Log request IDs for matched Nova external events

Nova notifier logs for external events only provide the event
details without showing its connection to the associated request_id.

That complicates debugging of corner cases for external events as we
cannot be sure to which exact request a logged event is related.

Make the matching request_ids logged alongside external event
details, whenever it is available.

Signed-off-by: Bogdan Dobrelya <bdobreli@redhat.com>
Change-Id: I047a28744a0bf52ace9f9a205993c6037a21083c

neutron/notifiers/nova.py

@@ -291,11 +291,15 @@ class Notifier(object):
                 except KeyError:
                     response_error = True
                     continue
-                if code != 200:
-                    LOG.warning("Nova event: %s returned with failed "
-                                "status", event)
+                if hasattr(response, 'request_ids'):
+                    msg = "Nova event matching {}".format(response.request_ids)
                 else:
-                    LOG.info("Nova event response: %s", event)
+                    msg = "Nova event"
+                if code != 200:
+                    LOG.warning("%s: %s returned with failed "
+                                "status", msg, event)
+                else:
+                    LOG.info("%s response: %s", msg, event)
             if response_error:
                 LOG.error("Error response returned from nova: %s",
                           response)