‘app unicornherder running’
This alert means the Unicorn Herder process has disappeared for the named app, so the app is still running but we don’t know about it and can’t control it.
At the moment, the fix is to run the Fabric
vm.bodge_unicorn for that app. (The name of the task should give a clue
as to why I say “At the moment”.)
Configure and activate your fabric environment as described in the fabric-scripts README.
Then run the
vm.bodge_unicorn task for the affected machine and application:
fab $environment -H whitehall-backend-1.backend vm.bodge_unicorn:whitehall
Job done. The Nagios alert should clear within a few minutes.