Fix scale subresource when used with admission webhooks

pkg/registry/apps/deployment/storage/storage.go

@@ -293,7 +293,15 @@ func (r *ScaleREST) Update(ctx context.Context, name string, objInfo rest.Update
 
 	deployment.Spec.Replicas = scale.Spec.Replicas
 	deployment.ResourceVersion = scale.ResourceVersion
-	obj, _, err = r.store.Update(ctx, deployment.Name, rest.DefaultUpdatedObjectInfo(deployment), createValidation, updateValidation, false, options)
+	obj, _, err = r.store.Update(
+		ctx,
+		deployment.Name,
+		rest.DefaultUpdatedObjectInfo(deployment),
+		toScaleCreateValidation(createValidation),
+		toScaleUpdateValidation(updateValidation),
+		false,
+		options,
+	)
 	if err != nil {
 		return nil, false, err
 	}
@@ -305,6 +313,30 @@ func (r *ScaleREST) Update(ctx context.Context, name string, objInfo rest.Update
 	return newScale, false, nil
 }
 
+func toScaleCreateValidation(f rest.ValidateObjectFunc) rest.ValidateObjectFunc {
+	return func(obj runtime.Object) error {
+		scale, err := scaleFromDeployment(obj.(*apps.Deployment))
+		if err != nil {
+			return err
+		}
+		return f(scale)
+	}
+}
+
+func toScaleUpdateValidation(f rest.ValidateObjectUpdateFunc) rest.ValidateObjectUpdateFunc {
+	return func(obj, old runtime.Object) error {
+		newScale, err := scaleFromDeployment(obj.(*apps.Deployment))
+		if err != nil {
+			return err
+		}
+		oldScale, err := scaleFromDeployment(old.(*apps.Deployment))
+		if err != nil {
+			return err
+		}
+		return f(newScale, oldScale)
+	}
+}
+
 // scaleFromDeployment returns a scale subresource for a deployment.
 func scaleFromDeployment(deployment *apps.Deployment) (*autoscaling.Scale, error) {
 	selector, err := metav1.LabelSelectorAsSelector(deployment.Spec.Selector)

pkg/registry/apps/replicaset/storage/storage.go

@@ -201,7 +201,15 @@ func (r *ScaleREST) Update(ctx context.Context, name string, objInfo rest.Update
 
 	rs.Spec.Replicas = scale.Spec.Replicas
 	rs.ResourceVersion = scale.ResourceVersion
-	obj, _, err = r.store.Update(ctx, rs.Name, rest.DefaultUpdatedObjectInfo(rs), createValidation, updateValidation, false, options)
+	obj, _, err = r.store.Update(
+		ctx,
+		rs.Name,
+		rest.DefaultUpdatedObjectInfo(rs),
+		toScaleCreateValidation(createValidation),
+		toScaleUpdateValidation(updateValidation),
+		false,
+		options,
+	)
 	if err != nil {
 		return nil, false, err
 	}
@@ -213,6 +221,30 @@ func (r *ScaleREST) Update(ctx context.Context, name string, objInfo rest.Update
 	return newScale, false, err
 }
 
+func toScaleCreateValidation(f rest.ValidateObjectFunc) rest.ValidateObjectFunc {
+	return func(obj runtime.Object) error {
+		scale, err := scaleFromReplicaSet(obj.(*apps.ReplicaSet))
+		if err != nil {
+			return err
+		}
+		return f(scale)
+	}
+}
+
+func toScaleUpdateValidation(f rest.ValidateObjectUpdateFunc) rest.ValidateObjectUpdateFunc {
+	return func(obj, old runtime.Object) error {
+		newScale, err := scaleFromReplicaSet(obj.(*apps.ReplicaSet))
+		if err != nil {
+			return err
+		}
+		oldScale, err := scaleFromReplicaSet(old.(*apps.ReplicaSet))
+		if err != nil {
+			return err
+		}
+		return f(newScale, oldScale)
+	}
+}
+
 // scaleFromReplicaSet returns a scale subresource for a replica set.
 func scaleFromReplicaSet(rs *apps.ReplicaSet) (*autoscaling.Scale, error) {
 	selector, err := metav1.LabelSelectorAsSelector(rs.Spec.Selector)

pkg/registry/apps/statefulset/storage/storage.go

@@ -188,7 +188,15 @@ func (r *ScaleREST) Update(ctx context.Context, name string, objInfo rest.Update
 
