CRConverter: change to UnstructuredList

Change the CRConverter interface to use *unstructured.UnstructuredList
for input/output to simplify what converter implementers must implement.

Signed-off-by: Andy Goldstein <andy.goldstein@redhat.com>

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

@@ -21,9 +21,12 @@ import (
 
 	autoscalingv1 "k8s.io/api/autoscaling/v1"
 	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
+	apivalidation "k8s.io/apimachinery/pkg/api/validation"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	metav1validation "k8s.io/apimachinery/pkg/apis/meta/v1/validation"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/util/validation/field"
 	"k8s.io/apiserver/pkg/util/webhook"
 	typedscheme "k8s.io/client-go/kubernetes/scheme"
 )
@@ -110,7 +113,7 @@ type CRConverter interface {
 	// Convert converts in object to the given gvk and returns the converted object.
 	// Note that the function may mutate in object and return it. A safe wrapper will make sure
 	// a safe converter will be returned.
-	Convert(in runtime.Object, targetGVK schema.GroupVersion) (runtime.Object, error)
+	Convert(in *unstructured.UnstructuredList, targetGVK schema.GroupVersion) (*unstructured.UnstructuredList, error)
 }
 
 // delegatingCRConverter extends the delegate converter with generic CR conversion behaviour. The delegate will implement the
@@ -173,13 +176,6 @@ func (c *delegatingCRConverter) Convert(in, out, context interface{}) error {
 // UnstructuredList with the request's GV, populates it from storage, then calls conversion to convert
 // the individual items. This function assumes it never gets a v1.List.
 func (c *delegatingCRConverter) ConvertToVersion(in runtime.Object, target runtime.GroupVersioner) (runtime.Object, error) {
-	fromGVK := in.GetObjectKind().GroupVersionKind()
-	toGVK, ok := target.KindForGroupVersionKinds([]schema.GroupVersionKind{fromGVK})
-	if !ok {
-		// TODO: should this be a typed error?
-		return nil, fmt.Errorf("%v is unstructured and is not suitable for converting to %q", fromGVK.String(), target)
-	}
-
 	// Special-case typed scale conversion if this custom resource supports a scale endpoint
 	if c.convertScale {
 		if _, isInScale := in.(*autoscalingv1.Scale); isInScale {
@@ -187,8 +183,28 @@ func (c *delegatingCRConverter) ConvertToVersion(in runtime.Object, target runti
 		}
 	}
 
+	fromGVK := in.GetObjectKind().GroupVersionKind()
+	toGVK, ok := target.KindForGroupVersionKinds([]schema.GroupVersionKind{fromGVK})
+	if !ok {
+		// TODO: should this be a typed error?
+		return nil, fmt.Errorf("%v is unstructured and is not suitable for converting to %q", fromGVK.String(), target)
+	}
+
+	isList := false
+	var list *unstructured.UnstructuredList
+	switch t := in.(type) {
+	case *unstructured.Unstructured:
+		list = &unstructured.UnstructuredList{Items: []unstructured.Unstructured{*t}}
+	case *unstructured.UnstructuredList:
+		list = t
+		isList = true
+	default:
+		return nil, fmt.Errorf("unexpected type %T", in)
+	}
+
+	desiredAPIVersion := toGVK.GroupVersion().String()
 	if !c.validVersions[toGVK.GroupVersion()] {
-		return nil, fmt.Errorf("request to convert CR to an invalid group/version: %s", toGVK.GroupVersion().String())
+		return nil, fmt.Errorf("request to convert CR to an invalid group/version: %s", desiredAPIVersion)
 	}
 	// Note that even if the request is for a list, the GV of the request UnstructuredList is what
 	// is expected to convert to. As mentioned in the function's document, it is not expected to
@@ -196,23 +212,101 @@ func (c *delegatingCRConverter) ConvertToVersion(in runtime.Object, target runti
 	if !c.validVersions[fromGVK.GroupVersion()] {
 		return nil, fmt.Errorf("request to convert CR from an invalid group/version: %s", fromGVK.GroupVersion().String())
 	}
-	// Check list item's apiVersion
-	if list, ok := in.(*unstructured.UnstructuredList); ok {
-		for i := range list.Items {
-			expectedGV := list.Items[i].GroupVersionKind().GroupVersion()
-			if !c.validVersions[expectedGV] {
-				return nil, fmt.Errorf("request to convert CR list failed, list index %d has invalid group/version: %s", i, expectedGV.String())
-			}
+
+	var objectsToConvert []*unstructured.Unstructured
+	objectsToConvert, err := getObjectsToConvert(list, desiredAPIVersion, c.validVersions)
+	if err != nil {
+		return nil, err
+	}
+
+	objCount := len(objectsToConvert)
+	if objCount == 0 {
+		// no objects needed conversion
+		if !isList {
+			// for a single item, return as-is
+			return in, nil
 		}
+		// for a list, set the version of the top-level list object (all individual objects are already in the correct version)
+		out := list.DeepCopy()
+		out.SetAPIVersion(desiredAPIVersion)
+		return out, nil
 	}
 
