Allow Meta lookup to work across ObjectType and ListMeta

cmd/kubecfg/kubecfg.go

@@ -31,6 +31,7 @@ import (
 
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/latest"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/meta"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/client"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubecfg"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/runtime"
@@ -372,11 +373,11 @@ func executeAPIRequest(ctx api.Context, method string, c *client.Client) bool {
 		if err != nil {
 			glog.Fatalf("error obtaining resource version for update: %v", err)
 		}
-		jsonBase, err := runtime.FindTypeMeta(obj)
+		meta, err := meta.Accessor(obj)
 		if err != nil {
 			glog.Fatalf("error finding json base for update: %v", err)
 		}
-		version = jsonBase.ResourceVersion()
+		version = meta.ResourceVersion()
 		verb = "PUT"
 		setBody = true
 		if !validStorage || !hasSuffix {
@@ -408,7 +409,7 @@ func executeAPIRequest(ctx api.Context, method string, c *client.Client) bool {
 			if err != nil {
 				glog.Fatalf("error setting resource version: %v", err)
 			}
-			jsonBase, err := runtime.FindTypeMeta(obj)
+			jsonBase, err := meta.Accessor(obj)
 			if err != nil {
 				glog.Fatalf("error setting resource version: %v", err)
 			}

pkg/api/latest/latest.go

@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"strings"
 
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/meta"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/v1beta1"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/v1beta2"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/runtime"
@@ -47,13 +48,13 @@ var Codec = v1beta1.Codec
 // ResourceVersioner describes a default versioner that can handle all types
 // of versioning.
 // TODO: when versioning changes, make this part of each API definition.
-var ResourceVersioner = runtime.NewTypeMetaResourceVersioner()
+var ResourceVersioner = meta.NewResourceVersioner()
 
 // SelfLinker can set or get the SelfLink field of all API types.
 // TODO: when versioning changes, make this part of each API definition.
 // TODO(lavalamp): Combine SelfLinker & ResourceVersioner interfaces, force all uses
 // to go through the InterfacesFor method below.
-var SelfLinker = runtime.NewTypeMetaSelfLinker()
+var SelfLinker = meta.NewSelfLinker()
 
 // VersionInterfaces contains the interfaces one should use for dealing with types of a particular version.
 type VersionInterfaces struct {

pkg/api/meta/doc.go

@@ -0,0 +1,19 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Package meta provides functions for retrieving API metadata from objects
+// belonging to the Kubernetes API
+package meta

