NK-47: Implemented webhook deregistration.

TLS pair initialization functionality moved to init.go.
Separated server and mutation webhook objects, implemented registration of webhook with the creation of corresponding object.
Added comments for webhook configuration definitions, changed name of configuration for debug.

definitions/MutatingWebhookConfiguration.yaml

@@ -1,4 +1,5 @@
 # MutatingWebhookConfiguration document which should be used when placing controller inside the cluster
+# This configuration is just an example. Webhook for in-cluster configuration is registered by controller (see webhooks/registration.go).
 apiVersion: admissionregistration.k8s.io/v1beta1
 kind: MutatingWebhookConfiguration
 metadata:

definitions/MutatingWebhookConfiguration_debug.yaml

@@ -1,8 +1,9 @@
 # Example of MutatingWebhookConfiguration which can be used for debug, when controller is placed on master node
+# To register webhook for debug, replace ${CA_BUNDLE} with corresponding data from ~/.kube/config and create this resource
 apiVersion: admissionregistration.k8s.io/v1beta1
 kind: MutatingWebhookConfiguration
 metadata:
-  name: nirmata-kube-policy-webhook-cfg
+  name: nirmata-kube-policy-webhook-cfg-debug
   labels:
     app: kube-policy
 webhooks:

init.go

@@ -23,7 +23,27 @@ func createClientConfig(kubeconfig string) (*rest.Config, error) {
 	}
 }
 
-func readTlsPairFromFiles(certFile, keyFile string) *utils.TlsPemPair {
+func initTlsPemPair(certFile, keyFile string, clientConfig *rest.Config, kubeclient *kubeclient.KubeClient) (*utils.TlsPemPair, error) {
+	var tlsPair *utils.TlsPemPair
+	if certFile != "" || keyFile != "" {
+		tlsPair = tlsPairFromFiles(certFile, keyFile)
+	}
+
+	var err error
+	if tlsPair != nil {
+		log.Print("Using given TLS key/certificate pair")
+		return tlsPair, nil
+	} else {
+		tlsPair, err = tlsPairFromCluster(clientConfig, kubeclient)
+		if err == nil {
+			log.Printf("Using TLS key/certificate from cluster")
+		}
+		return tlsPair, err
+	}
+}
+
+// Loads PEM private key and TLS certificate from given files
+func tlsPairFromFiles(certFile, keyFile string) *utils.TlsPemPair {
 	if certFile == "" || keyFile == "" {
 		return nil
 	}
@@ -46,9 +66,10 @@ func readTlsPairFromFiles(certFile, keyFile string) *utils.TlsPemPair {
 	}
 }
 
-// Loads or creates PEM private key and TLS certificate for webhook server
-// Returns struct with key/certificate pair
-func initTlsPemsPair(configuration *rest.Config, client *kubeclient.KubeClient) (*utils.TlsPemPair, error) {
+// Loads or creates PEM private key and TLS certificate for webhook server.
+// Created pair is stored in cluster's secret.
+// Returns struct with key/certificate pair.
+func tlsPairFromCluster(configuration *rest.Config, client *kubeclient.KubeClient) (*utils.TlsPemPair, error) {
 	apiServerUrl, err := url.Parse(configuration.Host)
 	if err != nil {
 		return nil, err

main.go

@@ -6,8 +6,8 @@ import (
 
 	"github.com/nirmata/kube-policy/controller"
 	"github.com/nirmata/kube-policy/kubeclient"
-	"github.com/nirmata/kube-policy/webhooks"
 	"github.com/nirmata/kube-policy/server"
+	"github.com/nirmata/kube-policy/webhooks"
 
 	signals "k8s.io/sample-controller/pkg/signals"
 )
@@ -24,11 +24,6 @@ func main() {
 		log.Fatalf("Error building kubeconfig: %v\n", err)
 	}
 
-	err = webhooks.RegisterMutationWebhook(clientConfig)
-	if err != nil {
-		log.Fatalf("Error registering mutation webhook server: %v\n", err)
-	}
-
 	controller, err := controller.NewPolicyController(clientConfig, nil)
 	if err != nil {
 		log.Fatalf("Error creating PolicyController: %s\n", err)
@@ -39,22 +34,17 @@ func main() {
 		log.Fatalf("Error creating kubeclient: %v\n", err)
 	}
 
