Expose a Prometheus /metrics HTTP endpoint

[nlewo]

Do not hesitate to propose comin metrics you would like to see exposed.

[nlewo]

Users would like to get the last deployed commit id and the last deployment status.

Maybe you could start to expose such kind of metrics:

comin_deployment_info{revision="git-commit-hash", status="succeeded|failed"} = 1

Note, i'm not sure this metric follows Prometheus good practices...

[jpds]

Would be good to have the epoch timestamps of when the remotes were last fetched and when the last config update was applied.

[charlot-shaw]

How long the update took, maybe how much memory it consumed as well. I've had builds fail on low memory environments because they tried to build a large package.

[tcurdt]

I see it's implemented already

https://github.com/nlewo/comin/blob/main/internal/http/http.go#L40