API modified to use source; now supports EmptyDirectory

API is now modified to use a Source struct to handle multiple volumes.

Two volume types are supported now, HostDirectory and EmptyDirectory.

pkg/volume/doc.go

@@ -14,6 +14,6 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-// Package volumes includes internal representations of external volume types
+// Package volume includes internal representations of external volume types
 // as well as utility methods required to mount/unmount volumes to kubelets.
 package volume

pkg/volume/volume.go

@@ -21,16 +21,19 @@ import (
 	"fmt"
 	"os"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
+	"github.com/golang/glog"
 )
 
 
 // All volume types are expected to implement this interface
 type Interface interface {
 	// Prepares and mounts/unpacks the volume to a directory path.
+	// This procedure must be idempotent.
 	SetUp()
 	// Returns the directory path the volume is mounted to.
 	GetPath() string
 	// Unmounts the volume and removes traces of the SetUp procedure.
+	// This procedure must be idempotent.
 	TearDown()
 }
 
@@ -52,7 +55,6 @@ func (hostVol *HostDirectory) GetPath() string {
 
 // EmptyDirectory volumes are temporary directories exposed to the pod.
 // These do not persist beyond the lifetime of a pod.
-
 type EmptyDirectory struct {
 	Name string
 	PodID string
@@ -60,7 +62,11 @@ type EmptyDirectory struct {
 
 // SetUp creates the new directory.
 func (emptyDir *EmptyDirectory) SetUp() {
-	os.MkdirAll(emptyDir.GetPath(), 0750)
+	if _, err := os.Stat(emptyDir.GetPath()); os.IsNotExist(err) {
+		os.MkdirAll(emptyDir.GetPath(), 0750)
+	} else {
+		glog.Warningf("Directory already exists: (%v)", emptyDir.GetPath())
+	}
 }
 
 // TODO(jonesdl) when we can properly invoke TearDown(), we should delete
@@ -72,6 +78,7 @@ func (emptyDir *EmptyDirectory) GetPath() string {
 	// directory for kubelet to write to. For now this will just be /exports
 	return fmt.Sprintf("/exports/%v/%v", emptyDir.PodID, emptyDir.Name)
 }
+
 // Interprets API volume as a HostDirectory
 func createHostDirectory(volume *api.Volume) *HostDirectory {
 	return &HostDirectory{volume.Source.HostDirectory.Path}
@@ -83,16 +90,23 @@ func createEmptyDirectory(volume *api.Volume, podID string) *EmptyDirectory {
 }
 
 // CreateVolume returns an Interface capable of mounting a volume described by an
-// *api.Volume, or an error.
+// *api.Volume and whether or not it is mounted, or an error.
 func CreateVolume(volume *api.Volume, podID string) (Interface, error) {
+	source := volume.Source
+	// TODO(jonesdl) We will want to throw an error here when we no longer
+	// support the default behavior.
+	if source == nil {
+		return nil, nil
+	}
+	var vol Interface
 	// TODO(jonesdl) We should probably not check every pointer and directly
 	// resolve these types instead.
-	source := volume.Source
 	if source.HostDirectory != nil {
-		return createHostDirectory(volume), nil
+		vol = createHostDirectory(volume)
 	} else if source.EmptyDirectory != nil {
-		return createEmptyDirectory(volume, podID), nil
+		vol = createEmptyDirectory(volume, podID)
 	} else {
 		return nil, errors.New("Unsupported volume type.")
 	}
+	return vol, nil
 }

pkg/volume/volume_test.go

@@ -26,12 +26,21 @@ func TestCreateVolumes(t *testing.T) {
 	volumes := []api.Volume{
 		{
 			Name: "host-dir",
-			HostDirectory: &api.HostDirectory{"/dir/path"},
+			Source: &api.VolumeSource{
+				HostDirectory: &api.HostDirectory{"/dir/path"},
+			},
+		},
+		{
+			Name: "empty-dir",
+			Source: &api.VolumeSource{
+				EmptyDirectory: &api.EmptyDirectory{},
+			},
 		},
 	}
-	expectedPaths := []string{"/dir/path"}
+	fakePodID := "my-id"
+	expectedPaths := []string{"/dir/path", "/exports/my-id/empty-dir"}
 	for i, volume := range volumes {
-		extVolume, _ := CreateVolume(&volume)
+		extVolume, _ := CreateVolume(&volume, fakePodID)
 		expectedPath := expectedPaths[i]
 		path := extVolume.GetPath()
 		if expectedPath != path {