Expose worker metrics for prometheus

[debelyoo]

Use case

Metrics are required to monitor properly the workers. By metrics, I mean numbers about the following things:

• processed messages rate
• error rate
• error rate by error type

The metrics should be then used to feed monitoring dashboards (i.e. Grafana dashboards).

Current Workaround

n/a

Proposed Solution

I propose to expose metrics for prometheus and use https://github.com/prometheus/client_python for that.

Additional Information

n/a

If the feature request is approved, would you be willing to submit a PR?

Yes