Decomission: Use Patch + FieldOwner

FieldOwner allows us to identify who maintains a field and detect
if there is a conflict between multiple controllers.

Author: fwiesel

internal/controller/decomission_controller.go

@@ -179,18 +179,19 @@ func (r *NodeDecommissionReconciler) removeFinalizer(ctx context.Context, node *
 
 	nodeBase := node.DeepCopy()
 	controllerutil.RemoveFinalizer(node, decommissionFinalizerName)
-	err := r.Patch(ctx, node, k8sclient.MergeFromWithOptions(nodeBase, k8sclient.MergeFromWithOptimisticLock{}))
+	err := r.Patch(ctx, node, k8sclient.MergeFromWithOptions(nodeBase, k8sclient.MergeFromWithOptimisticLock{}), k8sclient.FieldOwner(DecommissionControllerName))
 	return ctrl.Result{}, err
 }
 
 func (r *NodeDecommissionReconciler) setDecommissioningCondition(ctx context.Context, hv *kvmv1.Hypervisor, message string) (ctrl.Result, error) {
+	base := hv.DeepCopy()
 	meta.SetStatusCondition(&hv.Status.Conditions, metav1.Condition{
 		Type:    kvmv1.ConditionTypeReady,
 		Status:  metav1.ConditionFalse,
 		Reason:  "Decommissioning",
 		Message: message,
 	})
-	if err := r.Status().Update(ctx, hv); err != nil {
+	if err := r.Status().Patch(ctx, hv, k8sclient.MergeFromWithOptions(base, k8sclient.MergeFromWithOptimisticLock{}), k8sclient.FieldOwner(DecommissionControllerName)); err != nil {
 		return ctrl.Result{}, fmt.Errorf("cannot update hypervisor status due to %w", err)
 	}
 	return ctrl.Result{}, nil