Add Exec interface to VolumeHost

This exec should be used by volume plugins to execute mount utilities.
It will eventually execute things in mount containers.

pkg/controller/volume/attachdetach/attach_detach_controller.go

@@ -571,6 +571,10 @@ func (adc *attachDetachController) GetConfigMapFunc() func(namespace, name strin
 	}
 }
 
+func (adc *attachDetachController) GetExec(pluginName string) mount.Exec {
+	return mount.NewOsExec()
+}
+
 func (adc *attachDetachController) addNodeToDswp(node *v1.Node, nodeName types.NodeName) {
 	if _, exists := node.Annotations[volumehelper.ControllerManagedAttachAnnotation]; exists {
 		keepTerminatedPodVolumes := false

pkg/controller/volume/persistentvolume/volume_host.go

@@ -93,6 +93,10 @@ func (adc *PersistentVolumeController) GetConfigMapFunc() func(namespace, name s
 	}
 }
 
+func (adc *PersistentVolumeController) GetExec(pluginName string) mount.Exec {
+	return mount.NewOsExec()
+}
+
 func (ctrl *PersistentVolumeController) GetNodeLabels() (map[string]string, error) {
 	return nil, fmt.Errorf("GetNodeLabels() unsupported in PersistentVolumeController")
 }

pkg/kubelet/volume_host.go

@@ -156,3 +156,7 @@ func (kvh *kubeletVolumeHost) GetNodeLabels() (map[string]string, error) {
 	}
 	return node.Labels, nil
 }
+
+func (kvh *kubeletVolumeHost) GetExec(pluginName string) mount.Exec {
+	return mount.NewOsExec()
+}

pkg/util/mount/BUILD

@@ -10,6 +10,7 @@ go_library(
     name = "go_default_library",
     srcs = [
         "doc.go",
+        "exec.go",
         "fake.go",
         "mount.go",
         "mount_unsupported.go",

pkg/util/mount/exec.go

@@ -0,0 +1,50 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+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 mount
+
+import "k8s.io/utils/exec"
+
+func NewOsExec() Exec {
+	return &osExec{}
+}
+
+// Real implementation of Exec interface that uses simple util.Exec
+type osExec struct{}
+
+var _ Exec = &osExec{}
+
+func (e *osExec) Run(cmd string, args ...string) ([]byte, error) {
+	exe := exec.New()
+	return exe.Command(cmd, args...).CombinedOutput()
+}
+
+func NewFakeExec(run runHook) *FakeExec {
+	return &FakeExec{runHook: run}
+}
+
+// Fake for testing.
+type FakeExec struct {
+	runHook runHook
+}
+type runHook func(cmd string, args ...string) ([]byte, error)
+
+func (f *FakeExec) Run(cmd string, args ...string) ([]byte, error) {
+	if f.runHook != nil {
+		return f.runHook(cmd, args...)
+	}
+	return nil, nil
+}

pkg/util/mount/mount.go

@@ -70,6 +70,16 @@ type Interface interface {
 	GetDeviceNameFromMount(mountPath, pluginDir string) (string, error)
 }
 
+// Exec executes command where mount utilities are. This can be either the host,
+// container where kubelet runs or even a remote pod with mount utilities.
+// Usual pkg/util/exec interface is not used because kubelet.RunInContainer does
+// not provide stdin/stdout/stderr streams.
+type Exec interface {
+	// Run executes a command and returns its stdout + stderr combined in one
+	// stream.
+	Run(cmd string, args ...string) ([]byte, error)
+}
+
 // Compile-time check to ensure all Mounter implementations satisfy
 // the mount interface
 var _ Interface = &Mounter{}

pkg/volume/plugins.go

@@ -244,6 +244,9 @@ type VolumeHost interface {
 	// Returns a function that returns a configmap.
 	GetConfigMapFunc() func(namespace, name string) (*v1.ConfigMap, error)
 
+	// Returns an interface that should be used to execute any utilities in volume plugins
+	GetExec(pluginName string) mount.Exec
+
 	// Returns the labels on the node
 	GetNodeLabels() (map[string]string, error)
 }

pkg/volume/testing/testing.go

@@ -49,6 +49,7 @@ type fakeVolumeHost struct {
 	pluginMgr  VolumePluginMgr
 	cloud      cloudprovider.Interface
 	mounter    mount.Interface
+	exec       mount.Exec
 	writer     io.Writer
 }
 
@@ -64,6 +65,7 @@ func newFakeVolumeHost(rootDir string, kubeClient clientset.Interface, plugins [
 	host := &fakeVolumeHost{rootDir: rootDir, kubeClient: kubeClient, cloud: cloud}
 	host.mounter = &mount.FakeMounter{}
 	host.writer = &io.StdWriter{}
+	host.exec = mount.NewFakeExec(nil)
 	host.pluginMgr.InitPlugins(plugins, host)
 	return host
 }
@@ -142,6 +144,10 @@ func (f *fakeVolumeHost) GetSecretFunc() func(namespace, name string) (*v1.Secre
 	}
 }
 
+func (f *fakeVolumeHost) GetExec(pluginName string) mount.Exec {
+	return f.exec
+}
+
 func (f *fakeVolumeHost) GetConfigMapFunc() func(namespace, name string) (*v1.ConfigMap, error) {
 	return func(namespace, name string) (*v1.ConfigMap, error) {
 		return f.kubeClient.Core().ConfigMaps(namespace).Get(name, metav1.GetOptions{})