPENSSL=1 ADDLIB=-lz

The SSL stack supports session cache synchronization between all running
processes. This involves some atomic operations and synchronization operations
which come in multiple flavors depending on the system and architecture :

  Atomic operations :
    - internal assembler versions for x86/x86_64 architectures

    - gcc builtins for other architectures. Some architectures might not
      be fully supported or might require a more recent version of gcc.
      If your architecture is not supported, you willy have to either use
      pthread if supported, or to disable the shared cache.

    - pthread (posix threads). Pthreads are very common but inter-process
      support is not that common, and some older operating systems did not
      report an error when enabling multi-process mode, so they used to
      silently fail, possibly causing crashes. Linux's implementation is
      fine. OpenBSD doesn't support them and doesn't build. FreeBSD 9 builds
      and reports an error at runtime, while certain older versions might
      silently fail. Pthreads are enabled using USE_PTHREAD_PSHARED=1.

  Synchronization operations :
    - internal spinlock : this mode is OS-independant, light but will not
      scale well to many processes. However, accesses to the session cache
      are rare enough that this mode could certainly always be used. This
      is the default mode.

    - Futexes, which are Linux-specific highly scalable light weight mutexes
      implemented in user-space with some limited assistance from the kernel.
      This is the default on Linux 2.6 and above and is enabled by passing

    - pthread (posix threads). See above.

If none of these mechanisms is supported by your platform, you may need to
build with USE_PRIVATE_CACHE=1 to totally disable SSL cache sharing. Then
it is better not to run SSL on multiple processes.

If you need to pass other defines, includes, libraries, etc... then please
check the Makefile to see which ones will be available in your case, and
use the USE_* variables in the Makefile.

AIX 5.3 is known to work with the generic target. However, for the binary to
also run on 5.2 or earlier, you need to build with DEFINE="-D_MSGQSUPPORT",
otherwise __fd_select() will be used while not being present in the libc, but
this is easily addressed using the "aix52" target. If you get build errors
because of strange symbols or section mismatches, simply remove -g from

You can easily define your own target with the GNU Makefile. Unknown targets
are processed with no default option except USE_POLL=default. So you can very
well use that property to define your own set of options. USE_POLL can even be
disabled by setting USE_POLL="". For example :

    $ gmake TARGET=tiny USE_POLL="" TARGET_CFLAGS=-fomit-frame-pointer

1.1) DeviceAtlas Device Detection

In order to add DeviceAtlas Device Detection support, you would need to download
the API source code from and
once extracted :

    $ make TARGET=<target> USE_PCRE=1 USE_DEVICEATLAS=1 DEVICEATLAS_SRC=<path to the API root folder>

Optionally DEVICEATLAS_INC and DEVICEATLAS_LIB may be set to override the path
to the include files and libraries respectively if they're not in the source

These are supported DeviceAtlas directives (see doc/configuration.txt) :
  - deviceatlas-json-file <path to the DeviceAtlas JSON data file>.
  - deviceatlas-log-level <number> (0 to 3, level of information returned by
    the API, 0 by default).
  - deviceatlas-property-separator <character> (character used to separate the
    properties produced by the API, | by default).

Sample configuration :

	deviceatlas-json-file <path to json file>

	bind *:8881
	default_backend servers

There are two distinct methods available, one which leverages all HTTP headers
and one which uses only a single HTTP header for the detection. The former
method is highly recommended and more accurate. There are several possible use

# To transmit the DeviceAtlas data downstream to the target application

All HTTP headers via the sample / fetch

    http-request set-header X-DeviceAtlas-Data %[da-csv-fetch(primaryHardwareType,osName,osVersion,browserName,browserVersion,browserRenderingEngine)]

Single HTTP header (e.g. User-Agent) via the convertor

    http-request set-header X-DeviceAtlas-Data %[req.fhdr(User-Agent),da-csv-conv(primaryHardwareType,osName,osVersion,browserName,browserVersion,browserRenderingEngine)]

# Mobile content switching with ACL

All HTTP headers

    acl is_mobile da-csv-fetch(mobileDevice) 1

Single HTTP header

    acl device_type_tablet req.fhdr(User-Agent),da-csv-conv(primaryHardwareType) "Tablet"

Please find more information about DeviceAtlas and the detection methods at .

