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4.8.5 Dependent Scheduler

It is common to wind up with one kind of build which should only be performed if the same source code was successfully handled by some other kind of build first. An example might be a packaging step: you might only want to produce .deb or RPM packages from a tree that was known to compile successfully and pass all unit tests. You could put the packaging step in the same Build as the compile and testing steps, but there might be other reasons to not do this (in particular you might have several Builders worth of compiles/tests, but only wish to do the packaging once). Another example is if you want to skip the “full” builds after a failing “quick” build of the same source code. Or, if one Build creates a product (like a compiled library) that is used by some other Builder, you'd want to make sure the consuming Build is run after the producing one.

You can use “Dependencies” to express this relationship to the Buildbot. There is a special kind of scheduler named scheduler.Dependent that will watch an “upstream” scheduler for builds to complete successfully (on all of its Builders). Each time that happens, the same source code (i.e. the same SourceStamp) will be used to start a new set of builds, on a different set of Builders. This “downstream” scheduler doesn't pay attention to Changes at all. It only pays attention to the upstream scheduler.

If the build fails on any of the Builders in the upstream set, the downstream builds will not fire. Note that, for SourceStamps generated by a ChangeSource, the revision is None, meaning HEAD. If any changes are committed between the time the upstream scheduler begins its build and the time the dependent scheduler begins its build, then those changes will be included in the downstream build. See the see Triggerable Scheduler for a more flexible dependency mechanism that can avoid this problem.

The keyword arguments to this scheduler are:

The upstream scheduler to watch. Note that this is an “instance”, not the name of the scheduler.


     from buildbot.schedulers import dependent
     tests = basic.SingleBranchScheduler(name="just-tests", branch=None,
                     builderNames=["full-linux", "full-netbsd", "full-OSX"])
     package = dependent.Dependent(name="build-package",
                     upstream=tests, # <- no quotes!
                     builderNames=["make-tarball", "make-deb", "make-rpm"])
     c['schedulers'] = [tests, package]