Comment 3 for bug 1830680

@Wouter, thanks very much for the detailed steps; it's now clear (to me at least!) what you mean by the multi-phase commit in terms of the actions taken.

TRIAGE:

It seems clear that the charm should validate that each previous step completed properly before moving on, and also attempt to 'un-do' any actions if they fail. A series of nested "try: except: " statements would enable the except handling to handle undoing the current action, and the nested ones to undo their's. Only if no exception is thrown would everything happen. (obviously, there's the issue of handling exceptions in the 'undo' phase, but that 'should' be easier).