Adding panic-safe ResourceWatcher

Author: ewoutp

pkg/util/k8sutil/informer.go

@@ -0,0 +1,90 @@
+//
+// DISCLAIMER
+//
+// Copyright 2018 ArangoDB GmbH, Cologne, Germany
+//
+// 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.
+//
+// Copyright holder is ArangoDB GmbH, Cologne, Germany
+//
+// Author Ewout Prangsma
+//
+
+package k8sutil
+
+import (
+	"github.com/rs/zerolog"
+	"k8s.io/apimachinery/pkg/fields"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/client-go/tools/cache"
+)
+
+// ResourceWatcher is a helper to watch for events in a specific type
+// of resource. The handler functions are protected from panics.
+type ResourceWatcher struct {
+	informer cache.Controller
+}
+
+// NewResourceWatcher creates a helper that watches for changes in a resource of a specific type.
+// If wraps the given handler functions, such that panics are caught and logged.
+func NewResourceWatcher(log zerolog.Logger, getter cache.Getter, resource, namespace string,
+	objType runtime.Object, h cache.ResourceEventHandlerFuncs) *ResourceWatcher {
+	source := cache.NewListWatchFromClient(
+		getter,
+		resource,
+		namespace,
+		fields.Everything())
+
+	_, informer := cache.NewIndexerInformer(source, objType, 0, cache.ResourceEventHandlerFuncs{
+		AddFunc: func(obj interface{}) {
+			defer func() {
+				if err := recover(); err != nil {
+					log.Error().Interface("error", err).Msg("Recovered from panic")
+				}
+			}()
+			if h.AddFunc != nil {
+				h.AddFunc(obj)
+			}
+		},
+		UpdateFunc: func(oldObj, newObj interface{}) {
+			defer func() {
+				if err := recover(); err != nil {
+					log.Error().Interface("error", err).Msg("Recovered from panic")
+				}
+			}()
+			if h.UpdateFunc != nil {
+				h.UpdateFunc(oldObj, newObj)
+			}
+		},
+		DeleteFunc: func(obj interface{}) {
+			defer func() {
+				if err := recover(); err != nil {
+					log.Error().Interface("error", err).Msg("Recovered from panic")
+				}
+			}()
+			if h.DeleteFunc != nil {
+				h.DeleteFunc(obj)
+			}
+		},
+	}, cache.Indexers{})
+
+	return &ResourceWatcher{
+		informer: informer,
+	}
+}
+
+// Run continues to watch for events on the selected type of resource
+// until the given channel is closed.
+func (rw *ResourceWatcher) Run(stopCh <-chan struct{}) {
+	rw.informer.Run(stopCh)
+}