Installation

Buildbot Components

Buildbot is shipped in two components: the buildmaster (called buildbot for legacy reasons) and the buildslave. The buildslave component has far fewer requirements, and is more broadly compatible than the buildmaster. You will need to carefully pick the environment in which to run your buildmaster, but the buildslave should be able to run just about anywhere.

It is possible to install the buildmaster and buildslave on the same system, although for anything but the smallest installation this arrangement will not be very efficient.

Requirements

Common Requirements

At a bare minimum, you'll need the following for both the buildmaster and a buildslave:

Python: http://www.python.org

Buildbot requires Python-2.5 or later on the master, although Python-2.7 is recommended. The slave run on Python-2.4.

Twisted: http://twistedmatrix.com

Buildbot requires Twisted-11.0.0 or later on the master, and Twisted-8.1.0 on the slave. In upcoming versions of Buildbot, a newer Twisted will also be required on the slave. As always, the most recent version is recommended.

In some cases, 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.

Of course, your project's build process will impose additional requirements on the buildslaves. These hosts must have all the tools necessary to compile and test your project's source code.

Windows Support

Buildbot - both master and slave - runs well natively on Windows. The slave runs well on Cygwin, but because of problems with SQLite on Cygwin, the master does not.

Buildbot's windows testing is limited to the most recent Twisted and Python versions. For best results, use the most recent available versions of these libraries on Windows.

Pywin32: http://sourceforge.net/projects/pywin32/

Twisted requires PyWin32 in order to spawn processes on Windows.

Buildmaster Requirements

sqlite3: http://www.sqlite.org

Buildbot requires SQLite to store its state. Version 3.7.0 or higher is recommended, although Buildbot will run against earlier versions -- at the risk of "Database is locked" errors. The minimum version is 3.4.0, below which parallel database queries and schema introspection fail.

pysqlite: http://pypi.python.org/pypi/pysqlite

The SQLite Python package is required for Python-2.5 and earlier (it is already included in Python-2.5 and later, but the version in Python-2.5 has nasty bugs)

simplejson: http://pypi.python.org/pypi/simplejson

The simplejson package is required for Python-2.5 and earlier (it is already included as json in Python-2.6 and later)

Jinja2: http://jinja.pocoo.org/

Buildbot requires Jinja version 2.1 or higher.

Jinja2 is a general purpose templating language and is used by Buildbot to generate the HTML output.

SQLAlchemy: http://www.sqlalchemy.org/

Buildbot requires SQLAlchemy 0.6.0 or higher. SQLAlchemy allows Buildbot to build database schemas and queries for a wide variety of database systems.

SQLAlchemy-Migrate: http://code.google.com/p/sqlalchemy-migrate/

Buildbot requires one of the following SQLAlchemy-Migrate versions: 0.7.1, 0.7.2 and 0.9. SQLAlchemy-Migrate-0.9 is required for compatibility with SQLAlchemy versions 0.8 and above. Buildbot uses SQLAlchemy-Migrate to manage schema upgrades from version to version.

Python-Dateutil: http://labix.org/python-dateutil

The Nightly scheduler requires Python-Dateutil version 1.5 (the last version to support Python-2.x). This is a small, pure-python library. Buildbot will function properly without it if the Nightlys scheduler is not used.

Installing the code

The Distribution Package

Buildbot comes in two parts: buildbot (the master) and buildbot-slave (the slave). The two can be installed individually or together.

Installation From PyPI

The preferred way to install Buildbot is using pip. For the master:

pip install buildbot

and for the slave:

pip install buildbot-slave

When using pip to install instead of distribution specific package manangers, e.g. via apt-get or ports, it is simpler to choose exactly which version one wants to use. It may however be easier to install via distribution specific package mangers but note that they may provide an earlier version than what is available via pip.

Installation From Tarballs

Buildbot and Buildslave are installed using the standard Python distutils process. For either component, after unpacking the tarball, the process is:

python setup.py build
python setup.py install

where the install step may need to be done as root. This will put the bulk of the code in somewhere like /usr/lib/pythonx.y/site-packages/buildbot. It will also install the buildbot command-line tool in /usr/bin/buildbot.

