Scary "Cannot add or update a child row: a foreign key constraint fails" ERROR

[Attila Fazekas]

I see similar message in non dvr setups as mentioned in #1371696.

http://logstash.openstack.org/#eyJzZWFyY2giOiJtZXNzYWdlOlwiQ2Fubm90IGFkZCBvciB1cGRhdGUgYSBjaGlsZCByb3dcXDogYSBmb3JlaWduIGtleSBjb25zdHJhaW50IGZhaWxzXCIiLCJmaWVsZHMiOltdLCJvZmZzZXQiOjAsInRpbWVmcmFtZSI6IjYwNDgwMCIsImdyYXBobW9kZSI6ImNvdW50IiwidGltZSI6eyJ1c2VyX2ludGVydmFsIjowfSwic3RhbXAiOjE0MTQxNTQ0NTgzNDcsIm1vZGUiOiIiLCJhbmFseXplX2ZpZWxkIjoiIn0=

2014-10-24 12:01:09.517 1409 TRACE neutron.agent.l3_agent RemoteError: Remote error: DBReferenceError (IntegrityError) (1452, 'Cannot add or update a child row: a foreign key constraint fails (`neutron`.`routerl3agentbindings`, CONSTRAINT `routerl3agentbindings_ibfk_2` FOREIGN KEY (`router_id`) REFERENCES `routers` (`id`) ON DELETE CASCADE)') 'INSERT INTO routerl3agentbindings (router_id, l3_agent_id) VALUES (%s, %s)' ('63e69dd6-2964-42a2-ad67-9e7048c044e8', '24b9520c-0543-4968-9b2c-f4e86c5d26e4')

The ERROR most likely harmless, but very annoying when searching for a real issue.
Only a shorter message with lower error level (DEBUG) should be logged on a concurrent delete event.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/135011

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/135011
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=e0e8a2e9e81c2f6293eaa8556c5ecdac910358cb
Submitter: Jenkins
Branch: master

commit e0e8a2e9e81c2f6293eaa8556c5ecdac910358cb
Author: Eugene Nikanorov <email address hidden>
Date: Mon Nov 17 20:49:09 2014 +0400

    Catch DBReferenceError exception during binding a router

    In some cases (Concurrent API tests) router can be deleted
    before it is bound to an agent by scheduler.
    That may lead to traces on L3 agent side returned via RPC.
    Need to handle this case in more graceful way.

    Change-Id: Ic52c26ace7f32a615150bd6098b244ae0b98250c
    Closes-Bug: #1385257