Remove global variable dependency from runtimeclass admission

plugin/pkg/admission/runtimeclass/BUILD

@@ -16,9 +16,9 @@ go_library(
         "//staging/src/k8s.io/apimachinery/pkg/api/errors:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/admission:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/admission/initializer:go_default_library",
-        "//staging/src/k8s.io/apiserver/pkg/util/feature:go_default_library",
         "//staging/src/k8s.io/client-go/informers:go_default_library",
         "//staging/src/k8s.io/client-go/listers/node/v1beta1:go_default_library",
+        "//staging/src/k8s.io/component-base/featuregate:go_default_library",
     ],
 )
 
@@ -28,7 +28,6 @@ go_test(
     embed = [":go_default_library"],
     deps = [
         "//pkg/apis/core:go_default_library",
-        "//pkg/features:go_default_library",
         "//staging/src/k8s.io/api/core/v1:go_default_library",
         "//staging/src/k8s.io/api/node/v1beta1:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/api/resource:go_default_library",
@@ -36,8 +35,6 @@ go_test(
         "//staging/src/k8s.io/apimachinery/pkg/runtime:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/admission:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/authentication/user:go_default_library",
-        "//staging/src/k8s.io/apiserver/pkg/util/feature:go_default_library",
-        "//staging/src/k8s.io/component-base/featuregate/testing:go_default_library",
         "//vendor/github.com/stretchr/testify/assert:go_default_library",
     ],
 )

plugin/pkg/admission/runtimeclass/admission.go

@@ -31,9 +31,9 @@ import (
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apiserver/pkg/admission"
 	genericadmissioninitailizer "k8s.io/apiserver/pkg/admission/initializer"
-	utilfeature "k8s.io/apiserver/pkg/util/feature"
 	"k8s.io/client-go/informers"
 	nodev1beta1listers "k8s.io/client-go/listers/node/v1beta1"
+	"k8s.io/component-base/featuregate"
 	api "k8s.io/kubernetes/pkg/apis/core"
 	node "k8s.io/kubernetes/pkg/apis/node"
 	nodev1beta1 "k8s.io/kubernetes/pkg/apis/node/v1beta1"
@@ -58,6 +58,10 @@ func Register(plugins *admission.Plugins) {
 type RuntimeClass struct {
 	*admission.Handler
 	runtimeClassLister nodev1beta1listers.RuntimeClassLister
+
+	inspectedFeatures   bool
+	runtimeClassEnabled bool
+	podOverheadEnabled  bool
 }
 
 var _ admission.MutationInterface = &RuntimeClass{}
@@ -65,9 +69,16 @@ var _ admission.ValidationInterface = &RuntimeClass{}
 
 var _ genericadmissioninitailizer.WantsExternalKubeInformerFactory = &RuntimeClass{}
 
+// InspectFeatureGates allows setting bools without taking a dep on a global variable
+func (r *RuntimeClass) InspectFeatureGates(featureGates featuregate.FeatureGate) {
+	r.runtimeClassEnabled = featureGates.Enabled(features.RuntimeClass)
+	r.podOverheadEnabled = featureGates.Enabled(features.PodOverhead)
+	r.inspectedFeatures = true
+}
+
 // SetExternalKubeInformerFactory implements the WantsExternalKubeInformerFactory interface.
 func (r *RuntimeClass) SetExternalKubeInformerFactory(f informers.SharedInformerFactory) {
-	if !utilfeature.DefaultFeatureGate.Enabled(features.RuntimeClass) {
+	if !r.runtimeClassEnabled {
 		return
 	}
 	runtimeClassInformer := f.Node().V1beta1().RuntimeClasses()
@@ -77,7 +88,10 @@ func (r *RuntimeClass) SetExternalKubeInformerFactory(f informers.SharedInformer
 
 // ValidateInitialization implements the WantsExternalKubeInformerFactory interface.
 func (r *RuntimeClass) ValidateInitialization() error {
-	if !utilfeature.DefaultFeatureGate.Enabled(features.RuntimeClass) {
+	if !r.inspectedFeatures {
+		return fmt.Errorf("InspectFeatureGates was not called")
+	}
+	if !r.runtimeClassEnabled {
 		return nil
 	}
 	if r.runtimeClassLister == nil {
@@ -88,7 +102,7 @@ func (r *RuntimeClass) ValidateInitialization() error {
 
