How to add labels from resource attributes when exporting to prometheus in flow mode?

[madjar]

Hello there!

I've got a grafana agent in flow mode setup with an otlp receiver (otelcol.receiver.otlp) sending metrics to prometheus via otelcol.exporter.prometheus. My issue is that there are interesting attributes in the resource (like the service version) that I'd like to see in the metrics as labels.

I understand that otelcol.exporter.prometheus translates the resource to a target_info metric (as mentioned in #3520), but I'm not sure how I could use this. I also couldn't find any processor to add attributes based on the resource.

So, the question is: is there a way to add attributes to a metric based on the resource?

Alternatively, it's possible I'm looking at this the wrong way. In that case, what would be a better approach to have these as labels in my metrics? Should I solve this by changing my metrics at the source instead of trying to enrich them in the agent?

Thanks a lot!

[madjar]

After spending more time on this, I figured the missing piece of the puzzle: I forgot to have service.instance.id attribute in my otel resource, which means I didn't have an instance label in my metrics. Now that I've added it, a lot of things fall into place, and getting other attributes from the resources is a matter of joining a metric with target_info on the instance label.