Files
neon/libs/tracing-utils/src/http.rs
Arpad Müller 9d93dd4807 Rename hyper 1.0 to hyper and hyper 0.14 to hyper0 (#9254)
Follow-up of #9234 to give hyper 1.0 the version-free name, and the
legacy version of hyper the one with the version number inside. As we
move away from hyper 0.14, we can remove the `hyper0` name piece by
piece.

Part of #9255
2024-10-03 16:33:43 +02:00

97 lines
3.4 KiB
Rust

//! Tracing wrapper for Hyper HTTP server
use hyper0::HeaderMap;
use hyper0::{Body, Request, Response};
use std::future::Future;
use tracing::Instrument;
use tracing_opentelemetry::OpenTelemetrySpanExt;
/// Configuration option for what to use as the "otel.name" field in the traces.
pub enum OtelName<'a> {
/// Use a constant string
Constant(&'a str),
/// Use the path from the request.
///
/// That's very useful information, but is not appropriate if the
/// path contains parameters that differ on ever request, or worse,
/// sensitive information like usernames or email addresses.
///
/// See <https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/http.md#name>
UriPath,
}
/// Handle an incoming HTTP request using the given handler function,
/// with OpenTelemetry tracing.
///
/// This runs 'handler' on the request in a new span, with fields filled in
/// from the request. Notably, if the request contains tracing information,
/// it is propagated to the span, so that this request is traced as part of
/// the same trace.
///
/// XXX: Usually, this is handled by existing libraries, or built
/// directly into HTTP servers. However, I couldn't find one for Hyper,
/// so I had to write our own. OpenTelemetry website has a registry of
/// instrumentation libraries at:
/// <https://opentelemetry.io/registry/?language=rust&component=instrumentation>
/// If a Hyper crate appears, consider switching to that.
pub async fn tracing_handler<F, R>(
req: Request<Body>,
handler: F,
otel_name: OtelName<'_>,
) -> Response<Body>
where
F: Fn(Request<Body>) -> R,
R: Future<Output = Response<Body>>,
{
// Create a tracing span, with context propagated from the incoming
// request if any.
//
// See list of standard fields defined for HTTP requests at
// https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/http.md
// We only fill in a few of the most useful ones here.
let otel_name = match otel_name {
OtelName::Constant(s) => s,
OtelName::UriPath => req.uri().path(),
};
let span = tracing::info_span!(
"http request",
otel.name= %otel_name,
http.method = %req.method(),
http.status_code = tracing::field::Empty,
);
let parent_ctx = extract_remote_context(req.headers());
span.set_parent(parent_ctx);
// Handle the request within the span
let response = handler(req).instrument(span.clone()).await;
// Fill in the fields from the response code
let status = response.status();
span.record("http.status_code", status.as_str());
span.record(
"otel.status_code",
if status.is_success() { "OK" } else { "ERROR" },
);
response
}
// Extract remote tracing context from the HTTP headers
fn extract_remote_context(headers: &HeaderMap) -> opentelemetry::Context {
struct HeaderExtractor<'a>(&'a HeaderMap);
impl<'a> opentelemetry::propagation::Extractor for HeaderExtractor<'a> {
fn get(&self, key: &str) -> Option<&str> {
self.0.get(key).and_then(|value| value.to_str().ok())
}
fn keys(&self) -> Vec<&str> {
self.0.keys().map(|value| value.as_str()).collect()
}
}
let extractor = HeaderExtractor(headers);
opentelemetry::global::get_text_map_propagator(|propagator| propagator.extract(&extractor))
}