Better messaging for missing volume components on host to perform mount

pkg/volume/util/operationexecutor/operation_executor.go

@@ -119,7 +119,8 @@ type OperationExecutor interface {
 func NewOperationExecutor(
 	kubeClient internalclientset.Interface,
 	volumePluginMgr *volume.VolumePluginMgr,
-	recorder record.EventRecorder) OperationExecutor {
+	recorder record.EventRecorder,
+	checkNodeCapabilitiesBeforeMount bool) OperationExecutor {
 
 	return &operationExecutor{
 		kubeClient:      kubeClient,
@@ -127,6 +128,7 @@ func NewOperationExecutor(
 		pendingOperations: nestedpendingoperations.NewNestedPendingOperations(
 			true /* exponentialBackOffOnError */),
 		recorder: recorder,
+		checkNodeCapabilitiesBeforeMount: checkNodeCapabilitiesBeforeMount,
 	}
 }
 
@@ -371,6 +373,11 @@ type operationExecutor struct {
 
 	// recorder is used to record events in the API server
 	recorder record.EventRecorder
+
+	// checkNodeCapabilitiesBeforeMount, if set, enables the CanMount check,
+	// which verifies that the components (binaries, etc.) required to mount
+	// the volume are available on the underlying node before attempting mount.
+	checkNodeCapabilitiesBeforeMount bool
 }
 
 func (oe *operationExecutor) IsOperationPending(volumeName api.UniqueVolumeName, podName volumetypes.UniquePodName) bool {
@@ -877,6 +884,15 @@ func (oe *operationExecutor) generateMountVolumeFunc(
 			}
 		}
 
+		if oe.checkNodeCapabilitiesBeforeMount {
+			if canMountErr := volumeMounter.CanMount(); canMountErr != nil {
+				errMsg := fmt.Sprintf("Unable to mount volume %v (spec.Name: %v) on pod %v (UID: %v). Verify that your node machine has the required components before attempting to mount this volume type. %s", volumeToMount.VolumeName, volumeToMount.VolumeSpec.Name(), volumeToMount.Pod.Name, volumeToMount.Pod.UID, canMountErr.Error())
+				oe.recorder.Eventf(volumeToMount.Pod, api.EventTypeWarning, kevents.FailedMountVolume, errMsg)
+				glog.Errorf(errMsg)
+				return fmt.Errorf(errMsg)
+			}
+		}
+
 		// Execute mount
 		mountErr := volumeMounter.SetUp(fsGroup)
 		if mountErr != nil {