Metrics are emitted via the logs for few couple of reasons:
- Everything supports STDERR.
- User can optionally use them, if not, they just end up in the logs.
- No particular metrics system required, in other words, all metrics systems can be used via adapters (see below).
The metrics format follows logfmt format and looks like this:
metric=someevent value=1 type=count
metric=somegauge value=50 type=gauge
It's a very simple format that can be easily parsed by any logfmt parser and passed on to another stats service.
TODO: List all metrics we emit to logs.
The Logspout Statsd Adapter adapter can parse the log metrics and forward them to any statsd server.