address lavalamp's comments

cmd/kube-apiserver/app/server.go

@@ -35,7 +35,6 @@ import (
 	"k8s.io/kubernetes/pkg/api"
 	"k8s.io/kubernetes/pkg/api/latest"
 	"k8s.io/kubernetes/pkg/api/meta"
-	"k8s.io/kubernetes/pkg/api/registered"
 	"k8s.io/kubernetes/pkg/apiserver"
 	"k8s.io/kubernetes/pkg/capabilities"
 	client "k8s.io/kubernetes/pkg/client/unversioned"
@@ -331,10 +330,6 @@ func (s *APIServer) Run(_ []string) error {
 	// This takes preference over api/all, if specified.
 	enableExp := s.getRuntimeConfigValue("experimental/v1", false)
 
-	if enableExp && len(registered.GroupVersionsForGroup("experimental")) == 0 {
-		glog.Fatalf("experimental API is enabled in runtime config, but not registered throught environment variable KUBE_API_VERSIONS")
-	}
-
 	clientConfig := &client.Config{
 		Host:    net.JoinHostPort(s.InsecureBindAddress.String(), strconv.Itoa(s.InsecurePort)),
 		Version: s.StorageVersion,
@@ -351,8 +346,11 @@ func (s *APIServer) Run(_ []string) error {
 
 	var expEtcdStorage storage.Interface
 	if enableExp {
-		expEtcdStorage, err = newEtcd(s.EtcdConfigFile, s.EtcdServerList, latest.GroupOrDie("experimental").InterfacesFor, latest.GroupOrDie("experimental").Version, s.ExpStorageVersion, s.EtcdPathPrefix)
-
+		g, err := latest.Group("experimental")
+		if err != nil {
+			glog.Fatalf("experimental API is enabled in runtime config, but not enabled in the environment variable KUBE_API_VERSIONS. Error: %v", err)
+		}
+		expEtcdStorage, err = newEtcd(s.EtcdConfigFile, s.EtcdServerList, g.InterfacesFor, g.Version, s.ExpStorageVersion, s.EtcdPathPrefix)
 		if err != nil {
 			glog.Fatalf("Invalid experimental storage version or misconfigured etcd: %v", err)
 		}

pkg/api/install/install.go

@@ -14,6 +14,8 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+// Package install installs the v1 monolithic api, making it available as an
+// option to all of the API encoding/decoding machinery.
 package install
 
 import (

pkg/api/latest/latest.go

@@ -26,13 +26,18 @@ import (
 
 var (
 	allGroups = GroupMetaMap{}
+	// Group is a shortcut to allGroups.Group.
 	Group = allGroups.Group
+	// RegisterGroup is a shortcut to allGroups.RegisterGroup.
 	RegisterGroup = allGroups.RegisterGroup
+	// GroupOrDie is a shortcut to allGroups.GroupOrDie.
 	GroupOrDie = allGroups.GroupOrDie
 )
 
+// GroupMetaMap is a map between group names and their metadata.
 type GroupMetaMap map[string]*GroupMeta
 
+// RegisterGroup registers a group to GroupMetaMap.
 func (g GroupMetaMap) RegisterGroup(group string) (*GroupMeta, error) {
 	_, found := g[group]
 	if found {
@@ -45,6 +50,8 @@ func (g GroupMetaMap) RegisterGroup(group string) (*GroupMeta, error) {
 	return g[group], nil
 }
 
+// Group returns the metadata of a group if the gruop is registered, otherwise
+// an erorr is returned.
 func (g GroupMetaMap) Group(group string) (*GroupMeta, error) {
 	groupMeta, found := g[group]
 	if !found {
@@ -100,5 +107,7 @@ type GroupMeta struct {
 	// Kubernetes versions.
 	RESTMapper meta.RESTMapper
 
+	// InterfacesFor returns the default Codec and ResourceVersioner for a given version
+	// string, or an error if the version is not known.
 	InterfacesFor func(version string) (*meta.VersionInterfaces, error)
 }

pkg/client/unversioned/fake/fake.go

@@ -14,6 +14,8 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+// This is made a separate package and should only be imported by tests, because
+// it imports testapi
 package fake
 
 import (

pkg/client/unversioned/helper.go

@@ -33,7 +33,6 @@ import (
 	"github.com/golang/glog"
 	"k8s.io/kubernetes/pkg/api"
 	"k8s.io/kubernetes/pkg/api/latest"
-	"k8s.io/kubernetes/pkg/api/registered"
 	"k8s.io/kubernetes/pkg/runtime"
 	"k8s.io/kubernetes/pkg/util"
 	"k8s.io/kubernetes/pkg/util/sets"
@@ -142,7 +141,7 @@ func New(c *Config) (*Client, error) {
 		return nil, err
 	}
 
-	if len(registered.GroupVersionsForGroup("experimental")) == 0 {
+	if _, err := latest.Group("experimental"); err != nil {
 		return &Client{RESTClient: client, ExperimentalClient: nil}, nil
 	}
 	experimentalConfig := *c

pkg/client/unversioned/import_known_versions.go

@@ -16,6 +16,7 @@ limitations under the License.
 
 package unversioned
 
+// These imports are the API groups the client will support.
 import (
 	_ "k8s.io/kubernetes/pkg/api/install"
 	_ "k8s.io/kubernetes/pkg/expapi/install"

pkg/expapi/install/install.go

@@ -14,6 +14,8 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+// Package install installs the experimental API group, making it available as
+// an option to all of the API encoding/decoding machinery.
 package install
 
 import (

pkg/master/import_known_versions.go

@@ -16,6 +16,7 @@ limitations under the License.
 
 package master
 
+// These imports are the API groups the API server will support.
 import (
 	_ "k8s.io/kubernetes/pkg/api/install"
 	_ "k8s.io/kubernetes/pkg/expapi/install"