Tolerate alarm actions set to None

This change avoids a crash when an alarm action list is set to None by
the client, as Heat does in some of its tests.

Change-Id: I6feaf639e198a5af7ce970552ce7633a26629024
Closes-Bug: #1472891

ceilometer/api/controllers/v2/alarms.py

@@ -396,11 +396,13 @@ class Alarm(base.Base):
         auth_plugin = pecan.request.environ.get('keystone.token_auth')
         for actions in (self.ok_actions, self.alarm_actions,
                         self.insufficient_data_actions):
+            if actions is not None:
                 for index, action in enumerate(actions[:]):
                     url = netutils.urlsplit(action)
                     if self._is_trust_url(url):
                         if '@' not in url.netloc:
-                        # We have a trust action without a trust ID, create it
+                            # We have a trust action without a trust ID,
+                            # create it
                             trust_id = keystone_client.create_trust_id(
                                 trustor_user_id, trustor_project_id, roles,
                                 auth_plugin)

ceilometer/tests/api/v2/test_alarm_scenarios.py

@@ -1782,6 +1782,30 @@ class TestAlarms(v2.FunctionalTest,
         self.assertEqual(['test://', 'log://'],
                          alarms[0].alarm_actions)
 
+    def test_post_alarm_without_actions(self):
+        body = {
+            'name': 'alarm_actions_none',
+            'type': 'combination',
+            'combination_rule': {
+                'alarm_ids': ['a', 'b'],
+            },
+            'alarm_actions': None
+        }
+        headers = self.auth_headers
+        headers['X-Roles'] = 'admin'
+        self.post_json('/alarms', params=body, status=201,
+                       headers=headers)
+        alarms = list(self.alarm_conn.get_alarms(name='alarm_actions_none'))
+        self.assertEqual(1, len(alarms))
+
+        # FIXME(sileht): This should really returns [] not None
+        # but the mongodb and sql just store the json dict as is...
+        # migration script for sql will be a mess because we have
+        # to parse all JSON :(
+        # I guess we assume that wsme convert the None input to []
+        # because of the array type, but it won't...
+        self.assertIsNone(alarms[0].alarm_actions)
+
     def test_post_alarm_trust(self):
         json = {
             'name': 'added_alarm_defaults',