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

[loyd]

What problem are you trying to solve?

This is a clone of https://github.com/linkerd/linkerd2/issues/12319, which was closed (and comments are forbidden) despite open https://github.com/linkerd/linkerd2-proxy/pull/3044.

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Hi, we use linked (first of all, because the proxy is written in Rust, which is lightweight on my tests), and our 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?

yes, already: https://github.com/linkerd/linkerd2/issues/12319