Ensure that a resource is finalized/reconciled only once

[NArnott]

Is your feature request related to a problem? Please describe.
I'd like to be able to delay a finalizer, similar to how you can "requeue" controller actions. If I want to wait for certain conditions to pass before allowing a finalizer to complete, I thought it would be ok to just await Task.Delay in a loop, but it turns out than more and more calls into the finalizer begin.

Describe the solution you'd like
I'd like to be able to return a complete or not complete status inside a finalizer and a requeue time before the finalizer triggers again.

[buehler]

Hey @NArnott

In theory, the finalizer could just wait for a certain period. The intension would have been to allow the finalizer to wait for certain predicates. So, this seems like a bug that the system does not check which resources are already finalizing.

If it's possible to delay during the finalization method, would that suffice your usecase?

[NArnott]

Yes, that should also work. Just seems like long waiting loops/task delays inside the finalizer would be an anti-pattern, and make it harder to recover if, say, the controller were to shut down and recover on another instance. Rather, just like all reconcile loops, it would make sense for the finalizer to do it's checks as soon as possible and return complete or not complete just like the other reconcile loops.

[buehler]

Kind of an anti pattern. The thing is, the same applies to the reconcile loop. When I develop locally and I hit a breakpoint the same resource gets reconciled a second time after the reconnect to the watcher happens. As such, we need some kind of logic that checks if a resource with a particular UID is being reconciled/finalized.

[NArnott]

I agree that a UID check would be useful for all these cases.

[buehler]

should be fixed in v8 since only updates to the spec or the properties of an entity (resource) does call the watcher.