adds grpc-ecosystem go-grpc-prometheus interceptors to server.go

[michaelschiff]

This change is 

[michaelschiff]

Not sure how you feel about the addition of another dependency, but its nice to have the same standard metrics on all grpc services. Another option is giving the user an ability to pass options to the GRPC server (which may actually be more flexible long-term).

[jgraettinger]

I'm wary here because once added it can't be removed. I'd actually like to move away from "official" client-side metrics instrumentation in favor of #235 , and am a believer in decoupling responsibility for metric identification/extraction/aggregation from services themselves.

That said, one idea that occurs to me though is there's no particular reason the GRPCServer needs to be created in New. That could instead be a responsibility of InitApplication. It'd require moving RegisterShardServer to after InitApplication, and creating a default GRPCServer if one hasn't been yet, but that seems pretty minor?

Then the application has full flexibility to wire up any grpc.ServerOptions it wants.

Reviewable status: 0 of 2 files reviewed, all discussions resolved (waiting on @jgraettinger)

[michaelschiff]

I agree, that feels like a more flexible approach.

[jgraettinger]

Reconsidered this, and believe it's a good idea. Building on the grpc-prometheus ecosystem allows for things like mixing in prepackaged Grafana dashboards / Prometheus rules / alerts etc for exploring these metrics (though to be honest I'm not finding much, beyond grpc-ecosystem/go-grpc-prometheus#68)