only rollback DB when we have a connection to the DB

Story: 2006062
Task: 34775

Change-Id: I728a9aa82986edef8128907a48c9df87d119fa8f

octavia/controller/healthmanager/health_manager.py

@@ -85,6 +85,7 @@ class HealthManager(object):
         futs = []
         while not self.dead.is_set():
             amp_health = None
+            lock_session = None
             try:
                 lock_session = db_api.get_session(autocommit=False)
                 amp = None
@@ -123,7 +124,8 @@ class HealthManager(object):
                     time.sleep(CONF.health_manager.heartbeat_timeout)
             except Exception:
                 with excutils.save_and_reraise_exception():
-                    lock_session.rollback()
+                    if lock_session:
+                        lock_session.rollback()
 
             if amp_health is None:
                 break

octavia/tests/unit/controller/healthmanager/test_health_manager.py

@@ -117,3 +117,21 @@ class TestHealthManager(base.TestCase):
 
         session_mock.assert_called_once_with(autocommit=False)
         self.assertFalse(failover_mock.called)
+
+    @mock.patch('octavia.controller.worker.v1.controller_worker.'
+                'ControllerWorker.failover_amphora')
+    @mock.patch('octavia.db.repositories.AmphoraHealthRepository.'
+                'get_stale_amphora', return_value=None)
+    @mock.patch('octavia.db.api.get_session')
+    def test_health_check_db_error(self, session_mock, get_stale_amp_mock,
+                                   failover_mock):
+        get_stale_amp_mock.return_value = None
+
+        mock_session = mock.MagicMock()
+        session_mock.return_value = mock_session
+        session_mock.side_effect = TestException('DB Error')
+        exit_event = threading.Event()
+        hm = healthmanager.HealthManager(exit_event)
+
+        self.assertRaises(TestException, hm.health_check)
+        self.assertEqual(0, mock_session.rollback.call_count)

releasenotes/notes/Fix-HM-DB-Rollback-no-connection-2664c4f7823ecaec.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    Fixed an issue with the health manager reporting an UnboundLocalError if
+    it gets an exception attempting to get a database connection.