How to split Nest.js microservices into separate projects?

I got it working. Basically the way to do it is to create two separate projects. Let's say - one is a createMicroservice and another is just an HTTP app (but could easily be another microservice). I used a "normal" app just so I can call it easily for testing.

Here is the main.ts file that creates microservice.

import { NestFactory } from '@nestjs/core';import { AppModule } from './app.module';import { Transport } from '@nestjs/common/enums/transport.enum';async function bootstrap() {  const app = await NestFactory.createMicroservice(AppModule, {    transport: Transport.REDIS,    options: {      url: 'redis://localhost:6379',    },  });  await app.listen(() => console.log('MoviesService is running.'));}bootstrap();

And one of the controllers:

@Controller()export class AppController {  constructor(private readonly appService: AppService) {}  @MessagePattern({ cmd: 'LIST_MOVIES' })  listMovies(): string[] {    return ['Pulp Fiction', 'Blade Runner', 'Hatred'];  }}

Now - in the microservice you declare to what kinds of events should controllers react to (@MessagePattern). While in the "normal" service you do this in the controller when you want to ask other microservices for something (the main.ts is the simplest example that you get when you create a new project using @nestjs/cli.

The controller code:

@Controller()export class AppController {  private readonly client: ClientProxy;  constructor(private readonly appService: AppService) {    this.client = ClientProxyFactory.create({      transport: Transport.REDIS,      options: {        url: 'redis://localhost:6379',      },    });  }  @Get()  listMovies() {    const pattern = { cmd: 'LIST_MOVIES' };    return this.client.send<string[]>(pattern, []);  }}

So as long a client is connected to the same transport layer as the microservice - they can talk to each other by using the @MessagePattern.

For nicer code you can move the this.client part from a constructor to a provider and then use dependency injection by declaring the provider in the module.