feat(subscriber): support grpc-web and add grpc-web feature

console-subscriber/Cargo.toml

@@ -28,9 +28,9 @@ keywords = [
 default = ["env-filter"]
 parking_lot = ["parking_lot_crate", "tracing-subscriber/parking_lot"]
 env-filter = ["tracing-subscriber/env-filter"]
+grpc-web = ["tonic-web"]
 
 [dependencies]
-
 crossbeam-utils = "0.8.7"
 tokio = { version = "^1.21", features = ["sync", "time", "macros", "tracing"] }
 tokio-stream = { version = "0.1", features = ["net"] }
@@ -54,11 +54,20 @@ serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 crossbeam-channel = "0.5"
 
+# Only for the web feature:
+tonic-web = { version = "0.10.2", optional = true }
+
 [dev-dependencies]
 tokio = { version = "^1.21", features = ["full", "rt-multi-thread"] }
 tower = { version = "0.4", default-features = false }
 futures = "0.3"
+http = "0.2"
+tower-http = { version = "0.4", features = ["cors"] }
 
 [package.metadata.docs.rs]
 all-features = true
 rustdoc-args = ["--cfg", "docsrs"]
+
+[[example]]
+name = "grpc_web"
+required-features = ["grpc-web"]

console-subscriber/examples/grpc_web.rs

@@ -0,0 +1,122 @@
+//! Example of using the console subscriber with tonic-web.
+//! This example requires the `grpc-web` feature to be enabled.
+//! Run with:
+//! ```sh
+//! cargo run --example grpc_web --features grpc-web
+//! ```
+use std::{thread, time::Duration};
+
+use console_subscriber::{ConsoleLayer, ServerParts};
+use http::header::HeaderName;
+use tonic_web::GrpcWebLayer;
+use tower_http::cors::{AllowOrigin, CorsLayer};
+use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt};
+
+const DEFAULT_MAX_AGE: Duration = Duration::from_secs(24 * 60 * 60);
+const DEFAULT_EXPOSED_HEADERS: [&str; 3] =
+    ["grpc-status", "grpc-message", "grpc-status-details-bin"];
+const DEFAULT_ALLOW_HEADERS: [&str; 5] = [
+    "x-grpc-web",
+    "content-type",
+    "x-user-agent",
+    "grpc-timeout",
+    "user-agent",
+];
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
+    let (console_layer, server) = ConsoleLayer::builder().with_default_env().build();
+    thread::Builder::new()
+        .name("subscriber".into())
+        .spawn(move || {
+            // Do not trace anything in this thread.
+            let _subscriber_guard =
+                tracing::subscriber::set_default(tracing_core::subscriber::NoSubscriber::default());
+            // Custom CORS configuration.
+            let cors = CorsLayer::new()
+                .allow_origin(AllowOrigin::mirror_request())
+                .allow_credentials(true)
+                .max_age(DEFAULT_MAX_AGE)
+                .expose_headers(
+                    DEFAULT_EXPOSED_HEADERS
+                        .iter()
+                        .cloned()
+                        .map(HeaderName::from_static)
+                        .collect::<Vec<HeaderName>>(),
+                )
+                .allow_headers(
+                    DEFAULT_ALLOW_HEADERS
+                        .iter()
+                        .cloned()
+                        .map(HeaderName::from_static)
+                        .collect::<Vec<HeaderName>>(),
+                );
+            let runtime = tokio::runtime::Builder::new_current_thread()
+                .enable_all()
+                .build()
+                .expect("console subscriber runtime initialization failed");
+            runtime.block_on(async move {
+                let ServerParts {
+                    instrument_server,
+                    aggregator,
+                    ..
+                } = server.into_parts();
+                tokio::spawn(aggregator.run());
+                let router = tonic::transport::Server::builder()
+                    // Accept gRPC-Web requests and enable CORS.
+                    .accept_http1(true)
+                    .layer(cors)
+                    .layer(GrpcWebLayer::new())
+                    .add_service(instrument_server);
+                let serve = router.serve(std::net::SocketAddr::new(
+                    std::net::IpAddr::V4(std::net::Ipv4Addr::new(127, 0, 0, 1)),
+                    // 6669 is a restricted port on Chrome, so we cannot use it. We use a different port instead.
+                    9999,
+                ));
+                serve.await.expect("console subscriber server failed");
+            });
+        })
+        .expect("console subscriber could not spawn thread");
+    tracing_subscriber::registry().with(console_layer).init();
+
+    let task1 = tokio::task::Builder::new()
+        .name("task1")
+        .spawn(spawn_tasks(1, 10))
+        .unwrap();
+    let task2 = tokio::task::Builder::new()
+        .name("task2")
+        .spawn(spawn_tasks(10, 30))
+        .unwrap();
+
+    let result = tokio::try_join! {
+        task1,
+        task2,
+    };
+    result?;
+
+    Ok(())
+}
+
+#[tracing::instrument]
+async fn spawn_tasks(min: u64, max: u64) {
+    loop {
+        for i in min..max {
+            tracing::trace!(i, "spawning wait task");
+            tokio::task::Builder::new()
+                .name("wait")
+                .spawn(wait(i))
+                .unwrap();
+
+            let sleep = Duration::from_secs(max) - Duration::from_secs(i);
+            tracing::trace!(?sleep, "sleeping...");
+            tokio::time::sleep(sleep).await;
+        }
+    }
+}
+
+#[tracing::instrument]
+async fn wait(seconds: u64) {
+    tracing::debug!("waiting...");
+    tokio::time::sleep(Duration::from_secs(seconds)).await;
+    tracing::trace!("done!");
+}

