tonic_web::enable won't work with grpc services because Cors from tower_http does not implement NamedService

[jaysonsantos]

Bug Report

Hi there, first thank you very much for this lib, it has been a pleasure working with it!

Version

cargo tree | grep tonic
│   │   │   │   ├── tonic v0.8.3
│   │   │   ├── tonic v0.8.3 (*)
│   │   │   │   └── tonic v0.8.3 (*)
│   │   │   │   └── tonic-build v0.8.4
│   │   │   └── tonic v0.8.3 (*)
│   └── tonic v0.8.3 (*)
│   └── tonic-build v0.8.4 (*)
├── tonic v0.8.3 (*)
├── tonic-health v0.8.0
│   └── tonic v0.8.3 (*)
├── tonic-web v0.5.0
│   ├── tonic v0.8.3 (*)

Platform

Darwin Jaysons-MBP.localdomain 22.3.0 Darwin Kernel Version 22.3.0: Mon Jan 30 20:38:37 PST 2023; root:xnu-8792.81.3~2/RELEASE_ARM64_T6000 arm64

Crates

Description

While trying to follow the docs to enable cors in my service, I found that it actually does not work because Server::add_service requires NamedService to work.

A simple way to test it is to patch tonic_web's own test with:

diff --git a/tonic-web/tests/integration/tests/grpc_web.rs b/tonic-web/tests/integration/tests/grpc_web.rs
index e062a83..452c8fa 100644
--- a/tonic-web/tests/integration/tests/grpc_web.rs
+++ b/tonic-web/tests/integration/tests/grpc_web.rs
@@ -69,7 +69,7 @@ async fn spawn() -> String {
         Server::builder()
             .accept_http1(true)
             .layer(GrpcWebLayer::new())
-            .add_service(TestServer::new(Svc))
+            .add_service(tonic_web::enable(TestServer::new(Svc)))
             .serve_with_incoming(listener_stream)
             .await
             .unwrap()

and the build output is

 cargo build --tests -p integration
   ...
   Compiling tonic-build v0.8.4 (/Users/jayson.reis/src/tonic/tonic-build)
   Compiling integration v0.1.0 (/Users/jayson.reis/src/tonic/tonic-web/tests/integration)
error[E0277]: the trait bound `tower_http::cors::Cors<GrpcWebService<TestServer<Svc>>>: NamedService` is not satisfied
   --> tonic-web/tests/integration/tests/grpc_web.rs:72:26
    |
72  |             .add_service(tonic_web::enable(TestServer::new(Svc)))
    |              ----------- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `NamedService` is not implemented for `tower_http::cors::Cors<GrpcWebService<TestServer<Svc>>>`
    |              |
    |              required by a bound introduced by this call
    |
    = help: the following other types implement trait `NamedService`:
              GrpcWebService<S>
              InterceptedService<S, F>
              TestServer<T>
              tower::util::either::Either<S, T>
note: required by a bound in `tonic::transport::Server::<L>::add_service`
   --> /Users/jayson.reis/src/tonic/tonic/src/transport/server/mod.rs:347:15
    |
347 |             + NamedService
    |               ^^^^^^^^^^^^ required by this bound in `Server::<L>::add_service`

For more information about this error, try `rustc --explain E0277`.
error: could not compile `integration` due to previous error
warning: build failed, waiting for other jobs to finish...

[jaysonsantos]

A way I've managed to make it compile was by building a wrapper, maybe is it worth it to generate on the codegen crate?

diff --git a/tonic-web/tests/integration/tests/grpc_web.rs b/tonic-web/tests/integration/tests/grpc_web.rs
index e062a83..dd2645d 100644
--- a/tonic-web/tests/integration/tests/grpc_web.rs
+++ b/tonic-web/tests/integration/tests/grpc_web.rs
@@ -1,9 +1,11 @@
+use std::convert::Infallible;
 use std::net::SocketAddr;
+use std::task::{Context, Poll};
 
 use base64::Engine as _;
 use bytes::{Buf, BufMut, Bytes, BytesMut};
 use hyper::http::{header, StatusCode};
-use hyper::{Body, Client, Method, Request, Uri};
+use hyper::{Body, Client, Method, Request, Response, Uri};
 use prost::Message;
 use tokio::net::TcpListener;
 use tokio_stream::wrappers::TcpListenerStream;
@@ -11,6 +13,9 @@ use tonic::transport::Server;
 
 use integration::pb::{test_server::TestServer, Input, Output};
 use integration::Svc;
+use tonic::body::BoxBody;
+use tonic::codegen::Service;
+use tonic::server::NamedService;
 use tonic_web::GrpcWebLayer;
 
 #[tokio::test]
@@ -59,6 +64,38 @@ async fn text_request() {
     assert_eq!(&trailers[..], b"grpc-status:0\r\n");
 }
 
+#[derive(Clone)]
+pub struct NamedTestServerWrapper<S>(S);
+impl<S> NamedTestServerWrapper<S> {
+    pub fn new(service: S) -> Self {
+        Self(service)
+    }
+}
+impl<S> Service<Request<Body>> for NamedTestServerWrapper<S>
+where
+    S: Service<Request<Body>, Response = Response<BoxBody>, Error = Infallible>
+        + Clone
+        + Send
+        + 'static,
+    S::Future: Send + 'static,
+{
+    type Response = S::Response;
+    type Error = S::Error;
+    type Future = S::Future;
+
+    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+        self.0.poll_ready(cx)
+    }
+
+    fn call(&mut self, req: Request<Body>) -> Self::Future {
+        self.0.call(req)
+    }
+}
+
+impl<S> NamedService for NamedTestServerWrapper<S> {
+    const NAME: &'static str = "test.Test";
+}
+
 async fn spawn() -> String {
     let addr = SocketAddr::from(([127, 0, 0, 1], 0));
     let listener = TcpListener::bind(addr).await.expect("listener");
@@ -69,7 +106,9 @@ async fn spawn() -> String {
         Server::builder()
             .accept_http1(true)
             .layer(GrpcWebLayer::new())
-            .add_service(TestServer::new(Svc))
+            .add_service(NamedTestServerWrapper::new(tonic_web::enable(
+                TestServer::new(Svc),
+            )))
             .serve_with_incoming(listener_stream)
             .await
             .unwrap()

[Ben2146053]

This PR might be related.
#1286

[LucioFranco]

Kinda a duplicate #270 will be fixed in the next release.

[vdhanan]

@LucioFranco thanks for the fix! When will the next release be out?

[LucioFranco]

Yes, will come in the next release of tonic, I just have some tests to write before we make the release since it will contain some important/cross cutting changes.