If the environment variable $NO_INSTALL_REQS is set to 1, then setup.py will not try to install Buildbot's requirements. This is usually only useful when building a Buildbot package.

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

buildbot --version
# or
buildslave --version

If it shows you the versions of Buildbot and Twisted, the install went ok. If it says "no such command" or it gets an ImportError when it tries to load the libraries, then something went wrong. pydoc buildbot is another useful diagnostic tool.

Windows users will find these files in other places. You will need to make sure that Python can find the libraries, and will probably find it convenient to have buildbot on your PATH.

Installation in a Virtualenv

If you cannot or do not wish to install the buildbot into a site-wide location like /usr or /usr/local, you can also install it into the account's home directory or any other location using a tool like virtualenv.

Running Buildbot's Tests (optional)

If you wish, you can run the buildbot unit test suite. First, ensure you have the mock Python module installed from PyPi. This module is not required for ordinary Buildbot operation - only to run the tests. Note that this is not the same as the Fedora mock package! You can check with

python -mmock

Then, run the tests:

PYTHONPATH=. trial buildbot.test
# or
PYTHONPATH=. trial buildslave.test

Nothing should fail, although a few might be skipped.

If any of the tests fail for reasons other than a missing mock, you should stop and investigate the cause before continuing the installation process, as it will probably be easier to track down the bug early. In most cases, the problem is incorrectly installed Python modules or a badly configured PYTHONPATH. This may be a good time to contact the Buildbot developers for help.

Creating a buildmaster

As you learned earlier (System Architecture), the buildmaster runs on a central host (usually one that is publicly visible, so everybody can check on the status of the project), and controls all aspects of the buildbot system

You will probably wish to create a separate user account for the buildmaster, perhaps named buildmaster. Do not run the buildmaster as root!

You need to choose a directory for the buildmaster, called the basedir. This directory will be owned by the buildmaster. It will contain configuration, the database, and status information - including logfiles. On a large buildmaster this directory will see a lot of activity, so it should be on a disk with adequate space and speed.

Once you've picked a directory, use the buildbot create-master command to create the directory and populate it with startup files:

buildbot create-master -r basedir

You will need to create a configuration file before starting the buildmaster. Most of the rest of this manual is dedicated to explaining how to do this. A sample configuration file is placed in the working directory, named master.cfg.sample, which can be copied to master.cfg and edited to suit your purposes.

(Internal details: This command creates a file named buildbot.tac that contains all the state necessary to create the buildmaster. Twisted has a tool called twistd which can use this .tac file to create and launch a buildmaster instance. 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.)

Using A Database Server

If you want to use a database server (e.g., MySQL or Postgres) as the database backend for your Buildbot, add the --db option to the create-master invocation to specify the connection string for the database, and make sure that the same URL appears in the db_url of the db parameter in your configuration file.

Additional Requirements

Depending on the selected database, further Python packages will be required. Consult the SQLAlchemy dialect list for a full description.

The most common choice for MySQL is

MySQL-python: http://mysql-python.sourceforge.net/

To communicate with MySQL, SQLAlchemy requires MySQL-python. Any reasonably recent version of MySQL-python should suffice.

The most common choice for Postgres is

Psycopg: http://initd.org/psycopg/

SQLAlchemy uses Psycopg to communicate with Postgres. Any reasonably recent version should suffice.

Buildmaster Options

This section lists options to the create-master command. You can also type buildbot create-master --help for an up-to-the-moment summary.

--force

With this option, @command{create-master} will re-use an existing master directory.

--no-logrotate

This disables internal buildslave log management mechanism. With this option buildslave does not override the default logfile name and its behaviour giving a possibility to control those with command-line options of twistd daemon.

--relocatable

This creates a "relocatable" buildbot.tac, which uses relative paths instead of absolute paths, so that the buildmaster directory can be moved about.

--config

The name of the configuration file to use. This configuration file need not reside in the buildmaster directory.

