Run deleteValidation at the storage layer so that it will be retried on

conflict.

Adding unit test verify that deleteValidation is retried.

adding e2e test verifying the webhook can intercept configmap and custom
resource deletion, and the existing object is sent via the
admissionreview.OldObject.

update the admission integration test to verify that the existing object
is passed to the deletion admission webhook as oldObject, in case of an
immediate deletion and in case of an update-on-delete.

Kubernetes-commit: 7bb4a3bace048cb9cd93d0221a7bf7c4accbf6be

pkg/endpoints/apiserver_test.go

@@ -447,7 +447,7 @@ func (storage *SimpleRESTStorage) Delete(ctx context.Context, id string, deleteV
 	if err := storage.errors["delete"]; err != nil {
 		return nil, false, err
 	}
-	if err := deleteValidation(nil); err != nil {
+	if err := deleteValidation(&storage.item); err != nil {
 		return nil, false, err
 	}
 	var obj runtime.Object = &metav1.Status{Status: metav1.StatusSuccess}
@@ -572,18 +572,6 @@ func (s *ConnecterRESTStorage) NewConnectOptions() (runtime.Object, bool, string
 	return s.emptyConnectOptions, false, ""
 }
 
-<<<<<<< HEAD
-=======
-type LegacyRESTStorage struct {
-	*SimpleRESTStorage
-}
-
-func (storage LegacyRESTStorage) Delete(ctx context.Context, id string) (runtime.Object, error) {
-	obj, _, err := storage.SimpleRESTStorage.Delete(ctx, id, nil, nil)
-	return obj, err
-}
-
->>>>>>> ab07482ecb... validate deletion admission object
 type MetadataRESTStorage struct {
 	*SimpleRESTStorage
 	types []string

pkg/endpoints/handlers/delete.go

@@ -180,7 +180,6 @@ func DeleteCollection(r rest.CollectionDeleter, checkBody bool, scope *RequestSc
 		ctx := req.Context()
 		ctx = request.WithNamespace(ctx, namespace)
 		ae := request.AuditEventFrom(ctx)
-		admit = admission.WithAudit(admit, ae)
 
 		outputMediaType, _, err := negotiation.NegotiateOutputMediaType(req, scope.Serializer, scope)
 		if err != nil {
@@ -252,6 +251,7 @@ func DeleteCollection(r rest.CollectionDeleter, checkBody bool, scope *RequestSc
 		}
 		options.TypeMeta.SetGroupVersionKind(metav1.SchemeGroupVersion.WithKind("DeleteOptions"))
 
+		admit = admission.WithAudit(admit, ae)
 		userInfo, _ := request.UserFrom(ctx)
 		staticAdmissionAttrs := admission.NewAttributesRecord(nil, nil, scope.Kind, namespace, "", scope.Resource, scope.Subresource, admission.Delete, options, dryrun.IsDryRun(options.DryRun), userInfo)
 		result, err := finishRequest(timeout, func() (runtime.Object, error) {

pkg/registry/generic/registry/dryrun.go

@@ -44,14 +44,17 @@ func (s *DryRunnableStorage) Create(ctx context.Context, key string, obj, out ru
 	return s.Storage.Create(ctx, key, obj, out, ttl)
 }
 
-func (s *DryRunnableStorage) Delete(ctx context.Context, key string, out runtime.Object, preconditions *storage.Preconditions, dryRun bool) error {
+func (s *DryRunnableStorage) Delete(ctx context.Context, key string, out runtime.Object, preconditions *storage.Preconditions, deleteValidation storage.ValidateObjectFunc, dryRun bool) error {
 	if dryRun {
 		if err := s.Storage.Get(ctx, key, "", out, false); err != nil {
 			return err
 		}
-		return preconditions.Check(key, out)
+		if err := preconditions.Check(key, out); err != nil {
+			return err
 		}
-	return s.Storage.Delete(ctx, key, out, preconditions)
+		return deleteValidation(out)
+	}
+	return s.Storage.Delete(ctx, key, out, preconditions, deleteValidation)
 }
 
 func (s *DryRunnableStorage) Watch(ctx context.Context, key string, resourceVersion string, p storage.SelectionPredicate) (watch.Interface, error) {

pkg/registry/generic/registry/dryrun_test.go

@@ -29,6 +29,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/types"
 	examplev1 "k8s.io/apiserver/pkg/apis/example/v1"
+	"k8s.io/apiserver/pkg/registry/rest"
 	"k8s.io/apiserver/pkg/storage"
 	etcdtesting "k8s.io/apiserver/pkg/storage/etcd/testing"
 	"k8s.io/apiserver/pkg/storage/storagebackend/factory"
@@ -233,7 +234,7 @@ func TestDryRunDeleteDoesntDelete(t *testing.T) {
 		t.Fatalf("Failed to create new object: %v", err)
 	}
 
