Merge pull request #53156 from p0lyn0mial/move_admission_initializer_interfaces_to_apiserver

Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

moved admission interfaces WantsClientCert, WantsAuthorizer and Wants…

**What this PR does / why we need it**:
moves some admission interfaces to apiserver, hopefully moving the webhook admission in the future will be much easier.

**Release note**:

```
NONE
```

cmd/kube-apiserver/app/server.go

@@ -467,9 +467,28 @@ func BuildGenericConfig(s *options.ServerRunOptions, proxyTransport *http.Transp
 		return nil, nil, nil, nil, nil, fmt.Errorf("failed to create admission plugin initializer: %v", err)
 	}
 
+	// TODO: this is the wrong cert/key pair.
+	// Given the generic case of webhook admission from a generic apiserver,
+	// this key pair should be signed by the the API server's client CA.
+	// Read client cert/key for plugins that need to make calls out
+	certBytes, keyBytes := []byte{}, []byte{}
+	if len(s.ProxyClientCertFile) > 0 && len(s.ProxyClientKeyFile) > 0 {
+		var err error
+		certBytes, err = ioutil.ReadFile(s.ProxyClientCertFile)
+		if err != nil {
+			return nil, nil, nil, nil, nil, fmt.Errorf("failed to read proxy client cert file from: %s, err: %v", s.ProxyClientCertFile, err)
+		}
+		keyBytes, err = ioutil.ReadFile(s.ProxyClientKeyFile)
+		if err != nil {
+			return nil, nil, nil, nil, nil, fmt.Errorf("failed to read proxy client key file from: %s, err: %v", s.ProxyClientKeyFile, err)
+		}
+	}
+
 	err = s.Admission.ApplyTo(
 		genericConfig,
 		versionedInformers,
+		certBytes,
+		keyBytes,
 		pluginInitializer)
 	if err != nil {
 		return nil, nil, nil, nil, nil, fmt.Errorf("failed to initialize admission: %v", err)
@@ -498,19 +517,6 @@ func BuildAdmissionPluginInitializer(s *options.ServerRunOptions, client interna
 
 	pluginInitializer := kubeapiserveradmission.NewPluginInitializer(client, externalClient, sharedInformers, apiAuthorizer, cloudConfig, restMapper, quotaRegistry)
 
-	// Read client cert/key for plugins that need to make calls out
-	if len(s.ProxyClientCertFile) > 0 && len(s.ProxyClientKeyFile) > 0 {
-		certBytes, err := ioutil.ReadFile(s.ProxyClientCertFile)
-		if err != nil {
-			return nil, err
-		}
-		keyBytes, err := ioutil.ReadFile(s.ProxyClientKeyFile)
-		if err != nil {
-			return nil, err
-		}
-		pluginInitializer = pluginInitializer.SetClientCert(certBytes, keyBytes)
-	}
-
 	pluginInitializer = pluginInitializer.SetServiceResolver(serviceResolver)
 	pluginInitializer = pluginInitializer.SetProxyTransport(proxyTransport)
 

federation/cmd/federation-apiserver/app/server.go

@@ -219,6 +219,8 @@ func NonBlockingRun(s *options.ServerRunOptions, stopCh <-chan struct{}) error {
 	err = s.Admission.ApplyTo(
 		genericConfig,
 		versionedInformers,
+		nil,
+		nil,
 		pluginInitializer,
 	)
 	if err != nil {

pkg/kubeapiserver/admission/BUILD

@@ -12,6 +12,7 @@ go_test(
     library = ":go_default_library",
     deps = [
         "//vendor/k8s.io/apiserver/pkg/admission:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/admission/initializer:go_default_library",
         "//vendor/k8s.io/apiserver/pkg/authorization/authorizer:go_default_library",
     ],
 )
@@ -25,6 +26,7 @@ go_library(
         "//pkg/quota:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/api/meta:go_default_library",
         "//vendor/k8s.io/apiserver/pkg/admission:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/admission/initializer:go_default_library",
         "//vendor/k8s.io/apiserver/pkg/authorization/authorizer:go_default_library",
         "//vendor/k8s.io/client-go/kubernetes:go_default_library",
     ],

pkg/kubeapiserver/admission/init_test.go

@@ -21,6 +21,7 @@ import (
 	"testing"
 
 	"k8s.io/apiserver/pkg/admission"
+	genericadmissioninit "k8s.io/apiserver/pkg/admission/initializer"
 	"k8s.io/apiserver/pkg/authorization/authorizer"
 )
 
