Table of contents
This page describes what to do in case of an Icinga alert. For more information you could search the govuk-puppet repo for the source of the alert

Unicorn Herder

‘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 task vm.bodge_unicorn for that app. (The name of the task should give a clue as to why I say “At the moment”.)

Within fabric-scripts repo, make sure you have a virtualenv and it is activated. If you don’t have one, do this:

virtualenv .
. bin/activate

virtualenv is installed with pip - if you don’t have it, install it as such:

pip install virtualenv

You’ll also need a username in a .fabricrc file, if you haven’t already got one:

echo 'user = YOURNAME' >> ~/.fabricrc

Then, depending on the alert, look at which machine and which app it is that needs “bodging”. For example, if the machine was whitehall-backend-1 and the app is whitehall, then the command you would run is:

fab $environment -H whitehall-backend-1.backend vm.bodge_unicorn:whitehall

Job done. The Nagios alert should clear within a few minutes.

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