@ramaraochavali can you add a release note for this? approval is pending on adding that :)

Sure. I was thinking of adding it when the feature is implemented in Istio. I can add it if you prefer to add it here also.

🤔 🐛 You appear to be fixing a bug in Go code, yet your PR doesn't include updates to any test files. Did you forget to add a test?

Courtesy of your friendly test nag.

@ericvn @hzxuzhonghu PTAL

paging @douglas-reid

How is this intended to function with the Telemetry API ?

@louiscryan I think this is beyond the current scope of the Telemetry API. As I understand it, this is adding prefixes to envoy-generated stats, which has generally been distinct from the domain of the Telemetry API (which has focused on controlling Istio generation). Mostly, the envoy-level interactions for stats tend to be at the bootstrap level, which the Telemetry API has not tried to cover.

The use case is not fully fleshed out here, but I imagine that @ramaraochavali desires to include some envoy-level metrics specific to endpoints. @ramaraochavali is that correct?

The Telemetry API-based equivalent, iiuc, would be adding new labels to the istio metrics for path -- and using attribute-gen (or equivalent) to manage scoping of that generation for specific "high-value" destinations. That pattern is a bit complex, and involves bits outside the Telemetry API as well (existing docs).

I think at a minimum we should be clearer in the documentation provided that this prefix is only for proxy-level stats (envoy_*) and not service-level (istio_*) stats. It may also be worth noting that using this prefix may require bootstrap changes to stats_matcher configuration, etc., to properly use (although @ramaraochavali may solve that in the control plane implementation?).

I imagine that @ramaraochavali desires to include some envoy-level metrics specific to endpoints. @ramaraochavali is that correct?

Yes. This is to set the stat prefix to envoy route config so that it can generate route level stats.

I think at a minimum we should be clearer in the documentation provided that this prefix is only for proxy-level stats (envoy_) and not service-level (istio_) stats. It may also be worth noting that using this prefix may require bootstrap changes to stats_matcher configuration, etc., to properly use (although @ramaraochavali may solve that in the control plane implementation?).

I will update the docs.