@@ -51,7 +52,7 @@ func (self *WantAuthorizerAdmission) SetAuthorizer(a authorizer.Authorizer) {
 }
 
 var _ admission.Interface = &WantAuthorizerAdmission{}
-var _ WantsAuthorizer = &WantAuthorizerAdmission{}
+var _ genericadmissioninit.WantsAuthorizer = &WantAuthorizerAdmission{}
 
 // TestWantsAuthorizer ensures that the authorizer is injected when the WantsAuthorizer
 // interface is implemented.
@@ -106,19 +107,3 @@ func TestWantsServiceResolver(t *testing.T) {
 		t.Errorf("plumbing fail - %v %v#", ok, got)
 	}
 }
-
-type clientCertWanter struct {
-	doNothingAdmission
-	gotCert, gotKey []byte
-}
-
-func (s *clientCertWanter) SetClientCert(cert, key []byte) { s.gotCert, s.gotKey = cert, key }
-
-func TestWantsClientCert(t *testing.T) {
-	i := &PluginInitializer{}
-	ccw := &clientCertWanter{}
-	i.SetClientCert([]byte("cert"), []byte("key")).Initialize(ccw)
-	if string(ccw.gotCert) != "cert" || string(ccw.gotKey) != "key" {
-		t.Errorf("plumbing fail - %v %v", ccw.gotCert, ccw.gotKey)
-	}
-}

pkg/kubeapiserver/admission/initializer.go

@@ -22,6 +22,7 @@ import (
 
 	"k8s.io/apimachinery/pkg/api/meta"
 	"k8s.io/apiserver/pkg/admission"
+	admissioninit "k8s.io/apiserver/pkg/admission/initializer"
 	"k8s.io/apiserver/pkg/authorization/authorizer"
 	clientset "k8s.io/client-go/kubernetes"
 	"k8s.io/kubernetes/pkg/client/clientset_generated/internalclientset"
@@ -37,24 +38,12 @@ type WantsInternalKubeClientSet interface {
 	admission.Validator
 }
 
-// WantsExternalKubeClientSet defines a function which sets ClientSet for admission plugins that need it
-type WantsExternalKubeClientSet interface {
-	SetExternalKubeClientSet(clientset.Interface)
-	admission.Validator
-}
-
 // WantsInternalKubeInformerFactory defines a function which sets InformerFactory for admission plugins that need it
 type WantsInternalKubeInformerFactory interface {
 	SetInternalKubeInformerFactory(informers.SharedInformerFactory)
 	admission.Validator
 }
 
-// WantsAuthorizer defines a function which sets Authorizer for admission plugins that need it.
-type WantsAuthorizer interface {
-	SetAuthorizer(authorizer.Authorizer)
-	admission.Validator
-}
-
 // WantsCloudConfig defines a function which sets CloudConfig for admission plugins that need it.
 type WantsCloudConfig interface {
 	SetCloudConfig([]byte)
@@ -77,12 +66,6 @@ type WantsServiceResolver interface {
 	SetServiceResolver(ServiceResolver)
 }
 
-// WantsClientCert defines a fuction that accepts a cert & key for admission
-// plugins that need to make calls and prove their identity.
-type WantsClientCert interface {
-	SetClientCert(cert, key []byte)
-}
-
 // ServiceResolver knows how to convert a service reference into an actual
 // location.
 type ServiceResolver interface {
@@ -106,8 +89,6 @@ type PluginInitializer struct {
 	serviceResolver ServiceResolver
 
 	// for proving we are apiserver in call-outs
-	clientCert     []byte
-	clientKey      []byte
 	proxyTransport *http.Transport
 }
 
@@ -142,14 +123,6 @@ func (i *PluginInitializer) SetServiceResolver(s ServiceResolver) *PluginInitial
 	return i
 }
 
-// SetClientCert sets the client cert & key (identity used for calling out to
-// web hooks) which is needed by some plugins.
-func (i *PluginInitializer) SetClientCert(cert, key []byte) *PluginInitializer {
-	i.clientCert = cert
-	i.clientKey = key
-	return i
-}
-
 // SetProxyTransport sets the proxyTransport which is needed by some plugins.
 func (i *PluginInitializer) SetProxyTransport(proxyTransport *http.Transport) *PluginInitializer {
 	i.proxyTransport = proxyTransport
@@ -163,7 +136,7 @@ func (i *PluginInitializer) Initialize(plugin admission.Interface) {
 		wants.SetInternalKubeClientSet(i.internalClient)
 	}
 
-	if wants, ok := plugin.(WantsExternalKubeClientSet); ok {
+	if wants, ok := plugin.(admissioninit.WantsExternalKubeClientSet); ok {
 		wants.SetExternalKubeClientSet(i.externalClient)
 	}
 
