OpenTelemetry: How can I count requests for each downstream?

[tuanhd9173]

Hello,

I followed the sample in order to expose forwarder metrics to Prometheus.
But I want to expose metrics (RequestsStarted, RequestsFailed, CurrentRequests) for each downstream (each cluster) too.
I found that I can register an IForwarderTelemetryConsumer to consume forward events but I can not identify the downstream.
Do somebody have experience with?

Thanks.

[MihaZupan]

The ReverseProxy.Metrics.Sample project shows how you can correlate those IForwarderTelemetryConsumer (and other) events back to the route/cluster/destination.

E.g. in ForwarderTelemetryConsumer.OnForwarderStart, you can look at metrics.DestinationId.

.NET 8 will include more HttpClient metrics out of the box, so there should be less of a need to expose some of these metrics manually.