gRPC-web CORS issue

[Emulator000]

Bug Report

Version

❯ cargo tree | grep tonic
│   │   │   │   └── tonic v0.11.0
│   │   │   └── tonic v0.11.0 (*)
│   │   │   ├── tonic v0.11.0 (*)
│   │   │   └── tonic-reflection v0.11.0
│   │   │       └── tonic v0.11.0 (*)
│   │   │   └── tonic-build v0.11.0
│   ├── tonic v0.11.0 (*)
├── tonic v0.11.0 (*)
├── tonic-web v0.11.0
│   ├── tonic v0.11.0 (*)

Platform

Linux

Crates

tonic-web

Description

I'm trying to use gRPC-web example provided here but I'm getting a CORS error into the browser during the API call:

I resolved in the past this problem with this modified example configuration:

use tonic::{transport::Server, Request, Response, Status};

use hello_world::greeter_server::{Greeter, GreeterServer};
use hello_world::{HelloReply, HelloRequest};
use once_cell::sync::Lazy;

const DEFAULT_MAX_AGE: Duration = Duration::from_secs(24 * 60 * 60);
const DEFAULT_EXPOSED_HEADERS: [HeaderName; 3] = [
    HeaderName::from_static("grpc-status"),
    HeaderName::from_static("grpc-message"),
    HeaderName::from_static("grpc-status-details-bin"),
];

static GRPC_WEB_CORS: Lazy<CorsLayer> = Lazy::new(|| {
    CorsLayer::new()
        .allow_origin(AllowOrigin::mirror_request())
        .allow_headers(AllowHeaders::mirror_request())
        .allow_methods(AllowMethods::mirror_request())
        .allow_credentials(true)
        .max_age(DEFAULT_MAX_AGE)
        .expose_headers(ExposeHeaders::from(DEFAULT_EXPOSED_HEADERS))
});

pub mod hello_world {
    tonic::include_proto!("helloworld");
}

#[derive(Default)]
pub struct MyGreeter {}

#[tonic::async_trait]
impl Greeter for MyGreeter {
    async fn say_hello(
        &self,
        request: Request<HelloRequest>,
    ) -> Result<Response<HelloReply>, Status> {
        println!("Got a request from {:?}", request.remote_addr());

        let reply = hello_world::HelloReply {
            message: format!("Hello {}!", request.into_inner().name),
        };
        Ok(Response::new(reply))
    }
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    tracing_subscriber::fmt::init();

    let addr = "127.0.0.1:3000".parse().unwrap();

    let greeter = MyGreeter::default();
    let greeter = GreeterServer::new(greeter);

    println!("GreeterServer listening on {}", addr);

    Server::builder()
        // GrpcWeb is over http1 so we must enable it.
        .accept_http1(true)
        .layer(GrpcWebLayer::new())
        .layer(GRPC_WEB_CORS)
        .add_service(tonic_web::enable(greeter))
        .serve(addr)
        .await?;

    Ok(())
}

but within the new version I'm getting this compiler error:

    |
104 |         .serve(
    |          ^^^^^ the trait `Service<http::request::Request<tonic::transport::Body>>` is not implemented for `Cors<Routes>`, which is required by `Stack<GrpcWebLayer, tower::layer::util::Identity>: Layer<Cors<Routes>>`
    |
    = help: the trait `Service<http::Request<ReqBody>>` is implemented for `Cors<S>`
    = note: required for `GrpcWebLayer` to implement `Layer<Cors<Routes>>`
    = note: 1 redundant requirement hidden
    = note: required for `Stack<GrpcWebLayer, tower::layer::util::Identity>` to implement `Layer<Cors<Routes>>`

so I can't use it anymore and I've to relay entirely into the tonic_web::enable feature that is designed for the gRPC-web CORS problem.