Creating Axum Example

Want to have a minimal example to test usecase.

Relates #1337

Cargo.toml

@@ -28,6 +28,7 @@ members = [
     "examples/metrics-advanced",
     "examples/logs-basic",
     "examples/traceresponse",
+    "examples/tracing-axum",
     "examples/tracing-grpc",
     "stress",
 ]

examples/tracing-axum/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "tracing-axum"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+axum = "0.6.20"
+opentelemetry = { version = "0.21.0", path = "../../opentelemetry" }
+opentelemetry-otlp = { version = "0.13.0", path = "../../opentelemetry-otlp" }
+opentelemetry-stdout = { version = "0.1.0", path = "../../opentelemetry-stdout", features = ["trace"] }
+opentelemetry_sdk = { version = "0.20.0", path = "../../opentelemetry-sdk" }
+tokio = { version = "1.33.0", features = ["rt-multi-thread"] }
+tower-http = { version = "0.4.4", features = ["trace"] }
+tracing = "0.1.40"
+tracing-opentelemetry = "0.21.0"
+tracing-subscriber = { version = "0.3.17", features = ["env-filter"] }

examples/tracing-axum/src/main.rs

@@ -0,0 +1,81 @@
+use axum::{
+    body::Bytes,
+    extract::MatchedPath,
+    http::{HeaderMap, Request},
+    response::{Html, Response},
+    routing::get,
+    Router,
+};
+use opentelemetry::trace::TracerProvider as _;
+use std::time::Duration;
+use tower_http::{classify::ServerErrorsFailureClass, trace::TraceLayer};
+use tracing::{info_span, Span};
+use tracing_subscriber::layer::SubscriberExt;
+#[tokio::main]
+async fn main() {
+    let trace_provider = opentelemetry_sdk::trace::Builder::default()
+        .with_simple_exporter(opentelemetry_stdout::SpanExporter::default())
+        .build();
+    let tracer = trace_provider.tracer("Axum Example");
+    let telemetry = tracing_opentelemetry::layer().with_tracer(tracer);
+    tracing_subscriber::registry().with(telemetry);
+
+    // build our application with a route
+    let app = Router::new()
+        .route("/", get(handler))
+        // `TraceLayer` is provided by tower-http so you have to add that as a dependency.
+        // It provides good defaults but is also very customizable.
+        //
+        // See https://docs.rs/tower-http/0.1.1/tower_http/trace/index.html for more details.
+        //
+        // If you want to customize the behavior using closures here is how.
+        .layer(
+            TraceLayer::new_for_http()
+                .make_span_with(|request: &Request<_>| {
+                    // Log the matched route's path (with placeholders not filled in).
+                    // Use request.uri() or OriginalUri if you want the real path.
+                    let matched_path = request
+                        .extensions()
+                        .get::<MatchedPath>()
+                        .map(MatchedPath::as_str);
+
+                    info_span!(
+                        "http_request",
+                        method = ?request.method(),
+                        matched_path,
+                        some_other_field = tracing::field::Empty,
+                    )
+                })
+                .on_request(|_request: &Request<_>, _span: &Span| {
+                    // You can use `_span.record("some_other_field", value)` in one of these
+                    // closures to attach a value to the initially empty field in the info_span
+                    // created above.
+                })
+                .on_response(|_response: &Response, _latency: Duration, _span: &Span| {
+                    // ...
+                })
+                .on_body_chunk(|_chunk: &Bytes, _latency: Duration, _span: &Span| {
+                    // ...
+                })
+                .on_eos(
+                    |_trailers: Option<&HeaderMap>, _stream_duration: Duration, _span: &Span| {
+                        // ...
+                    },
+                )
+                .on_failure(
+                    |_error: ServerErrorsFailureClass, _latency: Duration, _span: &Span| {
+                        // ...
+                    },
+                ),
+        );
+
+    // Run it
+    axum::Server::bind(&"127.0.0.1:3000".parse().unwrap())
+        .serve(app.into_make_service())
+        .await
+        .unwrap();
+}
+
+async fn handler() -> Html<&'static str> {
+    Html("<h1>Hello, World!</h1>")
+}