OTel For Node.js

6min
In this guide, we will walk you through the process of setting up and using OpenTelemetry in Node.js. You will learn how to instrument a simple application to produce traces, metrics, and logs.
Step 1: Prerequisites
Before diving into OpenTelemetry, be sure that you have the following installed:
﻿Node.js﻿
﻿TypeScript, if you are going to use TypeScript
Step 2: Example Application
For this tutorial, we will be using a basic Express application. However, OpenTelemetry JavaScript is compatible with other web frameworks like Koa and Nest.JS as well. Feel free to adapt the instructions to your preferred framework.

Step 3: Installation
Set up an empty package.json in a new directory:
Text
npm init -y
npm init -y
﻿
2. Install Express dependencies
JS
TypeScript
npm install express

npm install express
﻿
3. Create and launch an HTTP Server by creating a file named app.js (app.ts, if you are using TypeScript) and adding the following code to it:
JS
TypeScript
/*app.js*/
const express = require('express');

const PORT = parseInt(process.env.PORT || '8080');
const app = express();

function getRandomNumber(min, max) {
  return Math.floor(Math.random() * (max - min) + min);
}

app.get('/rolldice', (req, res) => {
  res.send(getRandomNumber(1, 6).toString());
});

app.listen(PORT, () => {
  console.log(`Listening for requests on http://localhost:${PORT}`);
});
/*app.js*/
const express = require('express');

const PORT = parseInt(process.env.PORT || '8080');
const app = express();

function getRandomNumber(min, max) {
  return Math.floor(Math.random() * (max - min) + min);
}

app.get('/rolldice', (req, res) => {
  res.send(getRandomNumber(1, 6).toString());
});

app.listen(PORT, () => {
  console.log(`Listening for requests on http://localhost:${PORT}`);
});
﻿
4. Run the application using the following command then open http://localhost:8080/rolldice in your web browser:
JS
TypeScript
$ npx ts-node app.ts
Listening for requests on http://localhost:8080

$ npx ts-node app.ts
Listening for requests on http://localhost:8080
﻿
Step 4: Instrumentation
To install the instrumentation packages, we will use the auto-instrumentations-node package. It automatically creates spans corresponding to code called in libraries.

1. Use the following command to install the Node SDK auto-instrumentaion andexporter packages.
Text
npm install @opentelemetry/sdk-node \
  @opentelemetry/api \
  @opentelemetry/auto-instrumentations-node \
  @opentelemetry/sdk-metrics \
  @opentelemetry/exporter-trace-otlp-http \
  @opentelemetry/exporter-metrics-otlp-http
npm install @opentelemetry/sdk-node \
  @opentelemetry/api \
  @opentelemetry/auto-instrumentations-node \
  @opentelemetry/sdk-metrics \
  @opentelemetry/exporter-trace-otlp-http \
  @opentelemetry/exporter-metrics-otlp-http
﻿
2. The instrumentation setup and configuration are required to run before the application code. We will use the --require flag for this task.
﻿
3. Create a file named instrumentation.js (instrumentation.ts if you are using TypeScript) and add the following setup code to it:﻿
JS
TypeScript
/*instrumentation.js*/
const { NodeSDK } = require('@opentelemetry/sdk-node');
const {
  getNodeAutoInstrumentations,
} = require('@opentelemetry/auto-instrumentations-node');
const { PeriodicExportingMetricReader } = require('@opentelemetry/sdk-metrics');
const {
  OTLPMetricExporter,
} = require('@opentelemetry/exporter-metrics-otlp-http');
const {
  OTLPTraceExporter,
} = require('@opentelemetry/exporter-trace-otlp-http');

const sdk = new NodeSDK({
  traceExporter: new OTLPTraceExporter({
    url: `https://otel.kloudmate.com:4318/v1/traces`,
    headers: {
      Authorization: '<YOUR_SECRET)KEY>',
    },
  }),
  metricReader: new PeriodicExportingMetricReader({
    exporter: new OTLPMetricExporter({
      url: `https://otel.kloudmate.com:4318/v1/metrics`,
      headers: {
        Authorization: '<YOUR_SECRET_KEY>',
      },
    }),
  }),
  instrumentations: [getNodeAutoInstrumentations()],
});

sdk.start();

/*instrumentation.js*/
const { NodeSDK } = require('@opentelemetry/sdk-node');
const {
  getNodeAutoInstrumentations,
} = require('@opentelemetry/auto-instrumentations-node');
const { PeriodicExportingMetricReader } = require('@opentelemetry/sdk-metrics');
const {
  OTLPMetricExporter,
} = require('@opentelemetry/exporter-metrics-otlp-http');
const {
  OTLPTraceExporter,
} = require('@opentelemetry/exporter-trace-otlp-http');

const sdk = new NodeSDK({
  traceExporter: new OTLPTraceExporter({
    url: `https://otel.kloudmate.com:4318/v1/traces`,
    headers: {
      Authorization: '<YOUR_SECRET)KEY>',
    },
  }),
  metricReader: new PeriodicExportingMetricReader({
    exporter: new OTLPMetricExporter({
      url: `https://otel.kloudmate.com:4318/v1/metrics`,
      headers: {
        Authorization: '<YOUR_SECRET_KEY>',
      },
    }),
  }),
  instrumentations: [getNodeAutoInstrumentations()],
});

sdk.start();
﻿
 The exporter URL mentioned above, along with the KloudMate API-Key as the Authorization header will send the data to KloudMate.
Step 5: Run the Instrumented App
1. Run the instrumented application and use the --require flag to load the instrumentation before the application code.
JS
TypeScript
$ npx ts-node --require ./instrumentation.ts app.ts
Listening for requests on http://localhost:8080
$ npx ts-node --require ./instrumentation.ts app.ts
Listening for requests on http://localhost:8080
﻿
2. Open http://localhost:8080/rolldice in your web browser. You should see spans on the Traces page in your KloudMate account.
﻿
﻿
﻿
Source URL for the example application: https://opentelemetry.io/docs/instrumentation/js/getting-started/nodejs/
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