Add Identifier method to GroupVersioner interface

staging/src/k8s.io/apimachinery/pkg/runtime/codec.go

@@ -19,13 +19,17 @@ package runtime
 import (
 	"bytes"
 	"encoding/base64"
+	"encoding/json"
 	"fmt"
 	"io"
 	"net/url"
 	"reflect"
+	"strconv"
+	"strings"
 
 	"k8s.io/apimachinery/pkg/conversion/queryparams"
 	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/klog"
 )
 
 // codec binds an encoder and decoder.
@@ -238,6 +242,11 @@ var (
 	DisabledGroupVersioner GroupVersioner = disabledGroupVersioner{}
 )
 
+const (
+	internalGroupVersionerIdentifier = "internal"
+	disabledGroupVersionerIdentifier = "disabled"
+)
+
 type internalGroupVersioner struct{}
 
 // KindForGroupVersionKinds returns an internal Kind if one is found, or converts the first provided kind to the internal version.
@@ -253,6 +262,11 @@ func (internalGroupVersioner) KindForGroupVersionKinds(kinds []schema.GroupVersi
 	return schema.GroupVersionKind{}, false
 }
 
+// Identifier implements GroupVersioner interface.
+func (internalGroupVersioner) Identifier() string {
+	return internalGroupVersionerIdentifier
+}
+
 type disabledGroupVersioner struct{}
 
 // KindForGroupVersionKinds returns false for any input.
@@ -260,6 +274,11 @@ func (disabledGroupVersioner) KindForGroupVersionKinds(kinds []schema.GroupVersi
 	return schema.GroupVersionKind{}, false
 }
 
+// Identifier implements GroupVersioner interface.
+func (disabledGroupVersioner) Identifier() string {
+	return disabledGroupVersionerIdentifier
+}
+
 // Assert that schema.GroupVersion and GroupVersions implement GroupVersioner
 var _ GroupVersioner = schema.GroupVersion{}
 var _ GroupVersioner = schema.GroupVersions{}
@@ -315,3 +334,22 @@ func (v multiGroupVersioner) KindForGroupVersionKinds(kinds []schema.GroupVersio
 	}
 	return schema.GroupVersionKind{}, false
 }
+
+// Identifier implements GroupVersioner interface.
+func (v multiGroupVersioner) Identifier() string {
+	groupKinds := make([]string, 0, len(v.acceptedGroupKinds))
+	for _, gk := range v.acceptedGroupKinds {
+		groupKinds = append(groupKinds, gk.String())
+	}
+	result := map[string]string{
+		"name":     "multi",
+		"target":   v.target.String(),
+		"accepted": strings.Join(groupKinds, ","),
+		"coerce":   strconv.FormatBool(v.coerce),
+	}
+	identifier, err := json.Marshal(result)
+	if err != nil {
+		klog.Fatalf("Failed marshaling Identifier for %#v: %v", v, err)
+	}
+	return string(identifier)
+}