--log-size

This is the size in bytes when to rotate the Twisted log files. The default is 10MiB.

--log-count

This is the number of log rotations to keep around. You can either specify a number or None to keep all @file{twistd.log} files around. The default is 10.

--db

The database that the Buildmaster should use. Note that the same value must be added to the configuration file.

Upgrading an Existing Buildmaster

If you have just installed a new version of the Buildbot code, and you have buildmasters that were created using an older version, you'll need to upgrade these buildmasters before you can use them. The upgrade process adds and modifies files in the buildmaster's base directory to make it compatible with the new code.

buildbot upgrade-master basedir

This command will also scan your master.cfg file for incompatibilities (by loading it and printing any errors or deprecation warnings that occur). Each buildbot release tries to be compatible with configurations that worked cleanly (i.e. without deprecation warnings) on the previous release: any functions or classes that are to be removed will first be deprecated in a release, to give you a chance to start using the replacement.

The upgrade-master command is idempotent. It is safe to run it multiple times. After each upgrade of the buildbot code, you should use upgrade-master on all your buildmasters.

In general, Buildbot slaves and masters can be upgraded independently, although some new features will not be available, depending on the master and slave versions.

Beyond this general information, read all of the sections below that apply to versions through which you are upgrading.

Version-specific Notes

Upgrading a Buildmaster to Buildbot-0.7.6

The 0.7.6 release introduced the public_html/ directory, which contains index.html and other files served by the WebStatus and Waterfall status displays. The upgrade-master command will create these files if they do not already exist. It will not modify existing copies, but it will write a new copy in e.g. index.html.new if the new version differs from the version that already exists.

Upgrading a Buildmaster to Buildbot-0.8.0

Buildbot-0.8.0 introduces a database backend, which is SQLite by default. The upgrade-master command will automatically create and populate this database with the changes the buildmaster has seen. Note that, as of this release, build history is not contained in the database, and is thus not migrated.

The upgrade process renames the Changes pickle ($basedir/changes.pck) to changes.pck.old once the upgrade is complete. To reverse the upgrade, simply downgrade Buildbot and move this file back to its original name. You may also wish to delete the state database (state.sqlite).

Upgrading into a non-SQLite database

If you are not using sqlite, you will need to add an entry into your master.cfg to reflect the database version you are using. The upgrade process does not edit your master.cfg for you. So something like:

# for using mysql:
c['db_url'] = 'mysql://bbuser:<password>@localhost/buildbot'

Once the parameter has been added, invoke upgrade-master. This will extract the DB url from your configuration file.

buildbot upgrade-master

See Database Specification for more options to specify a database.

Change Encoding Issues

The upgrade process assumes that strings in your Changes pickle are encoded in UTF-8 (or plain ASCII). If this is not the case, and if there are non-UTF-8 characters in the pickle, the upgrade will fail with a suitable error message. If this occurs, you have two options. If the change history is not important to your purpose, you can simply delete changes.pck.

If you would like to keep the change history, then you will need to figure out which encoding is in use, and use contrib/fix_changes_pickle_encoding.py (Contrib Scripts) to rewrite the changes pickle into Unicode before upgrading the master. A typical invocation (with Mac-Roman encoding) might look like:

$ python $buildbot/contrib/fix_changes_pickle_encoding.py changes.pck macroman
decoding bytestrings in changes.pck using macroman
converted 11392 strings
backing up changes.pck to changes.pck.old

If your Changes pickle uses multiple encodings, you're on your own, but the script in contrib may provide a good starting point for the fix.

Upgrading a Buildmaster to Later Versions

Up to Buildbot version 0.8.14, no further steps beyond those described above are required.

Creating a buildslave

Typically, you will be adding a buildslave to an existing buildmaster, to provide additional architecture coverage. The buildbot administrator will give you several pieces of information necessary to connect to the buildmaster. You should also be somewhat familiar with the project being tested, so you can troubleshoot build problems locally.

