🐛 fix issue when webhook server refreshing cert

pkg/webhook/server.go

@@ -27,6 +27,7 @@ import (
 
 	"k8s.io/apimachinery/pkg/runtime"
 	apitypes "k8s.io/apimachinery/pkg/types"
+	"k8s.io/apimachinery/pkg/util/wait"
 	"sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/controller-runtime/pkg/manager"
 	"sigs.k8s.io/controller-runtime/pkg/runtime/inject"
@@ -36,6 +37,9 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/webhook/types"
 )
 
+// default interval for checking cert is 90 days (~3 months)
+var defaultCertRefreshInterval = 3 * 30 * 24 * time.Hour
+
 // ServerOptions are options for configuring an admission webhook server.
 type ServerOptions struct {
 	// Port is the port number that the server will serve.
@@ -128,6 +132,9 @@ type Server struct {
 	// manager is the manager that this webhook server will be registered.
 	manager manager.Manager
 
+	// httpServer is the actual server that serves the traffic.
+	httpServer *http.Server
+
 	once sync.Once
 }
 
@@ -209,21 +216,21 @@ func (s *Server) Start(stop <-chan struct{}) error {
 	return s.run(stop)
 }
 
-func (s *Server) run(stop <-chan struct{}) error {
-	srv := &http.Server{
-		Addr:    fmt.Sprintf(":%v", s.Port),
-		Handler: s.sMux,
-	}
+func (s *Server) run(stop <-chan struct{}) error { // nolint: gocyclo
 	errCh := make(chan error)
 	serveFn := func() {
-		errCh <- srv.ListenAndServeTLS(path.Join(s.CertDir, writer.ServerCertName), path.Join(s.CertDir, writer.ServerKeyName))
+		s.httpServer = &http.Server{
+			Addr:    fmt.Sprintf(":%v", s.Port),
+			Handler: s.sMux,
+		}
+		log.Info("starting the webhook server.")
+		errCh <- s.httpServer.ListenAndServeTLS(path.Join(s.CertDir, writer.ServerCertName), path.Join(s.CertDir, writer.ServerKeyName))
 	}
 
+	shutdownHappend := false
+	timer := time.Tick(wait.Jitter(defaultCertRefreshInterval, 0.1))
 	go serveFn()
 	for {
-		// TODO(mengqiy): add jitter to the timer
-		// Could use https://godoc.org/k8s.io/apimachinery/pkg/util/wait#Jitter
-		timer := time.Tick(6 * 30 * 24 * time.Hour)
 		select {
 		case <-timer:
 			changed, err := s.RefreshCert()
@@ -232,19 +239,28 @@ func (s *Server) run(stop <-chan struct{}) error {
 				return err
 			}
 			if !changed {
+				log.Info("no need to reload the certificates.")
 				continue
 			}
 			log.Info("server is shutting down to reload the certificates.")
-			err = srv.Shutdown(context.Background())
+			shutdownHappend = true
+			err = s.httpServer.Shutdown(context.Background())
 			if err != nil {
 				log.Error(err, "encountering error when shutting down")
 				return err
 			}
+			timer = time.Tick(wait.Jitter(defaultCertRefreshInterval, 0.1))
 			go serveFn()
 		case <-stop:
 			return nil
 		case e := <-errCh:
-			return e
+			// Don't exit when getting an http.ErrServerClosed error due to restarting the server.
+			if shutdownHappend && e == http.ErrServerClosed {
+				shutdownHappend = false
+			} else if e != nil {
+				log.Error(e, "server returns an unexpected error")
+				return e
+			}
 		}
 	}
 }

