Log health manager exceptions

The executor will hide any unhandled exceptions raised from the update_health
or update_stats methods. This patch updates the health manager to log those
exceptions.

Change-Id: I941730c5e0964ec319b5eb2b7992335b71f9d134

octavia/controller/healthmanager/health_drivers/update_db.py

@@ -75,6 +75,14 @@ class UpdateHealthDb(update_base.HealthUpdateBase):
             self.emit(entity_type, entity_id, message)
 
     def update_health(self, health):
+        # The executor will eat any exceptions from the update_health code
+        # so we need to wrap it and log the unhandled exception
+        try:
+            self._update_health(health)
+        except Exception:
+            LOG.exception('update_health encountered an unknown error')
+
+    def _update_health(self, health):
         """This function is to update db info based on amphora status
 
         :param health: map object that contains amphora, listener, member info
@@ -319,6 +327,14 @@ class UpdateStatsDb(update_base.StatsUpdateBase, stats.StatsMixin):
         self.event_streamer.emit(cnt)
 
     def update_stats(self, health_message):
+        # The executor will eat any exceptions from the update_stats code
+        # so we need to wrap it and log the unhandled exception
+        try:
+            self._update_stats(health_message)
+        except Exception:
+            LOG.exception('update_stats encountered an unknown error')
+
+    def _update_stats(self, health_message):
         """This function is to update the db with listener stats
 
         :param health_message: The health message containing the listener stats

octavia/tests/unit/controller/healthmanager/health_drivers/test_update_db.py

@@ -183,7 +183,7 @@ class TestUpdateHealthDb(base.TestCase):
 
         self.amphora_repo.get_all_lbs_on_amphora.return_value = []
 
-        self.assertRaises(TestException, self.hm.update_health, health)
+        self.hm.update_health(health)
         self.assertTrue(self.amphora_health_repo.replace.called)
         self.session_mock.rollback.assert_called_once()