Support upgrade/removal of existing App Definition

[jfaltermeier]

Is your feature request related to a problem? Please describe.

This issue is about dealing with App Definition Updates.
Currently our AppDefinitionHandlers are only reacting on added events.

This task is about identifying (and if time implementing) the required steps.

Describe the solution you'd like

Initial thoughts:

• removal
  • try to send warning to all sessions using the removed app definition (currently monitor extension is required for this) that they will be shut down soon
  • shut down sessions after some time
  • How to best configure this time?
• update
  • similar to the removal we should try to warn existing sessions that they will be shut down. However this can be much more time than in the removal case.
  • Check whether in some cases sessions can be live-patched without making them restart?
• it should be possible to turn off the shutdown on removal/update mechanism and let old sessions run (e.g. when the app does not use the monitor extension and user's can't be warned)

Describe alternatives you've considered

Only initial thoughts are listed above

Cluster provider

No response

Additional information

No response

[github-actions]

This issue is stale because it has been open for 180 days with no activity.

[sgraband]

Keep open