# Getting Started

LLMS index: [llms.txt](/llms.txt)

---

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][], [metrics][], and [logs][] are emitted to the console.

## Prerequisites

Ensure that you have the following installed locally:

- [Rust](https://www.rust-lang.org/)
- [Cargo](https://doc.rust-lang.org/cargo/)

## Example Application

The following example uses a basic [hyper](https://hyper.rs/) 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](/ecosystem/registry/?component=instrumentation&language=rust).

For more elaborate examples, see [examples](/docs/languages/rust/examples/).

### Dependencies

To begin, create an executable using `cargo new dice_server` in a new directory
and add the following content to the `Cargo.toml` file:

```toml
[package]
name = "dice_server"
version = "0.1.0"
edition = "2021"

[dependencies]
hyper = { version = "1", features = ["full"] }
tokio = { version = "1", features = ["full"] }
http-body-util = "0.1"
hyper-util = { version = "0.1", features = ["full"] }
rand = "0.9.0"
```

### Create and launch an HTTP Server

Modify `main.rs` to the following:

```rust
use std::convert::Infallible;
use std::net::SocketAddr;

use http_body_util::Full;
use hyper::body::Bytes;
use hyper::server::conn::http1;
use hyper::service::service_fn;
use hyper::Method;
use hyper::{Request, Response};
use hyper_util::rt::TokioIo;
use rand::Rng;
use tokio::net::TcpListener;

async fn roll_dice(_: Request<hyper::body::Incoming>) -> Result<Response<Full<Bytes>>, Infallible> {
    let random_number = rand::rng().random_range(1..=6);
    Ok(Response::new(Full::new(Bytes::from(
        random_number.to_string(),
    ))))
}

async fn handle(req: Request<hyper::body::Incoming>) -> Result<Response<Full<Bytes>>, Infallible> {
    match (req.method(), req.uri().path()) {
        (&Method::GET, "/rolldice") => roll_dice(req).await,
        _ => Ok(Response::builder()
            .status(404)
            .body(Full::new(Bytes::from("Not Found")))
            .unwrap()),
    }
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
    let addr = SocketAddr::from(([127, 0, 0, 1], 8080));

    let listener = TcpListener::bind(addr).await?;

    loop {
        let (stream, _) = listener.accept().await?;

        let io = TokioIo::new(stream);

        tokio::task::spawn(async move {
            if let Err(err) = http1::Builder::new()
                .serve_connection(io, service_fn(handle))
                .await
            {
                eprintln!("Error serving connection: {:?}", err);
            }
        });
    }
}
```

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

```console
$ cargo run
...
Listening on 127.0.0.1:8080
```

## Instrumentation

Now we'll show how to add OpenTelemetry instrumentation to the sample app. If
you are using your own application, you can follow along — your code may be
slightly different.

### Add dependencies

Update the `Cargo.toml` with the dependencies for the OpenTelemetry Rust SDK
[`opentelemetry`](https://crates.io/crates/opentelemetry), the OpenTelemetry
Stdout Exporter
[`opentelemetry-stdout`](https://crates.io/crates/opentelemetry-stdout), and the
[`opentelemetry-appender-tracing`](https://crates.io/crates/opentelemetry-appender-tracing)
bridge for logs:

```toml
opentelemetry = { version = "0.28.0", features = ["metrics"] }
opentelemetry_sdk = { version = "0.28.0", features = ["trace", "metrics", "logs"] }
opentelemetry-stdout = { version = "0.28.0", features = ["trace", "metrics", "logs"] }
opentelemetry-appender-tracing = "0.28.0"
tracing = "0.1"
tracing-subscriber = { version = "0.3", features = ["registry", "env-filter"] }
```