-	err = s.Delete(context.Background(), "key", out, nil, true)
+	err = s.Delete(context.Background(), "key", out, nil, rest.ValidateAllObjectFunc, true)
 	if err != nil {
 		t.Fatalf("Failed to dry-run delete the object: %v", err)
 	}
@@ -249,7 +250,7 @@ func TestDryRunDeleteMissingObjectFails(t *testing.T) {
 	defer destroy()
 
 	out := UnstructuredOrDie(`{}`)
-	err := s.Delete(context.Background(), "key", out, nil, true)
+	err := s.Delete(context.Background(), "key", out, nil, rest.ValidateAllObjectFunc, true)
 	if e, ok := err.(*storage.StorageError); !ok || e.Code != storage.ErrCodeKeyNotFound {
 		t.Errorf("Expected key to be not found, error: %v", err)
 	}
@@ -269,7 +270,7 @@ func TestDryRunDeleteReturnsObject(t *testing.T) {
 
 	out = UnstructuredOrDie(`{}`)
 	expected := UnstructuredOrDie(`{"kind": "Pod", "metadata": {"resourceVersion": "2"}}`)
-	err = s.Delete(context.Background(), "key", out, nil, true)
+	err = s.Delete(context.Background(), "key", out, nil, rest.ValidateAllObjectFunc, true)
 	if err != nil {
 		t.Fatalf("Failed to delete with valid precondition: %v", err)
 	}
@@ -292,12 +293,12 @@ func TestDryRunDeletePreconditions(t *testing.T) {
 
 	wrongID := types.UID("wrong-uid")
 	myID := types.UID("my-uid")
-	err = s.Delete(context.Background(), "key", out, &storage.Preconditions{UID: &wrongID}, true)
+	err = s.Delete(context.Background(), "key", out, &storage.Preconditions{UID: &wrongID}, rest.ValidateAllObjectFunc, true)
 	if e, ok := err.(*storage.StorageError); !ok || e.Code != storage.ErrCodeInvalidObj {
 		t.Errorf("Expected invalid object, error: %v", err)
 	}
 
-	err = s.Delete(context.Background(), "key", out, &storage.Preconditions{UID: &myID}, true)
+	err = s.Delete(context.Background(), "key", out, &storage.Preconditions{UID: &myID}, rest.ValidateAllObjectFunc, true)
 	if err != nil {
 		t.Fatalf("Failed to delete with valid precondition: %v", err)
 	}

pkg/registry/generic/registry/store.go

@@ -24,7 +24,6 @@ import (
 	"sync"
 	"time"
 
