Vault charm action needs to be run on leader

The vault charm action to authorise the charm within vault needs to
be run on the leader. This mp adds run_action_on_leader to support
that and updates the tests.

unit_tests/test_zaza_model.py

@@ -24,6 +24,11 @@ class TestModel(ut_utils.BaseTestCase):
         async def _wait():
             return
 
+        def _is_leader(leader):
+            async def _inner_is_leader():
+                return leader
+            return _inner_is_leader
+
         self.run_action = mock.MagicMock()
         self.run_action.wait.side_effect = _wait
         self.action = mock.MagicMock()
@@ -58,6 +63,8 @@ class TestModel(ut_utils.BaseTestCase):
         self.unit2.scp_from.side_effect = _scp_from
         self.unit1.run_action.side_effect = _run_action
         self.unit2.run_action.side_effect = _run_action
+        self.unit1.is_leader_from_status.side_effect = _is_leader(False)
+        self.unit2.is_leader_from_status.side_effect = _is_leader(True)
         self.units = [self.unit1, self.unit2]
         _units = mock.MagicMock()
         _units.units = self.units
@@ -175,3 +182,13 @@ class TestModel(ut_utils.BaseTestCase):
             {'action': "action desc"})
         self.check_output.assert_called_once_with(
             ['juju', 'actions', '-m', 'mname', 'myapp', '--format', 'yaml'])
+
+    def test_run_action_on_leader(self):
+        self.patch_object(model, 'Model')
+        self.Model.return_value = self.Model_mock
+        model.run_action_on_leader('modelname', 'app', 'backup',
+                                   {'backup_dir': '/dev/null'})
+        self.assertFalse(self.unit1.called)
+        self.unit2.run_action.assert_called_once_with(
+            'backup',
+            backup_dir='/dev/null')

zaza/charm_tests/vault/utils.py

@@ -203,9 +203,8 @@ def auth_all(clients, token):
 
 
 def run_charm_authorize(token):
-    unit = zaza.model.get_first_unit_name(utils.get_juju_model(), 'vault')
-    return zaza.model.run_action(
+    return zaza.model.run_action_on_leader(
         utils.get_juju_model(),
-        unit,
+        'vault',
         'authorize-charm',
         action_params={'token': token})

zaza/model.py

@@ -364,6 +364,33 @@ async def async_run_action(model_name, unit_name, action_name,
 run_action = sync_wrapper(async_run_action)
 
 
+async def async_run_action_on_leader(model_name, application_name, action_name,
+                                     action_params=None):
+    """Run action on given unit
+
+    :param model_name: Name of model to query.
+    :type model_name: str
+    :param application_name: Name of application
+    :type application_name: str
+    :param action_name: Name of action to run
+    :type action_name: str
+    :param action_params: Dictionary of config options for action
+    :type action_params: dict
+    :returns: Action object
+    :rtype: juju.action.Action
+    """
+    async with run_in_model(model_name) as model:
+        for unit in model.applications[application_name].units:
+            is_leader = await unit.is_leader_from_status()
+            if is_leader:
+                action_obj = await unit.run_action(action_name,
+                                                   **action_params)
+                await action_obj.wait()
+                return action_obj
+
+run_action_on_leader = sync_wrapper(async_run_action_on_leader)
+
+
 def get_actions(model_name, application_name):
     """Get the actions an applications supports