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Add EnqueueRequestForAnnotation enqueues Requests based on the presence of an annotation to watch resources
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‎examples/annotationbasedwatch/controller.go

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/*
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Copyright 2018 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package main
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import (
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"context"
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"github.com/go-logr/logr"
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"k8s.io/apimachinery/pkg/runtime/schema"
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"sigs.k8s.io/controller-runtime/pkg/handler"
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appsv1 "k8s.io/api/apps/v1"
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corev1 "k8s.io/api/core/v1"
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"k8s.io/apimachinery/pkg/api/errors"
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metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
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"k8s.io/apimachinery/pkg/types"
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"sigs.k8s.io/controller-runtime/pkg/client"
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"sigs.k8s.io/controller-runtime/pkg/reconcile"
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)
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// reconcileReplicaSet reconciles ReplicaSets
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type reconcileReplicaSet struct {
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// client can be used to retrieve objects from the APIServer.
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client client.Client
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log logr.Logger
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}
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// Implement reconcile.Reconciler so the controller can reconcile objects
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var _ reconcile.Reconciler = &reconcileReplicaSet{}
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func (r *reconcileReplicaSet) Reconcile(request reconcile.Request) (reconcile.Result, error) {
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// set up a convenient log object so we don't have to type request over and over again
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log := r.log.WithValues("request", request)
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// Fetch the ReplicaSet from the cache
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rs := &appsv1.ReplicaSet{}
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err := r.client.Get(context.TODO(), request.NamespacedName, rs)
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if errors.IsNotFound(err) {
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log.Error(nil, "Could not find ReplicaSet")
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return reconcile.Result{}, nil
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}
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if err != nil {
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log.Error(err, "Could not fetch ReplicaSet")
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return reconcile.Result{}, err
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}
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// Print the ReplicaSet
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log.Info("Reconciling ReplicaSet", "container name", rs.Spec.Template.Spec.Containers[0].Name)
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// Check if the Pod already exists, if not create a new one
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podRs := &corev1.Pod{}
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err = r.client.Get(context.TODO(), types.NamespacedName{Name: rs.Name, Namespace: rs.Namespace}, podRs)
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if err != nil && errors.IsNotFound(err) {
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// Define a new Deployment
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pod := r.podForReplicasetWithWatchAnnotations(rs)
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err = r.client.Create(context.TODO(), pod)
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if err != nil {
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log.Error(err, "Failed to create new Pod.", "Pod.Namespace", pod.Namespace, "Pod.Name", pod.Name)
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return reconcile.Result{}, err
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}
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return reconcile.Result{Requeue: true}, nil
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} else if err != nil {
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log.Error(err, "Failed to get Pod.")
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return reconcile.Result{}, err
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}
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// Set the label if it is missing
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if rs.Labels == nil {
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rs.Labels = map[string]string{}
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}
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if rs.Labels["hello"] == "world" {
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return reconcile.Result{}, nil
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}
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// Update the ReplicaSet
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rs.Labels["hello"] = "world"
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err = r.client.Update(context.TODO(), rs)
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if err != nil {
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log.Error(err, "Could not write ReplicaSet")
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return reconcile.Result{}, err
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}
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return reconcile.Result{}, nil
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}
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// podForReplicasetWithWatchAnnotations returns a pod object with the annotations required to be watched with.
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func (r *reconcileReplicaSet) podForReplicasetWithWatchAnnotations(rs *appsv1.ReplicaSet) *corev1.Pod {
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pod := &corev1.Pod{
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ObjectMeta: metav1.ObjectMeta{
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Name: rs.Name,
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Namespace: rs.Namespace,
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},
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}
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annotation := schema.GroupKind{Group: "ReplicaSet", Kind: "apps"}
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handler.SetWatchOwnerAnnotation(rs,pod, annotation)
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return pod
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}

‎examples/annotationbasedwatch/main.go

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/*
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Copyright 2018 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package main
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import (
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"k8s.io/apimachinery/pkg/runtime/schema"
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"os"
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corev1 "k8s.io/api/core/v1"
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rbacv1 "k8s.io/api/rbac/v1"
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_ "k8s.io/client-go/plugin/pkg/client/auth/gcp"
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"sigs.k8s.io/controller-runtime/pkg/client/config"
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"sigs.k8s.io/controller-runtime/pkg/controller"
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"sigs.k8s.io/controller-runtime/pkg/handler"
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logf "sigs.k8s.io/controller-runtime/pkg/log"
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"sigs.k8s.io/controller-runtime/pkg/log/zap"
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"sigs.k8s.io/controller-runtime/pkg/manager"
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"sigs.k8s.io/controller-runtime/pkg/manager/signals"
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"sigs.k8s.io/controller-runtime/pkg/source"
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)
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var log = logf.Log.WithName("example-annotationbasedwatch")
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func main() {
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logf.SetLogger(zap.Logger(false))
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entryLog := log.WithName("entrypoint")
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// Setup a Manager
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entryLog.Info("setting up manager")
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mgr, err := manager.New(config.GetConfigOrDie(), manager.Options{})
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if err != nil {
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entryLog.Error(err, "unable to set up overall controller manager")
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os.Exit(1)
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}
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// Setup a new controller to reconcile ReplicaSets
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entryLog.Info("Setting up controller")
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c, err := controller.New("foo-controller", mgr, controller.Options{
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Reconciler: &reconcileReplicaSet{client: mgr.GetClient(), log: log.WithName("reconciler")},
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})
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if err != nil {
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entryLog.Error(err, "unable to set up individual controller")
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os.Exit(1)
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}
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// Watch Pods that has the following annotations:
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// ...
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// annotations:
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// watch.kubebuilder.io/owner-namespaced-name:my-namespace/my-replicaset
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// watch.kubebuilder.io/owner-type:apps.ReplicaSet
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// ...
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// It will enqueue a Request to the primary-resource-namespace when some change occurs in a Pod resource with these
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// annotations
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annotation := schema.GroupKind{Group: "ReplicaSet", Kind: "apps"}
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if err := c.Watch(&source.Kind{Type: &corev1.Pod{}}, &handler.EnqueueRequestForAnnotation{annotation}); err != nil {
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entryLog.Error(err, "unable to watch Pods")
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os.Exit(1)
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}
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// Watch ClusterRoles that has the following annotations:
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// ...
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// annotations:
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// watch.kubebuilder.io/owner-namespaced-name:my-namespace/my-replicaset
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// watch.kubebuilder.io/owner-type:apps.ReplicaSet
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// ...
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// It will enqueue a Request to the primary-resource-namespace when some change occurs in a ClusterRole resource with these
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// annotations
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if err := c.Watch(&source.Kind{
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// Watch cluster roles
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Type: &rbacv1.ClusterRole{}},
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// Enqueue ReplicaSet reconcile requests using the
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// namespacedName annotation value in the request.
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&handler.EnqueueRequestForAnnotation{schema.GroupKind{Group:"ReplicaSet", Kind:"apps"}}); err != nil {
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entryLog.Error(err, "unable to watch Cluster Role")
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os.Exit(1)
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}
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entryLog.Info("starting manager")
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if err := mgr.Start(signals.SetupSignalHandler()); err != nil {
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entryLog.Error(err, "unable to run manager")
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os.Exit(1)
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}
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}

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