Nagios: Adjust messages posted to slack to allow keyword alerting

[sxa]

In order to get good notifications for important outages, it would be beneficial for certain classes of messages to be listed with a particular keyword that you can trigger slack notifications on.

I tried setting my notifications to alert me the word "CRITICAL" which will catch things like this:

HOST: test-osuosl-ubuntu1604-ppc64le-2 SERVICE: Current Load STATE: CRITICAL MESSAGE: CRITICAL - load average: 20.84, 20.96, 21.21

But not these: :fire: HOST: test-marist-ubuntu1804-s390x-2 SERVICE: STATE: MESSAGE:

HOST: build-equinix-centos8-armv8-1 SERVICE: RAM STATE: UNKNOWN MESSAGE: Remote command execution failed: bash: /usr/local/nagios/libexec/check_mem: No such file or directory

It is worth evaluating whether we could have a "critical eyecatcher" phrase of some sort that would be added into all such lines posted to slack (Possibly all the ones with the flame or ? prefix)

FYI @steelhead31 another requirement for you :-)