Node.js CRUD API

A simple REST API implementation using pure Node.js and TypeScript with horizontal scaling capabilities.

Prerequisites

• Node.js (v18 or higher)
• npm (Node Package Manager)

Installation

1. Clone the repository:

git clone <repository-url>
cd crud-api

2. Install dependencies:

npm install

3. Create a .env file in the root directory:

PORT=4000

Running the Application

There are three modes to run the application:

Development Mode (with auto-reload)

npm run start:dev

Production Mode (optimized build)

npm run start:prod

Multi-Instance Mode (with load balancer)

npm run start:multi

This mode starts multiple instances:

• Load balancer on PORT (default: 4000)
• Worker instances on PORT+1, PORT+2, etc.
• Automatically scales based on CPU cores

API Endpoints

Users

GET /api/users

• Returns all users
• Response: 200 OK

[
    {
        "id": "uuid",
        "username": "string",
        "age": "number",
        "hobbies": ["string"]
    }
]

GET /api/users/{userId}

• Returns user by id
• Response: 200 OK

{
    "id": "uuid",
    "username": "string",
    "age": "number",
    "hobbies": ["string"]
}

POST /api/users

• Creates a new user
• Request body:

{
    "username": "string",
    "age": "number",
    "hobbies": ["string"]
}

• Response: 201 Created

PUT /api/users/{userId}

• Updates existing user
• Request body (at least one field required):

{
    "username": "string",
    "age": "number",
    "hobbies": ["string"]
}

• Response: 200 OK

DELETE /api/users/{userId}

• Removes user
• Response: 204 No Content

Error Responses

• 400 Bad Request: Invalid user data or UUID
• 404 Not Found: Route not found
• 500 Internal Server Error: Server error

Response Headers

All responses have content type: application/json

Project Structure

crud-api/
├── src/
│   ├── data/
│   │   └── users.ts
│   ├── cluster.ts
│   ├── loadBalancer.ts
│   ├── store.ts
│   ├── server.ts
│   ├── utils.ts
│   ├── crud.ts
│   └── index.ts
├── __tests__/
│   └── crud.test.ts
├── package.json
├── tsconfig.json
├── webpack.config.js
└── .env

Technologies Used

• Node.js
• TypeScript
• UUID for generating unique identifiers
• dotenv for environment variables
• Jest for testing
• webpack for production builds

Testing

Run the test suite:

npm test

The tests cover:

• Basic CRUD operations
• Error handling
• Invalid input scenarios
• Data consistency

Load Balancing

In multi-instance mode, the application uses a Round-robin algorithm to distribute requests across worker instances. State is synchronized across all instances using Node.js IPC mechanisms.