 	// A smoke test in API machinery calls the converter on empty objects during startup. The test is initiated here:
 	// https://github.com/kubernetes/kubernetes/blob/dbb448bbdcb9e440eee57024ffa5f1698956a054/staging/src/k8s.io/apiserver/pkg/storage/cacher/cacher.go#L201
 	if isEmptyUnstructuredObject(in) {
-		return NewNOPConverter().Convert(in, toGVK.GroupVersion())
+		converted, err := NewNOPConverter().Convert(list, toGVK.GroupVersion())
+		if err != nil {
+			return nil, err
+		}
+		if !isList {
+			return &converted.Items[0], nil
+		}
+		return converted, nil
 	}
-	
-	return c.converter.Convert(in, toGVK.GroupVersion())
+
+	convertedObjects, err := c.converter.Convert(list, toGVK.GroupVersion())
+	if err != nil {
+		return nil, fmt.Errorf("conversion for %v failed: %w", in.GetObjectKind().GroupVersionKind(), err)
+	}
+	if len(convertedObjects.Items) != len(objectsToConvert) {
+		return nil, fmt.Errorf("conversion for %v returned %d objects, expected %d", in.GetObjectKind().GroupVersionKind(), len(convertedObjects.Items), len(objectsToConvert))
+	}
+
+	// start a deepcopy of the input and fill in the converted objects from the response at the right spots.
+	// The response list might be sparse because objects had the right version already.
+	convertedList := list.DeepCopy()
+	convertedList.SetAPIVersion(desiredAPIVersion)
+	convertedIndex := 0
+	for i := range convertedList.Items {
+		original := &convertedList.Items[i]
+		if original.GetAPIVersion() == desiredAPIVersion {
+			// This item has not been sent for conversion, and therefore does not show up in the response.
+			// convertedList has the right item already.
+			continue
+		}
+		converted := &convertedObjects.Items[convertedIndex]
+		convertedIndex++
+		if expected, got := toGVK.GroupVersion(), converted.GetObjectKind().GroupVersionKind().GroupVersion(); expected != got {
+			return nil, fmt.Errorf("conversion for %v returned invalid converted object at index %v: invalid groupVersion (expected %v, received %v)", in.GetObjectKind().GroupVersionKind(), convertedIndex, expected, got)
+		}
+		if expected, got := original.GetObjectKind().GroupVersionKind().Kind, converted.GetObjectKind().GroupVersionKind().Kind; expected != got {
+			return nil, fmt.Errorf("conversion for %v returned invalid converted object at index %v: invalid kind (expected %v, received %v)", in.GetObjectKind().GroupVersionKind(), convertedIndex, expected, got)
+		}
+		if err := validateConvertedObject(original, converted); err != nil {
+			return nil, fmt.Errorf("conversion for %v returned invalid converted object at index %v: %v", in.GetObjectKind().GroupVersionKind(), convertedIndex, err)
+		}
+		if err := restoreObjectMeta(original, converted); err != nil {
+			return nil, fmt.Errorf("conversion for %v returned invalid metadata in object at index %v: %v", in.GetObjectKind().GroupVersionKind(), convertedIndex, err)
+		}
+		convertedList.Items[i] = *converted
+	}
+
+	if isList {
+		return convertedList, nil
+	}
+
+	return &convertedList.Items[0], nil
+}
+
+func getObjectsToConvert(
+	list *unstructured.UnstructuredList,
+	desiredAPIVersion string,
+	validVersions map[schema.GroupVersion]bool,
+) ([]*unstructured.Unstructured, error) {
+	var objectsToConvert []*unstructured.Unstructured
+	for i := range list.Items {
+		expectedGV := list.Items[i].GroupVersionKind().GroupVersion()
+		if !validVersions[expectedGV] {
+			return nil, fmt.Errorf("request to convert CR list failed, list index %d has invalid group/version: %s", i, expectedGV.String())
+		}
+
+		// Only sent item for conversion, if the apiVersion is different
+		if list.Items[i].GetAPIVersion() != desiredAPIVersion {
+			objectsToConvert = append(objectsToConvert, &list.Items[i])
+		}
+	}
+	return objectsToConvert, nil
 }
 
