The counter metrics about the number of sent/received events in streams

[loyd]

What problem are you trying to solve?

Hi, I'm choosing between linkerd (first of all because the proxy is written in Rust, which is lightweight on my tests) and envoy-based solutions for a cluster of GRPC services. My primary requirement is excellent telemetry.

We heavily rely on streaming between all our services. However, linkerd doesn't provide any event counter for long-lived streams:

route_request_total{direction="outbound",dst="lve-server.default.svc.cluster.local:4242",rt_route="Subscribe"} 1

(no response metrics until the subscription is ended)

In the meantime, envoy provides such statistics, including in the response counter:

envoy_cluster_grpc_Subscribe_response_message_count{envoy_grpc_bridge_method="CounterService",envoy_grpc_bridge_service="counter",envoy_cluster_name="lve_server"} 327336

How should the problem be solved?

route_request_total (or another dedicated metric) should calculate the number of events in long-lived streaming

Any alternatives you've considered?

How would users interact with this feature?

No response

Would you like to work on this feature?

Maybe

[olix0r]

It sounds like this is more generally asking for gRPC-specific metrics. As far as I understand, it wouldn't be possible for Linkerd to measure this sort of thing arbitrarily at the HTTP-level. We'd have to parse the response bodies to count the number of gRPC messages included in the response, for instance.

[loyd]

It seems that envoy count frames for this metric. I think it's a reasonable trade-off. Although, I'm not sure it's easy to implement with outdated hyper (0.14).

Anyway, will a patch with this metric be considered?