Add service binary/host to service is down log for context

When we're logging that a service appears to be down in the
DB service group drive, add the service binary and host to
the message for context.

Change-Id: I8f676f7b498f4d7cb9b574a401ec892c2a3aacd3
Related-Bug: #1549854

nova/servicegroup/drivers/db.py

@@ -75,9 +75,11 @@ class DbDriver(base.Driver):
         elapsed = timeutils.delta_seconds(last_heartbeat, timeutils.utcnow())
         is_up = abs(elapsed) <= self.service_down_time
         if not is_up:
-            LOG.debug('Seems service is down. Last heartbeat was %(lhb)s. '
-                      'Elapsed time is %(el)s',
-                      {'lhb': str(last_heartbeat), 'el': str(elapsed)})
+            LOG.debug('Seems service %(binary)s on host %(host)s is down. '
+                      'Last heartbeat was %(lhb)s. Elapsed time is %(el)s',
+                      {'binary': service_ref.get('binary'),
+                       'host': service_ref.get('host'),
+                       'lhb': str(last_heartbeat), 'el': str(elapsed)})
         return is_up
 
     def _report_state(self, service):

nova/tests/unit/cells/test_cells_state_manager.py

@@ -92,7 +92,8 @@ def _fake_service_get_all_by_binary_nodedown(cls, context, binary):
         return objects.Service(host=host,
                                disabled=False,
                                forced_down=False,
-                               last_seen_up=last_seen)
+                               last_seen_up=last_seen,
+                               binary=binary)
 
     return [_service(*fake) for fake in FAKE_SERVICES]
 

nova/tests/unit/servicegroup/test_db_servicegroup.py

@@ -37,6 +37,7 @@ class DBServiceGroupTestCase(test.NoDBTestCase):
         service = objects.Service(
             host='fake-host',
             topic='compute',
+            binary='nova-compute',
             created_at=now,
             updated_at=now,
             last_seen_up=now,