-	tlsPair := readTlsPairFromFiles(cert, key)
-	if tlsPair != nil {
-		log.Print("Using given TLS key/certificate pair")
-	} else {
-		tlsPair, err = initTlsPemsPair(clientConfig, kubeclient)
-		if err != nil {
-			log.Fatalf("Failed to initialize TLS key/certificate pair: %v\n", err)
-		}
+	mutationWebhook, err := webhooks.CreateMutationWebhook(clientConfig, kubeclient, controller, nil)
+	if err != nil {
+		log.Fatalf("Error creating mutation webhook: %v\n", err)
 	}
 
-	serverConfig := server.WebhookServerConfig{
-		TlsPemPair: tlsPair,
-		Controller: controller,
-		Kubeclient: kubeclient,
+	tlsPair, err := initTlsPemPair(cert, key, clientConfig, kubeclient)
+	if err != nil {
+		log.Fatalf("Failed to initialize TLS key/certificate pair: %v\n", err)
 	}
-	server, err := server.NewWebhookServer(serverConfig, nil)
+
+	server, err := server.NewWebhookServer(tlsPair, mutationWebhook, nil)
 	if err != nil {
 		log.Fatalf("Unable to create webhook server: %v\n", err)
 	}
@@ -66,10 +56,15 @@ func main() {
 	if err != nil {
 		log.Fatalf("Error running PolicyController: %s\n", err)
 	}
-
 	log.Println("Policy Controller has started")
+
 	<-stopCh
 	server.Stop()
+	err = mutationWebhook.Deregister()
+	if err != nil {
+		log.Printf("Unable to deregister mutation webhook: %v", err)
+	}
+
 	log.Println("Policy Controller has stopped")
 }
 

server/server.go

@@ -13,8 +13,6 @@ import (
 	"time"
 
 	"github.com/nirmata/kube-policy/config"
-	"github.com/nirmata/kube-policy/controller"
-	"github.com/nirmata/kube-policy/kubeclient"
 	"github.com/nirmata/kube-policy/utils"
 	"github.com/nirmata/kube-policy/webhooks"
 
@@ -24,46 +22,32 @@ import (
 // WebhookServer contains configured TLS server with MutationWebhook.
 // MutationWebhook gets policies from policyController and takes control of the cluster with kubeclient.
 type WebhookServer struct {
-	server           http.Server
-	policyController *controller.PolicyController
-	mutationWebhook  *webhooks.MutationWebhook
-	logger           *log.Logger
-}
-
-// Configuration struct for WebhookServer used in NewWebhookServer
-// Controller and Kubeclient should be initialized and valid
-type WebhookServerConfig struct {
-	TlsPemPair *utils.TlsPemPair
-	Controller *controller.PolicyController
-	Kubeclient *kubeclient.KubeClient
+	server          http.Server
+	mutationWebhook *webhooks.MutationWebhook
+	logger          *log.Logger
 }
 
 // NewWebhookServer creates new instance of WebhookServer accordingly to given configuration
 // Policy Controller and Kubernetes Client should be initialized in configuration
-func NewWebhookServer(configuration WebhookServerConfig, logger *log.Logger) (*WebhookServer, error) {
+func NewWebhookServer(tlsPair *utils.TlsPemPair, mutationWebhook *webhooks.MutationWebhook, logger *log.Logger) (*WebhookServer, error) {
 	if logger == nil {
 		logger = log.New(os.Stdout, "HTTPS Server: ", log.LstdFlags|log.Lshortfile)
 	}
 
-	if configuration.TlsPemPair == nil || configuration.Controller == nil || configuration.Kubeclient == nil {
-		return nil, errors.New("WebhookServerConfig is not initialized properly")
+	if tlsPair == nil || mutationWebhook == nil {
+		return nil, errors.New("NewWebhookServer is not initialized properly")
 	}
 
 	var tlsConfig tls.Config
-	pair, err := tls.X509KeyPair(configuration.TlsPemPair.Certificate, configuration.TlsPemPair.PrivateKey)
+	pair, err := tls.X509KeyPair(tlsPair.Certificate, tlsPair.PrivateKey)
 	if err != nil {
 		return nil, err
 	}
 	tlsConfig.Certificates = []tls.Certificate{pair}
 
-	mw, err := webhooks.NewMutationWebhook(configuration.Kubeclient, configuration.Controller, logger)
-	if err != nil {
-		return nil, err
-	}
-
 	ws := &WebhookServer{
 		logger:          logger,
-		mutationWebhook: mw,
+		mutationWebhook: mutationWebhook,
 	}
 
 	mux := http.NewServeMux()