ObjDiff is a library designed to give you a list of deltas between 2 trees of objects. This list can include item additions, deletions and modifications.

>>> import objdiff
>>> list(objdiff.obj_diff({'a':[1,2,3]}, {}))
[deleted(path=['a'], val=[1, 2, 3])]

This library may be of use to you if you deal with yaml files or have a before and after copy of the data and need to respond or act on specific changes between those 2 versions (eg spinning up more processes when the workers var is updated).

The src repository (obtained from here) for this module containers 2 such yaml files to play with that model a prototype containers framework that can be used in conjunction with python -m objdiff FILE1 FILE2 to provide a list of changes.