The buildbot exists to make sure that the project's stated how to build it process actually works. To this end, the buildslave should run in an environment just like that of your regular developers. Typically the project build process is documented somewhere (README, INSTALL, etc), in a document that should mention all library dependencies and contain a basic set of build instructions. This document will be useful as you configure the host and account in which the buildslave runs.

Here's a good checklist for setting up a buildslave:

  1. Set up the account

    It is recommended (although not mandatory) to set up a separate user account for the buildslave. This account is frequently named buildbot or buildslave. This serves to isolate your personal working environment from that of the slave's, and helps to minimize the security threat posed by letting possibly-unknown contributors run arbitrary code on your system. The account should have a minimum of fancy init scripts.

  2. Install the buildbot code

    Follow the instructions given earlier (Installing the code). If you use a separate buildslave account, and you didn't install the buildbot code to a shared location, then you will need to install it with --home=~ for each account that needs it.

  3. Set up the host

    Make sure the host can actually reach the buildmaster. Usually the buildmaster is running a status webserver on the same machine, so simply point your web browser at it and see if you can get there. Install whatever additional packages or libraries the project's INSTALL document advises. (or not: if your buildslave is supposed to make sure that building without optional libraries still works, then don't install those libraries).

    Again, these libraries don't necessarily have to be installed to a site-wide shared location, but they must be available to your build process. Accomplishing this is usually very specific to the build process, so installing them to /usr or /usr/local is usually the best approach.

  4. Test the build process

    Follow the instructions in the INSTALL document, in the buildslave's account. Perform a full CVS (or whatever) checkout, configure, make, run tests, etc. Confirm that the build works without manual fussing. If it doesn't work when you do it by hand, it will be unlikely to work when the buildbot attempts to do it in an automated fashion.

  5. Choose a base directory

    This should be somewhere in the buildslave's account, typically named after the project which is being tested. The buildslave will not touch any file outside of this directory. Something like ~/Buildbot or ~/Buildslaves/fooproject is appropriate.

  6. Get the buildmaster host/port, botname, and password

    When the buildbot admin configures the buildmaster to accept and use your buildslave, they will provide you with the following pieces of information:

    • your buildslave's name
    • the password assigned to your buildslave
    • the hostname and port number of the buildmaster, i.e. buildbot.example.org:8007

  7. Create the buildslave

    Now run the 'buildslave' command as follows:

    buildslave create-slave BASEDIR MASTERHOST:PORT SLAVENAME PASSWORD

    This will create the base directory and a collection of files inside, including the buildbot.tac file that contains all the information you passed to the buildbot command.

  8. Fill in the hostinfo files

    When it first connects, the buildslave will send a few files up to the buildmaster which describe the host that it is running on. These files are presented on the web status display so that developers have more information to reproduce any test failures that are witnessed by the buildbot. There are sample files in the info subdirectory of the buildbot's base directory. You should edit these to correctly describe you and your host.

    BASEDIR/info/admin should contain your name and email address. This is the buildslave admin address, and will be visible from the build status page (so you may wish to munge it a bit if address-harvesting spambots are a concern).

    BASEDIR/info/host should be filled with a brief description of the host: OS, version, memory size, CPU speed, versions of relevant libraries installed, and finally the version of the buildbot code which is running the buildslave.

    The optional BASEDIR/info/access_uri can specify a URI which will connect a user to the machine. Many systems accept ssh://hostname URIs for this purpose.

    If you run many buildslaves, you may want to create a single ~buildslave/info file and share it among all the buildslaves with symlinks.

Buildslave Options

There are a handful of options you might want to use when creating the buildslave with the buildslave create-slave <options> DIR <params> command. You can type buildslave create-slave --help for a summary. To use these, just include them on the buildslave create-slave command line, like this

buildslave create-slave --umask=022 ~/buildslave buildmaster.example.org:42012 {myslavename} {mypasswd}
--no-logrotate

This disables internal buildslave log management mechanism. With this option buildslave does not override the default logfile name and its behaviour giving a possibility to control those with command-line options of twistd daemon.

