remove deprecated field mgr before apply patch

in the case that we have a deprecated field manager that we
need to remove, if the Patch() were to fail that code path
would not execute. To move it before the Patch() we also
have to do one Get() to know if the removal is neccessary.

this was uncovered while debugging this upgrade problem:

JIRA: https://issues.redhat.com/browse/OCPBUGS-22293

Signed-off-by: Jamo Luhrsen <jluhrsen@gmail.com>

pkg/apply/apply.go

@@ -125,29 +125,37 @@ func ApplyObject(ctx context.Context, client cnoclient.Client, obj Object, subco
 		log.Printf("could not encode %s for apply", objDesc)
 		return fmt.Errorf("could not encode for patching: %w", err)
 	}
-	us, err := clusterClient.Dynamic().Resource(rm.Resource).Namespace(namespace).Patch(ctx, name, types.ApplyPatchType, data, patchOptions, subresources...)
-	if err != nil {
-		return fmt.Errorf("failed to apply / update %s: %w", objDesc, err)
-	}
-
 	// consider removing in OCP 4.18 when we know field manager 'cluster-network-operator' no longer possibly
 	// exists in any object from all upgrade paths
+	// Retrieve the current state of the resource
 	if isDepFieldManagerCleanupNeeded(subcontroller) {
-		us.SetGroupVersionKind(gvk)
-
-		if doesManagerOpExist(us.GetManagedFields(), depreciatedFieldManager, metav1.ManagedFieldsOperationUpdate,
-			metav1.ManagedFieldsOperationApply) {
-
-			us.SetGroupVersionKind(obj.GetObjectKind().GroupVersionKind())
-			if err = mergeManager(ctx, clusterClient, us, depreciatedFieldManager, fieldManager, rm.Resource); err != nil {
-				klog.Errorf("Failed to merge field managers %q for object %q %s %s: %v", depreciatedFieldManager,
-					gvk.String(), obj.GetNamespace(), obj.GetName(), err)
-			} else {
-				klog.Infof("Depreciated field manager %s for object %q %s %s", depreciatedFieldManager,
-					gvk.String(), obj.GetNamespace(), obj.GetName())
+		us, err := clusterClient.Dynamic().Resource(rm.Resource).Namespace(namespace).Get(ctx, name, metav1.GetOptions{})
+		if err != nil && !apierrors.IsNotFound(err) {
+			return fmt.Errorf("failed to get current state of %s: %w", objDesc, err)
+		}
+		if us != nil {
+			us.SetGroupVersionKind(gvk)
+
+			if doesManagerOpExist(us.GetManagedFields(), depreciatedFieldManager, metav1.ManagedFieldsOperationUpdate,
+				metav1.ManagedFieldsOperationApply) {
+
+				us.SetGroupVersionKind(obj.GetObjectKind().GroupVersionKind())
+				if err = mergeManager(ctx, clusterClient, us, depreciatedFieldManager, fieldManager, rm.Resource); err != nil {
+					klog.Errorf("Failed to merge field managers %q for object %q %s %s: %v", depreciatedFieldManager,
+						gvk.String(), obj.GetNamespace(), obj.GetName(), err)
+				} else {
+					klog.Infof("Depreciated field manager %s for object %q %s %s", depreciatedFieldManager,
+						gvk.String(), obj.GetNamespace(), obj.GetName())
+				}
 			}
 		}
 	}
+
+	_, err = clusterClient.Dynamic().Resource(rm.Resource).Namespace(namespace).Patch(ctx, name, types.ApplyPatchType, data, patchOptions, subresources...)
+	if err != nil {
+		return fmt.Errorf("failed to apply / update %s: %w", objDesc, err)
+	}
+
 	log.Printf("Apply / Create of %s was successful", objDesc)
 	return nil
 }