"ownerReferences" consideration while deleting objects.

[sayan-biswas]

In the present implementation of the reconciler, we are checking the ownerReferences while deleting an object from the cluster.

results/pkg/watcher/reconciler/dynamic/dynamic.go

Lines 185 to 187 in 6e51562

	if ownerReferences := o.GetOwnerReferences(); len(ownerReferences) > 0 {
	logger.Debugw("Resource is owned by another object, deferring deletion to parent resource(s)", zap.Any("results.tekton.dev/ownerReferences", ownerReferences))
	return nil

Added from #255

While the intention specifies that those objects with ownerReferences are to be managed by the owner itself, but is there any value in keeping the object in the cluster even after it executed successfully and stored in results?
There are cases where other controllers will add ownerReferences for it purpose without knowing that TektonResults will ignore them, and they'll live in the cluster until deleted manually.

I suggest, if we need to keep this validation, we can keep it by default, and allow this behaviour to be altered with config parameters.

[adambkaplan]

I think this validation makes sense, period. We are ostensibly watching PipelineRun and TaskRun objects, which means we should get a reconcile event when a respective owner ref is updated/changed. I see this primarily impacting PipelineRun objects which have additional owner refs. If a PipelineRun is owned by another object, we IMO we should not prune it and wait for either:

• The owner to remove its owner ref, or
• The owner object to be deleted

Calling delete on an object will cascade deletion to its child objects by default, so Results shouldn't need to do anything regarding cleanup. And if the thing that deletes an object uses the --cascade=orphan option, Results should respect that.

[Roming22]

The issue is that we then have completed PipelineRuns hanging around because they have an ownerReference.

I don't see the value with keeping the PipelineRun resource on the cluster once all tasks have executed. Users should access the resources through Tekton-Results.

Also, I don't think the Tekton Pipelines pruner care about ownerReferences when pruning, so we have a change of behavior when going from the default pruner to Tekton-Results.

I'd rather there be an option to skip resources with ownerReferences that is set to false by default.

[Roming22]

There seems to be an agreement in the Working Group call to:

• Add a flag to enable/disable the behavior
• Have the default flag value disable the behavior, so Tekton Results behaves like the Tekton Pipelines pruner.