--usepty

This is a boolean flag that tells the buildslave whether to launch child processes in a PTY or with regular pipes (the default) when the master does not specify. This option is deprecated, as this particular parameter is better specified on the master.

--umask

This is a string (generally an octal representation of an integer) which will cause the buildslave process' umask value to be set shortly after initialization. The twistd daemonization utility forces the umask to 077 at startup (which means that all files created by the buildslave or its child processes will be unreadable by any user other than the buildslave account). If you want build products to be readable by other accounts, you can add --umask=022 to tell the buildslave to fix the umask after twistd clobbers it. If you want build products to be writable by other accounts too, use --umask=000, but this is likely to be a security problem.

--keepalive

This is a number that indicates how frequently keepalive messages should be sent from the buildslave to the buildmaster, expressed in seconds. The default (600) causes a message to be sent to the buildmaster at least once every 10 minutes. To set this to a lower value, use e.g. --keepalive=120.

If the buildslave is behind a NAT box or stateful firewall, these messages may help to keep the connection alive: some NAT boxes tend to forget about a connection if it has not been used in a while. When this happens, the buildmaster will think that the buildslave has disappeared, and builds will time out. Meanwhile the buildslave will not realize than anything is wrong.

--maxdelay

This is a number that indicates the maximum amount of time the buildslave will wait between connection attempts, expressed in seconds. The default (300) causes the buildslave to wait at most 5 minutes before trying to connect to the buildmaster again.

--log-size

This is the size in bytes when to rotate the Twisted log files.

--log-count

This is the number of log rotations to keep around. You can either specify a number or None to keep all twistd.log files around. The default is 10.

--allow-shutdown

Can also be passed directly to the BuildSlave constructor in buildbot.tac. If set, it allows the buildslave to initiate a graceful shutdown, meaning that it will ask the master to shut down the slave when the current build, if any, is complete.

Setting allow_shutdown to file will cause the buildslave to watch shutdown.stamp in basedir for updates to its mtime. When the mtime changes, the slave will request a graceful shutdown from the master. The file does not need to exist prior to starting the slave.

Setting allow_shutdown to signal will set up a SIGHUP handler to start a graceful shutdown. When the signal is received, the slave will request a graceful shutdown from the master.

The default value is None, in which case this feature will be disabled.

Both master and slave must be at least version 0.8.3 for this feature to work.

Other Buildslave Configuration

unicode_encoding

This represents the encoding that buildbot should use when converting unicode commandline arguments into byte strings in order to pass to the operating system when spawning new processes.

The default value is what Python's sys.getfilesystemencoding returns, which on Windows is 'mbcs', on Mac OSX is 'utf-8', and on Unix depends on your locale settings.

If you need a different encoding, this can be changed in your build slave's buildbot.tac file by adding a unicode_encoding argument to the BuildSlave constructor.

s = BuildSlave(buildmaster_host, port, slavename, passwd, basedir,
               keepalive, usepty, umask=umask, maxdelay=maxdelay,
               unicode_encoding='utf-8', allow_shutdown='signal')

Upgrading an Existing Buildslave

If you have just installed a new version of Buildbot-slave, you may need to take some steps to upgrade it. If you are upgrading to version 0.8.2 or later, you can run

buildslave upgrade-slave /path/to/buildslave/dir

Version-specific Notes

Upgrading a Buildslave to Buildbot-slave-0.8.1

Before Buildbot version 0.8.1, the Buildbot master and slave were part of the same distribution. As of version 0.8.1, the buildslave is a separate distribution.

As of this release, you will need to install buildbot-slave to run a slave.

Any automatic startup scripts that had run buildbot start for previous versions should be changed to run buildslave start instead.

If you are running a version later than 0.8.1, then you can skip the remainder of this section: the upgrade-slave command will take care of this. If you are upgrading directly to 0.8.1, read on.

The existing buildbot.tac for any buildslaves running older versions will need to be edited or replaced. If the loss of cached buildslave state (e.g., for Source steps in copy mode) is not problematic, the easiest solution is to simply delete the slave directory and re-run buildslave create-slave.

