✨ add EnqueueRequestForAnnotation enqueues Requests based on the presence of an annotation to watch resources

examples/annotationbasedwatch/controller.go

@@ -0,0 +1,113 @@
+/*
+Copyright 2018 The Kubernetes 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 main
+
+import (
+	"context"
+	"github.com/go-logr/logr"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"sigs.k8s.io/controller-runtime/pkg/handler"
+
+	appsv1 "k8s.io/api/apps/v1"
+	corev1 "k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/api/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/types"
+
+	"sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/controller-runtime/pkg/reconcile"
+)
+
+// reconcileReplicaSet reconciles ReplicaSets
+type reconcileReplicaSet struct {
+	// client can be used to retrieve objects from the APIServer.
+	client client.Client
+	log    logr.Logger
+}
+
+// Implement reconcile.Reconciler so the controller can reconcile objects
+var _ reconcile.Reconciler = &reconcileReplicaSet{}
+
+func (r *reconcileReplicaSet) Reconcile(request reconcile.Request) (reconcile.Result, error) {
+	// set up a convenient log object so we don't have to type request over and over again
+	log := r.log.WithValues("request", request)
+
+	// Fetch the ReplicaSet from the cache
+	rs := &appsv1.ReplicaSet{}
+	err := r.client.Get(context.TODO(), request.NamespacedName, rs)
+	if errors.IsNotFound(err) {
+		log.Error(nil, "Could not find ReplicaSet")
+		return reconcile.Result{}, nil
+	}
+
+	if err != nil {
+		log.Error(err, "Could not fetch ReplicaSet")
+		return reconcile.Result{}, err
+	}
+
+	// Print the ReplicaSet
+	log.Info("Reconciling ReplicaSet", "container name", rs.Spec.Template.Spec.Containers[0].Name)
+
+	// Check if the Pod already exists, if not create a new one
+	podRs := &corev1.Pod{}
+	err = r.client.Get(context.TODO(), types.NamespacedName{Name: rs.Name, Namespace: rs.Namespace}, podRs)
+	if err != nil && errors.IsNotFound(err) {
+		// Define a new Deployment
+		pod := r.podForReplicasetWithWatchAnnotations(rs)
+		err = r.client.Create(context.TODO(), pod)
+		if err != nil {
+			log.Error(err, "Failed to create new Pod.", "Pod.Namespace", pod.Namespace, "Pod.Name", pod.Name)
+			return reconcile.Result{}, err
+		}
+		return reconcile.Result{Requeue: true}, nil
+	} else if err != nil {
+		log.Error(err, "Failed to get Pod.")
+		return reconcile.Result{}, err
+	}
+
+	// Set the label if it is missing
+	if rs.Labels == nil {
+		rs.Labels = map[string]string{}
+	}
+
+	if rs.Labels["hello"] == "world" {
+		return reconcile.Result{}, nil
+	}
+
+	// Update the ReplicaSet
+	rs.Labels["hello"] = "world"
+	err = r.client.Update(context.TODO(), rs)
+	if err != nil {
+		log.Error(err, "Could not write ReplicaSet")
+		return reconcile.Result{}, err
+	}
+
+	return reconcile.Result{}, nil
+}
+
+// podForReplicasetWithWatchAnnotations returns a pod object with the annotations required to be watched with.
+func (r *reconcileReplicaSet) podForReplicasetWithWatchAnnotations(rs *appsv1.ReplicaSet) *corev1.Pod {
+	pod := &corev1.Pod{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      rs.Name,
+			Namespace: rs.Namespace,
+		},
+	}
+	annotation := schema.GroupKind{Group: "ReplicaSet", Kind: "apps"}
+	handler.SetWatchOwnerAnnotation(rs,pod, annotation)
+	return pod
+}

examples/annotationbasedwatch/main.go

@@ -0,0 +1,98 @@
+/*
+Copyright 2018 The Kubernetes 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 main
+
+import (
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"os"
+
+	corev1 "k8s.io/api/core/v1"
+	rbacv1 "k8s.io/api/rbac/v1"
+	_ "k8s.io/client-go/plugin/pkg/client/auth/gcp"
+	"sigs.k8s.io/controller-runtime/pkg/client/config"
+	"sigs.k8s.io/controller-runtime/pkg/controller"
+	"sigs.k8s.io/controller-runtime/pkg/handler"
+	logf "sigs.k8s.io/controller-runtime/pkg/log"
+	"sigs.k8s.io/controller-runtime/pkg/log/zap"
+	"sigs.k8s.io/controller-runtime/pkg/manager"
+	"sigs.k8s.io/controller-runtime/pkg/manager/signals"
+	"sigs.k8s.io/controller-runtime/pkg/source"
+)
+
+var log = logf.Log.WithName("example-annotationbasedwatch")
+
+func main() {
+	logf.SetLogger(zap.Logger(false))
+	entryLog := log.WithName("entrypoint")
+
+	// Setup a Manager
+	entryLog.Info("setting up manager")
+	mgr, err := manager.New(config.GetConfigOrDie(), manager.Options{})
+	if err != nil {
+		entryLog.Error(err, "unable to set up overall controller manager")
+		os.Exit(1)
+	}
+
+	// Setup a new controller to reconcile ReplicaSets
+	entryLog.Info("Setting up controller")
+	c, err := controller.New("foo-controller", mgr, controller.Options{
+		Reconciler: &reconcileReplicaSet{client: mgr.GetClient(), log: log.WithName("reconciler")},
+	})
+	if err != nil {
+		entryLog.Error(err, "unable to set up individual controller")
+		os.Exit(1)
+	}
+
+	// Watch Pods that has the following annotations:
+	// ...
+	// annotations:
+	//    watch.kubebuilder.io/owner-namespaced-name:my-namespace/my-replicaset
+	//    watch.kubebuilder.io/owner-type:apps.ReplicaSet
+	// ...
+	// It will enqueue a Request to the primary-resource-namespace when some change occurs in a Pod resource with these
+	// annotations
+	annotation := schema.GroupKind{Group: "ReplicaSet", Kind: "apps"}
+	if err := c.Watch(&source.Kind{Type: &corev1.Pod{}}, &handler.EnqueueRequestForAnnotation{annotation}); err != nil {
+		entryLog.Error(err, "unable to watch Pods")
+		os.Exit(1)
+	}
+
+	// Watch ClusterRoles that has the following annotations:
+	// ...
+	// annotations:
+	//    watch.kubebuilder.io/owner-namespaced-name:my-namespace/my-replicaset
+	//    watch.kubebuilder.io/owner-type:apps.ReplicaSet
+	// ...
+	// It will enqueue a Request to the primary-resource-namespace when some change occurs in a ClusterRole resource with these
+	// annotations
+	if err := c.Watch(&source.Kind{
+		// Watch cluster roles
+		Type: &rbacv1.ClusterRole{}},
+
+		// Enqueue ReplicaSet reconcile requests using the
+		// namespacedName annotation value in the request.
+		&handler.EnqueueRequestForAnnotation{schema.GroupKind{Group:"ReplicaSet", Kind:"apps"}}); err != nil {
+		entryLog.Error(err, "unable to watch Cluster Role")
+		os.Exit(1)
+	}
+
+	entryLog.Info("starting manager")
+	if err := mgr.Start(signals.SetupSignalHandler()); err != nil {
+		entryLog.Error(err, "unable to run manager")
+		os.Exit(1)
+	}
+}