-	"k8s.io/apimachinery/pkg/api/errors"
 	kubeerr "k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/api/meta"
 	"k8s.io/apimachinery/pkg/api/validation/path"
@@ -427,7 +426,8 @@ func ShouldDeleteDuringUpdate(ctx context.Context, key string, obj, existing run
 func (e *Store) deleteWithoutFinalizers(ctx context.Context, name, key string, obj runtime.Object, preconditions *storage.Preconditions, dryRun bool) (runtime.Object, bool, error) {
 	out := e.NewFunc()
 	klog.V(6).Infof("going to delete %s from registry, triggered by update", name)
-	if err := e.Storage.Delete(ctx, key, out, preconditions, dryRun); err != nil {
+	// Using the rest.ValidateAllObjectFunc because the request is an UPDATE request and has already passed the admission for the UPDATE verb.
+	if err := e.Storage.Delete(ctx, key, out, preconditions, rest.ValidateAllObjectFunc, dryRun); err != nil {
 		// Deletion is racy, i.e., there could be multiple update
 		// requests to remove all finalizers from the object, so we
 		// ignore the NotFound error.
@@ -801,7 +801,7 @@ func markAsDeleting(obj runtime.Object, now time.Time) (err error) {
 //    should be deleted immediately
 // 4. a new output object with the state that was updated
 // 5. a copy of the last existing state of the object
-func (e *Store) updateForGracefulDeletionAndFinalizers(ctx context.Context, name, key string, options *metav1.DeleteOptions, preconditions storage.Preconditions, in runtime.Object) (err error, ignoreNotFound, deleteImmediately bool, out, lastExisting runtime.Object) {
+func (e *Store) updateForGracefulDeletionAndFinalizers(ctx context.Context, name, key string, options *metav1.DeleteOptions, preconditions storage.Preconditions, deleteValidation rest.ValidateObjectFunc, in runtime.Object) (err error, ignoreNotFound, deleteImmediately bool, out, lastExisting runtime.Object) {
 	lastGraceful := int64(0)
 	var pendingFinalizers bool
 	out = e.NewFunc()
@@ -812,6 +812,9 @@ func (e *Store) updateForGracefulDeletionAndFinalizers(ctx context.Context, name
 		false, /* ignoreNotFound */
 		&preconditions,
 		storage.SimpleUpdate(func(existing runtime.Object) (runtime.Object, error) {
+			if err := deleteValidation(existing); err != nil {
+				return nil, err
+			}
 			graceful, pendingGraceful, err := rest.BeforeDelete(e.DeleteStrategy, ctx, existing, options)
 			if err != nil {
 				return nil, err
@@ -889,19 +892,8 @@ func (e *Store) Delete(ctx context.Context, name string, deleteValidation rest.V
 	}
 	obj := e.NewFunc()
 	qualifiedResource := e.qualifiedResourceFromContext(ctx)
-	err = e.Storage.Get(ctx, key, "", obj, false)
+	if err = e.Storage.Get(ctx, key, "", obj, false); err != nil {
-	if err != nil {
+		return nil, false, storeerr.InterpretDeleteError(err, qualifiedResource, name)
-		// Note that we continue the admission check on "Not Found" error is for the compatibility
-		// with the NodeRestriction admission controller.
-		if interpretedErr := storeerr.InterpretDeleteError(err, qualifiedResource, name); errors.IsNotFound(interpretedErr) {
-			if err := deleteValidation(obj); err != nil {
-				return nil, false, err
-			}
-			return nil, false, interpretedErr
-		}
-	}
-	if err := deleteValidation(obj.DeepCopyObject()); err != nil {
-		return nil, false, err
 	}
 
 	// support older consumers of delete by treating "nil" as delete immediately
@@ -937,7 +929,7 @@ func (e *Store) Delete(ctx context.Context, name string, deleteValidation rest.V
 	shouldUpdateFinalizers, _ := deletionFinalizersForGarbageCollection(ctx, e, accessor, options)
 	// TODO: remove the check, because we support no-op updates now.
 	if graceful || pendingFinalizers || shouldUpdateFinalizers {
-		err, ignoreNotFound, deleteImmediately, out, lastExisting = e.updateForGracefulDeletionAndFinalizers(ctx, name, key, options, preconditions, obj)
+		err, ignoreNotFound, deleteImmediately, out, lastExisting = e.updateForGracefulDeletionAndFinalizers(ctx, name, key, options, preconditions, deleteValidation, obj)
 	}
 
 	// !deleteImmediately covers all cases where err != nil. We keep both to be future-proof.
@@ -960,7 +952,7 @@ func (e *Store) Delete(ctx context.Context, name string, deleteValidation rest.V
 	// delete immediately, or no graceful deletion supported
 	klog.V(6).Infof("going to delete %s from registry: ", name)
 	out = e.NewFunc()
-	if err := e.Storage.Delete(ctx, key, out, &preconditions, dryrun.IsDryRun(options.DryRun)); err != nil {
+	if err := e.Storage.Delete(ctx, key, out, &preconditions, storage.ValidateObjectFunc(deleteValidation), dryrun.IsDryRun(options.DryRun)); err != nil {
 		// Please refer to the place where we set ignoreNotFound for the reason
 		// why we ignore the NotFound error .
 		if storage.IsNotFound(err) && ignoreNotFound && lastExisting != nil {
@@ -992,12 +984,6 @@ func (e *Store) DeleteCollection(ctx context.Context, deleteValidation rest.Vali
 		listOptions = listOptions.DeepCopy()
 	}
 
