NRPE check for ceilometer-collector

[David O Neill]

Our mongodb db was approaching 1.1 tb of data whihc required intervention.
During the intervention, the master was restarted.

Meanwhile on the charm-ceilomter units, then collector silently died whilst trying to push to mongo.

https://pastebin.canonical.com/p/8sqTN8ChW8/

juju run --unit rabbitmq-server/2 'sudo rabbitmqctl -p openstack list_queues|grep -vw 0'
Listing queues ...
compute.JFA1-0503-Compute-1 1
metering.sample 222920

We need check for collector running

[Alvaro Uria (aluria)]

I think the nrpe check should be added in charm-ceilometer, when the nrpe-external-master interface is available.

I'll go and mark the bug as "Invalid" in charm-nrpe.