If deleting the slave directory is problematic, the change to buildbot.tac is simple. On line 3, replace

from buildbot.slave.bot import BuildSlave

with

from buildslave.bot import BuildSlave

After this change, the buildslave should start as usual.

Launching the daemons

Both the buildmaster and the buildslave run as daemon programs. To launch them, pass the working directory to the buildbot and buildslave commands, as appropriate:

# start a master
buildbot start [ BASEDIR ]
# start a slave
buildslave start [ SLAVE_BASEDIR ]

The BASEDIR is option and can be omitted if the current directory contains the buildbot configuration (the buildbot.tac file).

buildbot start

This command will start the daemon and then return, so normally it will not produce any output. To verify that the programs are indeed running, look for a pair of files named twistd.log and twistd.pid that should be created in the working directory. twistd.pid contains the process ID of the newly-spawned daemon.

When the buildslave connects to the buildmaster, new directories will start appearing in its base directory. The buildmaster tells the slave to create a directory for each Builder which will be using that slave. All build operations are performed within these directories: CVS checkouts, compiles, and tests.

Once you get everything running, you will want to arrange for the buildbot daemons to be started at boot time. One way is to use cron, by putting them in a @reboot crontab entry [1]

@reboot buildbot start [ BASEDIR ]

When you run crontab to set this up, remember to do it as the buildmaster or buildslave account! If you add this to your crontab when running as your regular account (or worse yet, root), then the daemon will run as the wrong user, quite possibly as one with more authority than you intended to provide.

It is important to remember that the environment provided to cron jobs and init scripts can be quite different that your normal runtime. There may be fewer environment variables specified, and the PATH may be shorter than usual. It is a good idea to test out this method of launching the buildslave by using a cron job with a time in the near future, with the same command, and then check twistd.log to make sure the slave actually started correctly. Common problems here are for /usr/local or ~/bin to not be on your PATH, or for PYTHONPATH to not be set correctly. Sometimes HOME is messed up too.

Some distributions may include conveniences to make starting buildbot at boot time easy. For instance, with the default buildbot package in Debian-based distributions, you may only need to modify /etc/default/buildbot (see also /etc/init.d/buildbot, which reads the configuration in /etc/default/buildbot).

Buildbot also comes with its own init scripts that provide support for controlling multi-slave and multi-master setups (mostly because they are based on the init script from the Debian package). With a little modification these scripts can be used both on Debian and RHEL-based distributions and may thus prove helpful to package maintainers who are working on buildbot (or those that haven't yet split buildbot into master and slave packages).

# install as /etc/default/buildslave
#         or /etc/sysconfig/buildslave
master/contrib/init-scripts/buildslave.default

# install as /etc/default/buildmaster
#         or /etc/sysconfig/buildmaster
master/contrib/init-scripts/buildmaster.default

# install as /etc/init.d/buildslave
slave/contrib/init-scripts/buildslave.init.sh

# install as /etc/init.d/buildmaster
slave/contrib/init-scripts/buildmaster.init.sh

# ... and tell sysvinit about them
chkconfig buildmaster reset
# ... or
update-rc.d buildmaster defaults

Logfiles

While a buildbot daemon runs, it emits text to a logfile, named twistd.log. A command like tail -f twistd.log is useful to watch the command output as it runs.

The buildmaster will announce any errors with its configuration file in the logfile, so it is a good idea to look at the log at startup time to check for any problems. Most buildmaster activities will cause lines to be added to the log.

Shutdown

To stop a buildmaster or buildslave manually, use:

buildbot stop [ BASEDIR ]
# or
buildslave stop [ SLAVE_BASEDIR ]

This simply looks for the twistd.pid file and kills whatever process is identified within.

At system shutdown, all processes are sent a SIGKILL. The buildmaster and buildslave will respond to this by shutting down normally.

