Set rootwrap_config path to rootwrap.conf

Other components set
rootwrap_config = /etc/<component>/rootwrap.conf by default.
This commit brings cinder up-to-date with what other
components are doing by setting
rootwrap_config = /etc/cinder/rootwrap.conf by default.

A couple of test cases needed to be updated to handle the change
from 'None'.

Not counting this as a documentation impact as the documentation I
can find already lists /etc/cinder/rootwrap.conf as the default.

Closes-Bug 1226074

Change-Id: I68dd5fea1895a6365d6c69db0535d081c4a3460e

cinder/common/config.py

@@ -181,7 +181,7 @@ def _get_my_ip():
                default='sudo',
                help='Deprecated: command to use for running commands as root'),
     cfg.StrOpt('rootwrap_config',
-               default=None,
+               default='/etc/cinder/rootwrap.conf',
                help='Path to the rootwrap configuration file to use for '
                     'running commands as root'),
     cfg.BoolOpt('monkey_patch',

cinder/tests/test_coraid.py

@@ -771,7 +771,7 @@ def setUp(self):
         self.driver.terminate_connection(fake_volume, mox.IgnoreArg())\
             .AndReturn(None)
 
-        root_helper = 'sudo cinder-rootwrap None'
+        root_helper = 'sudo cinder-rootwrap /etc/cinder/rootwrap.conf'
 
         self.mox.StubOutWithMock(connector, 'get_connector_properties')
         connector.get_connector_properties(root_helper).\

cinder/tests/test_volume.py

@@ -1955,7 +1955,7 @@ def test_backup_volume(self):
         properties = {}
         attach_info = {'device': {'path': '/dev/null'}}
         backup_service = self.mox.CreateMock(backup_driver.BackupDriver)
-        root_helper = 'sudo cinder-rootwrap None'
+        root_helper = 'sudo cinder-rootwrap /etc/cinder/rootwrap.conf'
         self.mox.StubOutWithMock(self.volume.driver.db, 'volume_get')
         self.mox.StubOutWithMock(cinder.brick.initiator.connector,
                                  'get_connector_properties')
@@ -1989,7 +1989,7 @@ def test_restore_backup(self):
                   'id': 'backup-for-%s' % vol['id']}
         properties = {}
         attach_info = {'device': {'path': '/dev/null'}}
-        root_helper = 'sudo cinder-rootwrap None'
+        root_helper = 'sudo cinder-rootwrap /etc/cinder/rootwrap.conf'
         backup_service = self.mox.CreateMock(backup_driver.BackupDriver)
         self.mox.StubOutWithMock(cinder.brick.initiator.connector,
                                  'get_connector_properties')

etc/cinder/cinder.conf.sample

@@ -416,7 +416,7 @@
 
 # Path to the rootwrap configuration file to use for running
 # commands as root (string value)
-#rootwrap_config=<None>
+#rootwrap_config=/etc/cinder/rootwrap.conf
 
 # Whether to log monkey patching (boolean value)
 #monkey_patch=false