This updates the Elasticsearch health status expressions used in
Prometheus, Nagios and Grafana. The previous Prometheus rule
defined for Elasticsearch health checked for a status that was
> 0 to trigger an alarm for a green health status. The correct
returned values are: 1 for green, 0 for both red and yellow. This
changes the expression to use arithmetic operators to give us a
result that maps to: 2 for green, 1 for yellow, 0 for red.
This also updates the Elasticsearch dashboard in Grafana to add a
new mapping for the updated 2g,1y,0r scale.
Finally, this also updates the Nagios service check to be a bit
more verbose in its output.
For reference, see:
https://github.com/justwatchcom/elasticsearch_exporter/issues/120
Change-Id: I6ef2a7c308c6ebfdb693b46127a285bceb6ba872
9e5a295465