Feature: add beat version info

[SuperQ]

Feature idea, add beat info metrics from the stats endpoint /

{
  "beat": "pubsubbeat",
  "hostname": "pubsub-sidekiq-inf-gstg",
  "name": "pubsub-sidekiq-inf-gstg",
  "uuid": "FOO",
  "version": "7.5.1"
}

Would make a metrics like this:

pubsubbeat_build_info{version="7.5.1"} 1
pubsubbeat_beat_info{beat_name="pubsub-sidekiq-inf-gstg",uuid="FOO",} 1

[shivas]

beat version available in beat_exporter_target_info{beat="auditbeat",uri="localhost:",version="7.5.1"} adding UUID is tricky, as it's random value and could cause cardinality explosion? not sure how under the good UUID is generated

[SuperQ]

Oh, strange, I checked for info metrics previously and didn't see it.

It seems like the UUID is stored in a meta.json written out by the beat. Should be stable enough to expose.

[shivas]

I understand name and hostname, but does UUID really have value to be exposed?

[SuperQ]

Yes, there really is a UUID, at least on my instances. Having the UUID isn't that important to me, it was just an idea.

Weird, it seems like beat_exporter_target_info is not read at every scrape. I did some upgrade testing today and I saw no change in the version.

[shivas]

That data read only once on beat-exporter startup, so if you changed *beat without restarting actual exporter - could be u see stale data.

[SuperQ]

Ok, I will see about fixing the exporter to update at every scrape.