Do not automatically decode runtime.RawExtension

Make clients opt in to decoding objects that are stored
in the generic api.List object by invoking runtime.DecodeList()
with a set of schemes. Makes it easier to handle unknown
schema objects because decoding is in the control of the code.

Add runtime.Unstructured, which is a simple in memory
representation of an external object.

pkg/runtime/unstructured.go

@@ -0,0 +1,89 @@
+/*
+Copyright 2015 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 runtime
+
+import (
+	"encoding/json"
+	"fmt"
+	"reflect"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/conversion"
+)
+
+// UnstructuredJSONScheme is capable of converting JSON data into the Unstructured
+// type, which can be used for generic access to objects without a predefined scheme.
+var UnstructuredJSONScheme ObjectDecoder = unstructuredJSONScheme{}
+
+type unstructuredJSONScheme struct{}
+
+// Recognizes returns true for any version or kind that is specified (internal
+// versions are specifically excluded).
+func (unstructuredJSONScheme) Recognizes(version, kind string) bool {
+	return len(version) > 0 && len(kind) > 0
+}
+
+func (s unstructuredJSONScheme) Decode(data []byte) (Object, error) {
+	unstruct := &Unstructured{}
+	if err := s.DecodeInto(data, unstruct); err != nil {
+		return nil, err
+	}
+	return unstruct, nil
+}
+
+func (unstructuredJSONScheme) DecodeInto(data []byte, obj Object) error {
+	unstruct, ok := obj.(*Unstructured)
+	if !ok {
+		return fmt.Errorf("the unstructured JSON scheme does not recognize %v", reflect.TypeOf(obj))
+	}
+
+	m := make(map[string]interface{})
+	if err := json.Unmarshal(data, &m); err != nil {
+		return err
+	}
+	if v, ok := m["kind"]; ok {
+		if s, ok := v.(string); ok {
+			unstruct.Kind = s
+		}
+	}
+	if v, ok := m["apiVersion"]; ok {
+		if s, ok := v.(string); ok {
+			unstruct.APIVersion = s
+		}
+	}
+	if len(unstruct.APIVersion) == 0 {
+		return conversion.NewMissingVersionErr(string(data))
+	}
+	if len(unstruct.Kind) == 0 {
+		return conversion.NewMissingKindErr(string(data))
+	}
+	unstruct.Object = m
+	return nil
+}
+
+func (unstructuredJSONScheme) DataVersionAndKind(data []byte) (version, kind string, err error) {
+	obj := TypeMeta{}
+	if err := json.Unmarshal(data, &obj); err != nil {
+		return "", "", err
+	}
+	if len(obj.APIVersion) == 0 {
+		return "", "", conversion.NewMissingVersionErr(string(data))
+	}
+	if len(obj.Kind) == 0 {
+		return "", "", conversion.NewMissingKindErr(string(data))
+	}
+	return obj.APIVersion, obj.Kind, nil
+}