NestJS Microservices Application

A microservices-based application using NestJS that demonstrates user management with event-driven notifications. The application consists of two services: a User Service for managing user data and a Notification Service for handling user-related notifications.

Architecture

• User Service: RESTful API handling CRUD operations for users
• Notification Service: Event-driven service for sending notifications
• Message Broker: Redis for inter-service communication
• Error Handling: Comprehensive error handling with custom exceptions
• Testing: Unit tests for critical components

Prerequisites

• Node.js (v16 or later)
• npm (v8 or later)
• Docker and Docker Compose (for Redis)

Installation

1. Install dependencies for both services:

# Install User Service dependencies
cd user-service
npm install

# Install Notification Service dependencies
cd ../notification-service
npm install

2. Install global dependencies:

npm install -g @nestjs/cli

Configuration

The application uses Redis as a message broker. The default configuration assumes Redis is running on localhost:6379. You can modify the connection settings in:

• user-service/src/users/users.module.ts
• notification-service/src/main.ts

Running the Application

1. Start Redis using Docker:

docker-compose up -d

2. Start the User Service (in a new terminal):

cd user-service
npm run start:dev

3. Start the Notification Service (in a new terminal):

cd notification-service
npm run start:dev

The services will be available at:

• User Service: http://localhost:3000
• Notification Service: Running as a microservice (no HTTP endpoint)

API Endpoints

User Service

• POST /users - Create a new user

  curl -X POST http://localhost:3000/users \
    -H "Content-Type: application/json" \
    -d '{"email": "test@example.com", "name": "Test User"}'

• GET /users - Get all users

  curl http://localhost:3000/users

• GET /users/:id - Get a specific user

  curl http://localhost:3000/users/:id

• PUT /users/:id - Update a user

  curl -X PUT http://localhost:3000/users/:id \
    -H "Content-Type: application/json" \
    -d '{"name": "Updated Name"}'

• DELETE /users/:id - Delete a user

  curl -X DELETE http://localhost:3000/users/:id

Running Tests

Both services include unit tests for critical components.

# Run User Service tests
cd user-service
npm run test

# Run Notification Service tests
cd notification-service
npm run test