 // safeConverterWrapper is a wrapper over an unsafe object converter that makes copy of the input and then delegate to the unsafe converter.
@@ -259,3 +353,94 @@ func isEmptyUnstructuredObject(in runtime.Object) bool {
 	}
 	return true
 }
+
+// validateConvertedObject checks that ObjectMeta fields match, with the exception of
+// labels and annotations.
+func validateConvertedObject(in, out *unstructured.Unstructured) error {
+	if e, a := in.GetKind(), out.GetKind(); e != a {
+		return fmt.Errorf("must have the same kind: %v != %v", e, a)
+	}
+	if e, a := in.GetName(), out.GetName(); e != a {
+		return fmt.Errorf("must have the same name: %v != %v", e, a)
+	}
+	if e, a := in.GetNamespace(), out.GetNamespace(); e != a {
+		return fmt.Errorf("must have the same namespace: %v != %v", e, a)
+	}
+	if e, a := in.GetUID(), out.GetUID(); e != a {
+		return fmt.Errorf("must have the same UID: %v != %v", e, a)
+	}
+	return nil
+}
+
+// restoreObjectMeta deep-copies metadata from original into converted, while preserving labels and annotations from converted.
+func restoreObjectMeta(original, converted *unstructured.Unstructured) error {
+	obj, found := converted.Object["metadata"]
+	if !found {
+		return fmt.Errorf("missing metadata in converted object")
+	}
+	responseMetaData, ok := obj.(map[string]interface{})
+	if !ok {
+		return fmt.Errorf("invalid metadata of type %T in converted object", obj)
+	}
+
+	if _, ok := original.Object["metadata"]; !ok {
+		// the original will always have metadata. But just to be safe, let's clear in converted
+		// with an empty object instead of nil, to be able to add labels and annotations below.
+		converted.Object["metadata"] = map[string]interface{}{}
+	} else {
+		converted.Object["metadata"] = runtime.DeepCopyJSONValue(original.Object["metadata"])
+	}
+
+	obj = converted.Object["metadata"]
+	convertedMetaData, ok := obj.(map[string]interface{})
+	if !ok {
+		return fmt.Errorf("invalid metadata of type %T in input object", obj)
+	}
+
+	for _, fld := range []string{"labels", "annotations"} {
+		obj, found := responseMetaData[fld]
+		if !found || obj == nil {
+			delete(convertedMetaData, fld)
+			continue
+		}
+		responseField, ok := obj.(map[string]interface{})
+		if !ok {
+			return fmt.Errorf("invalid metadata.%s of type %T in converted object", fld, obj)
+		}
+
+		originalField, ok := convertedMetaData[fld].(map[string]interface{})
+		if !ok && convertedMetaData[fld] != nil {
+			return fmt.Errorf("invalid metadata.%s of type %T in original object", fld, convertedMetaData[fld])
+		}
+
+		somethingChanged := len(originalField) != len(responseField)
+		for k, v := range responseField {
+			if _, ok := v.(string); !ok {
+				return fmt.Errorf("metadata.%s[%s] must be a string, but is %T in converted object", fld, k, v)
+			}
+			if originalField[k] != interface{}(v) {
+				somethingChanged = true
+			}
+		}
+
+		if somethingChanged {
+			stringMap := make(map[string]string, len(responseField))
+			for k, v := range responseField {
+				stringMap[k] = v.(string)
+			}
+			var errs field.ErrorList
+			if fld == "labels" {
+				errs = metav1validation.ValidateLabels(stringMap, field.NewPath("metadata", "labels"))
+			} else {
+				errs = apivalidation.ValidateAnnotations(stringMap, field.NewPath("metadata", "annotation"))
+			}
+			if len(errs) > 0 {
+				return errs.ToAggregate()
+			}
+		}
+
+		convertedMetaData[fld] = responseField
+	}
+
+	return nil
+}

