Charm should either alert or flag blocked/error status when unable to log into MySQL

[Paul Goins]

On a customer cloud, we had a case where a gnocchi unit had generated over 10 gigs of error logs in about 12 hours. Upon inspecting the errors, it turned out to be a problem with the unit connecting to MySQL due to a bug resulting in a MySQL user record not being created for the new gnocchi unit.

The only reason I saw it is because Graylog started alerting periodically because of the flood of input logs, and when I checked what was the source of most of the logs, I found it was from the gnocchi unit.

At the time of this, "juju status" showed both gnocchi and percona-cluster as healthy, and there was nothing from nrpe which indicated a problem, either.

We may want to have some sort of sanity check that Gnocchi can actually talk to MySQL.