### Complete instrumented application

Replace `main.rs` with the following fully instrumented version. The sections
below explain what each signal adds:

```rust
use std::convert::Infallible;
use std::net::SocketAddr;
use std::sync::OnceLock;

use http_body_util::Full;
use hyper::body::Bytes;
use hyper::server::conn::http1;
use hyper::service::service_fn;
use hyper::Method;
use hyper::{Request, Response};
use hyper_util::rt::TokioIo;
use opentelemetry::global::{self, BoxedTracer};
use opentelemetry::trace::{Span, SpanKind, Status, Tracer};
use opentelemetry::KeyValue;
use opentelemetry_appender_tracing::layer::OpenTelemetryTracingBridge;
use opentelemetry_sdk::logs::SdkLoggerProvider;
use opentelemetry_sdk::metrics::SdkMeterProvider;
use opentelemetry_sdk::trace::SdkTracerProvider;
use opentelemetry_stdout::{LogExporter, MetricExporter, SpanExporter};
use rand::Rng;
use tokio::net::TcpListener;
use tracing_subscriber::layer::SubscriberExt;
use tracing_subscriber::util::SubscriberInitExt;

// --- Metrics: counter stored once for reuse across requests ---
static ROLL_COUNTER: OnceLock<opentelemetry::metrics::Counter<u64>> = OnceLock::new();

fn get_roll_counter() -> &'static opentelemetry::metrics::Counter<u64> {
    ROLL_COUNTER.get_or_init(|| {
        global::meter("dice_server")
            .u64_counter("dice.rolls")
            .with_description("The number of rolls by roll value")
            .build()
    })
}

// --- Application handlers ---
async fn roll_dice(_: Request<hyper::body::Incoming>) -> Result<Response<Full<Bytes>>, Infallible> {
    let random_number = rand::rng().random_range(1..=6);

    // Metrics: record each roll
    get_roll_counter().add(1, &[KeyValue::new("roll.value", random_number as i64)]);

    // Logs: emit a structured log event via the tracing bridge
    tracing::info!(name: "roll_dice", roll.value = random_number, message = "Player rolled the dice");

    Ok(Response::new(Full::new(Bytes::from(
        random_number.to_string(),
    ))))
}

async fn handle(req: Request<hyper::body::Incoming>) -> Result<Response<Full<Bytes>>, Infallible> {
    // Traces: create a server span for each incoming request
    let tracer = get_tracer();
    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") => roll_dice(req).await,
        _ => {
            span.set_status(Status::Ok);
            Ok(Response::builder()
                .status(404)
                .body(Full::new(Bytes::from("Not Found")))
                .unwrap())
        }
    }
}

// --- Traces: global tracer accessor ---
fn get_tracer() -> &'static BoxedTracer {
    static TRACER: OnceLock<BoxedTracer> = OnceLock::new();
    TRACER.get_or_init(|| global::tracer("dice_server"))
}

// --- Provider initialization ---
fn init_tracer_provider() -> SdkTracerProvider {
    let provider = SdkTracerProvider::builder()
        .with_simple_exporter(SpanExporter::default())
        .build();
    global::set_tracer_provider(provider.clone());
    provider
}

fn init_meter_provider() -> SdkMeterProvider {
    let provider = SdkMeterProvider::builder()
        .with_periodic_exporter(MetricExporter::default())
        .build();
    global::set_meter_provider(provider.clone());
    provider
}

fn init_logger_provider() -> SdkLoggerProvider {
    SdkLoggerProvider::builder()
        .with_simple_exporter(LogExporter::default())
        .build()
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
    let addr = SocketAddr::from(([127, 0, 0, 1], 8080));

    // Initialize providers and hold on to them for shutdown
    let tracer_provider = init_tracer_provider();
    let meter_provider = init_meter_provider();
    let logger_provider = init_logger_provider();

    // Logs: wire the tracing bridge so tracing::info! etc. go to OTel
    let otel_layer = OpenTelemetryTracingBridge::new(&logger_provider);
    tracing_subscriber::registry()
        .with(otel_layer)
        .init();

    let listener = TcpListener::bind(addr).await?;
    tracing::info!("Listening on {addr}");

    loop {
        tokio::select! {
            Ok((stream, _)) = listener.accept() => {
                let io = TokioIo::new(stream);
                tokio::task::spawn(async move {
                    if let Err(err) = http1::Builder::new()
                        .serve_connection(io, service_fn(handle))
                        .await
                    {
                        eprintln!("Error serving connection: {:?}", err);
                    }
                });
            }
            _ = tokio::signal::ctrl_c() => {
                break;
            }
        }
    }

    // Flush and shutdown all providers before exit
    if let Err(err) = tracer_provider.shutdown() {
        eprintln!("Error shutting down tracer provider: {err:?}");
    }
    if let Err(err) = meter_provider.shutdown() {
        eprintln!("Error shutting down meter provider: {err:?}");
    }
    if let Err(err) = logger_provider.shutdown() {
        eprintln!("Error shutting down logger provider: {err:?}");
    }

    Ok(())
}
```

Start your server:

```sh
$ cargo run
...
Listening on 127.0.0.1:8080
```

### Traces

Tracing is added in `handle()`. For each incoming HTTP request a **server span**
is created using a `Tracer` retrieved from the global provider:

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

`init_tracer_provider()` builds an `SdkTracerProvider` with the stdout exporter,
sets it globally, and returns it so `main()` can call `.shutdown()` on exit.

