How to accurately get the downstream service name in the upstream as its own `peer.service`

[CoderPoet]

Is your feature request related to a problem? Please describe. How to accurately get the downstream service name in the upstream as its own peer.service, so as to implement accurate service topology metrics

Assuming that a -> b, the following metrics can be generated: service_topology{service_name="b", peer_service="a", kind="server"}

Describe the solution you'd like Can we pass the service.name in the downstream resource attribute to the upstream through the propagation protocol?

For example, propagating the service.name in the resource attributes through the http header

Describe alternatives you've considered Is there a suitable protocol specification

[CoderPoet]

For client calls, it may be possible to use the peer.service mapping mechanism, but that requires the user to manually configure a mapping, which is not very friendly

[mateuszrzeszutek]

Hi @CoderPoet ,

Can we pass the service.name in the downstream resource attribute to the upstream through the propagation protocol?

For example, propagating the service.name in the resource attributes through the http header

This should be doable in the agent, but this kind of feature should probably go through the spec process first. (Also, it's worth noting that there already was a similar request before: https://github.com/open-telemetry/opentelemetry-java-instrumentation/issues/5353 -- implementation-wise, it'd be good to have a common, extensible mechanism for supplementing HTTP response headers across all server instrumentations)

[trask]

http response headers can be populated now using https://github.com/open-telemetry/opentelemetry-java-instrumentation/blob/main/javaagent-extension-api/src/main/java/io/opentelemetry/javaagent/bootstrap/http/HttpServerResponseCustomizer.java

this could probably be used to implement something like this in an agent extension

[github-actions[bot]]

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