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

@@ -21,6 +21,7 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/google/go-cmp/cmp"
 	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/runtime"
@@ -188,3 +189,102 @@ func TestConversion(t *testing.T) {
 		}
 	}
 }
+
+func TestGetObjectsToConvert(t *testing.T) {
+	v1Object := &unstructured.Unstructured{Object: map[string]interface{}{"apiVersion": "foo/v1", "kind": "Widget", "metadata": map[string]interface{}{"name": "myv1"}}}
+	v2Object := &unstructured.Unstructured{Object: map[string]interface{}{"apiVersion": "foo/v2", "kind": "Widget", "metadata": map[string]interface{}{"name": "myv2"}}}
+	v3Object := &unstructured.Unstructured{Object: map[string]interface{}{"apiVersion": "foo/v3", "kind": "Widget", "metadata": map[string]interface{}{"name": "myv3"}}}
+
+	testcases := []struct {
+		Name          string
+		List          *unstructured.UnstructuredList
+		APIVersion    string
+		ValidVersions map[schema.GroupVersion]bool
+
+		ExpectObjects []*unstructured.Unstructured
+		ExpectError   bool
+	}{
+		{
+			Name:       "empty list",
+			List:       &unstructured.UnstructuredList{},
+			APIVersion: "foo/v1",
+			ValidVersions: map[schema.GroupVersion]bool{
+				{Group: "foo", Version: "v1"}: true,
+			},
+			ExpectObjects: nil,
+		},
+		{
+			Name: "one-item list, in desired version",
+			List: &unstructured.UnstructuredList{
+				Items: []unstructured.Unstructured{*v1Object},
+			},
+			ValidVersions: map[schema.GroupVersion]bool{
+				{Group: "foo", Version: "v1"}: true,
+			},
+			APIVersion:    "foo/v1",
+			ExpectObjects: nil,
+		},
+		{
+			Name: "one-item list, not in desired version",
+			List: &unstructured.UnstructuredList{
+				Items: []unstructured.Unstructured{*v2Object},
+			},
+			ValidVersions: map[schema.GroupVersion]bool{
+				{Group: "foo", Version: "v1"}: true,
+				{Group: "foo", Version: "v2"}: true,
+			},
+			APIVersion:    "foo/v1",
+			ExpectObjects: []*unstructured.Unstructured{v2Object},
+		},
+		{
+			Name: "multi-item list, in desired version",
+			List: &unstructured.UnstructuredList{
+				Items: []unstructured.Unstructured{*v1Object, *v1Object, *v1Object},
+			},
+			ValidVersions: map[schema.GroupVersion]bool{
+				{Group: "foo", Version: "v1"}: true,
+				{Group: "foo", Version: "v2"}: true,
+			},
+			APIVersion:    "foo/v1",
+			ExpectObjects: nil,
+		},
+		{
+			Name: "multi-item list, mixed versions",
+			List: &unstructured.UnstructuredList{
+				Items: []unstructured.Unstructured{*v1Object, *v2Object, *v3Object},
+			},
+			ValidVersions: map[schema.GroupVersion]bool{
+				{Group: "foo", Version: "v1"}: true,
+				{Group: "foo", Version: "v2"}: true,
+				{Group: "foo", Version: "v3"}: true,
+			},
+			APIVersion:    "foo/v1",
+			ExpectObjects: []*unstructured.Unstructured{v2Object, v3Object},
+		},
+		{
+			Name: "multi-item list, invalid versions",
+			List: &unstructured.UnstructuredList{
+				Items: []unstructured.Unstructured{*v1Object, *v2Object, *v3Object},
+			},
+			ValidVersions: map[schema.GroupVersion]bool{
+				{Group: "foo", Version: "v2"}: true,
+				{Group: "foo", Version: "v3"}: true,
+			},
+			APIVersion:    "foo/v1",
+			ExpectObjects: nil,
+			ExpectError:   true,
+		},
+	}
+	for _, tc := range testcases {
+		t.Run(tc.Name, func(t *testing.T) {
+			objects, err := getObjectsToConvert(tc.List, tc.APIVersion, tc.ValidVersions)
+			gotError := err != nil
+			if e, a := tc.ExpectError, gotError; e != a {
+				t.Fatalf("error: expected %t, got %t", e, a)
+			}
+			if !reflect.DeepEqual(objects, tc.ExpectObjects) {
+				t.Errorf("unexpected diff: %s", cmp.Diff(tc.ExpectObjects, objects))
+			}
+		})
+	}
+}

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

@@ -21,7 +21,7 @@ import (
 	"sync"
 	"time"
 
-	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/component-base/metrics"
 	"k8s.io/component-base/metrics/legacyregistry"
@@ -73,7 +73,7 @@ func (c *converterMetricFactory) addMetrics(crdName string, converter CRConverte
 	return &converterMetric{latencies: metric, delegate: converter, crdName: crdName}, nil
 }
 
-func (m *converterMetric) Convert(in runtime.Object, targetGV schema.GroupVersion) (runtime.Object, error) {
+func (m *converterMetric) Convert(in *unstructured.UnstructuredList, targetGV schema.GroupVersion) (*unstructured.UnstructuredList, error) {
 	start := time.Now()
 	obj, err := m.delegate.Convert(in, targetGV)
 	fromVersion := in.GetObjectKind().GroupVersionKind().Version

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

@@ -18,7 +18,6 @@ package conversion
 
 import (
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
-	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 )
 
@@ -35,13 +34,9 @@ func NewNOPConverter() *nopConverter {
 var _ CRConverter = &nopConverter{}
 
 // ConvertToVersion converts in object to the given gv in place and returns the same `in` object.
-func (c *nopConverter) Convert(in runtime.Object, targetGV schema.GroupVersion) (runtime.Object, error) {
-	// Run the converter on the list items instead of list itself
-	if list, ok := in.(*unstructured.UnstructuredList); ok {
-		for i := range list.Items {
-			list.Items[i].SetGroupVersionKind(targetGV.WithKind(list.Items[i].GroupVersionKind().Kind))
-		}
+func (c *nopConverter) Convert(list *unstructured.UnstructuredList, targetGV schema.GroupVersion) (*unstructured.UnstructuredList, error) {
+	for i := range list.Items {
+		list.Items[i].SetGroupVersionKind(targetGV.WithKind(list.Items[i].GroupVersionKind().Kind))
 	}
-	in.GetObjectKind().SetGroupVersionKind(targetGV.WithKind(in.GetObjectKind().GroupVersionKind().Kind))
-	return in, nil
+	return list, nil
 }

