Hello World - Send Your First Trace

What You Will Build

A command-line app that creates three OpenTelemetry spans - a successful greeting, a disk-space warning, and a config-parsing error - and sends traces, logs, and metrics to your Scout collector. After running it you will see all three signal types correlated in TraceX and LogX. This guide covers all 9 officially supported languages.

Prerequisites

• A Scout account with a collector running (5-Minute Quick Start if you haven't set one up yet)
• The language runtime for the tab you pick installed on your machine
• Your collector endpoint (default http://localhost:4318)

Choose Your Language

Node.js

Install Dependencies

package.json

{
  "name": "hello-world-nodejs",
  "version": "1.0.0",
  "private": true,
  "dependencies": {
    "@opentelemetry/api": "^1.9.0",
    "@opentelemetry/api-logs": "^0.213.0",
    "@opentelemetry/exporter-logs-otlp-http": "^0.213.0",
    "@opentelemetry/exporter-metrics-otlp-http": "^0.213.0",
    "@opentelemetry/exporter-trace-otlp-http": "^0.213.0",
    "@opentelemetry/resources": "^2.6.0",
    "@opentelemetry/sdk-logs": "^0.213.0",
    "@opentelemetry/sdk-metrics": "^2.6.0",
    "@opentelemetry/sdk-trace-base": "^2.6.0",
    "@opentelemetry/sdk-trace-node": "^2.6.0"
  }
}

npm install

The Code

main.js

function sayHello(tracer, otelLogger, helloCounter) {
  tracer.startActiveSpan("say-hello", (span) => {
    otelLogger.emit({
      severityText: "INFO",
      severityNumber: SeverityNumber.INFO,
      body: "Hello, World!",
    });
    helloCounter.add(1);
    span.setAttribute("greeting", "Hello, World!");
    span.end();
  });
}

The full example also includes checkDiskSpace (warning) and parseConfig (error with exception). View full source on GitHub →

Run It

OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318 node main.js

Python

Install Dependencies

requirements.txt

opentelemetry-api==1.40.0
opentelemetry-sdk==1.40.0
opentelemetry-exporter-otlp-proto-http==1.40.0

pip install -r requirements.txt

The Code

main.py

def say_hello():
    with tracer.start_as_current_span("say-hello") as span:
        logger.info("Hello, World!")
        hello_counter.add(1)
        span.set_attribute("greeting", "Hello, World!")

The full example also includes check_disk_space (warning) and parse_config (error with exception). View full source on GitHub →

Run It

OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318 python main.py

Go

Install Dependencies

go.mod

module hello-world-go

go 1.25.0

require (
    go.opentelemetry.io/otel v1.42.0
    go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp v0.18.0
    go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp v1.42.0
    go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.42.0
    go.opentelemetry.io/otel/log v0.18.0
    go.opentelemetry.io/otel/metric v1.42.0
    go.opentelemetry.io/otel/sdk v1.42.0
    go.opentelemetry.io/otel/sdk/log v0.18.0
    go.opentelemetry.io/otel/sdk/metric v1.42.0
    go.opentelemetry.io/otel/trace v1.42.0
)

go mod tidy

The Code

main.go

func sayHello(ctx context.Context, tracer trace.Tracer, logger log.Logger, counter metric.Int64Counter) {
    ctx, span := tracer.Start(ctx, "say-hello")
    defer span.End()

    var rec log.Record
    rec.SetSeverityText("INFO")
    rec.SetSeverity(log.SeverityInfo)
    rec.SetBody(log.StringValue("Hello, World!"))
    logger.Emit(ctx, rec)

    counter.Add(ctx, 1)
    span.SetAttributes(attribute.String("greeting", "Hello, World!"))
}

The full example also includes checkDiskSpace (warning) and parseConfig (error with exception). View full source on GitHub →

Run It

OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318 go run .

Java

Install Dependencies

pom.xml (dependencies)

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>io.opentelemetry</groupId>
            <artifactId>opentelemetry-bom</artifactId>
            <version>1.60.1</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

<dependencies>
    <dependency>
        <groupId>io.opentelemetry</groupId>
        <artifactId>opentelemetry-api</artifactId>
    </dependency>
    <dependency>
        <groupId>io.opentelemetry</groupId>
        <artifactId>opentelemetry-sdk</artifactId>
    </dependency>
    <dependency>
        <groupId>io.opentelemetry</groupId>
        <artifactId>opentelemetry-exporter-otlp</artifactId>
    </dependency>
</dependencies>

mvn compile

The Code

Main.java

static void sayHello(Tracer tracer, Logger logger, LongCounter counter) {
    Span span = tracer.spanBuilder("say-hello").startSpan();
    try (var scope = span.makeCurrent()) {
        logger.logRecordBuilder()
                .setSeverity(Severity.INFO)
                .setSeverityText("INFO")
                .setBody("Hello, World!")
                .emit();
        counter.add(1);
        span.setAttribute("greeting", "Hello, World!");
    } finally {
        span.end();
    }
}

The full example also includes checkDiskSpace (warning) and parseConfig (error with exception). View full source on GitHub →