1.2) 51Degrees Device Detection

You can also include 51Degrees for inbuilt device detection enabling attributes
such as screen size (physical & pixels), supported input methods, release date,
hardware vendor and model, browser information, and device price among many
others. Such information can be used to improve the user experience of a web
site by tailoring the page content, layout and business processes to the
precise characteristics of the device. Such customisations improve profit by
making it easier for customers to get to the information or services they
need. Attributes of the device making a web request can be added to HTTP
headers as configurable parameters.

In order to enable 51Degrees download the 51Degrees source code from the
official github repository :

    git clone

then run 'make' with USE_51DEGREES and 51DEGREES_SRC set. Both 51DEGREES_INC
and 51DEGREES_LIB may additionally be used to force specific different paths
for .o and .h, but will default to 51DEGREES_SRC. Make sure to replace
'51D_REPO_PATH' with the path to the 51Degrees repository.

51Degrees provide 2 different detection algorithms:

    1. Pattern - balances main memory usage and CPU.
    2. Trie - a very high performance detection solution which uses more main
       memory than Pattern.

To make with 51Degrees Pattern algorithm use the following command line.

    $ make TARGET=<target> USE_51DEGREES=1 51DEGREES_SRC='51D_REPO_PATH'/src/pattern

To use the 51Degrees Trie algorithm use the following command line.

    $ make TARGET=<target> USE_51DEGREES=1 51DEGREES_SRC='51D_REPO_PATH'/src/trie

A data file containing information about devices, browsers, operating systems
and their associated signatures is then needed. 51Degrees provide a free
database with Github repo for this purpose. These free data files are located
in '51D_REPO_PATH'/data with the extensions .dat for Pattern data and .trie for
Trie data.

The configuration file needs to set the following parameters:

        51degrees-data-file           path to the Pattern or Trie data file
        51degrees-property-name-list  list of 51Degrees properties to detect
        51degrees-property-separator  separator to use between values
        51degrees-cache-size          LRU-based cache size (disabled by default)

The following is an example of the settings for Pattern.

        51degrees-data-file '51D_REPO_PATH'/data/51Degrees-LiteV3.2.dat
        51degrees-property-name-list IsTablet DeviceType IsMobile
        51degrees-property-separator ,
        51degrees-cache-size 10000

HAProxy needs a way to pass device information to the backend servers. This is
done by using the 51d converter or fetch method, which intercepts the HTTP
headers and creates some new headers. This is controlled in the frontend
http-in section.

The following is an example which adds two new HTTP headers prefixed X-51D-

    frontend http-in
        bind *:8081
        default_backend servers
        http-request set-header X-51D-DeviceTypeMobileTablet %[51d.all(DeviceType,IsMobile,IsTablet)]
        http-request set-header X-51D-Tablet %[51d.all(IsTablet)]

Here, two headers are created with 51Degrees data, X-51D-DeviceTypeMobileTablet
and X-51D-Tablet. Any number of headers can be created this way and can be
named anything. 51d.all( ) invokes the 51degrees fetch. It can be passed up to
five property names of values to return. Values will be returned in the same
order, seperated by the 51-degrees-property-separator configured earlier. If a
property name can't be found the value 'NoData' is returned instead.

