Skyline was a bit too much overhead, but we took the concept and adapted it to our needs.
When I say too much overhead, I'm referring to the carbon proxy and redis requirements. We found that just using the json output from graphite was sufficient to feed a trend monitoring system.
The output is pretty sensitive, moreso than Icinga2 (Nagios) expects, so we had to turn down a few of the "is this really down" re-checks, since it would silence legitimate trend alerts.