@@ -171,7 +144,7 @@ func (i *PluginInitializer) Initialize(plugin admission.Interface) {
 		wants.SetInternalKubeInformerFactory(i.informers)
 	}
 
-	if wants, ok := plugin.(WantsAuthorizer); ok {
+	if wants, ok := plugin.(admissioninit.WantsAuthorizer); ok {
 		wants.SetAuthorizer(i.authorizer)
 	}
 
@@ -191,13 +164,6 @@ func (i *PluginInitializer) Initialize(plugin admission.Interface) {
 		wants.SetServiceResolver(i.serviceResolver)
 	}
 
-	if wants, ok := plugin.(WantsClientCert); ok {
-		if i.clientCert == nil || i.clientKey == nil {
-			panic("An admission plugin wants a client cert/key, but they were not provided.")
-		}
-		wants.SetClientCert(i.clientCert, i.clientKey)
-	}
-
 	if wants, ok := plugin.(WantsProxyTransport); ok {
 		wants.SetProxyTransport(i.proxyTransport)
 	}

plugin/pkg/admission/security/podsecuritypolicy/BUILD

@@ -24,6 +24,7 @@ go_library(
         "//vendor/k8s.io/apimachinery/pkg/labels:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/util/validation/field:go_default_library",
         "//vendor/k8s.io/apiserver/pkg/admission:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/admission/initializer:go_default_library",
         "//vendor/k8s.io/apiserver/pkg/authentication/user:go_default_library",
         "//vendor/k8s.io/apiserver/pkg/authorization/authorizer:go_default_library",
     ],

plugin/pkg/admission/security/podsecuritypolicy/admission.go

@@ -26,6 +26,7 @@ import (
 	"k8s.io/apimachinery/pkg/labels"
 	"k8s.io/apimachinery/pkg/util/validation/field"
 	"k8s.io/apiserver/pkg/admission"
+	genericadmissioninit "k8s.io/apiserver/pkg/admission/initializer"
 	"k8s.io/apiserver/pkg/authentication/user"
 	"k8s.io/apiserver/pkg/authorization/authorizer"
 	"k8s.io/kubernetes/pkg/api"
@@ -82,7 +83,7 @@ func (plugin *podSecurityPolicyPlugin) Validate() error {
 }
 
 var _ admission.Interface = &podSecurityPolicyPlugin{}
-var _ kubeapiserveradmission.WantsAuthorizer = &podSecurityPolicyPlugin{}
+var _ genericadmissioninit.WantsAuthorizer = &podSecurityPolicyPlugin{}
 var _ kubeapiserveradmission.WantsInternalKubeInformerFactory = &podSecurityPolicyPlugin{}
 
 // NewPlugin creates a new PSP admission plugin.

plugin/pkg/admission/webhook/BUILD

@@ -52,6 +52,7 @@ go_library(
         "//vendor/k8s.io/apimachinery/pkg/util/runtime:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/util/wait:go_default_library",
         "//vendor/k8s.io/apiserver/pkg/admission:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/admission/initializer:go_default_library",
         "//vendor/k8s.io/client-go/kubernetes:go_default_library",
         "//vendor/k8s.io/client-go/rest:go_default_library",
     ],

plugin/pkg/admission/webhook/admission.go

@@ -38,6 +38,7 @@ import (
 	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
 	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/apiserver/pkg/admission"
+	genericadmissioninit "k8s.io/apiserver/pkg/admission/initializer"
 	clientset "k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/rest"
 	"k8s.io/kubernetes/pkg/api"
@@ -114,8 +115,8 @@ type GenericAdmissionWebhook struct {
 
 var (
 	_ = admissioninit.WantsServiceResolver(&GenericAdmissionWebhook{})
-	_ = admissioninit.WantsClientCert(&GenericAdmissionWebhook{})
-	_ = admissioninit.WantsExternalKubeClientSet(&GenericAdmissionWebhook{})
+	_ = genericadmissioninit.WantsClientCert(&GenericAdmissionWebhook{})
+	_ = genericadmissioninit.WantsExternalKubeClientSet(&GenericAdmissionWebhook{})
 )
 
 func (a *GenericAdmissionWebhook) SetProxyTransport(pt *http.Transport) {
@@ -140,6 +141,9 @@ func (a *GenericAdmissionWebhook) SetExternalKubeClientSet(client clientset.Inte
 }
 
 func (a *GenericAdmissionWebhook) Validate() error {
+	if a.clientCert == nil || a.clientKey == nil {
+		return fmt.Errorf("the GenericAdmissionWebhook admission plugin requires a client certificate and the private key to be provided")
+	}
 	if a.hookSource == nil {
 		return fmt.Errorf("the GenericAdmissionWebhook admission plugin requires a Kubernetes client to be provided")
 	}

