Circonus-agent is a lightweight monitoring agent that collects system,
user-defined metrics, statsD, or Prometheus. Metrics are forwarded to Circonus
(SaaS) or can be consumed locally as Prometheus metrics.

The circonus-agent is intelligent about the way it collects metrics in 
that it deliberately only fork(2)'s utilities once where possible and 
reads metrics streamed to it from continuously running processes 
(e.g. iostat(1) or vmstat(1)) or user defined scripts (e.g. PostgreSQL
or DTrace scripts). circonus-agent is a Go rewrite of the NAD.

WWW: https://www.circonus.com/