-	if deleteValidation != nil {
-		if err := deleteValidation(nil); err != nil {
-			return nil, err
-		}
-	}
-
 	listObj, err := e.List(ctx, listOptions)
 	if err != nil {
 		return nil, err
@@ -1044,7 +1030,7 @@ func (e *Store) DeleteCollection(ctx context.Context, deleteValidation rest.Vali
 					errs <- err
 					return
 				}
-				if _, _, err := e.Delete(ctx, accessor.GetName(), rest.ValidateAllObjectFunc, options); err != nil && !kubeerr.IsNotFound(err) {
+				if _, _, err := e.Delete(ctx, accessor.GetName(), deleteValidation, options); err != nil && !kubeerr.IsNotFound(err) {
 					klog.V(4).Infof("Delete %s in DeleteCollection failed: %v", accessor.GetName(), err)
 					errs <- err
 					return

pkg/registry/generic/registry/store_test.go

@@ -1885,7 +1885,7 @@ func TestDeleteWithCachedObject(t *testing.T) {
 		t.Fatal(err)
 	}
 	// The object shouldn't be deleted, because the persisted object has pending finalizers.
-	_, _, err = registry.Delete(ctx, podName, nil)
+	_, _, err = registry.Delete(ctx, podName, rest.ValidateAllObjectFunc, nil)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -1895,3 +1895,87 @@ func TestDeleteWithCachedObject(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+// TestRetryDeleteValidation checks if the deleteValidation is called again if
+// the GuaranteedUpdate in the Delete handler conflicts with a simultaneous
+// Update.
+func TestRetryDeleteValidation(t *testing.T) {
+	testContext := genericapirequest.WithNamespace(genericapirequest.NewContext(), "test")
+	destroyFunc, registry := NewTestGenericStoreRegistry(t)
+	defer destroyFunc()
+
+	tests := []struct {
+		pod     *example.Pod
+		deleted bool
+	}{
+		{
+			pod: &example.Pod{
+				ObjectMeta: metav1.ObjectMeta{Name: "foo", Namespace: "test", Finalizers: []string{"pending"}},
+				Spec:       example.PodSpec{NodeName: "machine"},
+			},
+			deleted: false,
+		},
+
+		{
+			pod: &example.Pod{
+				ObjectMeta: metav1.ObjectMeta{Name: "bar", Namespace: "test"},
+				Spec:       example.PodSpec{NodeName: "machine"},
+			},
+			deleted: true,
+		},
+	}
+
+	for _, test := range tests {
+		ready := make(chan struct{})
+		updated := make(chan struct{})
+		var readyOnce, updatedOnce sync.Once
+		var called int
+		deleteValidation := func(runtime.Object) error {
+			readyOnce.Do(func() {
+				close(ready)
+			})
+			// wait for the update completes
+			<-updated
+			called++
+			return nil
+		}
+
+		if _, err := registry.Create(testContext, test.pod, rest.ValidateAllObjectFunc, &metav1.CreateOptions{}); err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+
+		transformer := func(ctx context.Context, newObj runtime.Object, oldObj runtime.Object) (transformedNewObj runtime.Object, err error) {
+			<-ready
+			pod, ok := newObj.(*example.Pod)
+			if !ok {
+				t.Fatalf("unexpected object %v", newObj)
+			}
+			pod.Labels = map[string]string{
+				"modified": "true",
+			}
+			return pod, nil
+		}
+
+		go func() {
+			// This update will cause the Delete to retry due to conflict.
+			_, _, err := registry.Update(testContext, test.pod.Name, rest.DefaultUpdatedObjectInfo(test.pod, transformer), rest.ValidateAllObjectFunc, rest.ValidateAllObjectUpdateFunc, false, &metav1.UpdateOptions{})
+			if err != nil {
+				t.Fatal(err)
+			}
+			updatedOnce.Do(func() {
+				close(updated)
+			})
+		}()
+
+		_, deleted, err := registry.Delete(testContext, test.pod.Name, deleteValidation, &metav1.DeleteOptions{})
+		if err != nil {
+			t.Fatal(err)
+		}
+		if a, e := deleted, test.deleted; a != e {
+			t.Fatalf("expected deleted to be %v, got %v", e, a)
+		}
+		if called != 2 {
+			t.Fatalf("expected deleteValidation to be called twice")
+		}
+	}
+}

pkg/registry/rest/delete.go

@@ -147,27 +147,33 @@ func AdmissionToValidateObjectDeleteFunc(admit admission.Interface, staticAttrib
 	mutatingAdmission, isMutatingAdmission := admit.(admission.MutationInterface)
 	validatingAdmission, isValidatingAdmission := admit.(admission.ValidationInterface)
 
