Improve the warning message if the rbd command is not found.

pkg/volume/rbd/rbd_util.go

@@ -44,6 +44,7 @@ import (
 const (
 	imageWatcherStr = "watcher="
 	kubeLockMagic   = "kubelet_lock_magic_"
+	rbdCmdErr       = "executable file not found in $PATH"
 )
 
 // search /sys/bus for rbd device that matches given pool and image
@@ -103,6 +104,12 @@ type RBDUtil struct{}
 func (util *RBDUtil) MakeGlobalPDName(rbd rbd) string {
 	return makePDNameInternal(rbd.plugin.host, rbd.Pool, rbd.Image)
 }
+func rbdErrors(runErr, resultErr error) error {
+	if runErr.Error() == rbdCmdErr {
+		return fmt.Errorf("rbd: rbd cmd not found")
+	}
+	return resultErr
+}
 
 func (util *RBDUtil) rbdLock(b rbdMounter, lock bool) error {
 	var err error
@@ -269,7 +276,7 @@ func (util *RBDUtil) AttachDisk(b rbdMounter) error {
 
 		// fence off other mappers
 		if err = util.fencing(b); err != nil {
-			return fmt.Errorf("rbd: image %s is locked by other nodes", b.Image)
+			return rbdErrors(err, fmt.Errorf("rbd: failed to lock image %s (maybe locked by other nodes), error %v", b.Image, err))
 		}
 		// rbd lock remove needs ceph and image config
 		// but kubelet doesn't get them from apiserver during teardown
@@ -327,7 +334,7 @@ func (util *RBDUtil) DetachDisk(c rbdUnmounter, mntPath string) error {
 		// rbd unmap
 		_, err = c.plugin.execCommand("rbd", []string{"unmap", device})
 		if err != nil {
-			return fmt.Errorf("rbd: failed to unmap device %s:Error: %v", device, err)
+			return rbdErrors(err, fmt.Errorf("rbd: failed to unmap device %s:Error: %v", device, err))
 		}
 
 		// load ceph and image/pool info to remove fencing
@@ -435,8 +442,12 @@ func (util *RBDUtil) rbdStatus(b *rbdMounter) (bool, error) {
 		output = string(cmd)
 
 		if err != nil {
-			// ignore error code, just checkout output for watcher string
-			glog.Warningf("failed to execute rbd status on mon %s", mon)
+			if err.Error() == rbdCmdErr {
+				glog.Errorf("rbd cmd not found")
+			} else {
+				// ignore error code, just checkout output for watcher string
+				glog.Warningf("failed to execute rbd status on mon %s", mon)
+			}
 		}
 
 		if strings.Contains(output, imageWatcherStr) {