Todo App with OpenTelemetry Automatic Instrumentation

This Todo app demonstrates how to instrument a Node.js application using OpenTelemetry for tracing and sending telemetry data to an observability backend like Elastic APM.

Features

• Automatic instrumentation with OpenTelemetry
• CRUD operations for managing todos
• Traces sent to Elastic APM or other OTEL-compatible backends

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Prerequisites

1. Software Requirements

• Node.js: v14 or later
• NPM: v6 or later
• Elastic APM Server: Hosted on Elastic Cloud or self-hosted
• Elasticsearch and Kibana: For observing traces and spans

2. Environment Variables

Create a .env file in the root directory and include the following:

PORT=8081
indexName=todos
ELASTICSEARCH_ENDPOINT=https://<your-elasticsearch-url>
ELASTICSEARCH_API_KEY=<your-elasticsearch-api-key>
APM_SERVER_URL=https://<your-apm-server-url>
APM_API_KEY=<your-apm-api-key>

Replace <your-elasticsearch-url>, <your-elasticsearch-api-key>, <your-apm-server-url>, and <your-apm-api-key> with your Elastic Cloud or self-hosted APM details.

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Installation

1. Clone the Repository

   git clone https://github.com/justincastilla/Introduction-to-OpenTelemetry-with-JS
   cd Introduction-to-OpenTelemetry-with-JS

2. Install Dependencies

   npm install

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Usage

Start the Application with Automatic Instrumentation

Run the app using OpenTelemetry's Node.js instrumentation loader:

npm run telemetry

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Endpoints

CRUD Operations

Method	Endpoint	Description
GET	/	Returns the home page.
GET	/get_todos	Fetch all todos.
POST	/add_item	Add a new todo item.
DELETE	/delete/:id	Delete a todo by ID.

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Observability

OpenTelemetry Traces

• Traces are automatically collected for HTTP requests and interactions.
• Each trace is sent to the Elastic APM server configured in the .env file.

View Traces in Kibana

1. Open Kibana and navigate to Observability > APM.
2. Look for your service (todo-app) in the Services tab.
3. Explore traces, spans, and associated metrics.

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Resources

• OpenTelemetry Documentation
• Elastic APM Documentation

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