+	mutating := isMutatingAdmission && mutatingAdmission.Handles(staticAttributes.GetOperation())
+	validating := isValidatingAdmission && validatingAdmission.Handles(staticAttributes.GetOperation())
+
 	return func(old runtime.Object) error {
-		if !isMutatingAdmission && !isValidatingAdmission {
+		if !mutating && !validating {
 			return nil
 		}
 		finalAttributes := admission.NewAttributesRecord(
 			nil,
-			old,
+			// Deep copy the object to avoid accidentally changing the object.
+			old.DeepCopyObject(),
 			staticAttributes.GetKind(),
 			staticAttributes.GetNamespace(),
 			staticAttributes.GetName(),
 			staticAttributes.GetResource(),
 			staticAttributes.GetSubresource(),
 			staticAttributes.GetOperation(),
+			staticAttributes.GetOperationOptions(),
+			staticAttributes.IsDryRun(),
 			staticAttributes.GetUserInfo(),
 		)
-		if isMutatingAdmission && mutatingAdmission.Handles(finalAttributes.GetOperation()) {
+		if mutating {
 			if err := mutatingAdmission.Admit(finalAttributes, objInterfaces); err != nil {
 				return err
 			}
 		}
-		if isValidatingAdmission && validatingAdmission.Handles(finalAttributes.GetOperation()) {
+		if validating {
 			if err := validatingAdmission.Validate(finalAttributes, objInterfaces); err != nil {
 				return err
 			}

pkg/registry/rest/rest.go

@@ -148,6 +148,7 @@ type TableConvertor interface {
 // RESTful object.
 type GracefulDeleter interface {
 	// Delete finds a resource in the storage and deletes it.
+	// The delete attempt is validated by the deleteValidation first.
 	// If options are provided, the resource will attempt to honor them or return an invalid
 	// request error.
 	// Although it can return an arbitrary error value, IsNotFound(err) is true for the
@@ -163,8 +164,9 @@ type GracefulDeleter interface {
 // of RESTful resources.
 type CollectionDeleter interface {
 	// DeleteCollection selects all resources in the storage matching given 'listOptions'
-	// and deletes them. If 'options' are provided, the resource will attempt to honor
+	// and deletes them. The delete attempt is validated by the deleteValidation first.
-	// them or return an invalid request error.
+	// If 'options' are provided, the resource will attempt to honor them or return an
+	// invalid request error.
 	// DeleteCollection may not be atomic - i.e. it may delete some objects and still
 	// return an error after it. On success, returns a list of deleted objects.
 	DeleteCollection(ctx context.Context, deleteValidation ValidateObjectFunc, options *metav1.DeleteOptions, listOptions *metainternalversion.ListOptions) (runtime.Object, error)

