Possible entry points in Jenkions job configuration:

• Build Environment → Delete workspace before build starts → Advanced... → External Deletion Command is possibly too early as it is hard to retrieve information at that point to check what files the Diff will affect.
• Build Environment → Apply Phabricator Differential has various options on how to apply the patch like creating a commit, applying it to master, or creating a branch. We may use the easiest option to later check affected files in a new build step based on a script.

We also have the possibility to modify the Herald rule that triggers the jobs. For example, if the revision summary contains a certain keyword, trigger a complete rebuild instead of an incremental build. Two disadventages are: Revision creators have to be aware of this possibility, and this is not enough as there may be also some other changes on the master branch since the last build on the build client that affect critical files.

The latter is a general problem. It is easy to query the files affected by the Differential on Jenkins side by calling git diff --cached --name-only. But it is hard to query all affected files since the last build. These may include files from the last Diff and files from other commits on the master in between.

Possibly useful Jenkins plugins:

• pre-scm-buildstep: https://wiki.jenkins.io/display/JENKINS/pre-scm-buildstep

I just thought about it could be a good idea to actually do this in our CMake script right in MITK. We can check all sorts of things there before and after external project processing.

External projects have an install_manifest.txt file in their build folder listing all installed files, by the way.

Pushed new branch T27042-AutocleanExternalProjects.

I activated MITK_AUTOCLEAN_EXTERNAL_PROJECTS on Differential and Continuous jobs. Fingers crossed.