# OpenTelemetry for Node.js

The Baselime Node.js OpenTelemetry SDK enables you to instrument your Node.js services with OpenTelemetry without the boilerplate of using the OpenTelemetry SDK directly.

This SDK uses OpenTelemetry for JavaScript and provides a layer that facilitates instrumenting your Node.js applications.

If your application is already instrumented with OpenTelemetry, you can start sending your tracing data to Baselime without any additional code changes.

Add the Baselime OpenTelemetry endpoint to your exporter:

Endpoint https://otel.baselime.io/v1/
Header: x-api-key: <BASELIME_API_KEY>

# Instrumentation

# Step 1: Install the SDKs

Install the Baselime Node.js OpenTelemetry SDK.

 terminal
npm i --save \
  @baselime/node-opentelemetry \
  @opentelemetry/auto-instrumentations-node

# Step 2: Initialise the tracer

Create a tracing.cjs file inside your application working directory.

 src/tracing.cjs
const { BaselimeSDK } = require('@baselime/node-opentelemetry');
const { getNodeAutoInstrumentations } = require('@opentelemetry/auto-instrumentations-node');


const sdk = new BaselimeSDK({
  instrumentations: [
    getNodeAutoInstrumentations(),
  ],
});

sdk.start();

# Step 3: Set the Baselime environment variables

Set the environment variables of your comntainer service to include the Baselime API Key and set the NODE_OPTIONS enviroment variable to preload the OpenTelemetry SDK into your application.

Key	Value	Description
BASELIME_KEY	`your-api-key`	Get this key from the Baselime console or the Baselime CLI running `baselime iam`
NODE_OPTIONS	`-r ./src/tracing.cjs --experimental-loader=import-in-the-middle/hook.mjs`	Preloads the OpenTelemetry SDK at startup

Once these steps are completed, distributed traces from your Node.js container applications should be available in Baselime to query via the console or the Baselime CLI.

# Configuration

The BaselimeSDK class of the Baselime Node.js OpenTelemetry SDK takes the following configuration options.

Field	Type	Description
`instrumentations`	InstrumentationOption[]	An array of instrumentation options.
`baselimeKey`	string (optional)	The Baselime API key.
`collectorUrl`	string (optional)	The URL of the collector.
`service`	string (optional)	The service name.
`namespace`	string (optional)	The namespace.