pkg/registry/rest/resttest/resttest.go

@@ -923,14 +923,14 @@ func (t *Tester) testDeleteWithResourceVersion(obj runtime.Object, createFn Crea
 		t.Errorf("unexpected error: %v", err)
 	}
 	opts.Preconditions = metav1.NewRVDeletionPrecondition("RV1111").Preconditions
-	obj, wasDeleted, err := t.storage.(rest.GracefulDeleter).Delete(ctx, objectMeta.GetName(), &opts)
+	obj, wasDeleted, err := t.storage.(rest.GracefulDeleter).Delete(ctx, objectMeta.GetName(), rest.ValidateAllObjectFunc, &opts)
 	if err == nil || !errors.IsConflict(err) {
 		t.Errorf("unexpected error: %v", err)
 	}
 	if wasDeleted {
 		t.Errorf("unexpected, object %s should not have been deleted immediately", objectMeta.GetName())
 	}
-	obj, _, err = t.storage.(rest.GracefulDeleter).Delete(ctx, objectMeta.GetName(), metav1.NewRVDeletionPrecondition("RV0000"))
+	obj, _, err = t.storage.(rest.GracefulDeleter).Delete(ctx, objectMeta.GetName(), rest.ValidateAllObjectFunc, metav1.NewRVDeletionPrecondition("RV0000"))
 	if err != nil {
 		t.Errorf("unexpected error: %v", err)
 	}
@@ -962,7 +962,7 @@ func (t *Tester) testDeleteDryRunGracefulHasdefault(obj runtime.Object, createFn
 		t.Errorf("unexpected error: %v", err)
 	}
 	objectMeta := t.getObjectMetaOrFail(foo)
-	object, wasDeleted, err := t.storage.(rest.GracefulDeleter).Delete(ctx, objectMeta.GetName(), &metav1.DeleteOptions{DryRun: []string{metav1.DryRunAll}})
+	object, wasDeleted, err := t.storage.(rest.GracefulDeleter).Delete(ctx, objectMeta.GetName(), rest.ValidateAllObjectFunc, &metav1.DeleteOptions{DryRun: []string{metav1.DryRunAll}})
 	if err != nil {
 		t.Errorf("unexpected error: %v", err)
 	}
@@ -973,7 +973,7 @@ func (t *Tester) testDeleteDryRunGracefulHasdefault(obj runtime.Object, createFn
 	if objectMeta.GetDeletionTimestamp() == nil || objectMeta.GetDeletionGracePeriodSeconds() == nil || *objectMeta.GetDeletionGracePeriodSeconds() != expectedGrace {
 		t.Errorf("unexpected deleted meta: %#v", objectMeta)
 	}
-	_, _, err = t.storage.(rest.GracefulDeleter).Delete(ctx, objectMeta.GetName(), &metav1.DeleteOptions{})
+	_, _, err = t.storage.(rest.GracefulDeleter).Delete(ctx, objectMeta.GetName(), rest.ValidateAllObjectFunc, &metav1.DeleteOptions{})
 	if err != nil {
 		t.Errorf("unexpected error: %v", err)
 	}

pkg/storage/cacher/cacher.go

@@ -403,8 +403,8 @@ func (c *Cacher) Create(ctx context.Context, key string, obj, out runtime.Object
 }
 
 // Delete implements storage.Interface.
-func (c *Cacher) Delete(ctx context.Context, key string, out runtime.Object, preconditions *storage.Preconditions) error {
+func (c *Cacher) Delete(ctx context.Context, key string, out runtime.Object, preconditions *storage.Preconditions, validateDeletion storage.ValidateObjectFunc) error {
-	return c.storage.Delete(ctx, key, out, preconditions)
+	return c.storage.Delete(ctx, key, out, preconditions, validateDeletion)
 }
 
 // Watch implements storage.Interface.

pkg/storage/cacher/cacher_whitebox_test.go

@@ -299,7 +299,7 @@ func (d *dummyStorage) Versioner() storage.Versioner { return nil }
 func (d *dummyStorage) Create(_ context.Context, _ string, _, _ runtime.Object, _ uint64) error {
 	return fmt.Errorf("unimplemented")
 }
-func (d *dummyStorage) Delete(_ context.Context, _ string, _ runtime.Object, _ *storage.Preconditions) error {
+func (d *dummyStorage) Delete(_ context.Context, _ string, _ runtime.Object, _ *storage.Preconditions, _ storage.ValidateObjectFunc) error {
 	return fmt.Errorf("unimplemented")
 }
 func (d *dummyStorage) Watch(_ context.Context, _ string, _ string, _ storage.SelectionPredicate) (watch.Interface, error) {

pkg/storage/etcd3/store.go

@@ -181,44 +181,16 @@ func (s *store) Create(ctx context.Context, key string, obj, out runtime.Object,
 }
 
 // Delete implements storage.Interface.Delete.
-func (s *store) Delete(ctx context.Context, key string, out runtime.Object, preconditions *storage.Preconditions) error {
+func (s *store) Delete(ctx context.Context, key string, out runtime.Object, preconditions *storage.Preconditions, validateDeletion storage.ValidateObjectFunc) error {
 	v, err := conversion.EnforcePtr(out)
 	if err != nil {
 		panic("unable to convert output object to pointer")
 	}
 	key = path.Join(s.pathPrefix, key)
-	if preconditions == nil {
+	return s.conditionalDelete(ctx, key, out, v, preconditions, validateDeletion)
-		return s.unconditionalDelete(ctx, key, out)
-	}
-	return s.conditionalDelete(ctx, key, out, v, preconditions)
 }
 