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

@@ -26,15 +26,12 @@ import (
 
 	v1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
 	"k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1beta1"
-	apivalidation "k8s.io/apimachinery/pkg/api/validation"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
-	metav1validation "k8s.io/apimachinery/pkg/apis/meta/v1/validation"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apimachinery/pkg/util/uuid"
-	"k8s.io/apimachinery/pkg/util/validation/field"
 	"k8s.io/apiserver/pkg/util/webhook"
 	"k8s.io/client-go/rest"
 	"k8s.io/component-base/tracing"
@@ -113,36 +110,21 @@ func (f *webhookConverterFactory) NewWebhookConverter(crd *v1.CustomResourceDefi
 	}, nil
 }
 
-// getObjectsToConvert returns a list of objects requiring conversion.
-// if obj is a list, getObjectsToConvert returns a (potentially empty) list of the items that are not already in the desired version.
-// if obj is not a list, and is already in the desired version, getObjectsToConvert returns an empty list.
-// if obj is not a list, and is not already in the desired version, getObjectsToConvert returns a list containing only obj.
-func getObjectsToConvert(obj runtime.Object, apiVersion string) []runtime.RawExtension {
-	listObj, isList := obj.(*unstructured.UnstructuredList)
-	var objects []runtime.RawExtension
-	if isList {
-		for i := range listObj.Items {
-			// Only sent item for conversion, if the apiVersion is different
-			if listObj.Items[i].GetAPIVersion() != apiVersion {
-				objects = append(objects, runtime.RawExtension{Object: &listObj.Items[i]})
-			}
-		}
-	} else {
-		if obj.GetObjectKind().GroupVersionKind().GroupVersion().String() != apiVersion {
-			objects = []runtime.RawExtension{{Object: obj}}
+// createConversionReviewObjects returns ConversionReview request and response objects for the first supported version found in conversionReviewVersions.
+func createConversionReviewObjects(conversionReviewVersions []string, objects *unstructured.UnstructuredList, apiVersion string, requestUID types.UID) (request, response runtime.Object, err error) {
+	rawObjects := make([]runtime.RawExtension, len(objects.Items))
+	for i := range objects.Items {
+		rawObjects[i] = runtime.RawExtension{
+			Object: &objects.Items[i],
 		}
 	}
-	return objects
-}
 
-// createConversionReviewObjects returns ConversionReview request and response objects for the first supported version found in conversionReviewVersions.
-func createConversionReviewObjects(conversionReviewVersions []string, objects []runtime.RawExtension, apiVersion string, requestUID types.UID) (request, response runtime.Object, err error) {
 	for _, version := range conversionReviewVersions {
 		switch version {
 		case v1beta1.SchemeGroupVersion.Version:
 			return &v1beta1.ConversionReview{
 				Request: &v1beta1.ConversionRequest{
-					Objects:           objects,
+					Objects:           rawObjects,
 					DesiredAPIVersion: apiVersion,
 					UID:               requestUID,
 				},
@@ -151,7 +133,7 @@ func createConversionReviewObjects(conversionReviewVersions []string, objects []
 		case v1.SchemeGroupVersion.Version:
 			return &v1.ConversionReview{
 				Request: &v1.ConversionRequest{
-					Objects:           objects,
+					Objects:           rawObjects,
 					DesiredAPIVersion: apiVersion,
 					UID:               requestUID,
 				},
@@ -162,9 +144,13 @@ func createConversionReviewObjects(conversionReviewVersions []string, objects []
 	return nil, nil, fmt.Errorf("no supported conversion review versions")
 }
 
-func getRawExtensionObject(rx runtime.RawExtension) (runtime.Object, error) {
+func getRawExtensionObject(rx runtime.RawExtension) (*unstructured.Unstructured, error) {
 	if rx.Object != nil {
-		return rx.Object, nil
+		u, ok := rx.Object.(*unstructured.Unstructured)
+		if !ok {
+			return nil, fmt.Errorf("unexpected type %T", rx.Object)
+		}
+		return u, nil
 	}
 	u := unstructured.Unstructured{}
 	err := u.UnmarshalJSON(rx.Raw)
@@ -227,30 +213,16 @@ func getConvertedObjectsFromResponse(expectedUID types.UID, response runtime.Obj
 	}
 }
 
-func (c *webhookConverter) Convert(in runtime.Object, toGV schema.GroupVersion) (runtime.Object, error) {
+func (c *webhookConverter) Convert(in *unstructured.UnstructuredList, toGV schema.GroupVersion) (*unstructured.UnstructuredList, error) {
 	ctx := context.TODO()
-	listObj, isList := in.(*unstructured.UnstructuredList)
-
 	requestUID := uuid.NewUUID()
 	desiredAPIVersion := toGV.String()
-	objectsToConvert := getObjectsToConvert(in, desiredAPIVersion)
-	request, response, err := createConversionReviewObjects(c.conversionReviewVersions, objectsToConvert, desiredAPIVersion, requestUID)
+	request, response, err := createConversionReviewObjects(c.conversionReviewVersions, in, desiredAPIVersion, requestUID)
 	if err != nil {
 		return nil, err
 	}
 