 // Admit makes an admission decision based on the request attributes
 func (r *RuntimeClass) Admit(ctx context.Context, attributes admission.Attributes, o admission.ObjectInterfaces) error {
-	if !utilfeature.DefaultFeatureGate.Enabled(features.RuntimeClass) {
+	if !r.runtimeClassEnabled {
 		return nil
 	}
 
@@ -101,7 +115,7 @@ func (r *RuntimeClass) Admit(ctx context.Context, attributes admission.Attribute
 	if err != nil {
 		return err
 	}
-	if utilfeature.DefaultFeatureGate.Enabled(features.PodOverhead) {
+	if r.podOverheadEnabled {
 		if err := setOverhead(attributes, pod, runtimeClass); err != nil {
 			return err
 		}
@@ -116,7 +130,7 @@ func (r *RuntimeClass) Admit(ctx context.Context, attributes admission.Attribute
 
 // Validate makes sure that pod adhere's to RuntimeClass's definition
 func (r *RuntimeClass) Validate(ctx context.Context, attributes admission.Attributes, o admission.ObjectInterfaces) error {
-	if !utilfeature.DefaultFeatureGate.Enabled(features.RuntimeClass) {
+	if !r.runtimeClassEnabled {
 		return nil
 	}
 
@@ -129,7 +143,7 @@ func (r *RuntimeClass) Validate(ctx context.Context, attributes admission.Attrib
 	if err != nil {
 		return err
 	}
-	if utilfeature.DefaultFeatureGate.Enabled(features.PodOverhead) {
+	if r.podOverheadEnabled {
 		if err := validateOverhead(attributes, pod, runtimeClass); err != nil {
 			return err
 		}

plugin/pkg/admission/runtimeclass/admission_test.go

@@ -29,10 +29,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apiserver/pkg/admission"
 	"k8s.io/apiserver/pkg/authentication/user"
-	utilfeature "k8s.io/apiserver/pkg/util/feature"
-	featuregatetesting "k8s.io/component-base/featuregate/testing"
 	"k8s.io/kubernetes/pkg/apis/core"
-	"k8s.io/kubernetes/pkg/features"
 
 	"github.com/stretchr/testify/assert"
 )
@@ -319,8 +316,6 @@ func NewObjectInterfacesForTest() admission.ObjectInterfaces {
 }
 
 func TestValidate(t *testing.T) {
-	defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.PodOverhead, true)()
-
 	tests := []struct {
 		name         string
 		runtimeClass *v1beta1.RuntimeClass
@@ -368,6 +363,8 @@ func TestValidate(t *testing.T) {
 		},
 	}
 	rt := NewRuntimeClass()
+	rt.runtimeClassEnabled = true
+	rt.podOverheadEnabled = true
 	o := NewObjectInterfacesForTest()
 	for _, tc := range tests {
 		t.Run(tc.name, func(t *testing.T) {

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

@@ -51,6 +51,11 @@ func New(
 // Initialize checks the initialization interfaces implemented by a plugin
 // and provide the appropriate initialization data
 func (i pluginInitializer) Initialize(plugin admission.Interface) {
+	// First tell the plugin about enabled features, so it can decide whether to start informers or not
+	if wants, ok := plugin.(WantsFeatures); ok {
+		wants.InspectFeatureGates(i.featureGates)
+	}
+
 	if wants, ok := plugin.(WantsExternalKubeClientSet); ok {
 		wants.SetExternalKubeClientSet(i.externalClient)
 	}
@@ -62,10 +67,6 @@ func (i pluginInitializer) Initialize(plugin admission.Interface) {
 	if wants, ok := plugin.(WantsAuthorizer); ok {
 		wants.SetAuthorizer(i.authorizer)
 	}
-
-	if wants, ok := plugin.(WantsFeatures); ok {
-		wants.InspectFeatureGates(i.featureGates)
-	}
 }
 
 var _ admission.PluginInitializer = pluginInitializer{}