 	ss.Spec.Replicas = scale.Spec.Replicas
 	ss.ResourceVersion = scale.ResourceVersion
-	obj, _, err = r.store.Update(ctx, ss.Name, rest.DefaultUpdatedObjectInfo(ss), createValidation, updateValidation, false, options)
+	obj, _, err = r.store.Update(
+		ctx,
+		ss.Name,
+		rest.DefaultUpdatedObjectInfo(ss),
+		toScaleCreateValidation(createValidation),
+		toScaleUpdateValidation(updateValidation),
+		false,
+		options,
+	)
 	if err != nil {
 		return nil, false, err
 	}
@@ -200,6 +208,30 @@ func (r *ScaleREST) Update(ctx context.Context, name string, objInfo rest.Update
 	return newScale, false, err
 }
 
+func toScaleCreateValidation(f rest.ValidateObjectFunc) rest.ValidateObjectFunc {
+	return func(obj runtime.Object) error {
+		scale, err := scaleFromStatefulSet(obj.(*apps.StatefulSet))
+		if err != nil {
+			return err
+		}
+		return f(scale)
+	}
+}
+
+func toScaleUpdateValidation(f rest.ValidateObjectUpdateFunc) rest.ValidateObjectUpdateFunc {
+	return func(obj, old runtime.Object) error {
+		newScale, err := scaleFromStatefulSet(obj.(*apps.StatefulSet))
+		if err != nil {
+			return err
+		}
+		oldScale, err := scaleFromStatefulSet(old.(*apps.StatefulSet))
+		if err != nil {
+			return err
+		}
+		return f(newScale, oldScale)
+	}
+}
+
 // scaleFromStatefulSet returns a scale subresource for a statefulset.
 func scaleFromStatefulSet(ss *apps.StatefulSet) (*autoscaling.Scale, error) {
 	selector, err := metav1.LabelSelectorAsSelector(ss.Spec.Selector)

pkg/registry/core/replicationcontroller/storage/storage.go

@@ -183,7 +183,15 @@ func (r *ScaleREST) Update(ctx context.Context, name string, objInfo rest.Update
 
 	rc.Spec.Replicas = scale.Spec.Replicas
 	rc.ResourceVersion = scale.ResourceVersion
-	obj, _, err = r.store.Update(ctx, rc.Name, rest.DefaultUpdatedObjectInfo(rc), createValidation, updateValidation, false, options)
+	obj, _, err = r.store.Update(
+		ctx,
+		rc.Name,
+		rest.DefaultUpdatedObjectInfo(rc),
+		toScaleCreateValidation(createValidation),
+		toScaleUpdateValidation(updateValidation),
+		false,
+		options,
+	)
 	if err != nil {
 		return nil, false, err
 	}
@@ -191,6 +199,21 @@ func (r *ScaleREST) Update(ctx context.Context, name string, objInfo rest.Update
 	return scaleFromRC(rc), false, nil
 }
 
+func toScaleCreateValidation(f rest.ValidateObjectFunc) rest.ValidateObjectFunc {
+	return func(obj runtime.Object) error {
+		return f(scaleFromRC(obj.(*api.ReplicationController)))
+	}
+}
+
+func toScaleUpdateValidation(f rest.ValidateObjectUpdateFunc) rest.ValidateObjectUpdateFunc {
+	return func(obj, old runtime.Object) error {
+		return f(
+			scaleFromRC(obj.(*api.ReplicationController)),
+			scaleFromRC(old.(*api.ReplicationController)),
+		)
+	}
+}
+
 // scaleFromRC returns a scale subresource for a replication controller.
 func scaleFromRC(rc *api.ReplicationController) *autoscaling.Scale {
 	return &autoscaling.Scale{

pkg/registry/extensions/controller/storage/storage.go

@@ -95,7 +95,15 @@ func (r *ScaleREST) Update(ctx context.Context, name string, objInfo rest.Update
 
 	rc.Spec.Replicas = scale.Spec.Replicas
 	rc.ResourceVersion = scale.ResourceVersion
-	obj, _, err = r.store.Update(ctx, rc.Name, rest.DefaultUpdatedObjectInfo(rc), createValidation, updateValidation, false, options)
+	obj, _, err = r.store.Update(
+		ctx,
+		rc.Name,
+		rest.DefaultUpdatedObjectInfo(rc),
+		toScaleCreateValidation(createValidation),
+		toScaleUpdateValidation(updateValidation),
+		false,
+		options,
+	)
 	if err != nil {
 		return nil, false, errors.NewConflict(extensions.Resource("replicationcontrollers/scale"), scale.Name, err)
 	}
@@ -103,6 +111,21 @@ func (r *ScaleREST) Update(ctx context.Context, name string, objInfo rest.Update
 	return scaleFromRC(rc), false, nil
 }
 
