RBD: Fix missing root_helper

When using the RBD driver and running the cinderlib process as a
non-root user within a container we'll get a "Command requested root,
but did not specify a root helper." error.

This error happens because the library is not passing the "root_helper"
parameter in a couple of "_execute" calls.

Trivial-Fix
Closes-Bug: #1885291
Change-Id: Idf664fdab3daf21b99215edfe3e2c053c3a9e85c

cinderlib/nos_brick.py

@@ -128,7 +128,7 @@ class RBDConnector(connectors.rbd.RBDConnector):
                     raise
         else:
             self._execute('ln', '-s', '-f', source, link_name,
-                          run_as_root=True)
+                          root_helper=self._root_helper, run_as_root=True)
 
     def check_valid_device(self, path, run_as_root=True):
         """Verify an existing RBD handle is connected and valid."""
@@ -181,7 +181,8 @@ class RBDConnector(connectors.rbd.RBDConnector):
                 if exc.errno != errno.EEXIST:
                     raise
         else:
-            self._execute('mkdir', '-p', '-m0755', path, run_as_root=True)
+            self._execute('mkdir', '-p', '-m0755', path,
+                          root_helper=self._root_helper, run_as_root=True)
 
     def _setup_class(self):
         try:

cinderlib/tests/unit/test_nos_brick.py

@@ -243,8 +243,9 @@ class TestRBDConnector(base.BaseTest):
     @mock.patch('os.makedirs')
     def test__ensure_dir(self, mkdir_mock, exec_mock):
         self.connector._ensure_dir(mock.sentinel.path)
-        exec_mock.assert_called_once_with('mkdir', '-p', '-m0755',
-                                          mock.sentinel.path, run_as_root=True)
+        exec_mock.assert_called_once_with(
+            'mkdir', '-p', '-m0755', mock.sentinel.path,
+            root_helper=self.connector._root_helper, run_as_root=True)
         mkdir_mock.assert_not_called()
 
     @mock.patch.object(nos_brick.RBDConnector, '_execute')
@@ -284,8 +285,9 @@ class TestRBDConnector(base.BaseTest):
         link = '/dev/rbd/rbd/volume-xyz'
         self.connector._ensure_link(source, link)
         dir_mock.assert_called_once_with('/dev/rbd/rbd')
-        exec_mock.assert_called_once_with('ln', '-s', '-f', source, link,
-                                          run_as_root=True)
+        exec_mock.assert_called_once_with(
+            'ln', '-s', '-f', source, link,
+            root_helper=self.connector._root_helper, run_as_root=True)
         exists_mock.assert_not_called()
         remove_mock.assert_not_called()
         link_mock.assert_not_called()

releasenotes/notes/rbd-non-root-ac971f51461d4d6b.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fix issue on RBD driver about not specifying a root helper when running as
+    a non-root user inside a container.
+    (Bug #1885291).