Route metrics with `XDS`

[davinci26]

Image the following scenario:

You have a grpc-client that is using xds::///listener.name as the address and the XDS resolver and the client is advertising a routing table in the form:

if header-1 == foo
   route cluster foo
if header-2 == bar
   route cluster bar

Now the client would like to have stats on when cluster foo was used vs when cluster bar was used but the current stats hander don't provide this information.

Is this correct? How are people expected to have this observability client side?

[davinci26]

Envoy for example offers https://www.envoyproxy.io/docs/envoy/latest/api-v3/config/route/v3/route_components.proto

stat_prefix
(string) The human readable prefix to use when emitting statistics for this endpoint. The statistics are rooted at vhost..route.<stat_prefix>. This should be set for highly critical endpoints that one wishes to get “per-route” statistics on. If not set, endpoint statistics are not generated.

[arjan-bal]

Hi @davinci26, gRFC A89 proposes adding an optional grpc.lb.backend_service label that would contain the name of the cluster in xDS. Its implementation hasn't been prioritized for gRPC Go yet, but we are open to reviewing PRs for this.

Separately, gRFC A94, which is still under review, also proposes adding the grpc.lb.backend_service label to subchannel metrics.

Hope this helps!

[github-actions]

This issue is labeled as requiring an update from the reporter, and no update has been received after 6 days. If no update is provided in the next 7 days, this issue will be automatically closed.

[davinci26]

@arjan-bal can we mark this as help-wanted to avoid getting stale? I think we might be able to contribute to it because we want this feature