EventHandler pattern fails to subscribe to Redis channel

[RoxKilly]

Bug Report

Current behavior

• I successfully connect to Redis using client.connect()
• I successfully emit an event using client.emit()
• My controller handler decorated with @EventPattern does not get triggered

Input Code

Source code can be downloaded and run

main.ts

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

  await NestFactory.createMicroservice<RedisOptions>(AppModule, {
    transport: Transport.REDIS,
    options: { url: 'redis://localhost:6379' },
  });
  await app.listen(3000);
}
bootstrap();

AppModule

@Module({
  imports: [TransportModule],
  controllers: [AppController],
})
export class AppModule {}

AppController handler

  @EventPattern(EVENT_NAME) // <- EVENT_NAME is string constant 'EVENT_NAME'
  onEvent(data: any) {
    Logger.log('Event received'); // <- this is never executed
    Logger.log(data);
  }

TransportModule

export const EVENT_NAME = 'EVENT_NAME';
export const NEST_REDIS = Symbol('NEST_REDIS');

export const RedisProvider: Provider = {
  provide: NEST_REDIS,
  useFactory: () =>
    ClientProxyFactory.create({
      transport: Transport.REDIS,
      options: { url: 'redis://localhost:6379' },
    }),
};

@Module({ providers: [RedisProvider] })
export class TransportModule implements OnApplicationBootstrap {
  constructor(@Inject(NEST_REDIS) private client: ClientRedis) {}

  onApplicationBootstrap() {
    this.client.connect().then(() => {
      Logger.log('REDIS is connected');
      this.startEmitting();
    });
  }

  startEmitting() {
    let msgNumber = 0;

    // wait 3 secs, then start emitting every 8
    timer(3000, 8000)
      .pipe(
        tap(() => Logger.log(`Emitting message #${++msgNumber}`)),
        tap(() => this.client.emit(EVENT_NAME, { messageNumber: msgNumber })),
      )
      .subscribe();
  }
}

Application Log

redis-cli log

In the redis-cli log above, the 3rd line of response to my subscribe call is (integer) 1; this leads me to believe that NestJS is not subscribed to this channel at all (that the redis-cli is the 1 subscriber)

redis-server log

When the application starts up, the redis-server log shows two accepted connections on consecutive ports (I assume that's when I make the client.connect() call)

Expected behavior

I expected that when I use client.emit(EVENT_NAME), the controller handler decorated with @EventPattern(EVENT_NAME) would be executed with the event payload

Possible Solution

Environment

Nest version: 7.6.18
Redis 6.2.4
redis (NPM library) 3.1.2

 
For Tooling issues:
- Node version: 16.4.0 
- Platform:  Windows 10, but Redis is installed and running from the Windows subsystem for Linux
 
Other:
No error logged anywhere that I can find

Sorry for the long post. In case you missed it, the source files are available here.

[RoxKilly]

also posted on StackOverflow in case this is user error and not a bug

[RoxKilly]

Interestingly, if I try to take over the protected subClient within the ClientRedis instance of NestJS, I can subscribe to and receive those messages. Consider this code, which I've just inserted at the top of TransportModule.startEmitting from earlier:

  listen() {
    this.client['subClient'].subscribe(EVENT_NAME);
    this.client['subClient'].on('message', (channel, message) => {
      console.log(`subClient received; channel=${channel}, message=${message}`);
    });
  }

With this running, the controller handler still does not get triggered, but I can now see the messages come through in the logs:

[kamilmysliwiec]

Please, provide a minimum reproduction repository on Github.

[RoxKilly]

@kamilmysliwiec Sure. Here it is: https://github.com/RoxKilly/nestjs-redis-troubleshoot

[kamilmysliwiec]

Your minimum reproduction repository is invalid. In the main.ts file, you create the microservice instance:

await NestFactory.createMicroservice<RedisOptions>(AppModule, {
  transport: Transport.REDIS,
  options: { url: 'redis://localhost:6379' },
});

but since it's not assigned to any variable, it's automatically garbage collected (and the Redis "consumer" does not even bootstrap).

After making the following changes:

everything will start working as expected:

[RoxKilly]

Thank you @kamilmysliwiec I suspected as much. May I suggest that at least one of the examples on the Microservices section of the docs shows or links to this logAsync usage ? I read through that page, and also the Redis page several times over in the last 12hrs but the answer isn't there.

I appreciate your time, and I'm a big fan of your project.

[RoxKilly]

Hello. The solution offered above creates two full instances of the application (I have 2 AppModules and everything else). This led to some hard to debug errors.

In Kamil's solution, I changed this line::

const microservice =  await NestFactory.createMicroservice<RedisOptions>(AppModule, {
    transport: Transport.REDIS,
    options: { url: 'redis://localhost:6379' },
  });

To this:

const microservice = app.connectMicroservice({
    transport: Transport.REDIS,
    options: { url: 'redis://localhost:6379' },
  });

[RoxKilly]

The relevant section of the documentation:
https://docs.nestjs.com/faq/hybrid-application#hybrid-application

[kamilmysliwiec]

Yep, that was just an example. Using hybrid apps approach is totally fine