+func toScaleCreateValidation(f rest.ValidateObjectFunc) rest.ValidateObjectFunc {
+	return func(obj runtime.Object) error {
+		return f(scaleFromRC(obj.(*api.ReplicationController)))
+	}
+}
+
+func toScaleUpdateValidation(f rest.ValidateObjectUpdateFunc) rest.ValidateObjectUpdateFunc {
+	return func(obj, old runtime.Object) error {
+		return f(
+			scaleFromRC(obj.(*api.ReplicationController)),
+			scaleFromRC(old.(*api.ReplicationController)),
+		)
+	}
+}
+
 // scaleFromRC returns a scale subresource for a replication controller.
 func scaleFromRC(rc *api.ReplicationController) *autoscaling.Scale {
 	return &autoscaling.Scale{

staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/conversion/BUILD

@@ -12,6 +12,7 @@ go_library(
     importpath = "k8s.io/apiextensions-apiserver/pkg/apiserver/conversion",
     visibility = ["//visibility:public"],
     deps = [
+        "//staging/src/k8s.io/api/autoscaling/v1:go_default_library",
         "//staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions:go_default_library",
         "//staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1beta1:go_default_library",
         "//staging/src/k8s.io/apiextensions-apiserver/pkg/features:go_default_library",
@@ -22,6 +23,7 @@ go_library(
         "//staging/src/k8s.io/apimachinery/pkg/util/uuid:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/util/feature:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/util/webhook:go_default_library",
+        "//staging/src/k8s.io/client-go/kubernetes/scheme:go_default_library",
         "//staging/src/k8s.io/client-go/rest:go_default_library",
         "//vendor/github.com/prometheus/client_golang/prometheus:go_default_library",
     ],

staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/conversion/converter.go

@@ -19,6 +19,7 @@ package conversion
 import (
 	"fmt"
 
+	autoscalingv1 "k8s.io/api/autoscaling/v1"
 	"k8s.io/apiextensions-apiserver/pkg/apis/apiextensions"
 	apiextensionsfeatures "k8s.io/apiextensions-apiserver/pkg/features"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
@@ -26,6 +27,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	utilfeature "k8s.io/apiserver/pkg/util/feature"
 	"k8s.io/apiserver/pkg/util/webhook"
+	typedscheme "k8s.io/client-go/kubernetes/scheme"
 )
 
 // CRConverterFactory is the factory for all CR converters.
@@ -77,7 +79,20 @@ func (m *CRConverterFactory) NewConverter(crd *apiextensions.CustomResourceDefin
 	default:
 		return nil, nil, fmt.Errorf("unknown conversion strategy %q for CRD %s", crd.Spec.Conversion.Strategy, crd.Name)
 	}
+
+	// Determine whether we should expect to be asked to "convert" autoscaling/v1 Scale types
+	convertScale := false
+	if utilfeature.DefaultFeatureGate.Enabled(apiextensionsfeatures.CustomResourceSubresources) {
+		convertScale = crd.Spec.Subresources != nil && crd.Spec.Subresources.Scale != nil
+		for _, version := range crd.Spec.Versions {
+			if version.Subresources != nil && version.Subresources.Scale != nil {
+				convertScale = true
+			}
+		}
+	}
+
 	unsafe = &crConverter{
+		convertScale:  convertScale,
 		validVersions: validVersions,
 		clusterScoped: crd.Spec.Scope == apiextensions.ClusterScoped,
 		converter:     converter,
@@ -96,6 +111,7 @@ type crConverterInterface interface {
 // crConverter extends the delegate converter with generic CR conversion behaviour. The delegate will implement the
 // user defined conversion strategy given in the CustomResourceDefinition.
 type crConverter struct {
+	convertScale  bool
 	converter     crConverterInterface
 	validVersions map[schema.GroupVersion]bool
 	clusterScoped bool
@@ -114,14 +130,23 @@ func (c *crConverter) ConvertFieldLabel(gvk schema.GroupVersionKind, label, valu
 }
 
