Getting Started

This page will show you how to get started with OpenTelemetry in Rust.

You will learn how you can instrument a simple Rust application, in such a way that traces are emitted to the console.

Prerequisites

Ensure that you have the following installed locally:

Example Application

The following example uses a basic hyper application. If you are not using hyper, that’s OK — you can use OpenTelemetry Rust with other HTTP implementations as well, such as Actix Web and Tide. For a complete list of libraries for supported frameworks, see the registry.

For more elaborate examples, see examples.

Dependencies

To begin, create a file Cargo.toml in a new directory and add the following content:

[package]
name = "dice_server"
version = "0.1.0"
edition = "2021"
publish = false

[[bin]]
name = "dice_server"
path = "dice_server.rs"
doc = false

[dependencies]
hyper = { version = "0.14", features = ["full"] }
tokio = { version = "1.29", features = ["full"] }
rand = { version = "0.8" }

Create and launch an HTTP Server

In that same folder, create a file called dice_server.rs and add the following code to the file:

use hyper::service::{make_service_fn, service_fn};
use hyper::{Body, Request, Response, Server, Method, StatusCode};
use rand::Rng;
use std::{convert::Infallible, net::SocketAddr};

async fn handle(req: Request<Body>) -> Result<Response<Body>, Infallible> {
    let mut response = Response::new(Body::empty());

    match (req.method(), req.uri().path()) {
        (&Method::GET, "/rolldice") => {
            let random_number = rand::thread_rng().gen_range(1..7);
            *response.body_mut() = Body::from(random_number.to_string());
        }
        _ => {
            *response.status_mut() = StatusCode::NOT_FOUND;
        }
    };

    Ok(response)
}

#[tokio::main]
async fn main() {
    let addr = SocketAddr::from(([127, 0, 0, 1], 8080));

    let make_svc = make_service_fn(|_conn| async { Ok::<_, Infallible>(service_fn(handle)) });

    let server = Server::bind(&addr).serve(make_svc);

    println!("Listening on {addr}");
    if let Err(e) = server.await {
        eprintln!("server error: {e}");
    }
}

Build and run the application with the following command, then open http://localhost:8080/rolldice in your web browser to ensure it is working.

$ cargo run --bin dice_server
...
Listening on 127.0.0.1:8080

Instrumentation

To add OpenTelemetry to your application, update the Cargo.toml with the dependencies for the OpenTelemetry Rust SDK opentelemetry and the OpenTelemetry Stdout Exporter opentelemetry-stdout:

opentelemetry = { version = "0.21.0", features = ["trace"] }
opentelemetry-stdout = { version = "0.2.0", features = ["trace"] }

Update the dice_server.rs file with code to initialize a tracer and to emit spans when the handle function is called:

use hyper::service::{make_service_fn, service_fn};
use hyper::{Body, Method, Request, Response, Server, StatusCode};
use rand::Rng;
use std::{convert::Infallible, net::SocketAddr};
use opentelemetry::global::ObjectSafeSpan;
use opentelemetry::trace::{SpanKind, Status};
use opentelemetry::sdk::trace::TracerProvider;
use opentelemetry::{global, sdk::propagation::TraceContextPropagator, trace::Tracer};
use opentelemetry_stdout::SpanExporter;

async fn handle(req: Request<Body>) -> Result<Response<Body>, Infallible> {
    let mut response = Response::new(Body::empty());

    let tracer = global::tracer("dice_server");

    let mut span = tracer
        .span_builder(format!("{} {}", req.method(), req.uri().path()))
        .with_kind(SpanKind::Server)
        .start(&tracer);

    match (req.method(), req.uri().path()) {
        (&Method::GET, "/rolldice") => {
            let random_number = rand::thread_rng().gen_range(1..7);
            *response.body_mut() = Body::from(random_number.to_string());
            span.set_status(Status::Ok);
        }
        _ => {
            *response.status_mut() = StatusCode::NOT_FOUND;
            span.set_status(Status::error("Not Found"));
        }
    };

    Ok(response)
}

fn init_tracer() {
    global::set_text_map_propagator(TraceContextPropagator::new());
    let provider = TracerProvider::builder()
        .with_simple_exporter(SpanExporter::default())
        .build();
    global::set_tracer_provider(provider);
}

#[tokio::main]
async fn main() {
    init_tracer();
    let addr = SocketAddr::from(([127, 0, 0, 1], 8080));

    let make_svc = make_service_fn(|_conn| async { Ok::<_, Infallible>(service_fn(handle)) });

    let server =
        Server::bind(&addr).serve(make_svc);

    println!("Listening on {addr}");
    if let Err(e) = server.await {
        eprintln!("server error: {e}");
    }
}

Start your server again:

$ cargo run --bin dice_server
...
Listening on 127.0.0.1:8080

When you send a request to the server at http://localhost:8080/rolldice, you’ll see a span being emitted to the console (output is pretty printed for convenience):

{
  "resourceSpans": [
    {
      "resource": {
        "attributes": [
          {
            "key": "service.name",
            "value": {
              "stringValue": "unknown_service"
            }
          }
        ]
      },
      "scopeSpans": [
        {
          "scope": {
            "name": "dice_server"
          },
          "spans": [
            {
              "attributes": [],
              "droppedAttributesCount": 0,
              "droppedEventsCount": 0,
              "droppedLinksCount": 0,
              "endTimeUnixNano": 1691076354768034000,
              "kind": 2,
              "name": "GET /rolldice",
              "parentSpanId": "",
              "spanId": "27e1d7d8e44a63c5",
              "startTimeUnixNano": 1691076354768025000,
              "status": {
                "code": 2
              },
              "traceId": "adfe9d364ee19610adde517d722167ca"
            }
          ]
        }
      ]
    }
  ]
}

What next?

For more:

Last modified February 7, 2024: [IA] Auto-Update rust versions in docs from registry (#3944) (db3270ff)