How to build scalable microservices with NestJS and RabbitMQ: Step-by-step guide

Developing backend applications that are scalable, performant, and easy to maintain is a constant challenge. An architecture based on microservices, combined with NestJS and RabbitMQ, is a powerful solution to face this challenge.

In this guide, we will explore how to build microservices with NestJS and use RabbitMQ for asynchronous communication between services, thus achieving greater performance and resilience.

What are microservices?

Microservices are a way to structure applications as a set of small, independent services focused on a single responsibility. This approach brings several advantages:

• Independent scalability
• Easier maintainability
• Greater resilience in failures
• More flexible deployments

Why NestJS?

NestJS is a Node.js framework for building scalable applications with enterprise architecture. It combines concepts of object-oriented, functional, and reactive programming.

Advantages of NestJS for microservices:

• Modular architecture based on decorators
• Native support for asynchronous messages (via RabbitMQ, Kafka, etc.)
• Integration with TypeScript by default
• Dependency injection support

RabbitMQ: asynchronous messaging between services

RabbitMQ is an open-source message broker that allows asynchronous communication between decoupled systems, using the Publisher/Subscriber pattern.

Why use RabbitMQ?

• Decoupling between services
• Fault tolerance
• Asynchronous processing
• Queue management and delivery confirmations

Basic structure of a microservice with NestJS

The structure of a NestJS project with microservices follows a modular logic. Here is a simplified view of how to organize your project:

src/
├── app.module.ts
├── main.ts
├── user/
│   ├── user.module.ts
│   ├── user.service.ts
│   └── user.controller.ts
└── orders/
    ├── orders.module.ts
    ├── orders.service.ts
    └── orders.controller.ts

Connecting with RabbitMQ

You can configure a NestJS microservice to listen to messages via RabbitMQ with just a few lines:

// main.ts
async function bootstrap() {
  const app = await NestFactory.createMicroservice(AppModule, {
    transport: Transport.RMQ,
    options: {
      urls: ['amqp://localhost:5672'],
      queue: 'user_queue',
      queueOptions: { durable: false },
    },
  })
  await app.listen()
}
bootstrap()

And to send messages from another service:

@Injectable()
export class OrdersService {
  constructor(@Inject('USER_SERVICE') private client: ClientProxy) {}

  async notifyUser(data: any) {
    return this.client.emit('user_created', data)
  }
}

Comparison table: REST vs RabbitMQ for microservices

Aspect	REST	RabbitMQ
Communication	Synchronous	Asynchronous
Resilience	Low in failures	High (queue persists data)
Coupling	Higher	Lower

Practical use cases

• Order systems in e-commerce
• Payment processing
• Email or SMS notifications
• Scheduling and task queues

Best practices

• Create well-defined message contracts
• Keep services decoupled
• Use observability tools (like Prometheus + Grafana)
• Perform isolated tests on each microservice

Conclusion

Building scalable microservices with NestJS and RabbitMQ is a modern and efficient strategy for backend systems that need performance, resilience, and modularity.

Furthermore, the adoption of these tools reduces coupling and improves failure management - essential aspects in distributed applications and continuous growth.

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