Rollback

[bryanl]

kapp-controller could have the ability to perform a rollback. I'm currently unsure how this could be accomplished, but if the controller can somehow persist change requests, a previous one could be selected.

[cppforlife]

one thought is to record revision at the time of deploy into a separate CR:

AppRevision CR
  metadata
    labels
      kappctrl.k14s.io/app: app-name
  spec
    ... contents App CR Spec ...
  status
    conditions
      ReconcileSuccess/ReconcileFailure

there are few things to consider though:

1. should we resolve fetch configuration to its "absolute" form (git tag -> git commit)
2. what should be done to secrets/configMaps referenced

there is an argument to be made to follow same pattern apps.Deployment and not do anything about 2 points above.