Precedence between NS labels/annotations propagation should be documented

[erikgb]

What

We are performing a POC of Accurate, and one of our goals is to allow end-users to set selected NS labels/annotations. This seems to work very well, but I could not find the precedence between labelKeys/subNamespaceLabelKeys and annotationKeys/subNamespaceAnnotationKeys documented anywhere. Looking at the code this looks as expected and I have also verified this in our cluster:

accurate/controllers/namespace_controller.go

Lines 89 to 125 in 1cc371d

	for k, v := range parent.Labels {
	if ok := r.matchLabelKey(k); ok {
	ns.Labels[k] = v
	}
	}
	for k, v := range parent.Annotations {
	if ok := r.matchAnnotationKey(k); ok {
	if ns.Annotations == nil {
	ns.Annotations = make(map[string]string)
	}
	ns.Annotations[k] = v
	}
	}
	if _, ok := ns.Labels[constants.LabelParent]; ok {
	subNS := &accuratev1.SubNamespace{}
	err := r.Get(ctx, types.NamespacedName{Name: ns.Name, Namespace: parent.Name}, subNS)
	if err != nil {
	if !apierrors.IsNotFound(err) {
	return fmt.Errorf("failed to get sub namespace %s/%s: %w", ns.Name, parent.Name, err)
	}
	} else {
	for k, v := range subNS.Spec.Labels {
	if ok := r.matchSubNamespaceLabelKey(k); ok {
	ns.Labels[k] = v
	}
	}
	for k, v := range subNS.Spec.Annotations {
	if ok := r.matchSubNamespaceAnnotationKey(k); ok {
	if ns.Annotations == nil {
	ns.Annotations = make(map[string]string)
	}
	ns.Annotations[k] = v
	}
	}
	}
	}

But I still think the precedence should be clearly documented (and tested) as a commitment to the current behavior.

How

• Document that SubNamespace annotations/labels will take precedence over any labels/annotations propagated from parent-NS to sub-NS.
• Add tests for this behavior (if not already exists)

Checklist

• Finish implementation of the issue
• Test all functions
• Have enough logs to trace activities
• Notify developers of necessary actions