Export grpc request count metric

[shouichi]

Feature Description

The http_reqs metric is available for HTTP, we need a similar metric for gRPC.

Suggested Solution (optional)

Simply count grpc unary requests and export the count (I'm not sure k6 supports grpc stream).

[na--]

k6 doesn't support gRPC streaming yet. As to the count, there's a reason we don't have grpc_req_count - you can get the count from the grpc_req_duration metric by specifying count as a part of the summaryTrendStats option. For example:

k6 run --summary-trend-stats="avg,min,med,max,p(90),p(95),p(99.9),count" grpc-script.js

I see that's not documented very well, so I added a new issue (grafana/k6-docs#184) to correct that... And the reason that http_reqs exists is that it precedes the http_req_duration.count significantly, the count for Trend metrics was only introduced in k6 v0.26.0.

[shouichi]

Thanks for the explanation! Confirmed that the option you gave worked, feel free to close this.