pkg/webhook/server_test.go

@@ -0,0 +1,148 @@
+/*
+Copyright 2018 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 webhook
+
+import (
+	"context"
+	"io/ioutil"
+	"net/http"
+	"time"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+
+	"k8s.io/apimachinery/pkg/runtime"
+	"sigs.k8s.io/controller-runtime/pkg/webhook/internal/cert"
+	"sigs.k8s.io/controller-runtime/pkg/webhook/internal/cert/generator"
+	"sigs.k8s.io/controller-runtime/pkg/webhook/internal/cert/writer"
+)
+
+type fakeCertWriter struct {
+	changed bool
+}
+
+func (cw *fakeCertWriter) EnsureCert(dnsName string) (*generator.Artifacts, bool, error) {
+	return &generator.Artifacts{}, cw.changed, nil
+}
+
+func (cw *fakeCertWriter) Inject(objs ...runtime.Object) error {
+	return nil
+}
+
+var _ = Describe("webhook server", func() {
+	Describe("run", func() {
+		var stop chan struct{}
+		var s *Server
+		var cn = "example.com"
+
+		BeforeEach(func() {
+			s = &Server{
+				sMux: http.NewServeMux(),
+				ServerOptions: ServerOptions{
+					BootstrapOptions: &BootstrapOptions{
+						Host: &cn,
+					},
+				},
+			}
+
+			var err error
+			cg := &generator.SelfSignedCertGenerator{}
+			s.CertDir, err = ioutil.TempDir("/tmp", "controller-runtime-")
+			Expect(err).NotTo(HaveOccurred())
+			certWriter, err := writer.NewFSCertWriter(writer.FSCertWriterOptions{CertGenerator: cg, Path: s.CertDir})
+			Expect(err).NotTo(HaveOccurred())
+			_, _, err = certWriter.EnsureCert(cn)
+			Expect(err).NotTo(HaveOccurred())
+
+			stop = make(chan struct{})
+		})
+
+		It("should stop if the stop channel is closed", func() {
+			close(stop)
+			Expect(s.run(stop)).NotTo(HaveOccurred())
+		})
+
+		It("should exit if the server encounter an unexpected error", func() {
+			var e error
+
+			go func() {
+				defer GinkgoRecover()
+				e = s.run(stop)
+			}()
+
+			Eventually(func() *http.Server {
+				return s.httpServer
+			}).ShouldNot(BeNil())
+
+			err := s.httpServer.Shutdown(context.Background())
+			Expect(err).NotTo(HaveOccurred())
+
+			Eventually(func() error {
+				return e
+			}).Should(Equal(http.ErrServerClosed))
+
+			close(stop)
+		})
+
+		It("should be able to keep existing valid cert when timer fires", func() {
+			var e error
+			defaultCertRefreshInterval = time.Second
+
+			s.certProvisioner = &cert.Provisioner{
+				CertWriter: &fakeCertWriter{changed: false},
+			}
+
+			go func() {
+				defer GinkgoRecover()
+				e = s.run(stop)
+			}()
+
+			// Wait for multiple cycles of timer firing
+			time.Sleep(3 * time.Second)
+			Expect(e).NotTo(HaveOccurred())
+
+			close(stop)
+		})
+
+		It("should be able to rotate the cert when timer fires", func() {
+			var e error
+			defaultCertRefreshInterval = time.Second
+			s.certProvisioner = &cert.Provisioner{
+				CertWriter: &fakeCertWriter{changed: true},
+			}
+
+			go func() {
+				defer GinkgoRecover()
+				e = s.run(stop)
+			}()
+
+			Eventually(func() *http.Server {
+				return s.httpServer
+			}).ShouldNot(BeNil())
+
+			// Wait for multiple cycles of timer firing
+			time.Sleep(3 * time.Second)
+			Expect(e).NotTo(HaveOccurred())
+
+			close(stop)
+		})
+
+		AfterEach(func() {
+			defaultCertRefreshInterval = 3 * 30 * 24 * time.Hour
+		}, 60)
+	})
+})

pkg/webhook/webhook_suite_test.go

@@ -0,0 +1,57 @@
+/*
+Copyright 2018 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 webhook
+
+import (
+	"testing"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+
+	"k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/rest"
+	"sigs.k8s.io/controller-runtime/pkg/envtest"
+	logf "sigs.k8s.io/controller-runtime/pkg/runtime/log"
+)
+
+func TestSource(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecsWithDefaultAndCustomReporters(t, "Webhook Integration Suite", []Reporter{envtest.NewlineReporter{}})
+}
+
+var testenv *envtest.Environment
+var cfg *rest.Config
+var clientset *kubernetes.Clientset
+
+var _ = BeforeSuite(func(done Done) {
+	logf.SetLogger(logf.ZapLoggerTo(GinkgoWriter, true))
+
+	testenv = &envtest.Environment{}
+
+	var err error
+	cfg, err = testenv.Start()
+	Expect(err).NotTo(HaveOccurred())
+
+	clientset, err = kubernetes.NewForConfig(cfg)
+	Expect(err).NotTo(HaveOccurred())
+
+	close(done)
+}, 60)
+
+var _ = AfterSuite(func() {
+	testenv.Stop()
+})