If you look in the [http://hg.mozilla.org/build/tools/file/tip/scripts tools/scripts] repo you can see that we have a simple shell file to do this for the fuzzing automation. The buildbot factory that calls it is called [http://hg.mozilla.org/build/buildbotcustom/file/a70b38b40088/process/factory.py#l7895 ScriptFactorymozharness] and it is very simple. * mozharness is a single factory that buildbot can run; within mozharness, a script is selected for a specific job. This moves the job-definition responsibility out from buildbot; by separating the pieces, you avoid excessive complexity in buildbot and also open up the possibility of running mozharness manually (e.g., by a developer, to test something)