Introduce libvirt (un)mask)_command config option

On Ubunu Focal, libvirtd can be activated by other systemd units. To
avoid this unwanted activation, and only have libvirtd start when we
tell it to start, we need to mask it. This patch introduced the config
options to mask and unmask the libvirtd service. They will be used in
a susequent patch that starts using the Focal image to unskip some
tests.

Change-Id: Ib28811fd4f155cbc02f10b43d470f4cef142513b

devstack/plugin.sh

@@ -20,6 +20,8 @@ function configure {
 
     iniset $TEMPEST_CONFIG whitebox-libvirt start_command "$WHITEBOX_LIBVIRT_START_COMMAND"
     iniset $TEMPEST_CONFIG whitebox-libvirt stop_command "$WHITEBOX_LIBVIRT_STOP_COMMAND"
+    iniset $TEMPEST_CONFIG whitebox-libvirt mask_command "$WHITEBOX_LIBVIRT_MASK_COMMAND"
+    iniset $TEMPEST_CONFIG whitebox-libvirt unmask_command "$WHITEBOX_LIBVIRT_UNMASK_COMMAND"
 
     iniset $TEMPEST_CONFIG whitebox-database user $DATABASE_USER
     iniset $TEMPEST_CONFIG whitebox-database password $DATABASE_PASSWORD

devstack/settings

@@ -10,5 +10,7 @@ WHITEBOX_NOVA_COMPUTE_START_COMMAND=${WHITEBOX_NOVA_COMPUTE_START_COMMAND:-'syst
 
 WHITEBOX_LIBVIRT_START_COMMAND=${WHITEBOX_LIBVIRT_START_COMMAND:-'systemctl start libvirtd'}
 WHITEBOX_LIBVIRT_STOP_COMMAND=${WHITEBOX_LIBVIRT_STOP_COMMAND:-'systemctl stop libvirtd'}
+WHITEBOX_LIBVIRT_MASK_COMMAND=${WHITEBOX_LIBVIRT_MASK_COMMAND:-'systemctl mask libvirtd'}
+WHITEBOX_LIBVIRT_UNMASK_COMMAND=${WHITEBOX_LIBVIRT_UNMASK_COMMAND:-'systemctl unmask libvirtd'}
 
 WHITEBOX_CPU_TOPOLOGY=${WHITEBOX_CPU_TOPOLOGY:-''}

whitebox_tempest_plugin/config.py

@@ -109,7 +109,20 @@
         help='Command to stop the libvirt service, without any '
              'privilege management (ie, no sudo).',
         deprecated_opts=[cfg.DeprecatedOpt('stop_command',
-                                           group='whitebox-nova-libvirt')])
+                                           group='whitebox-nova-libvirt')]),
+    cfg.StrOpt(
+        'mask_command',
+        help='In some situations (Ubuntu Focal, for example), libvirtd can '
+             'be activated by other systemd units even if it is stopped. '
+             'In such cases, it can be useful to mask a service (ie, disable '
+             'it completely) to prevent it from being started outside of our '
+             'control. This config options sets the command to mask libvirt. '
+             'If set, it will be executed after every stop command.'),
+    cfg.StrOpt(
+        'unmask_command',
+        help='Similar to the mask_command option, this config options sets '
+             'the command to unmask libvirt. If set, it will be run before '
+             'every start command.'),
 ]
 
 database_group = cfg.OptGroup(

whitebox_tempest_plugin/services/clients.py

@@ -86,9 +86,11 @@ def __init__(self, hostname, service):
             raise exceptions.MissingServiceSectionException(service=service)
         self.service = service
         self.config_path = getattr(conf, 'config_path', None)
-        self.restart_command = getattr(conf, 'restart_command', None)
-        self.stop_command = getattr(conf, 'stop_command', None)
         self.start_command = getattr(conf, 'start_command', None)
+        self.stop_command = getattr(conf, 'stop_command', None)
+        self.restart_command = getattr(conf, 'restart_command', None)
+        self.mask_command = getattr(conf, 'mask_command', None)
+        self.unmask_command = getattr(conf, 'unmask_command', None)
 
     @contextlib.contextmanager
     def config_options(self, *opts):
@@ -162,10 +164,14 @@ def del_conf_opt(self, section, option):
         return self.execute(command, container_name=None, sudo=True)
 
     def start(self):
+        if self.unmask_command:
+            self.execute(self.unmask_command, sudo=True)
         self.execute(self.start_command, sudo=True)
 
     def stop(self):
         self.execute(self.stop_command, sudo=True)
+        if self.unmask_command:
+            self.execute(self.mask_command, sudo=True)
 
     def restart(self):
         self.execute(self.restart_command, sudo=True)