gracefully shutdown apiserver after all non-long running requests finish

cmd/kube-apiserver/app/server.go

@@ -156,7 +156,7 @@ func CreateServerChain(runOptions *options.ServerRunOptions, stopCh <-chan struc
 	if len(os.Getenv("KUBE_API_VERSIONS")) > 0 {
 		if insecureServingOptions != nil {
 			insecureHandlerChain := kubeserver.BuildInsecureHandlerChain(kubeAPIServer.GenericAPIServer.UnprotectedHandler(), kubeAPIServerConfig.GenericConfig)
-			if err := kubeserver.NonBlockingRun(insecureServingOptions, insecureHandlerChain, stopCh); err != nil {
+			if err := kubeserver.NonBlockingRun(insecureServingOptions, insecureHandlerChain, kubeAPIServerConfig.GenericConfig.RequestTimeout, stopCh); err != nil {
 				return nil, err
 			}
 		}
@@ -186,7 +186,7 @@ func CreateServerChain(runOptions *options.ServerRunOptions, stopCh <-chan struc
 
 	if insecureServingOptions != nil {
 		insecureHandlerChain := kubeserver.BuildInsecureHandlerChain(aggregatorServer.GenericAPIServer.UnprotectedHandler(), kubeAPIServerConfig.GenericConfig)
-		if err := kubeserver.NonBlockingRun(insecureServingOptions, insecureHandlerChain, stopCh); err != nil {
+		if err := kubeserver.NonBlockingRun(insecureServingOptions, insecureHandlerChain, kubeAPIServerConfig.GenericConfig.RequestTimeout, stopCh); err != nil {
 			return nil, err
 		}
 	}
@@ -488,6 +488,7 @@ func BuildGenericConfig(s *options.ServerRunOptions, proxyTransport *http.Transp
 	if err != nil {
 		return nil, nil, nil, nil, nil, fmt.Errorf("failed to initialize admission: %v", err)
 	}
+
 	return genericConfig, sharedInformers, versionedInformers, insecureServingOptions, serviceResolver, nil
 }
 

pkg/kubeapiserver/server/insecure_handler.go

@@ -19,6 +19,7 @@ package server
 import (
 	"net"
 	"net/http"
+	"time"
 
 	"github.com/golang/glog"
 
@@ -45,11 +46,12 @@ func BuildInsecureHandlerChain(apiHandler http.Handler, c *server.Config) http.H
 	}
 	handler = genericapifilters.WithAuthentication(handler, c.RequestContextMapper, insecureSuperuser{}, nil)
 	handler = genericfilters.WithCORS(handler, c.CorsAllowedOriginList, nil, nil, nil, "true")
-	handler = genericfilters.WithPanicRecovery(handler)
 	handler = genericfilters.WithTimeoutForNonLongRunningRequests(handler, c.RequestContextMapper, c.LongRunningFunc, c.RequestTimeout)
 	handler = genericfilters.WithMaxInFlightLimit(handler, c.MaxRequestsInFlight, c.MaxMutatingRequestsInFlight, c.RequestContextMapper, c.LongRunningFunc)
+	handler = genericfilters.WithWaitGroup(handler, c.RequestContextMapper, c.LongRunningFunc, c.HandlerChainWaitGroup)
 	handler = genericapifilters.WithRequestInfo(handler, server.NewRequestInfoResolver(c), c.RequestContextMapper)
 	handler = apirequest.WithRequestContext(handler, c.RequestContextMapper)
+	handler = genericfilters.WithPanicRecovery(handler)
 
 	return handler
 }
@@ -84,12 +86,12 @@ func (s *InsecureServingInfo) NewLoopbackClientConfig(token string) (*rest.Confi
 
