Address comments and pull kubernetes-sigs#316 in

drop server name and client
fix injector

example/main.go

@@ -92,7 +92,7 @@ func main() {
 		Build()
 
 	entryLog.Info("setting up webhook server")
-	as, err := webhook.NewServer("foo-admission-server", mgr, webhook.ServerOptions{
+	as, err := webhook.NewServer(mgr, webhook.ServerOptions{
 		Port:    9876,
 		CertDir: "/tmp/cert",
 	})
@@ -102,8 +102,7 @@ func main() {
 	}
 
 	entryLog.Info("registering webhooks to the webhook server")
-	as.Register(mutatingWebhook, validatingWebhook)
-	err = as.Complete()
+	err = as.Register(mutatingWebhook, validatingWebhook)
 	if err != nil {
 		entryLog.Error(err, "unable to setup the admission server")
 		os.Exit(1)

pkg/webhook/admission/webhook.go

@@ -30,7 +30,6 @@ import (
 
 	admissionv1beta1 "k8s.io/api/admission/v1beta1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
-	"sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/controller-runtime/pkg/runtime/inject"
 	atypes "sigs.k8s.io/controller-runtime/pkg/webhook/admission/types"
 	"sigs.k8s.io/controller-runtime/pkg/webhook/types"
@@ -210,24 +209,12 @@ func (w *Webhook) Validate() error {
 	return nil
 }
 
-var _ inject.Client = &Webhook{}
+var _ inject.Injector = &Webhook{}
 
-// InjectClient injects the client into the handlers
-func (w *Webhook) InjectClient(c client.Client) error {
+// InjectFunc injects dependencies into the handlers.
+func (w *Webhook) InjectFunc(f inject.Func) error {
 	for _, handler := range w.Handlers {
-		if _, err := inject.ClientInto(c, handler); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-var _ inject.Decoder = &Webhook{}
-
-// InjectDecoder injects the decoder into the handlers
-func (w *Webhook) InjectDecoder(d atypes.Decoder) error {
-	for _, handler := range w.Handlers {
-		if _, err := inject.DecoderInto(d, handler); err != nil {
+		if err := f(handler); err != nil {
 			return err
 		}
 	}

pkg/webhook/server.go

@@ -25,8 +25,6 @@ import (
 	"strconv"
 	"sync"
 
-	"sigs.k8s.io/controller-runtime/pkg/client"
-	"sigs.k8s.io/controller-runtime/pkg/client/config"
 	"sigs.k8s.io/controller-runtime/pkg/manager"
 	"sigs.k8s.io/controller-runtime/pkg/runtime/inject"
 )
@@ -48,32 +46,24 @@ type ServerOptions struct {
 	// If using SecretCertWriter in Provisioner, the server will provision the certificate in a secret,
 	// the user is responsible to mount the secret to the this location for the server to consume.
 	CertDir string
-
-	// Client is a client defined in controller-runtime instead of a client-go client.
-	// It knows how to talk to a kubernetes cluster.
-	// Client will be injected by the manager if not set.
-	Client client.Client
 }
 
 // Server is an admission webhook server that can serve traffic and
 // generates related k8s resources for deploying.
 type Server struct {
-	// Name is the name of server
-	Name string
-
 	// ServerOptions contains options for configuring the admission server.
 	ServerOptions
 
 	sMux *http.ServeMux
 	// registry maps a path to a http.Handler.
 	registry map[string]http.Handler
 
+	// setFields is used to inject dependencies into webhooks
+	setFields func(i interface{}) error
+
 	// manager is the manager that this webhook server will be registered.
 	manager manager.Manager
 
-	// err will be non-nil if there is an error occur during initialization.
-	err error
-
 	once sync.Once
 }
 
