Cannot use TraceLayer with GrpcService

[conradludgate]

Bug Report

Version

tonic: 0.7.1
prost: 0.10
tonic-build: 0.7.0
tower: 0.4
tower-http: 0.2.5

Platform

N/A

Crates

tonic/tower-http

Description

tower-http's trace::TraceLayer is incompatible with a tonic client GrpcService. It's Response does not implement Default, but since this change it's now required.

Demo

We use this layer to automatically propagate our opentelemetry contexts

[LucioFranco]

cc @davidpdrsn

[davidpdrsn]

If you box the response body like this it works:

let mut tester_client = TesterClient::new(
    ServiceBuilder::new()
        .layer(tower_http::map_response_body::MapResponseBodyLayer::new(http_body::Body::boxed_unsync))
        .layer(tower_http::trace::TraceLayer::new_for_grpc())
        .service(conn),
);

Requires adding the map-response-body feature to tower-http.

[davidpdrsn]

Also, looking at https://github.com/NAlexPear/tonic/blob/2a61ea0e3e7e746f21a1f82f7d6e34bff58640c0/tonic-build/src/client.rs#L61 I think the T::ResponseBody: Default default bound should only be on with_interceptor and not on new. That'd be worth looking into I think. I believe default bodies are only used for interceptors errors.

[conradludgate]

I think you are correct. I've forked locally and can confirm that new does not seem to need it, shall I make a PR?

[davidpdrsn]

Sure!

[davidpdrsn]

Fixed by #974