 // NonBlockingRun spawns the insecure http server. An error is
 // returned if the ports cannot be listened on.
-func NonBlockingRun(insecureServingInfo *InsecureServingInfo, insecureHandler http.Handler, stopCh <-chan struct{}) error {
+func NonBlockingRun(insecureServingInfo *InsecureServingInfo, insecureHandler http.Handler, shutDownTimeout time.Duration, stopCh <-chan struct{}) error {
 	// Use an internal stop channel to allow cleanup of the listeners on error.
 	internalStopCh := make(chan struct{})
 
 	if insecureServingInfo != nil && insecureHandler != nil {
-		if err := serveInsecurely(insecureServingInfo, insecureHandler, internalStopCh); err != nil {
+		if err := serveInsecurely(insecureServingInfo, insecureHandler, shutDownTimeout, internalStopCh); err != nil {
 			close(internalStopCh)
 			return err
 		}
@@ -109,7 +111,7 @@ func NonBlockingRun(insecureServingInfo *InsecureServingInfo, insecureHandler ht
 // serveInsecurely run the insecure http server. It fails only if the initial listen
 // call fails. The actual server loop (stoppable by closing stopCh) runs in a go
 // routine, i.e. serveInsecurely does not block.
-func serveInsecurely(insecureServingInfo *InsecureServingInfo, insecureHandler http.Handler, stopCh <-chan struct{}) error {
+func serveInsecurely(insecureServingInfo *InsecureServingInfo, insecureHandler http.Handler, shutDownTimeout time.Duration, stopCh <-chan struct{}) error {
 	insecureServer := &http.Server{
 		Addr:           insecureServingInfo.BindAddress,
 		Handler:        insecureHandler,
@@ -117,7 +119,7 @@ func serveInsecurely(insecureServingInfo *InsecureServingInfo, insecureHandler h
 	}
 	glog.Infof("Serving insecurely on %s", insecureServingInfo.BindAddress)
 	var err error
-	_, err = server.RunServer(insecureServer, insecureServingInfo.BindNetwork, stopCh)
+	_, err = server.RunServer(insecureServer, insecureServingInfo.BindNetwork, shutDownTimeout, stopCh)
 	return err
 }
 

staging/src/k8s.io/apiserver/pkg/server/config.go

@@ -36,6 +36,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/serializer"
 	"k8s.io/apimachinery/pkg/util/sets"
+	utilwaitgroup "k8s.io/apimachinery/pkg/util/waitgroup"
 	"k8s.io/apimachinery/pkg/version"
 	"k8s.io/apiserver/pkg/admission"
 	"k8s.io/apiserver/pkg/audit"
@@ -128,6 +129,8 @@ type Config struct {
 
 	// BuildHandlerChainFunc allows you to build custom handler chains by decorating the apiHandler.
 	BuildHandlerChainFunc func(apiHandler http.Handler, c *Config) (secure http.Handler)
+	// HandlerChainWaitGroup allows you to wait for all chain handlers exit after the server shutdown.
+	HandlerChainWaitGroup *utilwaitgroup.SafeWaitGroup
 	// DiscoveryAddresses is used to build the IPs pass to discovery. If nil, the ExternalAddress is
 	// always reported
 	DiscoveryAddresses discovery.Addresses
@@ -236,6 +239,7 @@ func NewConfig(codecs serializer.CodecFactory) *Config {
 		ReadWritePort:                443,
 		RequestContextMapper:         apirequest.NewRequestContextMapper(),
 		BuildHandlerChainFunc:        DefaultBuildHandlerChain,
+		HandlerChainWaitGroup:        new(utilwaitgroup.SafeWaitGroup),
 		LegacyAPIGroupPrefixes:       sets.NewString(DefaultLegacyAPIPrefix),
 		DisabledPostStartHooks:       sets.NewString(),
 		HealthzChecks:                []healthz.HealthzChecker{healthz.PingHealthz},
@@ -446,8 +450,10 @@ func (c completedConfig) New(name string, delegationTarget DelegationTarget) (*G
 		Serializer:             c.Serializer,
 		AuditBackend:           c.AuditBackend,
 		delegationTarget:       delegationTarget,
+		HandlerChainWaitGroup:  c.HandlerChainWaitGroup,
 
 		minRequestTimeout: time.Duration(c.MinRequestTimeout) * time.Second,
+		ShutdownTimeout:   c.RequestTimeout,
 
