Aggregate Metrics

[gallypette]

D4 provides a analyzer for logs, but it would be interesting to provide an analyzer aggregates metrics compiled client-side. The main argument being that participants may be willing to share data while preserving their privacy.
Some ideas:

• support https://github.com/google/mtail
  see http://google.github.io/mtail/Deploying.html :
  Pull based collection: Point your collection tool at localhost:3903/json for JSON format metrics.

[drt24]

I like this idea and mtail looks like a plausible tool.