@@ -91,9 +81,8 @@ type Webhook interface {
 }
 
 // NewServer creates a new admission webhook server.
-func NewServer(name string, mgr manager.Manager, options ServerOptions) (*Server, error) {
+func NewServer(mgr manager.Manager, options ServerOptions) (*Server, error) {
 	as := &Server{
-		Name:          name,
 		sMux:          http.NewServeMux(),
 		registry:      map[string]http.Handler{},
 		ServerOptions: options,
@@ -105,74 +94,54 @@ func NewServer(name string, mgr manager.Manager, options ServerOptions) (*Server
 
 // setDefault does defaulting for the Server.
 func (s *Server) setDefault() {
-	if len(s.Name) == 0 {
-		s.Name = "default-k8s-webhook-server"
-	}
 	if s.registry == nil {
 		s.registry = map[string]http.Handler{}
 	}
 	if s.sMux == nil {
-		s.sMux = http.DefaultServeMux
+		s.sMux = http.NewServeMux()
 	}
 	if s.Port <= 0 {
 		s.Port = 443
 	}
 	if len(s.CertDir) == 0 {
 		s.CertDir = path.Join("k8s-webhook-server", "cert")
 	}
-
-	if s.Client == nil {
-		cfg, err := config.GetConfig()
-		if err != nil {
-			s.err = err
-			return
-		}
-		s.Client, err = client.New(cfg, client.Options{})
-		if err != nil {
-			s.err = err
-			return
-		}
-	}
 }
 
 // Register validates and registers webhook(s) in the server
-func (s *Server) Register(webhooks ...Webhook) {
+func (s *Server) Register(webhooks ...Webhook) error {
 	for i, webhook := range webhooks {
 		// validate the webhook before registering it.
 		err := webhook.Validate()
 		if err != nil {
-			s.err = err
-			return
+			return err
 		}
 		// Handle actually ensures that no duplicate paths are registered.
 		s.sMux.Handle(webhook.GetPath(), webhook.Handler())
 		s.registry[webhook.GetPath()] = webhooks[i]
+
+		// Inject dependencies to each webhook.
+		if err := s.setFields(webhooks[i]); err != nil {
+			return err
+		}
 	}
+
+	// Lazily add Server to manager.
+	// Because the all webhook handlers to be in place, so we can inject the things they need.
+	return s.manager.Add(s)
 }
 
 // Handle registers a http.Handler for the given pattern.
 func (s *Server) Handle(pattern string, handler http.Handler) {
 	s.sMux.Handle(pattern, handler)
 }
 
-// Complete must be called to complete the server setup
-func (s *Server) Complete() error {
-	if s.err != nil {
-		return s.err
-	}
-	// TODO(mengqiy): inject dependencies into each http.Handler
-	return s.manager.Add(s)
-}
-
 var _ manager.Runnable = &Server{}
 
 // Start runs the server.
 // It will install the webhook related resources depend on the server configuration.
 func (s *Server) Start(stop <-chan struct{}) error {
 	s.once.Do(s.setDefault)
-	if s.err != nil {
-		return s.err
-	}
 
 	// TODO: watch the cert dir. Reload the cert if it changes
 	cert, err := tls.LoadX509KeyPair(path.Join(s.CertDir, certName), path.Join(s.CertDir, keyName))
@@ -214,18 +183,10 @@ func (s *Server) Start(stop <-chan struct{}) error {
 	return nil
 }
 
-var _ inject.Client = &Server{}
-
-// InjectClient injects the client into the server
-func (s *Server) InjectClient(c client.Client) error {
-	s.Client = c
-	for path := range s.registry {
-		// TODO(mengqiy): remove this in PR #316
-		if wh, ok := s.registry[path].(Webhook); ok {
-			if _, err := inject.ClientInto(c, wh.Handler()); err != nil {
-				return err
-			}
-		}
-	}
+var _ inject.Injector = &Server{}
+
+// InjectFunc injects dependencies into the handlers.
+func (s *Server) InjectFunc(f inject.Func) error {
+	s.setFields = f
 	return nil
 }