pkg/api/meta/meta.go

@@ -0,0 +1,281 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package meta
+
+import (
+	"fmt"
+	"reflect"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/conversion"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/runtime"
+)
+
+// Interface lets you work with object metadata from any of the versioned or
+// internal API objects.
+type Interface interface {
+	Name() string
+	SetName(name string)
+	UID() string
+	SetUID(uid string)
+	APIVersion() string
+	SetAPIVersion(version string)
+	Kind() string
+	SetKind(kind string)
+	ResourceVersion() string
+	SetResourceVersion(version string)
+	SelfLink() string
+	SetSelfLink(selfLink string)
+}
+
+// Accessor takes an arbitary object pointer and returns meta.Interface.
+// obj must be a pointer to an API type. An error is returned if the minimum
+// required fields are missing. Fields that are not required return the default
+// value and are a no-op if set.
+func Accessor(obj interface{}) (Interface, error) {
+	v, err := conversion.EnforcePtr(obj)
+	if err != nil {
+		return nil, err
+	}
+	t := v.Type()
+	if v.Kind() != reflect.Struct {
+		return nil, fmt.Errorf("expected struct, but got %v: %v (%#v)", v.Kind(), t, v.Interface())
+	}
+
+	typeMeta := v.FieldByName("TypeMeta")
+	if !typeMeta.IsValid() {
+		return nil, fmt.Errorf("struct %v lacks embedded TypeMeta type", t)
+	}
+
+	a := &genericAccessor{}
+	if err := extractFromTypeMeta(typeMeta, a); err != nil {
+		return nil, fmt.Errorf("unable to find type fields on %#v", typeMeta)
+	}
+
+	objectMeta := v.FieldByName("ObjectMeta")
+	if objectMeta.IsValid() {
+		// look for the ObjectMeta fields
+		if err := extractFromObjectMeta(objectMeta, a); err != nil {
+			return nil, fmt.Errorf("unable to find object fields on %#v", objectMeta)
+		}
+	} else {
+		listMeta := v.FieldByName("ListMeta")
+		if listMeta.IsValid() {
+			// look for the ListMeta fields
+			if err := extractFromListMeta(listMeta, a); err != nil {
+				return nil, fmt.Errorf("unable to find list fields on %#v", listMeta)
+			}
+		} else {
+			// look for the older TypeMeta with all metadata
+			if err := extractFromObjectMeta(typeMeta, a); err != nil {
+				return nil, fmt.Errorf("unable to find object fields on %#v", typeMeta)
+			}
+		}
+	}
+
+	return a, nil
+}
+
+// NewResourceVersioner returns a ResourceVersioner that can set or
+// retrieve ResourceVersion on objects derived from TypeMeta.
+func NewResourceVersioner() runtime.ResourceVersioner {
+	return resourceAccessor{}
+}
+
+// resourceAccessor implements ResourceVersioner and SelfLinker.
+type resourceAccessor struct{}
+
+func (v resourceAccessor) ResourceVersion(obj runtime.Object) (string, error) {
+	accessor, err := Accessor(obj)
+	if err != nil {
+		return "", err
+	}
+	return accessor.ResourceVersion(), nil
+}
+
+func (v resourceAccessor) SetResourceVersion(obj runtime.Object, version string) error {
+	accessor, err := Accessor(obj)
+	if err != nil {
+		return err
+	}
+	accessor.SetResourceVersion(version)
+	return nil
+}
+
+func (v resourceAccessor) Name(obj runtime.Object) (string, error) {
+	accessor, err := Accessor(obj)
+	if err != nil {
+		return "", err
+	}
+	return accessor.Name(), nil
+}
+
+func (v resourceAccessor) SelfLink(obj runtime.Object) (string, error) {
+	accessor, err := Accessor(obj)
+	if err != nil {
+		return "", err
+	}
+	return accessor.SelfLink(), nil
+}
+
+func (v resourceAccessor) SetSelfLink(obj runtime.Object, selfLink string) error {
+	accessor, err := Accessor(obj)
+	if err != nil {
+		return err
+	}
+	accessor.SetSelfLink(selfLink)
+	return nil
+}
+
+// NewSelfLinker returns a SelfLinker that works on all TypeMeta SelfLink fields.
+func NewSelfLinker() runtime.SelfLinker {
+	return resourceAccessor{}
+}
+
+// genericAccessor contains pointers to strings that can modify an arbitrary
+// struct and implements the Accessor interface.
+type genericAccessor struct {
+	name            *string
+	uid             *string
+	apiVersion      *string
+	kind            *string
+	resourceVersion *string
+	selfLink        *string
+}
+
+func (a genericAccessor) Name() string {
+	if a.name == nil {
+		return ""
+	}
+	return *a.name
+}
+
+func (a genericAccessor) SetName(name string) {
+	if a.name == nil {
+		return
+	}
+	*a.name = name
+}
+
+func (a genericAccessor) UID() string {
+	if a.uid == nil {
+		return ""
+	}
+	return *a.uid
+}
+
+func (a genericAccessor) SetUID(uid string) {
+	if a.uid == nil {
+		return
+	}
+	*a.uid = uid
+}
+
+func (a genericAccessor) APIVersion() string {
+	return *a.apiVersion
+}
+
+func (a genericAccessor) SetAPIVersion(version string) {
+	*a.apiVersion = version
+}
+
+func (a genericAccessor) Kind() string {
+	return *a.kind
+}
+
+func (a genericAccessor) SetKind(kind string) {
+	*a.kind = kind
+}
+
+func (a genericAccessor) ResourceVersion() string {
+	return *a.resourceVersion
+}
+
+func (a genericAccessor) SetResourceVersion(version string) {
+	*a.resourceVersion = version
+}
+
+func (a genericAccessor) SelfLink() string {
+	return *a.selfLink
+}
+
+func (a genericAccessor) SetSelfLink(selfLink string) {
+	*a.selfLink = selfLink
+}
+
+// fieldPtr puts the address of fieldName, which must be a member of v,
+// into dest, which must be an address of a variable to which this field's
+// address can be assigned.
+func fieldPtr(v reflect.Value, fieldName string, dest interface{}) error {
+	field := v.FieldByName(fieldName)
+	if !field.IsValid() {
+		return fmt.Errorf("Couldn't find %v field in %#v", fieldName, v.Interface())
+	}
+	v = reflect.ValueOf(dest)
+	if v.Kind() != reflect.Ptr {
+		return fmt.Errorf("dest should be ptr")
+	}
+	v = v.Elem()
+	field = field.Addr()
+	if field.Type().AssignableTo(v.Type()) {
+		v.Set(field)
+		return nil
+	}
+	if field.Type().ConvertibleTo(v.Type()) {
+		v.Set(field.Convert(v.Type()))
+		return nil
+	}
+	return fmt.Errorf("Couldn't assign/convert %v to %v", field.Type(), v.Type())
+}
+
+// extractFromTypeMeta extracts pointers to version and kind fields from an object
+func extractFromTypeMeta(v reflect.Value, a *genericAccessor) error {
+	if err := fieldPtr(v, "APIVersion", &a.apiVersion); err != nil {
+		return err
+	}
+	if err := fieldPtr(v, "Kind", &a.kind); err != nil {
+		return err
+	}
+	return nil
+}
+
+// extractFromObjectMeta extracts pointers to metadata fields from an object
+func extractFromObjectMeta(v reflect.Value, a *genericAccessor) error {
+	if err := fieldPtr(v, "Name", &a.name); err != nil {
+		return err
+	}
+	if err := fieldPtr(v, "UID", &a.uid); err != nil {
+		return err
+	}
+	if err := fieldPtr(v, "ResourceVersion", &a.resourceVersion); err != nil {
+		return err
+	}
+	if err := fieldPtr(v, "SelfLink", &a.selfLink); err != nil {
+		return err
+	}
+	return nil
+}
+
+// extractFromObjectMeta extracts pointers to metadata fields from a list object
+func extractFromListMeta(v reflect.Value, a *genericAccessor) error {
+	if err := fieldPtr(v, "ResourceVersion", &a.resourceVersion); err != nil {
+		return err
+	}
+	if err := fieldPtr(v, "SelfLink", &a.selfLink); err != nil {
+		return err
+	}
+	return nil
+}