Document available cert-manager Prometheus metrics

[irbekrm]

We should document what Prometheus metrics cert-manager exposes.

This information could be added to https://cert-manager.io/docs/usage/prometheus-metrics/

The metrics could be gathered by looking at cert-manager/pkg/metrics. We should then also add a note somewhere in code that, if a new metric is added, the docs should be updated.

It would also be good to add a warning that metrics will only be available at /metrics path when they are first used as this might be confusing for users see i.e https://github.com/cert-manager/cert-manager/issues/3446#issuecomment-739762015

Here is an example how Linkerd have documented their available proxy metrics.

[tewarig]

hi @irbekrm is this issue still open I would love to contribute

[irbekrm]

Hi @tewarig !

Thanks for showing interest in contributing. Yes, the issue is still open, please feel free to assign yourself to it.

See our contributing guide if you need help getting started https://cert-manager.io/docs/contributing/ and feel free to ask for help on #cert-manager-dev Slack channel https://cert-manager.io/docs/contributing/#slack

[irbekrm]

Hi @tewarig ! Are you still interested in working on this? Perhaps somebody else would like to pick this up.

[tewarig]

hey @irbekrm , you can assign this issue to someone else