Younus Foysal

In modern web development, microservices have gained immense popularity due to their scalability, flexibility, and maintainability. NestJS, a progressive Node.js framework, provides excellent support for building microservices efficiently. In this blog, we will explore how to use NestJS to build and manage microservices effectively.

Why NestJS for Microservices?

• Built-in support for microservices via different transport layers like TCP, Redis, Kafka, and NATS.
• Dependency Injection for better service management.
• Scalability with modular architecture.
• Powerful decorators and metadata reflection for seamless development.

Setting Up a NestJS Microservices Architecture

1. Install NestJS CLI

npm install -g @nestjs/cli

2. Create a New Microservice

nest new microservice-app cd microservice-app nest g app user-service

3. Implement a Microservice

import { NestFactory } from '@nestjs/core';
import { MicroserviceOptions, Transport } from '@nestjs/microservices';
import { UserModule } from './user.module';

async function bootstrap() {
  const app = await NestFactory.createMicroservice<MicroserviceOptions>(UserModule, {
    transport: Transport.TCP,
    options: { port: 3001 },
  });

  await app.listen();
  console.log('User microservice is running on port 3001');
}

bootstrap();

4. Create a Service to Handle Requests

import { Injectable } from '@nestjs/common';
import { MessagePattern } from '@nestjs/microservices';

@Injectable()
export class UserService {
  private users = [{ id: 1, name: 'John Doe' }];

  @MessagePattern({ cmd: 'get_users' })
  getUsers() {
    return this.users;
  }
}

5. Create a Client Gateway

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
import { ClientProxyFactory, Transport } from '@nestjs/microservices';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);

  const client = ClientProxyFactory.create({
    transport: Transport.TCP,
    options: { host: 'localhost', port: 3001 },
  });

  await app.startAllMicroservices();
  await app.listen(3000);
  console.log('Main application is running on port 3000');

  const users = await client.send({ cmd: 'get_users' }, {}).toPromise();
  console.log(users);
}

bootstrap();

Scaling with Different Transport Strategies

• TCP (default and simple to use)
• Redis (for event-driven communication)
• Kafka (for high-performance streaming)
• NATS (lightweight and cloud-native messaging)
• RabbitMQ (message queuing for asynchronous tasks)

NestJS makes building microservices efficient and scalable with its built-in support for various transport mechanisms and modular architecture. Whether you are handling inter-service communication via TCP, Redis, or Kafka, NestJS provides a robust foundation for developing microservices in Node.js.

🚀 Start building your microservices with NestJS today!