 		SecureServingInfo: c.SecureServingInfo,
 		ExternalAddress:   c.ExternalAddress,
@@ -488,6 +494,7 @@ func (c completedConfig) New(name string, delegationTarget DelegationTarget) (*G
 			return nil, err
 		}
 	}
+
 	for _, delegateCheck := range delegationTarget.HealthzChecks() {
 		skip := false
 		for _, existingCheck := range c.HealthzChecks {
@@ -535,6 +542,7 @@ func DefaultBuildHandlerChain(apiHandler http.Handler, c *Config) http.Handler {
 	handler = genericapifilters.WithAuthentication(handler, c.RequestContextMapper, c.Authenticator, failedHandler)
 	handler = genericfilters.WithCORS(handler, c.CorsAllowedOriginList, nil, nil, nil, "true")
 	handler = genericfilters.WithTimeoutForNonLongRunningRequests(handler, c.RequestContextMapper, c.LongRunningFunc, c.RequestTimeout)
+	handler = genericfilters.WithWaitGroup(handler, c.RequestContextMapper, c.LongRunningFunc, c.HandlerChainWaitGroup)
 	handler = genericapifilters.WithRequestInfo(handler, c.RequestInfoResolver, c.RequestContextMapper)
 	handler = apirequest.WithRequestContext(handler, c.RequestContextMapper)
 	handler = genericfilters.WithPanicRecovery(handler)

staging/src/k8s.io/apiserver/pkg/server/filters/waitgroup.go

+/*
+Copyright 2017 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 filters
+
+import (
+	"net/http"
+
+	utilwaitgroup "k8s.io/apimachinery/pkg/util/waitgroup"
+	apirequest "k8s.io/apiserver/pkg/endpoints/request"
+)
+
+// WithWaitGroup adds all non long-running requests to wait group, which is used for graceful shutdown.
+func WithWaitGroup(handler http.Handler, requestContextMapper apirequest.RequestContextMapper, longRunning apirequest.LongRunningRequestCheck, wg *utilwaitgroup.SafeWaitGroup) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		ctx, ok := requestContextMapper.Get(req)
+		if !ok {
+			// if this happens, the handler chain isn't setup correctly because there is no context mapper
+			handler.ServeHTTP(w, req)
+			return
+		}
+
+		requestInfo, ok := apirequest.RequestInfoFrom(ctx)
+		if !ok {
+			// if this happens, the handler chain isn't setup correctly because there is no request info
+			handler.ServeHTTP(w, req)
+			return
+		}
+
+		if !longRunning(req, requestInfo) {
+			if err := wg.Add(1); err != nil {
+				http.Error(w, "Apisever is shutting down.", http.StatusInternalServerError)
+				return
+			}
+			defer wg.Done()
+		}
+
+		handler.ServeHTTP(w, req)
+	})
+}

staging/src/k8s.io/apiserver/pkg/server/genericapiserver.go

@@ -34,6 +34,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/runtime/serializer"
 	"k8s.io/apimachinery/pkg/util/sets"
+	utilwaitgroup "k8s.io/apimachinery/pkg/util/waitgroup"
 	"k8s.io/apiserver/pkg/admission"
 	"k8s.io/apiserver/pkg/audit"
 	genericapi "k8s.io/apiserver/pkg/endpoints"
@@ -83,6 +84,10 @@ type GenericAPIServer struct {
 	// minRequestTimeout is how short the request timeout can be.  This is used to build the RESTHandler
 	minRequestTimeout time.Duration
 
+	// ShutdownTimeout is the timeout used for server shutdown. This specifies the timeout before server
+	// gracefully shutdown returns.
+	ShutdownTimeout time.Duration
+
 	// legacyAPIGroupPrefixes is used to set up URL parsing for authorization and for validating requests
 	// to InstallLegacyAPIGroup
 	legacyAPIGroupPrefixes sets.String
@@ -146,6 +151,9 @@ type GenericAPIServer struct {
 