staging/src/k8s.io/apiserver/pkg/admission/initializer/initializer.go

@@ -27,14 +27,21 @@ type pluginInitializer struct {
 	externalClient    kubernetes.Interface
 	externalInformers informers.SharedInformerFactory
 	authorizer        authorizer.Authorizer
+	// serverIdentifyingClientCert used to provide identity when calling out to admission plugins
+	serverIdentifyingClientCert []byte
+	// serverIdentifyingClientKey private key for the client certificate used when calling out to admission plugins
+	serverIdentifyingClientKey []byte
 }
 
 // New creates an instance of admission plugins initializer.
-func New(extClientset kubernetes.Interface, extInformers informers.SharedInformerFactory, authz authorizer.Authorizer) (pluginInitializer, error) {
+// TODO(p0lyn0mial): make the parameters public, this construction seems to be redundant.
+func New(extClientset kubernetes.Interface, extInformers informers.SharedInformerFactory, authz authorizer.Authorizer, serverIdentifyingClientCert, serverIdentifyingClientKey []byte) (pluginInitializer, error) {
 	return pluginInitializer{
 		externalClient:              extClientset,
 		externalInformers:           extInformers,
 		authorizer:                  authz,
+		serverIdentifyingClientCert: serverIdentifyingClientCert,
+		serverIdentifyingClientKey:  serverIdentifyingClientKey,
 	}, nil
 }
 
@@ -52,6 +59,10 @@ func (i pluginInitializer) Initialize(plugin admission.Interface) {
 	if wants, ok := plugin.(WantsAuthorizer); ok {
 		wants.SetAuthorizer(i.authorizer)
 	}
+
+	if wants, ok := plugin.(WantsClientCert); ok {
+		wants.SetClientCert(i.serverIdentifyingClientCert, i.serverIdentifyingClientKey)
+	}
 }
 
 var _ admission.PluginInitializer = pluginInitializer{}

staging/src/k8s.io/apiserver/pkg/admission/initializer/initializer_test.go

@@ -31,7 +31,7 @@ import (
 // TestWantsAuthorizer ensures that the authorizer is injected
 // when the WantsAuthorizer interface is implemented by a plugin.
 func TestWantsAuthorizer(t *testing.T) {
-	target, err := initializer.New(nil, nil, &TestAuthorizer{})
+	target, err := initializer.New(nil, nil, &TestAuthorizer{}, nil, nil)
 	if err != nil {
 		t.Fatalf("expected to create an instance of initializer but got an error = %s", err.Error())
 	}
@@ -46,7 +46,7 @@ func TestWantsAuthorizer(t *testing.T) {
 // when the WantsExternalKubeClientSet interface is implemented by a plugin.
 func TestWantsExternalKubeClientSet(t *testing.T) {
 	cs := &fake.Clientset{}
-	target, err := initializer.New(cs, nil, &TestAuthorizer{})
+	target, err := initializer.New(cs, nil, &TestAuthorizer{}, nil, nil)
 	if err != nil {
 		t.Fatalf("expected to create an instance of initializer but got an error = %s", err.Error())
 	}
@@ -62,7 +62,7 @@ func TestWantsExternalKubeClientSet(t *testing.T) {
 func TestWantsExternalKubeInformerFactory(t *testing.T) {
 	cs := &fake.Clientset{}
 	sf := informers.NewSharedInformerFactory(cs, time.Duration(1)*time.Second)
-	target, err := initializer.New(cs, sf, &TestAuthorizer{})
+	target, err := initializer.New(cs, sf, &TestAuthorizer{}, nil, nil)
 	if err != nil {
 		t.Fatalf("expected to create an instance of initializer but got an error = %s", err.Error())
 	}
@@ -73,6 +73,20 @@ func TestWantsExternalKubeInformerFactory(t *testing.T) {
 	}
 }
 