In addition to the device properties three additional properties related to the
validity of the result can be returned when used with the Pattern method. The
following example shows how Method, Difference and Rank could be included as one
new HTTP header X-51D-Stats.

    frontend http-in
        http-request set-header X-51D-Stats %[51d.all(Method,Difference,Rank)]

These values indicate how confident 51Degrees is in the result that that was
returned. More information is available on the 51Degrees web site at:

The above 51d.all fetch method uses all available HTTP headers for detection. A
modest performance improvement can be obtained by only passing one HTTP header
to the detection method with the 51d.single converter. The following example
uses the User-Agent HTTP header only for detection.

    frontend http-in
        http-request set-header X-51D-DeviceTypeMobileTablet %[req.fhdr(User-Agent),51d.single(DeviceType,IsMobile,IsTablet)]

Any HTTP header could be used inplace of User-Agent by changing the parameter
provided to req.fhdr.

When compiled to use the Trie detection method the trie format data file needs
to be provided. Changing the extension of the data file from dat to trie will
use the correct data.

        51degrees-data-file '51D_REPO_PATH'/data/51Degrees-LiteV3.2.trie

When used with Trie the Method, Difference and Rank properties are not

The free Lite data file contains information about screen size in pixels and
whether the device is a mobile. A full list of available properties is located
on the 51Degrees web site at:

Some properties are only available in the paid for Premium and Enterprise
versions of 51Degrees. These data sets not only contain more properties but
are updated weekly and daily and contain signatures for 100,000s of different
device combinations. For more information see the data options comparison web

2) How to install it

To install haproxy, you can either copy the single resulting binary to the
place you want, or run :

    $ sudo make install

If you're packaging it for another system, you can specify its root directory
in the usual DESTDIR variable.

3) How to set it up

There is some documentation in the doc/ directory :

    - intro.txt : this is an introduction to haproxy, it explains what it is
      what it is not. Useful for beginners or to re-discover it when planning
      for an upgrade.

    - architecture.txt : this is the architecture manual. It is quite old and
      does not tell about the nice new features, but it's still a good starting
      point when you know what you want but don't know how to do it.

    - configuration.txt : this is the configuration manual. It recalls a few
      essential HTTP basic concepts, and details all the configuration file
      syntax (keywords, units). It also describes the log and stats format. It
      is normally always up to date. If you see that something is missing from
      it, please report it as this is a bug. Please note that this file is
      huge and that it's generally more convenient to review Cyril Bonté's
      HTML translation online here :


    - management.txt : it explains how to start haproxy, how to manage it at
      runtime, how to manage it on multiple nodes, how to proceed with seamless

    - gpl.txt / lgpl.txt : the copy of the licenses covering the software. See
      the 'LICENSE' file at the top for more information.

    - the rest is mainly for developers.

There are also a number of nice configuration examples in the "examples"
directory as well as on several sites and articles on the net which are linked
to from the haproxy web site.

4) How to report a bug

It is possible that from time to time you'll find a bug. A bug is a case where
what you see is not what is documented. Otherwise it can be a misdesign. If you
find that something is stupidly design, please discuss it on the list (see the
"how to contribute" section below). If you feel like you're proceeding right
and haproxy doesn't obey, then first ask yourself if it is possible that nobody
before you has even encountered this issue. If it's unlikely, the you probably
have an issue in your setup. Just in case of doubt, please consult the mailing
list archives :


Otherwise, please try to gather the maximum amount of information to help
reproduce the issue and send that to the mailing list :


Please include your configuration and logs. You can mask your IP addresses and
passwords, we don't need them. But it's essential that you post your config if
you want people to guess what is happening.

Also, keep in mind that haproxy is designed to NEVER CRASH. If you see it die
without any reason, then it definitely is a critical bug that must be reported
and urgently fixed. It has happened a couple of times in the past, essentially
on development versions running on new architectures. If you think your setup
is fairly common, then it is possible that the issue is totally unrelated.
Anyway, if that happens, feel free to contact me directly, as I will give you
instructions on how to collect a usable core file, and will probably ask for
other captures that you'll not want to share with the list.

5) How to contribute

Please carefully read the CONTRIBUTING file that comes with the sources. It is

-- end