Add more CI/CD metrics to Prometheus
The CI team is heavily relying gitlab-monitor for metrics, but this has some downsides:
- its cumbersome to have to contribute to two projects to get metrics in
- we can use the 'native' prometheus unicorn exporter now
- one god-class like exporter has performance impact on .com as heavy queries will be executed when the scraping request is made
Now we can use the normal way of exposing data on the /-/metrics
path, we should.
This issue is a META issue to collect ideas on what data we need and what type of data. (counters vs gauges vs summeries vs histograms)
Data we'd like:
- Pages Deploy counter
- Runners active
- Runners busy
- Runners polling for work
- Environment created counter
- Deployment created counter