WithFinalizer

[scothis]

WithFinalizer is a SubReconciler that allows external state to be
allocated and then cleaned up once the parent resource is deleted. When
the parent resource is not terminating, the finalizer is set on the
parent resource before the nested reconciler is called. When the parent
resource is terminating, the finalizer is cleared only after the nested
reconciler returns without an error.

func SyncExternalState() *reconcilers.SubReconciler {
	return &reconcilers.WithFinalizer{
		Finalizer: "unique.finalizer.name"
		Reconciler: &reconcilers.SyncReconciler{
			Sync: func(ctx context.Context, parent *resources.TestResource) error {
				// allocate external state
				return nil
			},
			Finalize: func(ctx context.Context, parent *resources.TestResource) error {
				// cleanup the external state
				return nil
			},
		},
	}
}

Signed-off-by: Scott Andrews andrewssc@vmware.com

[codecov]

Codecov Report

Merging #228 (a9ce88c) into main (af55ebc) will increase coverage by 1.52%.
The diff coverage is 80.64%.

@@            Coverage Diff             @@
##             main     #228      +/-   ##
==========================================
+ Coverage   65.07%   66.60%   +1.52%     
==========================================
  Files           9        9              
  Lines        1008     1099      +91     
==========================================
+ Hits          656      732      +76     
- Misses        330      345      +15     
  Partials       22       22              

Impacted Files	Coverage Δ
reconcilers/reconcilers.go	81.91% <80.64%> (+0.21%)	⬆️

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[mamachanko]

Given that finalizers can be tricky, I could imagine it to be helpful if there’re a few words of guidance when to choose WithFinalizer over Sync/ChildReconciler with Finalize. I would find convenience or expressiveness or improved composability ensuring for the adopter.

Nice, @scothis!

[mamachanko]

[suggestion]: Can you motivate usage of a WithFinalizer subreconciler over a ChildReconciler/SyncRenciler with Finalize?

[scothis]

added a note under the finalizers section. We can continue to iterate on it