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/helper.go

@@ -23,7 +23,7 @@ import (
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/conversion"
 )
 
-// TODO: move me to pkg/api/meta
+// IsListType returns true if the provided Object has a slice called Items
 func IsListType(obj Object) bool {
 	_, err := GetItemsPtr(obj)
 	return err == nil
@@ -33,7 +33,6 @@ func IsListType(obj Object) bool {
 // If 'list' doesn't have an Items member, it's not really a list type
 // and an error will be returned.
 // This function will either return a pointer to a slice, or an error, but not both.
-// TODO: move me to pkg/api/meta
 func GetItemsPtr(list Object) (interface{}, error) {
 	v, err := conversion.EnforcePtr(list)
 	if err != nil {
@@ -150,9 +149,36 @@ func FieldPtr(v reflect.Value, fieldName string, dest interface{}) error {
 	return fmt.Errorf("couldn't assign/convert %v to %v", field.Type(), v.Type())
 }
 
+// DecodeList alters the list in place, attempting to decode any objects found in
+// the list that have the runtime.Unknown type. Any errors that occur are returned
+// after the entire list is processed. Decoders are tried in order.
+func DecodeList(objects []Object, decoders ...ObjectDecoder) []error {
+	errs := []error(nil)
+	for i, obj := range objects {
+		switch t := obj.(type) {
+		case *Unknown:
+			for _, decoder := range decoders {
+				if !decoder.Recognizes(t.APIVersion, t.Kind) {
+					continue
+				}
+				obj, err := decoder.Decode(t.RawJSON)
+				if err != nil {
+					errs = append(errs, err)
+					break
+				}
+				objects[i] = obj
+				break
+			}
+		}
+	}
+	return errs
+}
+
 // MultiObjectTyper returns the types of objects across multiple schemes in order.
 type MultiObjectTyper []ObjectTyper
 
+var _ ObjectTyper = MultiObjectTyper{}
+
 func (m MultiObjectTyper) DataVersionAndKind(data []byte) (version, kind string, err error) {
 	for _, t := range m {
 		version, kind, err = t.DataVersionAndKind(data)
@@ -162,6 +188,7 @@ func (m MultiObjectTyper) DataVersionAndKind(data []byte) (version, kind string,
 	}
 	return
 }
+
 func (m MultiObjectTyper) ObjectVersionAndKind(obj Object) (version, kind string, err error) {
 	for _, t := range m {
 		version, kind, err = t.ObjectVersionAndKind(obj)
@@ -171,3 +198,12 @@ func (m MultiObjectTyper) ObjectVersionAndKind(obj Object) (version, kind string
 	}
 	return
 }
+
+func (m MultiObjectTyper) Recognizes(version, kind string) bool {
+	for _, t := range m {
+		if t.Recognizes(version, kind) {
+			return true
+		}
+	}
+	return false
+}