Support for custom / additional labels

[dpoldrugo]

It would be great to have a possibility to specify custom / additional labels which could be specified per cluster.

Example:

kafka-lag-exporter {
  port = 9999
  lookup-table-size = 60
  clusters = [
    {
      name = "us-east_ny_a-cluster"                                   
      bootstrap-brokers = "us-east_ny_a-1.cluster-a.xyzcorp.com:9092,us-east_ny_a-2.cluster-a.xyzcorp.com:9092,us-east_ny_a-3.cluster-a.xyzcorp.com:9092"
      labels {
        location = "ny"
        zone = "us-east"
      }
    }
  ]
}

And this should add to all metrics for this cluster those two labels with given values.

This would simplify the Prometheus job config. Because now Prometheus relabelling tricks must be applied to get this labels.

[seglo]

Thanks for trying the project, @dpoldrugo. I can see how that would be useful. I'll add it to the backlog. Let me know if this is something you would consider contributing.

[anbarasantr]

I would like to pick this up @seglo

[seglo]

@anbarasantr Excellent. Thanks!