 func (c *crConverter) Convert(in, out, context interface{}) error {
+	// Special-case typed scale conversion if this custom resource supports a scale endpoint
+	if c.convertScale {
+		_, isInScale := in.(*autoscalingv1.Scale)
+		_, isOutScale := out.(*autoscalingv1.Scale)
+		if isInScale || isOutScale {
+			return typedscheme.Scheme.Convert(in, out, context)
+		}
+	}
+
 	unstructIn, ok := in.(*unstructured.Unstructured)
 	if !ok {
-		return fmt.Errorf("input type %T in not valid for unstructured conversion", in)
+		return fmt.Errorf("input type %T in not valid for unstructured conversion to %T", in, out)
 	}
 
 	unstructOut, ok := out.(*unstructured.Unstructured)
 	if !ok {
-		return fmt.Errorf("output type %T in not valid for unstructured conversion", out)
+		return fmt.Errorf("output type %T in not valid for unstructured conversion from %T", out, in)
 	}
 
 	outGVK := unstructOut.GroupVersionKind()

staging/src/k8s.io/apiextensions-apiserver/pkg/registry/customresource/etcd.go

@@ -268,7 +268,15 @@ func (r *ScaleREST) Update(ctx context.Context, name string, objInfo rest.Update
 	}
 	cr.SetResourceVersion(scale.ResourceVersion)
 
-	obj, _, err = r.store.Update(ctx, cr.GetName(), rest.DefaultUpdatedObjectInfo(cr), createValidation, updateValidation, false, options)
+	obj, _, err = r.store.Update(
+		ctx,
+		cr.GetName(),
+		rest.DefaultUpdatedObjectInfo(cr),
+		toScaleCreateValidation(createValidation, r.specReplicasPath, r.statusReplicasPath, r.labelSelectorPath),
+		toScaleUpdateValidation(updateValidation, r.specReplicasPath, r.statusReplicasPath, r.labelSelectorPath),
+		false,
+		options,
+	)
 	if err != nil {
 		return nil, false, err
 	}
@@ -281,6 +289,30 @@ func (r *ScaleREST) Update(ctx context.Context, name string, objInfo rest.Update
 	return newScale, false, err
 }
 
+func toScaleCreateValidation(f rest.ValidateObjectFunc, specReplicasPath, statusReplicasPath, labelSelectorPath string) rest.ValidateObjectFunc {
+	return func(obj runtime.Object) error {
+		scale, _, err := scaleFromCustomResource(obj.(*unstructured.Unstructured), specReplicasPath, statusReplicasPath, labelSelectorPath)
+		if err != nil {
+			return err
+		}
+		return f(scale)
+	}
+}
+
+func toScaleUpdateValidation(f rest.ValidateObjectUpdateFunc, specReplicasPath, statusReplicasPath, labelSelectorPath string) rest.ValidateObjectUpdateFunc {
+	return func(obj, old runtime.Object) error {
+		newScale, _, err := scaleFromCustomResource(obj.(*unstructured.Unstructured), specReplicasPath, statusReplicasPath, labelSelectorPath)
+		if err != nil {
+			return err
+		}
+		oldScale, _, err := scaleFromCustomResource(old.(*unstructured.Unstructured), specReplicasPath, statusReplicasPath, labelSelectorPath)
+		if err != nil {
+			return err
+		}
+		return f(newScale, oldScale)
+	}
+}
+
 // scaleFromCustomResource returns a scale subresource for a customresource and a bool signalling wether
 // the specReplicas value was found.
 func scaleFromCustomResource(cr *unstructured.Unstructured, specReplicasPath, statusReplicasPath, labelSelectorPath string) (*autoscalingv1.Scale, bool, error) {
@@ -310,6 +342,11 @@ func scaleFromCustomResource(cr *unstructured.Unstructured, specReplicasPath, st
 	}
 
 	scale := &autoscalingv1.Scale{
+		// Populate apiVersion and kind so conversion recognizes we are already in the desired GVK and doesn't try to convert
+		TypeMeta: metav1.TypeMeta{
+			APIVersion: "autoscaling/v1",
+			Kind:       "Scale",
+		},
 		ObjectMeta: metav1.ObjectMeta{
 			Name:              cr.GetName(),
 			Namespace:         cr.GetNamespace(),

staging/src/k8s.io/apiextensions-apiserver/pkg/registry/customresource/etcd_test.go

@@ -381,6 +381,10 @@ func TestScaleGet(t *testing.T) {
 	}
 
 	want := &autoscalingv1.Scale{
+		TypeMeta: metav1.TypeMeta{
+			Kind:       "Scale",
+			APIVersion: "autoscaling/v1",
+		},
 		ObjectMeta: metav1.ObjectMeta{
 			Name:              cr.GetName(),
 			Namespace:         metav1.NamespaceDefault,