-func (s *store) unconditionalDelete(ctx context.Context, key string, out runtime.Object) error {
+func (s *store) conditionalDelete(ctx context.Context, key string, out runtime.Object, v reflect.Value, preconditions *storage.Preconditions, validateDeletion storage.ValidateObjectFunc) error {
-	// We need to do get and delete in single transaction in order to
-	// know the value and revision before deleting it.
-	startTime := time.Now()
-	txnResp, err := s.client.KV.Txn(ctx).If().Then(
-		clientv3.OpGet(key),
-		clientv3.OpDelete(key),
-	).Commit()
-	metrics.RecordEtcdRequestLatency("delete", getTypeName(out), startTime)
-	if err != nil {
-		return err
-	}
-	getResp := txnResp.Responses[0].GetResponseRange()
-	if len(getResp.Kvs) == 0 {
-		return storage.NewKeyNotFoundError(key, 0)
-	}
-
-	kv := getResp.Kvs[0]
-	data, _, err := s.transformer.TransformFromStorage(kv.Value, authenticatedDataString(key))
-	if err != nil {
-		return storage.NewInternalError(err.Error())
-	}
-	return decode(s.codec, s.versioner, data, out, kv.ModRevision)
-}
-
-func (s *store) conditionalDelete(ctx context.Context, key string, out runtime.Object, v reflect.Value, preconditions *storage.Preconditions) error {
 	startTime := time.Now()
 	getResp, err := s.client.KV.Get(ctx, key)
 	metrics.RecordEtcdRequestLatency("get", getTypeName(out), startTime)
@@ -230,9 +202,14 @@ func (s *store) conditionalDelete(ctx context.Context, key string, out runtime.O
 		if err != nil {
 			return err
 		}
+		if preconditions != nil {
 			if err := preconditions.Check(key, origState.obj); err != nil {
 				return err
 			}
+		}
+		if err := validateDeletion(origState.obj); err != nil {
+			return err
+		}
 		startTime := time.Now()
 		txnResp, err := s.client.KV.Txn(ctx).If(
 			clientv3.Compare(clientv3.ModRevision(key), "=", origState.rev),

pkg/storage/etcd3/store_test.go

@@ -74,7 +74,7 @@ func (p prefixTransformer) TransformFromStorage(b []byte, ctx value.Context) ([]
 		panic("no context provided")
 	}
 	if !bytes.HasPrefix(b, p.prefix) {
-		return nil, false, fmt.Errorf("value does not have expected prefix: %s", string(b))
+		return nil, false, fmt.Errorf("value does not have expected prefix %q: %s,", p.prefix, string(b))
 	}
 	return bytes.TrimPrefix(b, p.prefix), p.stale, p.err
 }
@@ -241,7 +241,7 @@ func TestUnconditionalDelete(t *testing.T) {
 
 	for i, tt := range tests {
 		out := &example.Pod{} // reset
-		err := store.Delete(ctx, tt.key, out, nil)
+		err := store.Delete(ctx, tt.key, out, nil, storage.ValidateAllObjectFunc)
 		if tt.expectNotFoundErr {
 			if err == nil || !storage.IsNotFound(err) {
 				t.Errorf("#%d: expecting not found error, but get: %s", i, err)
@@ -275,7 +275,7 @@ func TestConditionalDelete(t *testing.T) {
 
 	for i, tt := range tests {
 		out := &example.Pod{}
-		err := store.Delete(ctx, key, out, tt.precondition)
+		err := store.Delete(ctx, key, out, tt.precondition, storage.ValidateAllObjectFunc)
 		if tt.expectInvalidObjErr {
 			if err == nil || !storage.IsInvalidObj(err) {
 				t.Errorf("#%d: expecting invalid UID error, but get: %s", i, err)
@@ -740,12 +740,11 @@ func TestTransformationFailure(t *testing.T) {
 		t.Errorf("Unexpected error: %v", err)
 	}
 
