Support for WithSubsystem() about go-grpc-middleware HOT 5 OPEN

What is a subsystem? I'm not a prometheus expert, could you elaborate on the problem and use case you have?

from go-grpc-middleware.

Hello,
Sorry for the delayed response.

Similar to ConstLabels, prometheus.CounterOpts, GaugeOpts, etc also accepts a parameter "Subsystem".
As per github.com/prometheus/client_golang/prometheus, Namespace, Subsystem, and Name are components of the fully-qualified name of the Metric (created by joining these components with "_"). Only Name is mandatory, the others merely help structuring the name.

Use case:
I have different microservices in my system. All expose metrics along with subsystem name. subsystem name is the identity/name of microservice.
ex:
SUB1_metricname, SUB2_metricname

So, this helps in readability and debuggability to understand which system component was the source of metric without even looking at metric instance label.

This is the reason for seeking subsystem support for grpc metrics also.

from go-grpc-middleware.

OK, so the proposal is for a new WithSubsystem(subsystem string) option when insantiating the prometheus provider? That sounds reasonable to me. Are you interested in helping to implement this?

from go-grpc-middleware.

Thanks Johan. Raised #639

from go-grpc-middleware.

@johanbrandhorst Raised new PR #643 . I had to close earlier one due to some CLA issues.

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