Public bug reported: The handling of os-server-external-events API [1] has a bug. It is designed to handle multiple events, with the following expected behavior: * If all events are successfully handled, it should return HTTP 200. * If no event is successfully handled, it should return HTTP 404. * If some are handled successfully but not all, it should return HTTP 207, with per-event status codes.
However, when Cyborg sends a single event for a single instance, and that instance is not yet associated with a host [*], the 'else' clause in Line 137 [1] will set HTTP 207 as return code; but, since accepted_events is [] in Line 146, that will throw an exception and return 404. IOW, the expected return is 207 but the actual return is 404. This has been discussed in IRC [2]. A patch has been proposed [3] to address this. [*] This happens because Nova calls into Cyborg from the conductor to initiate binding of accelerator requests (ARQs), lets it proceed asynchronously, and waits for the binding notification event in the compute manager. The notification event could come before the compute manager has called self._rt.instance_claim(), which would associate the instance with a host and a node. That race condition triggers the behavior above. [1] https://github.com/openstack/nova/blob/62f6a0a1bc6c4b24621e1c2e927177f99501bef3/nova/api/openstack/compute/server_external_events.py [2] http://eavesdrop.openstack.org/irclogs/%23openstack-nova /%23openstack-nova.2019-12-09.log.html#t2019-12-09T15:45:18 [3] https://review.opendev.org/#/c/698037/ ** Affects: nova Importance: Undecided Assignee: Eric Fried (efried) Status: In Progress -- You received this bug notification because you are a member of Yahoo! Engineering Team, which is subscribed to OpenStack Compute (nova). https://bugs.launchpad.net/bugs/1855752 Title: Inappropriate HTTP error status from os-server-external-events Status in OpenStack Compute (nova): In Progress Bug description: The handling of os-server-external-events API [1] has a bug. It is designed to handle multiple events, with the following expected behavior: * If all events are successfully handled, it should return HTTP 200. * If no event is successfully handled, it should return HTTP 404. * If some are handled successfully but not all, it should return HTTP 207, with per-event status codes. However, when Cyborg sends a single event for a single instance, and that instance is not yet associated with a host [*], the 'else' clause in Line 137 [1] will set HTTP 207 as return code; but, since accepted_events is [] in Line 146, that will throw an exception and return 404. IOW, the expected return is 207 but the actual return is 404. This has been discussed in IRC [2]. A patch has been proposed [3] to address this. [*] This happens because Nova calls into Cyborg from the conductor to initiate binding of accelerator requests (ARQs), lets it proceed asynchronously, and waits for the binding notification event in the compute manager. The notification event could come before the compute manager has called self._rt.instance_claim(), which would associate the instance with a host and a node. That race condition triggers the behavior above. [1] https://github.com/openstack/nova/blob/62f6a0a1bc6c4b24621e1c2e927177f99501bef3/nova/api/openstack/compute/server_external_events.py [2] http://eavesdrop.openstack.org/irclogs/%23openstack-nova /%23openstack-nova.2019-12-09.log.html#t2019-12-09T15:45:18 [3] https://review.opendev.org/#/c/698037/ To manage notifications about this bug go to: https://bugs.launchpad.net/nova/+bug/1855752/+subscriptions -- Mailing list: https://launchpad.net/~yahoo-eng-team Post to : [email protected] Unsubscribe : https://launchpad.net/~yahoo-eng-team More help : https://help.launchpad.net/ListHelp