+// TestWantsClientCert ensures that the client certificate and key are injected
+// when the WantsClientCert interface is implemented by a plugin.
+func TestWantsClientCert(t *testing.T) {
+	target, err := initializer.New(nil, nil, nil, []byte("cert"), []byte("key"))
+	if err != nil {
+		t.Fatalf("expected to create an instance of initializer but got an error = %s", err.Error())
+	}
+	wantClientCert := &clientCertWanter{}
+	target.Initialize(wantClientCert)
+	if string(wantClientCert.gotCert) != "cert" || string(wantClientCert.gotKey) != "key" {
+		t.Errorf("expected client cert to be initialized, clientCert = %v, clientKey = %v", wantClientCert.gotCert, wantClientCert.gotKey)
+	}
+}
+
 // WantExternalKubeInformerFactory is a test stub that fulfills the WantsExternalKubeInformerFactory interface
 type WantExternalKubeInformerFactory struct {
 	sf informers.SharedInformerFactory
@@ -114,9 +128,19 @@ func (self *WantAuthorizerAdmission) Validate() error                       { re
 var _ admission.Interface = &WantAuthorizerAdmission{}
 var _ initializer.WantsAuthorizer = &WantAuthorizerAdmission{}
 
-// TestAuthorizer is a test stub for testing that fulfills the authorizer interface.
+// TestAuthorizer is a test stub that fulfills the WantsAuthorizer interface.
 type TestAuthorizer struct{}
 
 func (t *TestAuthorizer) Authorize(a authorizer.Attributes) (authorized bool, reason string, err error) {
 	return false, "", nil
 }
+
+// wantClientCert is a test stub for testing that fulfulls the WantsClientCert interface.
+type clientCertWanter struct {
+	gotCert, gotKey []byte
+}
+
+func (s *clientCertWanter) SetClientCert(cert, key []byte)     { s.gotCert, s.gotKey = cert, key }
+func (s *clientCertWanter) Admit(a admission.Attributes) error { return nil }
+func (s *clientCertWanter) Handles(o admission.Operation) bool { return false }
+func (s *clientCertWanter) Validate() error                    { return nil }

staging/src/k8s.io/apiserver/pkg/admission/initializer/interfaces.go

@@ -40,3 +40,10 @@ type WantsAuthorizer interface {
 	SetAuthorizer(authorizer.Authorizer)
 	admission.Validator
 }
+
+// WantsClientCert defines a fuction that accepts a cert & key for admission
+// plugins that need to make calls and prove their identity.
+type WantsClientCert interface {
+	SetClientCert(cert, key []byte)
+	admission.Validator
+}

staging/src/k8s.io/apiserver/pkg/admission/plugin/namespace/lifecycle/admission_test.go

@@ -48,7 +48,7 @@ func newHandlerForTestWithClock(c clientset.Interface, cacheClock clock.Clock) (
 	if err != nil {
 		return nil, f, err
 	}
-	pluginInitializer, err := kubeadmission.New(c, f, nil)
+	pluginInitializer, err := kubeadmission.New(c, f, nil, nil, nil)
 	if err != nil {
 		return handler, f, err
 	}

staging/src/k8s.io/apiserver/pkg/server/options/admission.go

@@ -73,9 +73,14 @@ func (a *AdmissionOptions) AddFlags(fs *pflag.FlagSet) {
 // In addition the method lazily initializes a generic plugin that is appended to the list of pluginInitializers
 // note this method uses:
 //  genericconfig.LoopbackClientConfig
-//  genericconfig.SharedInformerFactory
 //  genericconfig.Authorizer
-func (a *AdmissionOptions) ApplyTo(c *server.Config, informers informers.SharedInformerFactory, pluginInitializers ...admission.PluginInitializer) error {
+func (a *AdmissionOptions) ApplyTo(
+	c *server.Config,
+	informers informers.SharedInformerFactory,
+	serverIdentifyingClientCert []byte,
+	serverIdentifyingClientKey []byte,
+	pluginInitializers ...admission.PluginInitializer,
+) error {
 	pluginNames := a.PluginNames
 	if len(a.PluginNames) == 0 {
 		pluginNames = a.enabledPluginNames()
@@ -90,7 +95,7 @@ func (a *AdmissionOptions) ApplyTo(c *server.Config, informers informers.SharedI
 	if err != nil {
 		return err
 	}
-	genericInitializer, err := initializer.New(clientset, informers, c.Authorizer)
+	genericInitializer, err := initializer.New(clientset, informers, c.Authorizer, serverIdentifyingClientCert, serverIdentifyingClientKey)
 	if err != nil {
 		return err
 	}

staging/src/k8s.io/sample-apiserver/pkg/cmd/server/start.go

@@ -119,7 +119,7 @@ func (o WardleServerOptions) Config() (*apiserver.Config, error) {
 		return nil, err
 	}
 
-	if err := o.Admission.ApplyTo(&serverConfig.Config, serverConfig.SharedInformerFactory, admissionInitializer); err != nil {
+	if err := o.Admission.ApplyTo(&serverConfig.Config, serverConfig.SharedInformerFactory, nil, nil, admissionInitializer); err != nil {
 		return nil, err
 	}