3.6. How to get HAProxy

HAProxy is an open source project covered by the GPLv2 license, meaning that
everyone is allowed to redistribute it provided that access to the sources is
also provided upon request, especially if any modifications were made.
 
HAProxy evolves as a main development branch called "master" or "mainline", from
which new branches are derived once the code is considered stable. A lot of web
sites run some development branches in production on a voluntarily basis, either
to participate to the project or because they need a bleeding edge feature, and
their feedback is highly valuable to fix bugs and judge the overall quality and
stability of the version being developed.
 
The new branches that are created when the code is stable enough constitute a
stable version and are generally maintained for several years, so that there is
no emergency to migrate to a newer branch even when you're not on the latest.
Once a stable branch is issued, it may only receive bug fixes, and very rarely
minor feature updates when that makes users' life easier. All fixes that go into
a stable branch necessarily come from the master branch. This guarantees that no
fix will be lost after an upgrade. For this reason, if you fix a bug, please
make the patch against the master branch, not the stable branch. You may even
discover it was already fixed. This process also ensures that regressions in a
stable branch are extremely rare, so there is never any excuse for not upgrading
to the latest version in your current branch.
 
Branches are numbered with two digits delimited with a dot, such as "1.6". A
complete version includes one or two sub-version numbers indicating the level of
fix. For example, version 1.5.14 is the 14th fix release in branch 1.5 after
version 1.5.0 was issued. It contains 126 fixes for individual bugs, 24 updates
on the documentation, and 75 other backported patches, most of which were needed
to fix the aforementioned 126 bugs. An existing feature may never be modified
nor removed in a stable branch, in order to guarantee that upgrades within the
same branch will always be harmless.
 
HAProxy is available from multiple sources, at different release rhythms :
 
  - The official community web site : http://www.haproxy.org/ : this site
    provides the sources of the latest development release, all stable releases,
    as well as nightly snapshots for each branch. The release cycle is not fast,
    several months between stable releases, or between development snapshots.
    Very old versions are still supported there. Everything is provided as
    sources only, so whatever comes from there needs to be rebuilt and/or
    repackaged;
 
  - A number of operating systems such as Linux distributions and BSD ports.
    These systems generally provide long-term maintained versions which do not
    always contain all the fixes from the official ones, but which at least
    contain the critical fixes. It often is a good option for most users who do
    not seek advanced configurations and just want to keep updates easy;
 
  - Commercial versions from http://www.haproxy.com/ : these are supported
    professional packages built for various operating systems or provided as
    appliances, based on the latest stable versions and including a number of
    features backported from the next release for which there is a strong
    demand. It is the best option for users seeking the latest features with
    the reliability of a stable branch, the fastest response time to fix bugs,
    or simply support contracts on top of an open source product;
 
 
In order to ensure that the version you're using is the latest one in your
branch, you need to proceed this way :
 
  - verify which HAProxy executable you're running : some systems ship it by
    default and administrators install their versions somewhere else on the
    system, so it is important to verify in the startup scripts which one is
    used;
 
  - determine which source your HAProxy version comes from. For this, it's
    generally sufficient to type "haproxy -v". A development version will
    appear like this, with the "dev" word after the branch number :
 
      HA-Proxy version 1.6-dev3-385ecc-68 2015/08/18
 
    A stable version will appear like this, as well as unmodified stable
    versions provided by operating system vendors :
 
      HA-Proxy version 1.5.14 2015/07/02
 
    And a nightly snapshot of a stable version will appear like this with an
    hexadecimal sequence after the version, and with the date of the snapshot
    instead of the date of the release :
 
      HA-Proxy version 1.5.14-e4766ba 2015/07/29
 
    Any other format may indicate a system-specific package with its own
    patch set. For example HAProxy Enterprise versions will appear with the
    following format (<branch>-<latest commit>-<revision>) :
 
      HA-Proxy version 1.5.0-994126-357 2015/07/02
 
  - for system-specific packages, you have to check with your vendor's package
    repository or update system to ensure that your system is still supported,
    and that fixes are still provided for your branch. For community versions
    coming from haproxy.org, just visit the site, verify the status of your
    branch and compare the latest version with yours to see if you're on the
    latest one. If not you can upgrade. If your branch is not maintained
    anymore, you're definitely very late and will have to consider an upgrade
    to a more recent branch (carefully read the README when doing so).
 
HAProxy will have to be updated according to the source it came from. Usually it
follows the system vendor's way of upgrading a package. If it was taken from
sources, please read the README file in the sources directory after extracting
the sources and follow the instructions for your operating system.