-	// Delete succeeds but reports an error because we cannot access the body
+	// Delete fails with internal error.
-	if err := store.Delete(ctx, preset[1].key, &example.Pod{}, nil); !storage.IsInternalError(err) {
+	if err := store.Delete(ctx, preset[1].key, &example.Pod{}, nil, storage.ValidateAllObjectFunc); !storage.IsInternalError(err) {
 		t.Errorf("Unexpected error: %v", err)
 	}
-
+	if err := store.Get(ctx, preset[1].key, "", &example.Pod{}, false); !storage.IsInternalError(err) {
-	if err := store.Get(ctx, preset[1].key, "", &example.Pod{}, false); !storage.IsNotFound(err) {
 		t.Errorf("Unexpected error: %v", err)
 	}
 }
@@ -1349,7 +1348,7 @@ func testSetup(t *testing.T) (context.Context, *store, *integration.ClusterV3) {
 func testPropogateStore(ctx context.Context, t *testing.T, store *store, obj *example.Pod) (string, *example.Pod) {
 	// Setup store with a key and grab the output for returning.
 	key := "/testkey"
-	err := store.unconditionalDelete(ctx, key, &example.Pod{})
+	err := store.conditionalDelete(ctx, key, &example.Pod{}, reflect.ValueOf(example.Pod{}), nil, storage.ValidateAllObjectFunc)
 	if err != nil && !storage.IsNotFound(err) {
 		t.Fatalf("Cleanup failed: %v", err)
 	}

pkg/storage/etcd3/watcher_test.go

@@ -135,7 +135,7 @@ func TestDeleteTriggerWatch(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Watch failed: %v", err)
 	}
-	if err := store.Delete(ctx, key, &example.Pod{}, nil); err != nil {
+	if err := store.Delete(ctx, key, &example.Pod{}, nil, storage.ValidateAllObjectFunc); err != nil {
 		t.Fatalf("Delete failed: %v", err)
 	}
 	testCheckEventType(t, watch.Deleted, w)
@@ -295,7 +295,7 @@ func TestWatchDeleteEventObjectHaveLatestRV(t *testing.T) {
 	}
 	etcdW := cluster.RandClient().Watch(ctx, "/", clientv3.WithPrefix())
 
-	if err := store.Delete(ctx, key, &example.Pod{}, &storage.Preconditions{}); err != nil {
+	if err := store.Delete(ctx, key, &example.Pod{}, &storage.Preconditions{}, storage.ValidateAllObjectFunc); err != nil {
 		t.Fatalf("Delete failed: %v", err)
 	}
 

pkg/storage/interfaces.go

@@ -95,6 +95,16 @@ var Everything = SelectionPredicate{
 // See the comment for GuaranteedUpdate for more details.
 type UpdateFunc func(input runtime.Object, res ResponseMeta) (output runtime.Object, ttl *uint64, err error)
 
+// ValidateObjectFunc is a function to act on a given object. An error may be returned
+// if the hook cannot be completed. The function may NOT transform the provided
+// object.
+type ValidateObjectFunc func(obj runtime.Object) error
+
+// ValidateAllObjectFunc is a "admit everything" instance of ValidateObjectFunc.
+func ValidateAllObjectFunc(obj runtime.Object) error {
+	return nil
+}
+
 // Preconditions must be fulfilled before an operation (update, delete, etc.) is carried out.
 type Preconditions struct {
 	// Specifies the target UID.
@@ -153,7 +163,7 @@ type Interface interface {
 
 	// Delete removes the specified key and returns the value that existed at that spot.
 	// If key didn't exist, it will return NotFound storage error.
-	Delete(ctx context.Context, key string, out runtime.Object, preconditions *Preconditions) error
+	Delete(ctx context.Context, key string, out runtime.Object, preconditions *Preconditions, validateDeletion ValidateObjectFunc) error
 
 	// Watch begins watching the specified key. Events are decoded into API objects,
 	// and any items selected by 'p' are sent down to returned watch.Interface.

pkg/storage/tests/cacher_test.go

@@ -259,7 +259,7 @@ func TestList(t *testing.T) {
 	updatePod(t, etcdStorage, podFooNS2, nil)
 
 	deleted := example.Pod{}
-	if err := etcdStorage.Delete(context.TODO(), "pods/ns/bar", &deleted, nil); err != nil {
+	if err := etcdStorage.Delete(context.TODO(), "pods/ns/bar", &deleted, nil, storage.ValidateAllObjectFunc); err != nil {
 		t.Errorf("Unexpected error: %v", err)
 	}
 
@@ -521,7 +521,7 @@ func TestFiltering(t *testing.T) {
 	_ = updatePod(t, etcdStorage, podFooPrime, fooUnfiltered)
 
 	deleted := example.Pod{}
-	if err := etcdStorage.Delete(context.TODO(), "pods/ns/foo", &deleted, nil); err != nil {
+	if err := etcdStorage.Delete(context.TODO(), "pods/ns/foo", &deleted, nil, storage.ValidateAllObjectFunc); err != nil {
 		t.Errorf("Unexpected error: %v", err)
 	}