 	// delegationTarget is the next delegate in the chain or nil
 	delegationTarget DelegationTarget
+
+	// HandlerChainWaitGroup allows you to wait for all chain handlers finish after the server shutdown.
+	HandlerChainWaitGroup *utilwaitgroup.SafeWaitGroup
 }
 
 // DelegationTarget is an interface which allows for composition of API servers with top level handling that works
@@ -275,16 +283,28 @@ func (s preparedGenericAPIServer) Run(stopCh <-chan struct{}) error {
 
 	<-stopCh
 
-	return s.RunPreShutdownHooks()
+	err = s.RunPreShutdownHooks()
+	if err != nil {
+		return err
+	}
+
+	// Wait for all requests to finish, which are bounded by the RequestTimeout variable.
+	s.HandlerChainWaitGroup.Wait()
+
+	return nil
 }
 
 // NonBlockingRun spawns the secure http server. An error is
 // returned if the secure port cannot be listened on.
 func (s preparedGenericAPIServer) NonBlockingRun(stopCh <-chan struct{}) error {
+	// Use an stop channel to allow graceful shutdown without dropping audit events
+	// after http server shutdown.
+	auditStopCh := make(chan struct{})
+
 	// Start the audit backend before any request comes in. This means we must call Backend.Run
 	// before http server start serving. Otherwise the Backend.ProcessEvents call might block.
 	if s.AuditBackend != nil {
-		if err := s.AuditBackend.Run(stopCh); err != nil {
+		if err := s.AuditBackend.Run(auditStopCh); err != nil {
 			return fmt.Errorf("failed to run the audit backend: %v", err)
 		}
 	}
@@ -305,6 +325,8 @@ func (s preparedGenericAPIServer) NonBlockingRun(stopCh <-chan struct{}) error {
 	go func() {
 		<-stopCh
 		close(internalStopCh)
+		s.HandlerChainWaitGroup.Wait()
+		close(auditStopCh)
 	}()
 
 	s.RunPostStartHooks(stopCh)

staging/src/k8s.io/apiserver/pkg/server/genericapiserver_test.go

@@ -25,6 +25,8 @@ import (
 	"net/http"
 	"net/http/httptest"
 	goruntime "runtime"
+	"strconv"
+	"sync"
 	"testing"
 	"time"
 
