1 files changed, 59 insertions, 0 deletions
diff --git a/third_party/rust/warp/examples/tracing.rs b/third_party/rust/warp/examples/tracing.rs
new file mode 100644
index 0000000000..103f747a93
--- /dev/null
+++ b/third_party/rust/warp/examples/tracing.rs
@@ -0,0 +1,59 @@
+//! [`tracing`] is a framework for instrumenting Rust programs to
+//! collect scoped, structured, and async-aware diagnostics. This example
+//! demonstrates how the `warp::trace` module can be used to instrument `warp`
+//! applications with `tracing`.
+//!
+//! [`tracing`]: https://crates.io/crates/tracing
+#![deny(warnings)]
+use tracing_subscriber::fmt::format::FmtSpan;
+use warp::Filter;
+
+#[tokio::main]
+async fn main() {
+    // Filter traces based on the RUST_LOG env var, or, if it's not set,
+    // default to show the output of the example.
+    let filter = std::env::var("RUST_LOG").unwrap_or_else(|_| "tracing=info,warp=debug".to_owned());
+
+    // Configure the default `tracing` subscriber.
+    // The `fmt` subscriber from the `tracing-subscriber` crate logs `tracing`
+    // events to stdout. Other subscribers are available for integrating with
+    // distributed tracing systems such as OpenTelemetry.
+    tracing_subscriber::fmt()
+        // Use the filter we built above to determine which traces to record.
+        .with_env_filter(filter)
+        // Record an event when each span closes. This can be used to time our
+        // routes' durations!
+        .with_span_events(FmtSpan::CLOSE)
+        .init();
+
+    let hello = warp::path("hello")
+        .and(warp::get())
+        // When the `hello` route is called, emit a `tracing` event.
+        .map(|| {
+            tracing::info!("saying hello...");
+            "Hello, World!"
+        })
+        // Wrap the route in a `tracing` span to add the route's name as context
+        // to any events that occur inside it.
+        .with(warp::trace::named("hello"));
+
+    let goodbye = warp::path("goodbye")
+        .and(warp::get())
+        .map(|| {
+            tracing::info!("saying goodbye...");
+            "So long and thanks for all the fish!"
+        })
+        // We can also provide our own custom `tracing` spans to wrap a route.
+        .with(warp::trace(|info| {
+            // Construct our own custom span for this route.
+            tracing::info_span!("goodbye", req.path = ?info.path())
+        }));
+
+    let routes = hello
+        .or(goodbye)
+        // Wrap all the routes with a filter that creates a `tracing` span for
+        // each request we receive, including data about the request.
+        .with(warp::trace::request());
+
+    warp::serve(routes).run(([127, 0, 0, 1], 3030)).await;
+}