Opentracing middleware implementation for reqwest_middleware.

Attach TracingMiddleware to your client to automatically trace HTTP requests.

The simplest possible usage:

use reqwest_middleware::{ClientBuilder};
use dogdata_reqwest_middleware::TracingMiddleware;

let reqwest_client = reqwest::Client::builder().build().unwrap();
let client = ClientBuilder::new(reqwest_client)
   // Insert the tracing middleware
   .with(TracingMiddleware::default())
   .build();

let resp = client.get("https://truelayer.com").send().await.unwrap();

To customise the span names use OtelName.

use reqwest_middleware::{ClientBuilder, Extension};
use dogdata_reqwest_middleware::{
    TracingMiddleware, OtelName
};
let reqwest_client = reqwest::Client::builder().build().unwrap();
let client = ClientBuilder::new(reqwest_client)
   // Inserts the extension before the request is started
   .with_init(Extension(OtelName("my-client".into())))
   // Makes use of that extension to specify the otel name
   .with(TracingMiddleware::default())
   .build();

let resp = client.get("https://truelayer.com").send().await.unwrap();

// Or specify it on the individual request (will take priority)
let resp = client.post("https://api.truelayer.com/payment")
    .with_extension(OtelName("POST /payment".into()))
   .send()
   .await
   .unwrap();

In this example we define a custom span builder to calculate the request time elapsed and we register the TracingMiddleware.

Note that Opentelemetry tracks start and stop already, there is no need to have a custom builder like this.

use reqwest_middleware::Result;
use http::Extensions;
use reqwest::{Request, Response};
use reqwest_middleware::ClientBuilder;
use dogdata_reqwest_middleware::{
    default_on_request_end, reqwest_otel_span, ReqwestOtelSpanBackend, TracingMiddleware
};
use tracing::Span;
use std::time::{Duration, Instant};

pub struct TimeTrace;

impl ReqwestOtelSpanBackend for TimeTrace {
    fn on_request_start(req: &Request, extension: &mut Extensions) -> Span {
        extension.insert(Instant::now());
        reqwest_otel_span!(name="example-request", req, time_elapsed = tracing::field::Empty)
    }

    fn on_request_end(span: &Span, outcome: &Result<Response>, extension: &mut Extensions) {
        let time_elapsed = extension.get::<Instant>().unwrap().elapsed().as_millis() as i64;
        default_on_request_end(span, outcome);
        span.record("time_elapsed", &time_elapsed);
    }
}

let http = ClientBuilder::new(reqwest::Client::new())
    .with(TracingMiddleware::<TimeTrace>::new())
    .build();

dogdata-reqwest-middleware