Prometheus metrics

[Kernald]

While there are already OpenTelemetry metrics, do you have any plans on exposing those in Prometheus format as well?

[kalbasit]

@Kernald tbh I have not made a decision either way yet. Is there no otelcol that can export to Prometheus?

[Kernald]

It's indeed possible to set up opentelemetry-collector, but that means having a service deployed just for metrics translation, potential alerts to set up for that... I would definitely prefer native Prometheus metrics, but I definitely understand that it'd be low priority given that there is a way to get that already.

[kalbasit]

@Kernald I added prometheus exporter in #282 and released it in v0.3.0-rc3. Since I use open-telemetry collector, I couldn't test this further, would you be able to test it for me? Thanks!

[Kernald]

Thanks for this! I'm traveling over the next few weeks, so won't be able to test that for a little while unfortunately - happy to test as soon as I'm back though!

[Kernald]

I finally was able to give this a try - overall it looks great, but a couple potential improvements:

• Having the peer's port number results in a very high label cardinality for those metrics, which is something that should be avoided in Prometheus
• Similarly, avoiding unnecessary labels, filtering these would be nice: otel_scope_name="github.com/riandyrn/otelchi/metric", otel_scope_schema_url="https://opentelemetry.io/schemas/1.20.0", otel_scope_service.name="galatea", otel_scope_version="0.12.1"

Thanks for this!

[kalbasit]

Closing this as done in #282.