Run It

OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318 mvn compile exec:java

C#

Install Dependencies

HelloWorldCsharp.csproj

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net9.0</TargetFramework>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="OpenTelemetry" Version="1.15.0" />
    <PackageReference Include="OpenTelemetry.Exporter.OpenTelemetryProtocol" Version="1.15.0" />
    <PackageReference Include="OpenTelemetry.Extensions.Hosting" Version="1.15.0" />
  </ItemGroup>
</Project>

dotnet restore

The Code

Program.cs

void SayHello()
{
    using var activity = activitySource.StartActivity("say-hello");
    activity?.SetTag("greeting", "Hello, World!");
    logger.LogInformation("Hello, World!");
    helloCounter.Add(1);
}

The full example also includes CheckDiskSpace (warning) and ParseConfig (error with exception). View full source on GitHub →

Run It

OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318 dotnet run

Rust

Install Dependencies

Cargo.toml

[package]
name = "hello-world-rust"
version = "0.1.0"
edition = "2021"

[dependencies]
opentelemetry = "0.31.0"
opentelemetry_sdk = { version = "0.31.0", features = ["rt-tokio", "logs", "metrics"] }
opentelemetry-otlp = { version = "0.31.0", features = ["http-proto", "trace", "logs", "metrics"] }
opentelemetry-appender-tracing = "0.31.0"
tokio = { version = "1", features = ["full"] }
tracing = "0.1"
tracing-subscriber = { version = "0.3", features = ["env-filter"] }

cargo build

The Code

src/main.rs

fn say_hello(counter: &opentelemetry::metrics::Counter<u64>) {
    let tracer = global::tracer("hello-world-rust");
    tracer.in_span("say-hello", |cx| {
        let span = cx.span();
        span.set_attribute(KeyValue::new("greeting", "Hello, World!"));
        tracing::info!("Hello, World!");
        counter.add(1, &[]);
    });
}

The full example also includes check_disk_space (warning) and parse_config (error with exception). View full source on GitHub →

Run It

OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318 cargo run

PHP

Install Dependencies

composer.json

{
  "require": {
    "php": ">=8.1",
    "open-telemetry/api": "^1.8",
    "open-telemetry/sdk": "^1.13",
    "open-telemetry/exporter-otlp": "^1.4",
    "php-http/guzzle7-adapter": "^1.1"
  }
}

composer install

The Code

main.php

function sayHello(TracerInterface $tracer, $logger, $counter): void {
    $span = $tracer->spanBuilder('say-hello')->startSpan();
    $scope = $span->activate();
    try {
        $logger->emit(
            (new \OpenTelemetry\API\Logs\LogRecord())
                ->setSeverityNumber(Severity::INFO)
                ->setSeverityText('INFO')
                ->setBody('Hello, World!')
        );
        $counter->add(1);
        $span->setAttribute('greeting', 'Hello, World!');
    } finally {
        $scope->detach();
        $span->end();
    }
}

The full example also includes checkDiskSpace (warning) and parseConfig (error with exception). View full source on GitHub →

Run It

OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318 php main.php

Ruby

Traces only

The Ruby OpenTelemetry logs SDK is not yet stable. This example sends traces only and uses span events as log equivalents.

Install Dependencies

Gemfile

source "https://rubygems.org"

gem "opentelemetry-api", "~> 1.8.0"
gem "opentelemetry-sdk", "~> 1.10.0"
gem "opentelemetry-exporter-otlp", "~> 0.32.0"

bundle install

The Code

main.rb

def say_hello(tracer)
  tracer.in_span("say-hello") do |span|
    span.set_attribute("greeting", "Hello, World!")
    span.add_event("greeting.sent", attributes: { "message" => "Hello, World!" })
  end
end

The full example also includes check_disk_space (warning event) and parse_config (error with exception). View full source on GitHub →

Run It

OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318 ruby main.rb

Elixir

Traces only

The Elixir OpenTelemetry logs SDK is not yet stable. This example sends traces only and uses span events as log equivalents.

Install Dependencies

mix.exs (deps)

defp deps do
  [
    {:opentelemetry_api, "~> 1.5"},
    {:opentelemetry, "~> 1.7"},
    {:opentelemetry_exporter, "~> 1.10"}
  ]
end

mix deps.get

The Code

lib/hello_world.ex

def say_hello do
  Tracer.with_span "say-hello" do
    Tracer.set_attribute(:greeting, "Hello, World!")
    Tracer.add_event("greeting.sent", %{message: "Hello, World!"})
  end
end

The full example also includes check_disk_space (warning event) and parse_config (error with exception). View full source on GitHub →

Run It

OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318 mix run run.exs

Verify in Scout

1. Open TraceX and search for the service name (e.g. hello-world-nodejs).
2. Click the trace to see three spans: say-hello, check-disk-space, and parse-config.
3. Open LogX - logs from say-hello and the other spans carry the same trace ID, so you can jump between the trace and its logs.
4. Check Metrics for the hello.count counter.

What Each Span Demonstrates

Span	Signals	What it shows
say-hello	trace + log + metric	Normal operation with an INFO log and counter
check-disk-space	trace + log (or event)	Degraded state with a WARN log
parse-config	trace + log (or event)	Error path with exception recording and ERROR status

What's Next

• Auto-instrumentation guides - add tracing to your real app with zero code changes
• Custom instrumentation - add manual spans, metrics, and logs where auto-instrumentation doesn't reach
• Create Your First Dashboard - visualize the metrics you're collecting
• 5-Minute Quick Start - set up the collector if you haven't already