Building Microservices with NestJS: Architecture and Best Practices

Microservices with NestJS

Build scalable, maintainable microservices using NestJS framework.

Project Setup

npm i -g @nestjs/cli
nest new user-service
cd user-service
npm install @nestjs/microservices

Creating a Microservice

// main.ts
import { NestFactory } from '@nestjs/core';
import { Transport, MicroserviceOptions } from '@nestjs/microservices';

async function bootstrap() {
    const app = await NestFactory.createMicroservice<MicroserviceOptions>(
        AppModule,
        {
            transport: Transport.RMQ,
            options: {
                urls: ['amqp://localhost:5672'],
                queue: 'users_queue',
            },
        },
    );
    await app.listen();
}
bootstrap();

Message Patterns

// users.controller.ts
@Controller()
export class UsersController {
    @MessagePattern({ cmd: 'get_user' })
    getUser(@Payload() data: { id: number }) {
        return this.usersService.findOne(data.id);
    }

    @EventPattern('user_created')
    handleUserCreated(@Payload() data: User) {
        this.analyticsService.trackUserCreation(data);
    }
}

API Gateway

// gateway/users.controller.ts
@Controller('users')
export class UsersController {
    constructor(
        @Inject('USER_SERVICE') private client: ClientProxy,
    ) {}

    @Get(':id')
    async getUser(@Param('id') id: number) {
        return this.client.send({ cmd: 'get_user' }, { id });
    }
}

Service Discovery with Consul

// Register service on startup
const consul = new Consul();
await consul.agent.service.register({
    name: 'user-service',
    address: 'localhost',
    port: 3001,
    check: { http: 'http://localhost:3001/health', interval: '10s' },
});

NestJS provides excellent patterns for building enterprise-grade microservices.