
BuildBot: build/test automation
  http://buildbot.net
  Brian Warner <warner-buildbot @ lothar . com>


Abstract:

The BuildBot is a system to automate the compile/test cycle required by most
software projects to validate code changes. By automatically rebuilding and
testing the tree each time something has changed, build problems are
pinpointed quickly, before other developers are inconvenienced by the
failure. The guilty developer can be identified and harassed without human
intervention. By running the builds on a variety of platforms, developers
who do not have the facilities to test their changes everywhere before
checkin will at least know shortly afterwards whether they have broken the
build or not. Warning counts, lint checks, image size, compile time, and
other build parameters can be tracked over time, are more visible, and
are therefore easier to improve.

The overall goal is to reduce tree breakage and provide a platform to run
tests or code-quality checks that are too annoying or pedantic for any human
to waste their time with. Developers get immediate (and potentially public)
feedback about their changes, encouraging them to be more careful about
testing before checkin.


Features:

 * run builds on a variety of slave platforms
 * arbitrary build process: handles projects using C, Python, whatever
 * minimal host requirements: python and Twisted
 * slaves can be behind a firewall if they can still do checkout
 * status delivery through web page, email, IRC, other protocols
 * track builds in progress, provide estimated completion time
 * flexible configuration by subclassing generic build process classes
 * debug tools to force a new build, submit fake Changes, query slave status
 * released under the GPL


DOCUMENTATION:

The PyCon paper has a good description of the overall architecture. It is
available in HTML form in docs/PyCon-2003/buildbot.html, or on the web page.

The User's Manual is in docs/buildbot.info, and the Installation chapter is
the best guide to use for setup instructions. The .texinfo source can also be
turned into printed documentation. An HTML representation is available on the
Buildbot home page.

REQUIREMENTS:

 Python: http://www.python.org

   Buildbot requires python-2.3 or later, and is primarily developed against
   python-2.4 . It is also tested against python-2.5 .

 Twisted: http://twistedmatrix.com

   Both the buildmaster and the buildslaves require Twisted-2.0.x or later.
   As always, the most recent version is recommended. It has been tested
   against Twisted-2.5.0 and Twisted SVN as of the date of release.

   Twisted is delivered as a collection of subpackages. You'll need at least
   "Twisted" (the core package), and you'll also want TwistedMail,
   TwistedWeb, and TwistedWords (for sending email, serving a web status
   page, and delivering build status via IRC, respectively). You might also
   want TwistedConch (for the encrypted Manhole debug port). Note that
   Twisted requires ZopeInterface to be installed as well.

INSTALLATION:

Please read the User's Manual in docs/buildbot.info or docs/buildbot.html for
complete instructions. This file only contains a brief summary.

 RUNNING THE UNIT TESTS

If you would like to run the unit test suite, use a command like this:

 PYTHONPATH=. trial buildbot.test

This should run up to 221 tests, depending upon what VC tools you have
installed. On my desktop machine it takes about six minutes to complete.
Nothing should fail (at least under unix), a few might be skipped. If any of
the tests fail, you should stop and investigate the cause before continuing
the installation process, as it will probably be easier to track down the bug
early. There are a few known failures under windows and OS-X, but please
report these to the mailing list so we can isolate and resolve them.

Neither CVS nor SVN support file based repositories on network filesystem
(or network drives in Windows parlance). Therefore it is recommended to run
all unit tests on local hard disks.

 INSTALLING THE LIBRARIES:

The first step is to install the python libraries. This package uses the
standard 'distutils' module, so installing them is usually a matter of
doing something like:

 python ./setup.py install

To test this, shift to a different directory (like /tmp), and run:

 buildbot --version

If it announces the versions of Buildbot and Twisted, the install went ok.


 SETTING UP A BUILD SLAVE:

If you want to run a build slave, you need to obtain the following pieces of
information from the administrator of the buildmaster you intend to connect
to:

 your buildslave's name
 the password assigned to your buildslave
 the hostname and port number of the buildmaster, i.e. example.com:8007
 
You also need to pick a working directory for the buildslave. All commands
will be run inside this directory.

Now run the 'buildbot' command as follows:

 buildbot create-slave WORKDIR MASTERHOST:PORT SLAVENAME PASSWORD

This will create a file called "buildbot.tac", which bundles up all the state
needed by the build slave application. Twisted has a tool called "twistd"
which knows how to load these saved applications and start running them.
twistd takes care of logging and daemonization (running the program in the
background). /usr/bin/buildbot is a front end which runs twistd for you.

Once you've set up the directory with the .tac file, you start it running
like this:

 buildbot start WORKDIR

This will start the build slave in the background and finish, so you don't
need to put it in the background yourself with "&". The process ID of the
background task is written to a file called "twistd.pid", and all output from
the program is written to a log file named "twistd.log". Look in twistd.log
to make sure the buildslave has started.

To shut down the build slave, use:

 buildbot stop WORKDIR


 RUNNING BEHIND A NAT BOX:

Some network environments will not properly maintain a TCP connection that
appears to be idle. NAT boxes which do some form of connection tracking may
drop the port mapping if it looks like the TCP session has been idle for too
long. The buildslave attempts to turn on TCP "keepalives" (supported by
Twisted 1.0.6 and later), and if these cannot be activated, it uses
application level keepalives (which send a dummy message to the build master
on a periodic basis). The TCP keepalive is typically sent at intervals of
about 2 hours, and is configurable through the kernel. The application-level
keepalive defaults to running once every 10 minutes.

To manually turn on application-level keepalives, or to set them to use some
other interval, add "--keepalive NNN" to the 'buildbot slave' command line.
NNN is the number of seconds between keepalives. Use as large a value as your
NAT box allows to reduce the amount of unnecessary traffic on the wire. 600
seconds (10 minutes) is a reasonable value.


 SETTING UP A BUILD MASTER:

Please read the user's manual for instructions. The short form is that you
use 'buildbot create-master MASTERDIR' to create the base directory, then you
edit the 'master.cfg' file to configure the buildmaster. Once this is ready,
you use 'buildbot start MASTERDIR' to launch it.

A sample configuration file will be created for you in WORKDIR/master.cfg .
There are more examples in docs/examples/, and plenty of documentation in the
user's manual. Everything is controlled by the config file.


SUPPORT:

 Please send questions, bugs, patches, etc, to the buildbot-devel mailing
 list reachable through http://buildbot.net/, so that everyone can see them.