When you send a request to <http://localhost:8080/rolldice> you'll see a span
printed to the console:

<details>
<summary>View example output</summary>

```txt
Spans
Resource
         ->  telemetry.sdk.version=String(Static("0.28.0"))
         ->  service.name=String(Static("unknown_service"))
         ->  telemetry.sdk.language=String(Static("rust"))
         ->  telemetry.sdk.name=String(Static("opentelemetry"))
Span #0
        Instrumentation Scope
                Name         : "dice_server"

        Name        : GET /rolldice
        TraceId     : 9f03de7cf14780bd54b95d7095332107
        SpanId      : 9faed88b3f9ed699
        TraceFlags  : TraceFlags(1)
        ParentSpanId: 0000000000000000
        Kind        : Server
        Start time: 2025-03-11 00:47:26.687497
        End time: 2025-03-11 00:47:26.687653
        Status: Unset
```

</details>

### Metrics

A `u64_counter` named `dice.rolls` is created once (via `OnceLock`) and
incremented in `roll_dice()`:

```rust
get_roll_counter().add(1, &[KeyValue::new("roll.value", random_number as i64)]);
```

`init_meter_provider()` builds an `SdkMeterProvider` with a periodic stdout
exporter. After a short interval you'll see the counter emitted:

<details>
<summary>View example output</summary>

```txt
Metrics
Resource
         ->  service.name=String(Static("unknown_service"))
         ->  telemetry.sdk.language=String(Static("rust"))
         ->  telemetry.sdk.name=String(Static("opentelemetry"))
         ->  telemetry.sdk.version=String(Static("0.28.0"))
Metric #0
        Instrumentation Scope
                Name         : "dice_server"

        Name        : dice.rolls
        Description : The number of rolls by roll value
        Unit        :
        Type        : Sum
              Value: 1
              Attributes:
                   ->  roll.value: Int(3)
              Value: 2
              Attributes:
                   ->  roll.value: Int(5)
```

</details>

### Logs

OpenTelemetry Rust does not provide its own end-user logging API. Instead, it
bridges existing Rust logging frameworks into the OpenTelemetry data model. The
recommended approach uses the [`tracing`](https://crates.io/crates/tracing)
crate together with the
[`opentelemetry-appender-tracing`](https://crates.io/crates/opentelemetry-appender-tracing)
bridge.

`init_logger_provider()` builds an `SdkLoggerProvider` with the stdout exporter.
In `main()`, `OpenTelemetryTracingBridge` is wired into the `tracing_subscriber`
stack so that any `tracing::info!` (or other level) call is forwarded to the
OTel log pipeline:

```rust
let otel_layer = OpenTelemetryTracingBridge::new(&logger_provider);
tracing_subscriber::registry()
    .with(otel_layer)
    .init();
```

In `roll_dice()`, a structured log event is emitted:

```rust
tracing::info!(name: "roll_dice", roll.value = random_number, message = "Player rolled the dice");
```

Along with the span and metric, you'll now see log records on the console:

<details>
<summary>View example output</summary>

```txt
Logs
Resource
         ->  service.name=String(Static("unknown_service"))
         ->  telemetry.sdk.language=String(Static("rust"))
         ->  telemetry.sdk.name=String(Static("opentelemetry"))
         ->  telemetry.sdk.version=String(Static("0.28.0"))
Log #0
        Instrumentation Scope
                Name         : "dice_server"

        Timestamp   : 2025-03-11 00:47:26.687497
        Severity    : Info
        Body        : Player rolled the dice
        Attributes:
             ->  roll.value: Int(3)
```

</details>

## What next?

For more:

- Consult the [API & SDK](/docs/languages/rust/api/) reference
- Try other [examples](/docs/languages/rust/examples/).

[traces]: /docs/concepts/signals/traces/
[metrics]: /docs/concepts/signals/metrics/
[logs]: /docs/concepts/signals/logs/