Publish metrics with Telemetry

[derekkraan]

No description provided.

[hubertlepicki]

@derekkraan which event (I assume events, not metrics) you want to publish? I was thinking all events related to processes being started, killed, restarted by Supervisor and all the registration and de-registration in the Registry, which would allow building more complex metrics on top of that - am I right or you had something else in mind?

[derekkraan]

Right now we publish only one event from horde, and one additional event from delta_crdt.

I should probably add a page in the docs to highlight this.

If you have ideas for more events, I would accept a PR adding them.