-	objCount := len(objectsToConvert)
-	if objCount == 0 {
-		// no objects needed conversion
-		if !isList {
-			// for a single item, return as-is
-			return in, nil
-		}
-		// for a list, set the version of the top-level list object (all individual objects are already in the correct version)
-		out := listObj.DeepCopy()
-		out.SetAPIVersion(toGV.String())
-		return out, nil
-	}
+	objCount := len(in.Items)
 
 	ctx, span := tracing.Start(ctx, "Call conversion webhook",
 		attribute.String("custom-resource-definition", c.name),
@@ -275,170 +247,14 @@ func (c *webhookConverter) Convert(in runtime.Object, toGV schema.GroupVersion)
 		return nil, fmt.Errorf("conversion webhook for %v failed: %v", in.GetObjectKind().GroupVersionKind(), err)
 	}
 
-	if len(convertedObjects) != len(objectsToConvert) {
-		return nil, fmt.Errorf("conversion webhook for %v returned %d objects, expected %d", in.GetObjectKind().GroupVersionKind(), len(convertedObjects), len(objectsToConvert))
-	}
-
-	if isList {
-		// start a deepcopy of the input and fill in the converted objects from the response at the right spots.
-		// The response list might be sparse because objects had the right version already.
-		convertedList := listObj.DeepCopy()
-		convertedIndex := 0
-		for i := range convertedList.Items {
-			original := &convertedList.Items[i]
-			if original.GetAPIVersion() == toGV.String() {
-				// This item has not been sent for conversion, and therefore does not show up in the response.
-				// convertedList has the right item already.
-				continue
-			}
-			converted, err := getRawExtensionObject(convertedObjects[convertedIndex])
-			if err != nil {
-				return nil, fmt.Errorf("conversion webhook for %v returned invalid converted object at index %v: %v", in.GetObjectKind().GroupVersionKind(), convertedIndex, err)
-			}
-			convertedIndex++
-			if expected, got := toGV, converted.GetObjectKind().GroupVersionKind().GroupVersion(); expected != got {
-				return nil, fmt.Errorf("conversion webhook for %v returned invalid converted object at index %v: invalid groupVersion (expected %v, received %v)", in.GetObjectKind().GroupVersionKind(), convertedIndex, expected, got)
-			}
-			if expected, got := original.GetObjectKind().GroupVersionKind().Kind, converted.GetObjectKind().GroupVersionKind().Kind; expected != got {
-				return nil, fmt.Errorf("conversion webhook for %v returned invalid converted object at index %v: invalid kind (expected %v, received %v)", in.GetObjectKind().GroupVersionKind(), convertedIndex, expected, got)
-			}
-			unstructConverted, ok := converted.(*unstructured.Unstructured)
-			if !ok {
-				// this should not happened
-				return nil, fmt.Errorf("conversion webhook for %v returned invalid converted object at index %v: invalid type, expected=Unstructured, got=%T", in.GetObjectKind().GroupVersionKind(), convertedIndex, converted)
-			}
-			if err := validateConvertedObject(original, unstructConverted); err != nil {
-				return nil, fmt.Errorf("conversion webhook for %v returned invalid converted object at index %v: %v", in.GetObjectKind().GroupVersionKind(), convertedIndex, err)
-			}
-			if err := restoreObjectMeta(original, unstructConverted); err != nil {
-				return nil, fmt.Errorf("conversion webhook for %v returned invalid metadata in object at index %v: %v", in.GetObjectKind().GroupVersionKind(), convertedIndex, err)
-			}
-			convertedList.Items[i] = *unstructConverted
+	out := &unstructured.UnstructuredList{}
+	out.Items = make([]unstructured.Unstructured, len(convertedObjects))
+	for i := range convertedObjects {
+		u, err := getRawExtensionObject(convertedObjects[i])
+		if err != nil {
+			return nil, err
 		}
-		convertedList.SetAPIVersion(toGV.String())
-		return convertedList, nil
+		out.Items[i] = *u
 	}
-
-	if len(convertedObjects) != 1 {
-		// This should not happened
-		return nil, fmt.Errorf("conversion webhook for %v failed, no objects returned", in.GetObjectKind())
-	}
-	converted, err := getRawExtensionObject(convertedObjects[0])
-	if err != nil {
-		return nil, err
-	}
-	if e, a := toGV, converted.GetObjectKind().GroupVersionKind().GroupVersion(); e != a {
-		return nil, fmt.Errorf("conversion webhook for %v returned invalid object at index 0: invalid groupVersion (expected %v, received %v)", in.GetObjectKind().GroupVersionKind(), e, a)
-	}
