Provide Flex volume metrics if the plugin supports.

pkg/volume/flexvolume/driver-call.go

@@ -222,12 +222,14 @@ type DriverStatus struct {
 type DriverCapabilities struct {
 	Attach          bool `json:"attach"`
 	SELinuxRelabel  bool `json:"selinuxRelabel"`
+	SupportsMetrics bool `json:"supportsMetrics"`
 }
 
 func defaultCapabilities() *DriverCapabilities {
 	return &DriverCapabilities{
 		Attach:          true,
 		SELinuxRelabel:  true,
+		SupportsMetrics: false,
 	}
 }
 

pkg/volume/flexvolume/mounter.go

@@ -32,7 +32,6 @@ type flexVolumeMounter struct {
 	// the considered volume spec
 	spec     *volume.Spec
 	readOnly bool
-	volume.MetricsNil
 }
 
 var _ volume.Mounter = &flexVolumeMounter{}

pkg/volume/flexvolume/plugin.go

@@ -177,6 +177,14 @@ func (plugin *flexVolumePlugin) newMounterInternal(spec *volume.Spec, pod *api.P
 		return nil, err
 	}
 
+	var metricsProvider volume.MetricsProvider
+	if plugin.capabilities.SupportsMetrics {
+		metricsProvider = volume.NewMetricsStatFS(plugin.host.GetPodVolumeDir(
+			pod.UID, utilstrings.EscapeQualifiedNameForDisk(sourceDriver), spec.Name()))
+	} else {
+		metricsProvider = &volume.MetricsNil{}
+	}
+
 	return &flexVolumeMounter{
 		flexVolume: &flexVolume{
 			driverName:            sourceDriver,
@@ -188,6 +196,7 @@ func (plugin *flexVolumePlugin) newMounterInternal(spec *volume.Spec, pod *api.P
 			podNamespace:          pod.Namespace,
 			podServiceAccountName: pod.Spec.ServiceAccountName,
 			volName:               spec.Name(),
+			MetricsProvider:       metricsProvider,
 		},
 		runner:   runner,
 		spec:     spec,
@@ -202,6 +211,14 @@ func (plugin *flexVolumePlugin) NewUnmounter(volName string, podUID types.UID) (
 
 // newUnmounterInternal is the internal unmounter routine to clean the volume.
 func (plugin *flexVolumePlugin) newUnmounterInternal(volName string, podUID types.UID, mounter mount.Interface, runner exec.Interface) (volume.Unmounter, error) {
+	var metricsProvider volume.MetricsProvider
+	if plugin.capabilities.SupportsMetrics {
+		metricsProvider = volume.NewMetricsStatFS(plugin.host.GetPodVolumeDir(
+			podUID, utilstrings.EscapeQualifiedNameForDisk(plugin.driverName), volName))
+	} else {
+		metricsProvider = &volume.MetricsNil{}
+	}
+
 	return &flexVolumeUnmounter{
 		flexVolume: &flexVolume{
 			driverName:      plugin.driverName,
@@ -210,6 +227,7 @@ func (plugin *flexVolumePlugin) newUnmounterInternal(volName string, podUID type
 			plugin:          plugin,
 			podUID:          podUID,
 			volName:         volName,
+			MetricsProvider: metricsProvider,
 		},
 		runner: runner,
 	}, nil

pkg/volume/flexvolume/unmounter.go

@@ -31,7 +31,6 @@ type flexVolumeUnmounter struct {
 	*flexVolume
 	// Runner used to teardown the volume.
 	runner exec.Interface
-	volume.MetricsNil
 }
 
 var _ volume.Unmounter = &flexVolumeUnmounter{}

pkg/volume/flexvolume/volume.go

@@ -20,6 +20,7 @@ import (
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/kubernetes/pkg/util/mount"
 	utilstrings "k8s.io/kubernetes/pkg/util/strings"
+	"k8s.io/kubernetes/pkg/volume"
 )
 
 type flexVolume struct {
@@ -42,6 +43,8 @@ type flexVolume struct {
 	volName string
 	// the underlying plugin
 	plugin *flexVolumePlugin
+	// the metric plugin
+	volume.MetricsProvider
 }
 
 // volume.Volume interface