A Version Control System mantains a source tree, and tells the buildmaster when it changes. The first step of each Build is typically to acquire a copy of some version of this tree.
This chapter describes how the Buildbot learns about what Changes have occurred. For more information on VC systems and Changes, see Version Control Systems.
Changes can be provided by a variety of ChangeSource types, although any given project will typically have only a single ChangeSource active. This section provides a description of all available ChangeSource types and explains how to set up each of them.
In general, each Buildmaster watches a single source tree. It is possible to work around this, but true support for multi-tree builds remains elusive.