//! [`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;
}
