Support endpoints event handlers in kube-proxy

pkg/proxy/config/config.go

@@ -60,12 +60,31 @@ type EndpointsConfigHandler interface {
 	OnEndpointsUpdate(endpoints []*api.Endpoints)
 }
 
+// EndpointsHandler is an abstract interface o objects which receive
+// notifications about endpoints object changes.
+type EndpointsHandler interface {
+	// OnEndpointsAdd is called whenever creation of new endpoints object
+	// is observed.
+	OnEndpointsAdd(endpoints *api.Endpoints)
+	// OnEndpointsUpdate is called whenever modification of an existing
+	// endpoints object is observed.
+	OnEndpointsUpdate(oldEndpoints, endpoints *api.Endpoints)
+	// OnEndpointsDelete is called whever deletion of an existing endpoints
+	// object is observed.
+	OnEndpointsDelete(endpoints *api.Endpoints)
+	// OnEndpointsSynced is called once all the initial event handlers were
+	// called and the state is fully propagated to local cache.
+	OnEndpointsSynced()
+}
+
 // EndpointsConfig tracks a set of endpoints configurations.
 // It accepts "set", "add" and "remove" operations of endpoints via channels, and invokes registered handlers on change.
 type EndpointsConfig struct {
-	lister       listers.EndpointsLister
-	listerSynced cache.InformerSynced
-	handlers     []EndpointsConfigHandler
+	lister        listers.EndpointsLister
+	listerSynced  cache.InformerSynced
+	eventHandlers []EndpointsHandler
+	// TODO: Remove handlers by switching them to eventHandlers.
+	handlers []EndpointsConfigHandler
 	// updates channel is used to trigger registered handlers.
 	updates chan struct{}
 	stop    chan struct{}
@@ -101,6 +120,11 @@ func (c *EndpointsConfig) RegisterHandler(handler EndpointsConfigHandler) {
 	c.handlers = append(c.handlers, handler)
 }
 
+// RegisterEventHandler registers a handler which is called on every endpoints change.
+func (c *EndpointsConfig) RegisterEventHandler(handler EndpointsHandler) {
+	c.eventHandlers = append(c.eventHandlers, handler)
+}
+
 // Run starts the goroutine responsible for calling registered handlers.
 func (c *EndpointsConfig) Run(stopCh <-chan struct{}) {
 	if !cache.WaitForCacheSync(stopCh, c.listerSynced) {
@@ -111,6 +135,10 @@ func (c *EndpointsConfig) Run(stopCh <-chan struct{}) {
 	// We have synced informers. Now we can start delivering updates
 	// to the registered handler.
 	go func() {
+		for i := range c.eventHandlers {
+			glog.V(3).Infof("Calling handler.OnEndpointsSynced()")
+			c.eventHandlers[i].OnEndpointsSynced()
+		}
 		for {
 			select {
 			case <-c.updates:
@@ -140,15 +168,54 @@ func (c *EndpointsConfig) Run(stopCh <-chan struct{}) {
 	}()
 }
 
-func (c *EndpointsConfig) handleAddEndpoints(_ interface{}) {
+func (c *EndpointsConfig) handleAddEndpoints(obj interface{}) {
+	endpoints, ok := obj.(*api.Endpoints)
+	if !ok {
+		utilruntime.HandleError(fmt.Errorf("unexpected object type: %v", obj))
+		return
+	}
+	for i := range c.eventHandlers {
+		glog.V(4).Infof("Calling handler.OnEndpointsAdd")
+		c.eventHandlers[i].OnEndpointsAdd(endpoints)
+	}
 	c.dispatchUpdate()
 }
 
-func (c *EndpointsConfig) handleUpdateEndpoints(_, _ interface{}) {
+func (c *EndpointsConfig) handleUpdateEndpoints(oldObj, newObj interface{}) {
+	oldEndpoints, ok := oldObj.(*api.Endpoints)
+	if !ok {
+		utilruntime.HandleError(fmt.Errorf("unexpected object type: %v", oldObj))
+		return
+	}
+	endpoints, ok := newObj.(*api.Endpoints)
+	if !ok {
+		utilruntime.HandleError(fmt.Errorf("unexpected object type: %v", newObj))
+		return
+	}
+	for i := range c.eventHandlers {
+		glog.V(4).Infof("Calling handler.OnEndpointsUpdate")
+		c.eventHandlers[i].OnEndpointsUpdate(oldEndpoints, endpoints)
+	}
 	c.dispatchUpdate()
 }
 
-func (c *EndpointsConfig) handleDeleteEndpoints(_ interface{}) {
+func (c *EndpointsConfig) handleDeleteEndpoints(obj interface{}) {
+	endpoints, ok := obj.(*api.Endpoints)
+	if !ok {
+		tombstone, ok := obj.(cache.DeletedFinalStateUnknown)
+		if !ok {
+			utilruntime.HandleError(fmt.Errorf("unexpected object type: %v", obj))
+			return
+		}
+		if endpoints, ok = tombstone.Obj.(*api.Endpoints); !ok {
+			utilruntime.HandleError(fmt.Errorf("unexpected object type: %v", obj))
+			return
+		}
+	}
+	for i := range c.eventHandlers {
+		glog.V(4).Infof("Calling handler.OnEndpointsUpdate")
+		c.eventHandlers[i].OnEndpointsDelete(endpoints)
+	}
 	c.dispatchUpdate()
 }