Add support for additional labels when doing prometheus remote writes

[amarao]

Feature Description

Currently, when k6 is doing remote writes into Prometheus, it does add a single label 'scenario'. When multiple k6 copies are run from multiple servers, they don't work together with a single Prometheus server.

It would be nice to be able to distinct different jobs in the Prometheus with different labels.

Suggested Solution (optional)

Add an environment variable (e.g. K6_PROMETHEUS_REMOTE_LABELS="environment=production,server=srv1") to specify list of labels to be set on the series send to the Prometheus.

Any other solution (e.g. configuration within js file) will solve the problem too.

[joanlopez]

Hi @amarao,

Thanks for the feature request, we'll consider it within the team during one of our following issues review, as it goes through the pipeline.