The buildmaster will respond to a SIGHUP by re-reading its config file. Of course, this only works on Unix-like systems with signal support, and won't work on Windows. The following shortcut is available:

buildbot reconfig [ BASEDIR ]

When you update the Buildbot code to a new release, you will need to restart the buildmaster and/or buildslave before it can take advantage of the new code. You can do a buildbot stop BASEDIR and buildbot start BASEDIR in quick succession, or you can use the restart shortcut, which does both steps for you:

buildbot restart [ BASEDIR ]

Buildslaves can similarly be restarted with:

buildslave restart [ BASEDIR ]

There are certain configuration changes that are not handled cleanly by buildbot reconfig. If this occurs, buildbot restart is a more robust tool to fully switch over to the new configuration.

buildbot restart may also be used to start a stopped Buildbot instance. This behaviour is useful when writing scripts that stop, start and restart Buildbot.

A buildslave may also be gracefully shutdown from the WebStatus status plugin. This is useful to shutdown a buildslave without interrupting any current builds. The buildmaster will wait until the buildslave is finished all its current builds, and will then tell the buildslave to shutdown.

Maintenance

The buildmaster can be configured to send out email notifications when a slave has been offline for a while. Be sure to configure the buildmaster with a contact email address for each slave so these notifications are sent to someone who can bring it back online.

If you find you can no longer provide a buildslave to the project, please let the project admins know, so they can put out a call for a replacement.

The Buildbot records status and logs output continually, each time a build is performed. The status tends to be small, but the build logs can become quite large. Each build and log are recorded in a separate file, arranged hierarchically under the buildmaster's base directory. To prevent these files from growing without bound, you should periodically delete old build logs. A simple cron job to delete anything older than, say, two weeks should do the job. The only trick is to leave the buildbot.tac and other support files alone, for which find's -mindepth argument helps skip everything in the top directory. You can use something like the following:

@weekly cd BASEDIR && find . -mindepth 2 i-path './public_html/*' \
    -prune -o -type f -mtime +14 -exec rm {} \;
@weekly cd BASEDIR && find twistd.log* -mtime +14 -exec rm {} \;

Alternatively, you can configure a maximum number of old logs to be kept using the --log-count command line option when running buildslave create-slave or buildbot create-master.

Troubleshooting

Here are a few hints on diagnosing common problems.

Starting the buildslave

Cron jobs are typically run with a minimal shell (/bin/sh, not /bin/bash), and tilde expansion is not always performed in such commands. You may want to use explicit paths, because the PATH is usually quite short and doesn't include anything set by your shell's startup scripts (.profile, .bashrc, etc). If you've installed buildbot (or other Python libraries) to an unusual location, you may need to add a PYTHONPATH specification (note that Python will do tilde-expansion on PYTHONPATH elements by itself). Sometimes it is safer to fully-specify everything:

@reboot PYTHONPATH=~/lib/python /usr/local/bin/buildbot \
    start /usr/home/buildbot/basedir

Take the time to get the @reboot job set up. Otherwise, things will work fine for a while, but the first power outage or system reboot you have will stop the buildslave with nothing but the cries of sorrowful developers to remind you that it has gone away.

Connecting to the buildmaster

If the buildslave cannot connect to the buildmaster, the reason should be described in the twistd.log logfile. Some common problems are an incorrect master hostname or port number, or a mistyped bot name or password. If the buildslave loses the connection to the master, it is supposed to attempt to reconnect with an exponentially-increasing backoff. Each attempt (and the time of the next attempt) will be logged. If you get impatient, just manually stop and re-start the buildslave.

When the buildmaster is restarted, all slaves will be disconnected, and will attempt to reconnect as usual. The reconnect time will depend upon how long the buildmaster is offline (i.e. how far up the exponential backoff curve the slaves have travelled). Again, buildslave restart BASEDIR will speed up the process.

[1]This @reboot syntax is understood by Vixie cron, which is the flavor usually provided with Linux systems. Other unices may have a cron that doesn't understand @reboot:

Contrib Scripts

While some features of Buildbot are included in the distribution, others are only available in contrib/ in the source directory. The latest versions of such scripts are available at http://github.com/buildbot/buildbot/tree/master/master/contrib.