pkg/internal/predicate: refactor DependentPredicate (#3365)

Author: joelanford

predicate/dependent.go

@@ -0,0 +1,101 @@
+// Copyright 2019 The Operator-SDK Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package predicate
+
+import (
+	"reflect"
+
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	"sigs.k8s.io/controller-runtime/pkg/event"
+	logf "sigs.k8s.io/controller-runtime/pkg/log"
+	"sigs.k8s.io/controller-runtime/pkg/predicate"
+)
+
+var log = logf.Log.WithName("predicate")
+
+var _ predicate.Predicate = DependentPredicate{}
+
+// DependentPredicate is a predicate that filters events for resources
+// created as dependents of a primary resource. It follows the following
+// rules:
+//
+//   - Create events are ignored because it is assumed that the controller
+//     reconciling the parent is the client creating the dependent
+//     resources.
+//   - Update events that change only the dependent resource status are
+//     ignored because it is not typical for the controller of a primary
+//     resource to write to the status of one its dependent resources.
+//   - Deletion events are always handled because a controller will
+//     typically want to recreate deleted dependent resources if the
+//     primary resource is not deleted.
+//   - Generic events are ignored.
+//
+// DependentPredicate is most often used in conjunction with
+// controller-runtime's handler.EnqueueRequestForOwner
+type DependentPredicate struct {
+	predicate.Funcs
+}
+
+// Create filters out all events. It assumes that the controller
+// reconciling the parent is the only client creating the dependent
+// resources.
+func (DependentPredicate) Create(e event.CreateEvent) bool {
+	o := e.Object.(*unstructured.Unstructured)
+	log.V(1).Info("Skipping reconciliation for dependent resource creation",
+		"name", o.GetName(), "namespace", o.GetNamespace(), "apiVersion",
+		o.GroupVersionKind().GroupVersion(), "kind", o.GroupVersionKind().Kind)
+	return false
+}
+
+// Delete passes all events through. This allows the controller to
+// recreate deleted dependent resources if the primary resource is
+// not deleted.
+func (DependentPredicate) Delete(e event.DeleteEvent) bool {
+	o := e.Object.(*unstructured.Unstructured)
+	log.V(1).Info("Reconciling due to dependent resource deletion",
+		"name", o.GetName(), "namespace", o.GetNamespace(), "apiVersion",
+		o.GroupVersionKind().GroupVersion(), "kind", o.GroupVersionKind().Kind)
+	return true
+}
+
+// Generic filters out all events.
+func (DependentPredicate) Generic(e event.GenericEvent) bool {
+	o := e.Object.(*unstructured.Unstructured)
+	log.V(1).Info("Skipping reconcile due to generic event", "name", o.GetName(),
+		"namespace", o.GetNamespace(), "apiVersion", o.GroupVersionKind().GroupVersion(),
+		"kind", o.GroupVersionKind().Kind)
+	return false
+}
+
+// Update filters out events that change only the dependent resource
+// status. It is not typical for the controller of a primary
+// resource to write to the status of one its dependent resources.
+func (DependentPredicate) Update(e event.UpdateEvent) bool {
+	old := e.ObjectOld.(*unstructured.Unstructured).DeepCopy()
+	new := e.ObjectNew.(*unstructured.Unstructured).DeepCopy()
+
+	delete(old.Object, "status")
+	delete(new.Object, "status")
+	old.SetResourceVersion("")
+	new.SetResourceVersion("")
+
+	if reflect.DeepEqual(old.Object, new.Object) {
+		return false
+	}
+	log.V(1).Info("Reconciling due to dependent resource update",
+		"name", new.GetName(), "namespace", new.GetNamespace(), "apiVersion",
+		new.GroupVersionKind().GroupVersion(), "kind", new.GroupVersionKind().Kind)
+	return true
+}