Implement volumes as plugins.

Break up the monolithic volumes code in kubelet into very small individual
modules with a well-defined interface.  Move them all into their own packages
and beef up testing along the way.

pkg/kubelet/volume/empty_dir/empty_dir_test.go

@@ -0,0 +1,153 @@
+/*
+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 empty_dir
+
+import (
+	"os"
+	"testing"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/volume"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/types"
+)
+
+func TestCanSupport(t *testing.T) {
+	plugMgr := volume.PluginMgr{}
+	plugMgr.InitPlugins(ProbeVolumePlugins(), &volume.FakeHost{"/tmp/fake"})
+
+	plug, err := plugMgr.FindPluginByName("kubernetes.io/empty-dir")
+	if err != nil {
+		t.Errorf("Can't find the plugin by name")
+	}
+	if plug.Name() != "kubernetes.io/empty-dir" {
+		t.Errorf("Wrong name: %s", plug.Name())
+	}
+	if !plug.CanSupport(&api.Volume{Source: &api.VolumeSource{EmptyDir: &api.EmptyDir{}}}) {
+		t.Errorf("Expected true")
+	}
+	if !plug.CanSupport(&api.Volume{Source: nil}) {
+		t.Errorf("Expected true")
+	}
+}
+
+func TestPlugin(t *testing.T) {
+	plugMgr := volume.PluginMgr{}
+	plugMgr.InitPlugins(ProbeVolumePlugins(), &volume.FakeHost{"/tmp/fake"})
+
+	plug, err := plugMgr.FindPluginByName("kubernetes.io/empty-dir")
+	if err != nil {
+		t.Errorf("Can't find the plugin by name")
+	}
+	spec := &api.Volume{
+		Name:   "vol1",
+		Source: &api.VolumeSource{EmptyDir: &api.EmptyDir{}},
+	}
+	builder, err := plug.NewBuilder(spec, types.UID("poduid"))
+	if err != nil {
+		t.Errorf("Failed to make a new Builder: %v", err)
+	}
+	if builder == nil {
+		t.Errorf("Got a nil Builder: %v")
+	}
+
+	path := builder.GetPath()
+	if path != "/tmp/fake/pods/poduid/volumes/kubernetes.io~empty-dir/vol1" {
+		t.Errorf("Got unexpected path: %s", path)
+	}
+
+	if err := builder.SetUp(); err != nil {
+		t.Errorf("Expected success, got: %v", err)
+	}
+	if _, err := os.Stat(path); err != nil {
+		if os.IsNotExist(err) {
+			t.Errorf("SetUp() failed, volume path not created: %s", path)
+		} else {
+			t.Errorf("SetUp() failed: %v", err)
+		}
+	}
+
+	cleaner, err := plug.NewCleaner("vol1", types.UID("poduid"))
+	if err != nil {
+		t.Errorf("Failed to make a new Cleaner: %v", err)
+	}
+	if cleaner == nil {
+		t.Errorf("Got a nil Cleaner: %v")
+	}
+
+	if err := cleaner.TearDown(); err != nil {
+		t.Errorf("Expected success, got: %v", err)
+	}
+	if _, err := os.Stat(path); err == nil {
+		t.Errorf("TearDown() failed, volume path still exists: %s", path)
+	} else if !os.IsNotExist(err) {
+		t.Errorf("SetUp() failed: %v", err)
+	}
+}
+
+func TestPluginBackCompat(t *testing.T) {
+	plugMgr := volume.PluginMgr{}
+	plugMgr.InitPlugins(ProbeVolumePlugins(), &volume.FakeHost{"/tmp/fake"})
+
+	plug, err := plugMgr.FindPluginByName("kubernetes.io/empty-dir")
+	if err != nil {
+		t.Errorf("Can't find the plugin by name")
+	}
+	spec := &api.Volume{
+		Name:   "vol1",
+		Source: nil,
+	}
+	builder, err := plug.NewBuilder(spec, types.UID("poduid"))
+	if err != nil {
+		t.Errorf("Failed to make a new Builder: %v", err)
+	}
+	if builder == nil {
+		t.Errorf("Got a nil Builder: %v")
+	}
+
+	path := builder.GetPath()
+	if path != "/tmp/fake/pods/poduid/volumes/kubernetes.io~empty-dir/vol1" {
+		t.Errorf("Got unexpected path: %s", path)
+	}
+}
+
+func TestPluginLegacy(t *testing.T) {
+	plugMgr := volume.PluginMgr{}
+	plugMgr.InitPlugins(ProbeVolumePlugins(), &volume.FakeHost{"/tmp/fake"})
+
+	plug, err := plugMgr.FindPluginByName("empty")
+	if err != nil {
+		t.Errorf("Can't find the plugin by name")
+	}
+	if plug.Name() != "empty" {
+		t.Errorf("Wrong name: %s", plug.Name())
+	}
+	if plug.CanSupport(&api.Volume{Source: &api.VolumeSource{EmptyDir: &api.EmptyDir{}}}) {
+		t.Errorf("Expected false")
+	}
+
+	if _, err := plug.NewBuilder(&api.Volume{Source: &api.VolumeSource{EmptyDir: &api.EmptyDir{}}}, types.UID("poduid")); err == nil {
+		t.Errorf("Expected failiure")
+	}
+
+	cleaner, err := plug.NewCleaner("vol1", types.UID("poduid"))
+	if err != nil {
+		t.Errorf("Failed to make a new Cleaner: %v", err)
+	}
+	if cleaner == nil {
+		t.Errorf("Got a nil Cleaner: %v")
+	}
+}