Adding a root filesystem override for kubelet mounter

This is useful for supporting hostPath volumes via containerized
mounters in kubelet.

Signed-off-by: Vishnu kannan <vishnuk@google.com>

test/e2e_node/remote/remote.go

@@ -42,9 +42,10 @@ var resultsDir = flag.String("results-dir", "/tmp/", "Directory to scp test resu
 var sshOptionsMap map[string]string
 
 const (
-	archiveName  = "e2e_node_test.tar.gz"
-	CNIRelease   = "07a8a28637e97b22eb8dfe710eeae1344f69d16e"
-	CNIDirectory = "cni"
+	archiveName              = "e2e_node_test.tar.gz"
+	CNIRelease               = "07a8a28637e97b22eb8dfe710eeae1344f69d16e"
+	CNIDirectory             = "cni"
+	mounterRootfsPath string = "/"
 )
 
 var CNIURL = fmt.Sprintf("https://storage.googleapis.com/kubernetes-release/network-plugins/cni-%s.tar.gz", CNIRelease)
@@ -263,7 +264,7 @@ func RunRemote(archive string, host string, cleanup bool, junitFilePrefix string
 		return "", false, fmt.Errorf("Issue detecting node's OS via node's /etc/os-release. Err: %v, Output:\n%s", err, output)
 	}
 	if strings.Contains(output, "ID=gci") {
-		glog.Infof("GCI node and GCI mounter both detected, modifying --experimental-mounter-path accordingly")
+		glog.Infof("GCI node and GCI mounter both detected, modifying --mounter-path & --experimental-mounter-rootfs-path accordingly")
 
 		// Note this implicitly requires the script to be where we expect in the tarball, so if that location changes the error
 		// here will tell us to update the remote test runner.
@@ -274,6 +275,7 @@ func RunRemote(archive string, host string, cleanup bool, junitFilePrefix string
 			return "", false, err
 		}
 		// Insert args at beginning of testArgs, so any values from command line take precedence
+		testArgs = fmt.Sprintf("--experimental-mounter-rootfs-path=%s ", mounterRootfsPath) + testArgs
 		testArgs = fmt.Sprintf("--experimental-mounter-path=%s ", mounterPath) + testArgs
 	}