Cleanup rest storage resources on shutdown

Kubernetes-commit: 0527a0dd453c4b76259389ec8e8e6888c5e2a5ab

pkg/registry/generic/registry/storage_factory.go

@@ -70,9 +70,12 @@ func StorageWithCacher() generic.StorageDecorator {
 		if err != nil {
 			return nil, func() {}, err
 		}
+		var once sync.Once
 		destroyFunc := func() {
+			once.Do(func() {
 				cacher.Stop()
 				d()
+			})
 		}
 
 		// TODO : Remove RegisterStorageCleanup below when PR

pkg/registry/generic/registry/store.go

@@ -217,7 +217,10 @@ type Store struct {
 	// If the StorageVersioner is nil, apiserver will leave the
 	// storageVersionHash as empty in the discovery document.
 	StorageVersioner runtime.GroupVersioner
-	// Called to cleanup clients used by the underlying Storage; optional.
+
+	// DestroyFunc cleans up clients used by the underlying Storage; optional.
+	// If set, DestroyFunc has to be implemented in thread-safe way and
+	// be prepared for being called more than once.
 	DestroyFunc func()
 }
 
@@ -279,6 +282,13 @@ func (e *Store) New() runtime.Object {
 	return e.NewFunc()
 }
 
+// Destroy cleans up its resources on shutdown.
+func (e *Store) Destroy() {
+	if e.DestroyFunc != nil {
+		e.DestroyFunc()
+	}
+}
+
 // NewList implements rest.Lister.
 func (e *Store) NewList() runtime.Object {
 	return e.NewListFunc()
@@ -1433,11 +1443,14 @@ func (e *Store) CompleteWithOptions(options *generic.StoreOptions) error {
 		if opts.CountMetricPollPeriod > 0 {
 			stopFunc := e.startObservingCount(opts.CountMetricPollPeriod, opts.StorageObjectCountTracker)
 			previousDestroy := e.DestroyFunc
+			var once sync.Once
 			e.DestroyFunc = func() {
+				once.Do(func() {
 					stopFunc()
 					if previousDestroy != nil {
 						previousDestroy()
 					}
+				})
 			}
 		}
 	}

pkg/server/genericapiserver.go

@@ -89,6 +89,16 @@ type APIGroupInfo struct {
 	StaticOpenAPISpec *spec.Swagger
 }
 
+func (a *APIGroupInfo) destroyStorage() {
+	for _, stores := range a.VersionedResourcesStorageMap {
+		for _, store := range stores {
+			// TODO(wojtek-t): Uncomment once all storage support it.
+			klog.Errorf("Destroying storage: %v", store)
+			// store.Destroy()
+		}
+	}
+}
+
 // GenericAPIServer contains state for a Kubernetes cluster api server.
 type GenericAPIServer struct {
 	// discoveryAddresses is used to build cluster IPs for discovery.
@@ -222,6 +232,9 @@ type GenericAPIServer struct {
 	// lifecycleSignals provides access to the various signals that happen during the life cycle of the apiserver.
 	lifecycleSignals lifecycleSignals
 
+	// destroyFns contains a list of functions that should be called on shutdown to clean up resources.
+	destroyFns []func()
+
 	// muxAndDiscoveryCompleteSignals holds signals that indicate all known HTTP paths have been registered.
 	// it exists primarily to avoid returning a 404 response when a resource actually exists but we haven't installed the path to a handler.
 	// it is exposed for easier composition of the individual servers.
@@ -264,6 +277,11 @@ type DelegationTarget interface {
 
 	// MuxAndDiscoveryCompleteSignals exposes registered signals that indicate if all known HTTP paths have been installed.
 	MuxAndDiscoveryCompleteSignals() map[string]<-chan struct{}
+
+	// Destroy cleans up its resources on shutdown.
+	// Destroy has to be implemented in thread-safe way and be prepared
+	// for being called more than once.
+	Destroy()
 }
 
 func (s *GenericAPIServer) UnprotectedHandler() http.Handler {
@@ -301,6 +319,18 @@ func (s *GenericAPIServer) MuxAndDiscoveryCompleteSignals() map[string]<-chan st
 	return s.muxAndDiscoveryCompleteSignals
 }
 
