Implementing dropwizard emitter for druid (fixes #3927)

[rohitkochar]

Corresponding issues are
#3927
#1996

[rohitkochar]

@b-slim @himanshug
Requesting you to review this pull request.
The code structure is based on the graphite-emitter contributed by @b-slim

[jeffwidman]

Any update on this?

I'm not super familiar with Dropwizard, so I may be conflating things, but I know Kafka uses Dropwizard's metrics library internally, and that's a pretty battle-tested piece of software. So it'd be nice to see this in Druid as well as it'd be very convenient to emit these metrics over JMX/StatsD, etc.

[dkhwangbo]

Hi. Any update? Any schedule to review it?

[jihoonson]

Sorry about the delayed review. @rohitkochar would you please update this PR by merging master? You also need to update the package name and the license of all new files to org.apache.druid and the Apache license, respectively.

[mlubavin-vg]

This would be great if it would allow emitting metrics in the various dropwizard supported formats. We're specifically looking for prometheus exporting, which can be hooked up through the jmx exporter with https://github.com/prometheus/jmx_exporter

[nishantmonu51]

@rohitkochar Thanks for the PR. We are also looking for enabling exposing druid metrics via JMX.
@rohitkochar, are you still planning to work on this PR ?

[nishantmonu51]

FYI, I am working on refactoring this patch for latest druid. Will start by cherry-picking @rohitkochar commit so that he gets credit for the work done.

[nishantmonu51]

Closing in favor of #7363