staging/src/k8s.io/apimachinery/pkg/runtime/codec_test.go

@@ -39,6 +39,7 @@ func TestCoercingMultiGroupVersioner(t *testing.T) {
 		preferredKinds []schema.GroupKind
 		kinds          []schema.GroupVersionKind
 		expectKind     schema.GroupVersionKind
+		expectedId     string
 	}{
 		{
 			name:           "matched preferred group/kind",
@@ -46,6 +47,7 @@ func TestCoercingMultiGroupVersioner(t *testing.T) {
 			preferredKinds: []schema.GroupKind{gk("mygroup", "Foo"), gk("anothergroup", "Bar")},
 			kinds:          []schema.GroupVersionKind{gvk("yetanother", "v1", "Baz"), gvk("anothergroup", "v1", "Bar")},
 			expectKind:     gvk("mygroup", "__internal", "Bar"),
+			expectedId:     "{\"accepted\":\"Foo.mygroup,Bar.anothergroup\",\"coerce\":\"true\",\"name\":\"multi\",\"target\":\"mygroup/__internal\"}",
 		},
 		{
 			name:           "matched preferred group",
@@ -53,6 +55,7 @@ func TestCoercingMultiGroupVersioner(t *testing.T) {
 			preferredKinds: []schema.GroupKind{gk("mygroup", ""), gk("anothergroup", "")},
 			kinds:          []schema.GroupVersionKind{gvk("yetanother", "v1", "Baz"), gvk("anothergroup", "v1", "Bar")},
 			expectKind:     gvk("mygroup", "__internal", "Bar"),
+			expectedId:     "{\"accepted\":\".mygroup,.anothergroup\",\"coerce\":\"true\",\"name\":\"multi\",\"target\":\"mygroup/__internal\"}",
 		},
 		{
 			name:           "no preferred group/kind match, uses first kind in list",
@@ -60,6 +63,7 @@ func TestCoercingMultiGroupVersioner(t *testing.T) {
 			preferredKinds: []schema.GroupKind{gk("mygroup", ""), gk("anothergroup", "")},
 			kinds:          []schema.GroupVersionKind{gvk("yetanother", "v1", "Baz"), gvk("yetanother", "v1", "Bar")},
 			expectKind:     gvk("mygroup", "__internal", "Baz"),
+			expectedId:     "{\"accepted\":\".mygroup,.anothergroup\",\"coerce\":\"true\",\"name\":\"multi\",\"target\":\"mygroup/__internal\"}",
 		},
 	}
 
@@ -73,6 +77,9 @@ func TestCoercingMultiGroupVersioner(t *testing.T) {
 			if kind != tc.expectKind {
 				t.Errorf("expected %#v, got %#v", tc.expectKind, kind)
 			}
+			if e, a := tc.expectedId, v.Identifier(); e != a {
+				t.Errorf("unexpected identifier: %s, expected: %s", a, e)
+			}
 		})
 	}
 }

staging/src/k8s.io/apimachinery/pkg/runtime/interfaces.go

@@ -37,6 +37,10 @@ type GroupVersioner interface {
 	// Scheme.New(target) and then perform a conversion between the current Go type and the destination Go type.
 	// Sophisticated implementations may use additional information about the input kinds to pick a destination kind.
 	KindForGroupVersionKinds(kinds []schema.GroupVersionKind) (target schema.GroupVersionKind, ok bool)
+	// Identifier returns string representation of the object.
+	// Identifiers of two different encoders should be equal only if for every input
+	// kinds they return the same result.
+	Identifier() string
 }
 
 // Identifier represents an identifier.

staging/src/k8s.io/apimachinery/pkg/runtime/schema/group_version.go

@@ -191,6 +191,11 @@ func (gv GroupVersion) String() string {
 	return gv.Version
 }
 
+// Identifier implements runtime.GroupVersioner interface.
+func (gv GroupVersion) Identifier() string {
+	return gv.String()
+}
+
 // KindForGroupVersionKinds identifies the preferred GroupVersionKind out of a list. It returns ok false
 // if none of the options match the group. It prefers a match to group and version over just group.
 // TODO: Move GroupVersion to a package under pkg/runtime, since it's used by scheme.
@@ -246,6 +251,15 @@ func (gv GroupVersion) WithResource(resource string) GroupVersionResource {
 //   in fewer places.
 type GroupVersions []GroupVersion
 
+// Identifier implements runtime.GroupVersioner interface.
+func (gv GroupVersions) Identifier() string {
+	groupVersions := make([]string, 0, len(gv))
+	for i := range gv {
+		groupVersions = append(groupVersions, gv[i].String())
+	}
+	return fmt.Sprintf("[%s]", strings.Join(groupVersions, ","))
+}
+
 // KindForGroupVersionKinds identifies the preferred GroupVersionKind out of a list. It returns ok false
 // if none of the options match the group.
 func (gvs GroupVersions) KindForGroupVersionKinds(kinds []GroupVersionKind) (GroupVersionKind, bool) {

staging/src/k8s.io/apimachinery/pkg/runtime/scheme_test.go

@@ -610,6 +610,10 @@ func (m testGroupVersioner) KindForGroupVersionKinds(kinds []schema.GroupVersion
 	return m.target, m.ok
 }
 
+func (m testGroupVersioner) Identifier() string {
+	return "testGroupVersioner"
+}
+
 func TestConvertToVersion(t *testing.T) {
 	testCases := []struct {
 		scheme *runtime.Scheme