-	if e, a := in.GetObjectKind().GroupVersionKind().Kind, converted.GetObjectKind().GroupVersionKind().Kind; e != a {
-		return nil, fmt.Errorf("conversion webhook for %v returned invalid object at index 0: invalid kind (expected %v, received %v)", in.GetObjectKind().GroupVersionKind(), e, a)
-	}
-	unstructConverted, ok := converted.(*unstructured.Unstructured)
-	if !ok {
-		// this should not happened
-		return nil, fmt.Errorf("conversion webhook for %v failed, unexpected type %T at index 0", in.GetObjectKind().GroupVersionKind(), converted)
-	}
-	unstructIn, ok := in.(*unstructured.Unstructured)
-	if !ok {
-		// this should not happened
-		return nil, fmt.Errorf("conversion webhook for %v failed unexpected input type %T", in.GetObjectKind().GroupVersionKind(), in)
-	}
-	if err := validateConvertedObject(unstructIn, unstructConverted); err != nil {
-		return nil, fmt.Errorf("conversion webhook for %v returned invalid object: %v", in.GetObjectKind().GroupVersionKind(), err)
-	}
-	if err := restoreObjectMeta(unstructIn, unstructConverted); err != nil {
-		return nil, fmt.Errorf("conversion webhook for %v returned invalid metadata: %v", in.GetObjectKind().GroupVersionKind(), err)
-	}
-	return converted, nil
-}
-
-// validateConvertedObject checks that ObjectMeta fields match, with the exception of
-// labels and annotations.
-func validateConvertedObject(in, out *unstructured.Unstructured) error {
-	if e, a := in.GetKind(), out.GetKind(); e != a {
-		return fmt.Errorf("must have the same kind: %v != %v", e, a)
-	}
-	if e, a := in.GetName(), out.GetName(); e != a {
-		return fmt.Errorf("must have the same name: %v != %v", e, a)
-	}
-	if e, a := in.GetNamespace(), out.GetNamespace(); e != a {
-		return fmt.Errorf("must have the same namespace: %v != %v", e, a)
-	}
-	if e, a := in.GetUID(), out.GetUID(); e != a {
-		return fmt.Errorf("must have the same UID: %v != %v", e, a)
-	}
-	return nil
-}
-
-// restoreObjectMeta deep-copies metadata from original into converted, while preserving labels and annotations from converted.
-func restoreObjectMeta(original, converted *unstructured.Unstructured) error {
-	obj, found := converted.Object["metadata"]
-	if !found {
-		return fmt.Errorf("missing metadata in converted object")
-	}
-	responseMetaData, ok := obj.(map[string]interface{})
-	if !ok {
-		return fmt.Errorf("invalid metadata of type %T in converted object", obj)
-	}
-
-	if _, ok := original.Object["metadata"]; !ok {
-		// the original will always have metadata. But just to be safe, let's clear in converted
-		// with an empty object instead of nil, to be able to add labels and annotations below.
-		converted.Object["metadata"] = map[string]interface{}{}
-	} else {
-		converted.Object["metadata"] = runtime.DeepCopyJSONValue(original.Object["metadata"])
-	}
-
-	obj = converted.Object["metadata"]
-	convertedMetaData, ok := obj.(map[string]interface{})
-	if !ok {
-		return fmt.Errorf("invalid metadata of type %T in input object", obj)
-	}
-
-	for _, fld := range []string{"labels", "annotations"} {
-		obj, found := responseMetaData[fld]
-		if !found || obj == nil {
-			delete(convertedMetaData, fld)
-			continue
-		}
-		responseField, ok := obj.(map[string]interface{})
-		if !ok {
-			return fmt.Errorf("invalid metadata.%s of type %T in converted object", fld, obj)
-		}
-
-		originalField, ok := convertedMetaData[fld].(map[string]interface{})
-		if !ok && convertedMetaData[fld] != nil {
-			return fmt.Errorf("invalid metadata.%s of type %T in original object", fld, convertedMetaData[fld])
-		}
-
-		somethingChanged := len(originalField) != len(responseField)
-		for k, v := range responseField {
-			if _, ok := v.(string); !ok {
-				return fmt.Errorf("metadata.%s[%s] must be a string, but is %T in converted object", fld, k, v)
-			}
-			if originalField[k] != interface{}(v) {
-				somethingChanged = true
-			}
-		}
-
-		if somethingChanged {
-			stringMap := make(map[string]string, len(responseField))
-			for k, v := range responseField {
-				stringMap[k] = v.(string)
-			}
-			var errs field.ErrorList
-			if fld == "labels" {
-				errs = metav1validation.ValidateLabels(stringMap, field.NewPath("metadata", "labels"))
-			} else {
-				errs = apivalidation.ValidateAnnotations(stringMap, field.NewPath("metadata", "annotation"))
-			}
-			if len(errs) > 0 {
-				return errs.ToAggregate()
-			}
-		}
-
-		convertedMetaData[fld] = responseField
-	}
-
-	return nil
+	return out, nil
 }

