This module is a custom strategy for NestJS microservice library. It allows you to use RabbitMQ as a transport for microservice messages. Learn about NestJS here.

To generate your microservice, just use @nestjs/cli:

nest new my-microservice

Then install nestjs-rmq:

npm i nestjs-rmq

Each one of your services can be a server and/or a client. To start server, change bootstrap() function in main.ts

import { ServerRMQ } from 'nestjs-rmq';

//...

async function bootstrap() {
  const app = await NestFactory.createMicroservice(AppModule, {
    strategy: new ServerRMQ({
      urls: [`amqp://login:password@host`],
      queue: 'test',
      queueOptions: { durable: false }
    })
  });
  app.listen(() => console.log('Server is listening'));
}

Options are: urls (string[]) - Connection urls to one or more RabbitMQ instance. Each url contains user, password and host. queue (string) - Name of queue, your server will lusten to. prefetchCount | number | Number of prefetched messages. You can read more here. isGlobalPrefetchCount (boolean) - You can read more here. queueOptions (object) - Additional queue options. You can read more here.

After initializing server you can use @MessagePattern in controllers as described in NestJS docs.

@MessagePattern({ cmd: 'test' })
test(data: string): string {
    console.log('Server got: ' + data);
    return 'test' + data;
}

As for the clients, they have the same options:

import { ClientRMQ } from 'nestjs-rmq';

//...

client = new ClientRMQ({
    urls: [`amqp://login:password@host`],
    queue: 'test',
    queueOptions: { durable: false }
});

To send a message simply use send() function, which returns an Observable:

@Get('a')
a(): Observable<string> {
    let msg = 'test ' + Math.random();
    console.log('Client sent: ' + msg);
    return this.client.send<string, string>({ cmd: 'test' }, msg);
}

You need to use urls option instead of url and pass string[] instead of string for cluster support.