+// Destroy cleans up all its and its delegation target resources on shutdown.
+// It starts with destroying its own resources and later proceeds with
+// its delegation target.
+func (s *GenericAPIServer) Destroy() {
+	for _, destroyFn := range s.destroyFns {
+		destroyFn()
+	}
+	if s.delegationTarget != nil {
+		s.delegationTarget.Destroy()
+	}
+}
+
 type emptyDelegate struct {
 	// handler is called at the end of the delegation chain
 	// when a request has been made against an unregistered HTTP path the individual servers will simply pass it through until it reaches the handler.
@@ -340,6 +370,8 @@ func (s emptyDelegate) PrepareRun() preparedGenericAPIServer {
 func (s emptyDelegate) MuxAndDiscoveryCompleteSignals() map[string]<-chan struct{} {
 	return map[string]<-chan struct{}{}
 }
+func (s emptyDelegate) Destroy() {
+}
 
 // preparedGenericAPIServer is a private wrapper that enforces a call of PrepareRun() before Run can be invoked.
 type preparedGenericAPIServer struct {
@@ -395,6 +427,9 @@ func (s preparedGenericAPIServer) Run(stopCh <-chan struct{}) error {
 	delayedStopCh := s.lifecycleSignals.AfterShutdownDelayDuration
 	shutdownInitiatedCh := s.lifecycleSignals.ShutdownInitiated
 
+	// Clean up resources on shutdown.
+	defer s.Destroy()
+
 	// spawn a new goroutine for closing the MuxAndDiscoveryComplete signal
 	// registration happens during construction of the generic api server
 	// the last server in the chain aggregates signals from the previous instances
@@ -584,6 +619,8 @@ func (s *GenericAPIServer) installAPIResources(apiPrefix string, apiGroupInfo *A
 		resourceInfos = append(resourceInfos, r...)
 	}
 
+	s.destroyFns = append(s.destroyFns, apiGroupInfo.destroyStorage)
+
 	if utilfeature.DefaultFeatureGate.Enabled(features.StorageVersionAPI) &&
 		utilfeature.DefaultFeatureGate.Enabled(features.APIServerIdentity) {
 		// API installation happens before we start listening on the handlers,
@@ -595,6 +632,9 @@ func (s *GenericAPIServer) installAPIResources(apiPrefix string, apiGroupInfo *A
 	return nil
 }
 
+// InstallLegacyAPIGroup exposes the given legacy api group in the API.
+// The <apiGroupInfo> passed into this function shouldn't be used elsewhere as the
+// underlying storage will be destroyed on this servers shutdown.
 func (s *GenericAPIServer) InstallLegacyAPIGroup(apiPrefix string, apiGroupInfo *APIGroupInfo) error {
 	if !s.legacyAPIGroupPrefixes.Has(apiPrefix) {
 		return fmt.Errorf("%q is not in the allowed legacy API prefixes: %v", apiPrefix, s.legacyAPIGroupPrefixes.List())
@@ -616,7 +656,9 @@ func (s *GenericAPIServer) InstallLegacyAPIGroup(apiPrefix string, apiGroupInfo
 	return nil
 }
 
-// Exposes given api groups in the API.
+// InstallAPIGroups exposes given api groups in the API.
+// The <apiGroupInfos> passed into this function shouldn't be used elsewhere as the
+// underlying storage will be destroyed on this servers shutdown.
 func (s *GenericAPIServer) InstallAPIGroups(apiGroupInfos ...*APIGroupInfo) error {
 	for _, apiGroupInfo := range apiGroupInfos {
 		// Do not register empty group or empty version.  Doing so claims /apis/ for the wrong entity to be returned.
@@ -669,7 +711,9 @@ func (s *GenericAPIServer) InstallAPIGroups(apiGroupInfos ...*APIGroupInfo) erro
 	return nil
 }
 
-// Exposes the given api group in the API.
+// InstallAPIGroup exposes the given api group in the API.
+// The <apiGroupInfo> passed into this function shouldn't be used elsewhere as the
+// underlying storage will be destroyed on this servers shutdown.
 func (s *GenericAPIServer) InstallAPIGroup(apiGroupInfo *APIGroupInfo) error {
 	return s.InstallAPIGroups(apiGroupInfo)
 }