console-subscriber/src/builder.rs

@@ -56,6 +56,10 @@ pub struct Builder {
     /// Any scheduled times exceeding this duration will be clamped to this
     /// value. Higher values will result in more memory usage.
     pub(super) scheduled_duration_max: Duration,
+
+    #[cfg(feature = "grpc-web")]
+    /// Whether to enable the grpc-web support.
+    enable_grpc_web: bool,
 }
 
 impl Default for Builder {
@@ -71,6 +75,8 @@ impl Default for Builder {
             recording_path: None,
             filter_env_var: "RUST_LOG".to_string(),
             self_trace: false,
+            #[cfg(feature = "grpc-web")]
+            enable_grpc_web: false,
         }
     }
 }
@@ -268,6 +274,24 @@ impl Builder {
         Self { self_trace, ..self }
     }
 
+    #[cfg(feature = "grpc-web")]
+    /// Sets whether to enable the grpc-web support.
+    ///
+    /// By default, this is `false`. If enabled, the console subscriber will
+    /// serve the gRPC-Web protocol in addition to the standard gRPC protocol.
+    /// This is useful for serving the console subscriber to web clients.
+    ///
+    /// [serve_with_grpc_web] is used to provide more advanced configuration
+    /// for the gRPC-Web server.
+    ///
+    /// [serve_with_grpc_web]: crate::Server::serve_with_grpc_web
+    pub fn enable_grpc_web(self, enable_grpc_web: bool) -> Self {
+        Self {
+            enable_grpc_web,
+            ..self
+        }
+    }
+
     /// Completes the builder, returning a [`ConsoleLayer`] and [`Server`] task.
     pub fn build(self) -> (ConsoleLayer, Server) {
         ConsoleLayer::build(self)
@@ -481,6 +505,8 @@ impl Builder {
         }
 
         let self_trace = self.self_trace;
+        #[cfg(feature = "grpc-web")]
+        let enable_grpc_web = self.enable_grpc_web;
 
         let (layer, server) = self.build();
         let filter =
@@ -501,8 +527,16 @@ impl Builder {
                     .enable_time()
                     .build()
                     .expect("console subscriber runtime initialization failed");
-
                 runtime.block_on(async move {
+                    #[cfg(feature = "grpc-web")]
+                    if enable_grpc_web {
+                        server
+                            .serve_with_grpc_web(tonic::transport::Server::builder())
+                            .await
+                            .expect("console subscriber server failed");
+                        return;
+                    }
+
                     server
                         .serve()
                         .await