@@ -44,8 +46,11 @@ import (
 	"k8s.io/apiserver/pkg/authentication/user"
 	"k8s.io/apiserver/pkg/authorization/authorizer"
 	"k8s.io/apiserver/pkg/endpoints/discovery"
+	genericapifilters "k8s.io/apiserver/pkg/endpoints/filters"
+	apirequest "k8s.io/apiserver/pkg/endpoints/request"
 	genericapirequest "k8s.io/apiserver/pkg/endpoints/request"
 	"k8s.io/apiserver/pkg/registry/rest"
+	genericfilters "k8s.io/apiserver/pkg/server/filters"
 	etcdtesting "k8s.io/apiserver/pkg/storage/etcd/testing"
 	"k8s.io/client-go/informers"
 	"k8s.io/client-go/kubernetes/fake"
@@ -509,3 +514,75 @@ func fakeVersion() version.Info {
 		Platform:     fmt.Sprintf("%s/%s", goruntime.GOOS, goruntime.GOARCH),
 	}
 }
+
+// TestGracefulShutdown verifies server shutdown after request handler finish.
+func TestGracefulShutdown(t *testing.T) {
+	etcdserver, config, _ := setUp(t)
+	defer etcdserver.Terminate(t)
+
+	var graceShutdown bool
+	wg := sync.WaitGroup{}
+	wg.Add(1)
+
+	config.BuildHandlerChainFunc = func(apiHandler http.Handler, c *Config) http.Handler {
+		handler := genericfilters.WithWaitGroup(apiHandler, c.RequestContextMapper, c.LongRunningFunc, c.HandlerChainWaitGroup)
+		handler = genericapifilters.WithRequestInfo(handler, c.RequestInfoResolver, c.RequestContextMapper)
+		handler = apirequest.WithRequestContext(handler, c.RequestContextMapper)
+		return handler
+	}
+
+	handler := http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		wg.Done()
+		time.Sleep(2 * time.Second)
+		w.WriteHeader(http.StatusOK)
+		graceShutdown = true
+	})
+
+	s, err := config.Complete(nil).New("test", EmptyDelegate)
+	if err != nil {
+		t.Fatalf("Error in bringing up the server: %v", err)
+	}
+
+	s.Handler.NonGoRestfulMux.Handle("/test", handler)
+
+	insecureServer := &http.Server{
+		Addr:    "0.0.0.0:0",
+		Handler: s.Handler,
+	}
+	stopCh := make(chan struct{})
+	serverPort, err := RunServer(insecureServer, "tcp", 10*time.Second, stopCh)
+	if err != nil {
+		t.Errorf("RunServer err: %v", err)
+	}
+
+	graceCh := make(chan struct{})
+	// mock a client request
+	go func() {
+		resp, err := http.Get("http://127.0.0.1:" + strconv.Itoa(serverPort) + "/test")
+		if err != nil {
+			t.Errorf("Unexpected http error: %v", err)
+		}
+		if resp.StatusCode != http.StatusOK {
+			t.Errorf("Unexpected http status code: %v", resp.StatusCode)
+		}
+		close(graceCh)
+	}()
+
+	// close stopCh after request sent to server to guarantee request handler is running.
+	wg.Wait()
+	close(stopCh)
+	// wait for wait group handler finish
+	s.HandlerChainWaitGroup.Wait()
+
+	// check server all handlers finished.
+	if !graceShutdown {
+		t.Errorf("server shutdown not gracefully.")
+	}
+	// check client to make sure receive response.
+	select {
+	case <-graceCh:
+		t.Logf("server shutdown gracefully.")
+	case <-time.After(30 * time.Second):
+		t.Errorf("Timed out waiting for response.")
+	}
+}

staging/src/k8s.io/apiserver/pkg/server/serve.go

@@ -17,6 +17,7 @@ limitations under the License.
 package server
 
 import (
+	"context"
 	"crypto/tls"
 	"crypto/x509"
 	"fmt"
@@ -84,13 +85,13 @@ func (s *GenericAPIServer) serveSecurely(stopCh <-chan struct{}) error {
 
 	glog.Infof("Serving securely on %s", s.SecureServingInfo.BindAddress)
 	var err error
-	s.effectiveSecurePort, err = RunServer(secureServer, s.SecureServingInfo.BindNetwork, stopCh)
+	s.effectiveSecurePort, err = RunServer(secureServer, s.SecureServingInfo.BindNetwork, s.ShutdownTimeout, stopCh)
 	return err
 }
 
 // RunServer listens on the given port, then spawns a go-routine continuously serving
 // until the stopCh is closed. The port is returned. This function does not block.
-func RunServer(server *http.Server, network string, stopCh <-chan struct{}) (int, error) {
+func RunServer(server *http.Server, network string, shutDownTimeout time.Duration, stopCh <-chan struct{}) (int, error) {
 	if len(server.Addr) == 0 {
 		return 0, errors.New("address cannot be empty")
 	}
@@ -111,10 +112,12 @@ func RunServer(server *http.Server, network string, stopCh <-chan struct{}) (int
 		return 0, fmt.Errorf("invalid listen address: %q", ln.Addr().String())
 	}
 
-	// Stop the server by closing the listener
+	// Shutdown server gracefully.
 	go func() {
 		<-stopCh
-		ln.Close()
+		ctx, cancel := context.WithTimeout(context.Background(), shutDownTimeout)
+		server.Shutdown(ctx)
+		cancel()
 	}()
 
 	go func() {