Use prepare-shutdown feature

[toabi]

When a restart is necessary because of plugin upgrades or other configuration, jenkins should be restarted as gracefully as possible.

It could enable shutdown mode (in the UI under /manage/prepareShutdown/) and then wait until all jobs are done and then recreate the pod.

[brokenpip3]

Yeah could be a great improvement. however:

• right now the operator does not restart the pod if a new plugins version is present (was like that in the past, we changed the behavior)
• in these weeks my free time is super limited so I need to continue the work with the more urgent tasks but I will find the time if a PR around this will be created :)

[toabi]

Ah, thanks for the answer :)

We actually wondered why the operator doesn't auto-restart the pod. For now with that new behaviour we can manually do this process with a graceful restart. It's not a top priority.