2.2.5. Buildmaster Setup 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.)

Your master will need a database to store the various information about your builds, and its configuration. By default, the sqlite3 backend will be used. This needs no configuration, neither extra software. All information will be stored in the file state.sqlite. Buildbot however supports multiple backends. See Using A Database Server for more options.

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.


This option will allow to re-use an existing directory.


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


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


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


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


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.


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 workers and masters can be upgraded independently, although some new features will not be available, depending on the master and worker versions.

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

Version-specific Notes

Upgrading from Buildbot-0.8.x to Buildbot-0.9.x

See Upgrading to Nine for a guide to upgrading from 0.8.x to 0.9.x

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.

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.