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

@@ -206,81 +206,19 @@ func TestRestoreObjectMeta(t *testing.T) {
 	}
 }
 
-func TestGetObjectsToConvert(t *testing.T) {
-	v1Object := &unstructured.Unstructured{Object: map[string]interface{}{"apiVersion": "foo/v1", "kind": "Widget", "metadata": map[string]interface{}{"name": "myv1"}}}
-	v2Object := &unstructured.Unstructured{Object: map[string]interface{}{"apiVersion": "foo/v2", "kind": "Widget", "metadata": map[string]interface{}{"name": "myv2"}}}
-	v3Object := &unstructured.Unstructured{Object: map[string]interface{}{"apiVersion": "foo/v3", "kind": "Widget", "metadata": map[string]interface{}{"name": "myv3"}}}
-
-	testcases := []struct {
-		Name       string
-		Object     runtime.Object
-		APIVersion string
-
-		ExpectObjects []runtime.RawExtension
-	}{
-		{
-			Name:          "empty list",
-			Object:        &unstructured.UnstructuredList{},
-			APIVersion:    "foo/v1",
-			ExpectObjects: nil,
-		},
-		{
-			Name: "one-item list, in desired version",
-			Object: &unstructured.UnstructuredList{
-				Items: []unstructured.Unstructured{*v1Object},
-			},
-			APIVersion:    "foo/v1",
-			ExpectObjects: nil,
-		},
-		{
-			Name: "one-item list, not in desired version",
-			Object: &unstructured.UnstructuredList{
-				Items: []unstructured.Unstructured{*v2Object},
-			},
-			APIVersion:    "foo/v1",
-			ExpectObjects: []runtime.RawExtension{{Object: v2Object}},
-		},
-		{
-			Name: "multi-item list, in desired version",
-			Object: &unstructured.UnstructuredList{
-				Items: []unstructured.Unstructured{*v1Object, *v1Object, *v1Object},
-			},
-			APIVersion:    "foo/v1",
-			ExpectObjects: nil,
-		},
-		{
-			Name: "multi-item list, mixed versions",
-			Object: &unstructured.UnstructuredList{
-				Items: []unstructured.Unstructured{*v1Object, *v2Object, *v3Object},
-			},
-			APIVersion:    "foo/v1",
-			ExpectObjects: []runtime.RawExtension{{Object: v2Object}, {Object: v3Object}},
-		},
-		{
-			Name:          "single item, in desired version",
-			Object:        v1Object,
-			APIVersion:    "foo/v1",
-			ExpectObjects: nil,
-		},
-		{
-			Name:          "single item, not in desired version",
-			Object:        v2Object,
-			APIVersion:    "foo/v1",
-			ExpectObjects: []runtime.RawExtension{{Object: v2Object}},
-		},
-	}
-	for _, tc := range testcases {
-		t.Run(tc.Name, func(t *testing.T) {
-			if objects := getObjectsToConvert(tc.Object, tc.APIVersion); !reflect.DeepEqual(objects, tc.ExpectObjects) {
-				t.Errorf("unexpected diff: %s", cmp.Diff(tc.ExpectObjects, objects))
-			}
-		})
-	}
-}
-
 func TestCreateConversionReviewObjects(t *testing.T) {
-	objects := []runtime.RawExtension{
-		{Object: &unstructured.Unstructured{Object: map[string]interface{}{"apiVersion": "foo/v2", "Kind": "Widget"}}},
+	objects := &unstructured.UnstructuredList{
+		Items: []unstructured.Unstructured{
+			{
+				Object: map[string]interface{}{"apiVersion": "foo/v2", "Kind": "Widget"},
+			},
+		},
+	}
+
+	rawObjects := []runtime.RawExtension{
+		{
+			Object: &objects.Items[0],
+		},
 	}
 
 	testcases := []struct {
@@ -300,7 +238,7 @@ func TestCreateConversionReviewObjects(t *testing.T) {
 			Name:     "v1",
 			Versions: []string{"v1", "v1beta1", "v2"},
 			ExpectRequest: &v1.ConversionReview{
-				Request:  &v1.ConversionRequest{UID: "uid", DesiredAPIVersion: "foo/v1", Objects: objects},
+				Request:  &v1.ConversionRequest{UID: "uid", DesiredAPIVersion: "foo/v1", Objects: rawObjects},
 				Response: &v1.ConversionResponse{},
 			},
 			ExpectResponse: &v1.ConversionReview{},
@@ -309,7 +247,7 @@ func TestCreateConversionReviewObjects(t *testing.T) {
 			Name:     "v1beta1",
 			Versions: []string{"v1beta1", "v1", "v2"},
 			ExpectRequest: &v1beta1.ConversionReview{
-				Request:  &v1beta1.ConversionRequest{UID: "uid", DesiredAPIVersion: "foo/v1", Objects: objects},
+				Request:  &v1beta1.ConversionRequest{UID: "uid", DesiredAPIVersion: "foo/v1", Objects: rawObjects},
 				Response: &v1beta1.ConversionResponse{},
 			},
 			ExpectResponse: &v1beta1.ConversionReview{},