Use go-metrics extensively

[schmichael]

Instrument everything

Alternatively we could use go's builtin lightweight expvar and httpprof.

[epsniff]

Im all for limiting dependencies. Can we use expvar without automatically exposing it via HTTP? IMO, surfacing the metrics should be left to the hosting project.

[schmichael]

@epsniff

Can we use expvar without automatically exposing it via HTTP?

You don't have to start the HTTP server, but it does register its endpoints on the default HTTP server mux. You can't change that without forking it like I did with https://github.com/lytics/httppprof

However, in hindsight it seems like using the default HTTP server mux for debugging/monitoring is idiomatic, so I'm actually leaning towards just enabling both libraries by default.

[epsniff]

I'm ok with that, so long as it doesn't turn on the http server.