RabbitMQ: events are being consumed before application is ready on Nest 8

Hey all, I’m running into an issue where RabbitMQ consumers start up and consume events before the main Nest application is completely initialized. This started happening after we migrated from Nest 7 to Nest 8. I’ve resolved the issue in my application by moving the RabbitMQ module to the very end of the application module imports list:

// consumers start before application initialized
@Module({
  imports: [
    RabbitMQModule,
    ...ModulesThatDependOnRabbitMQ
  ]
})

// consumers start after application initialized 
@Module({
  imports: [
    ...ModulesThatDependOnRabbitMQ,
    RabbitMQModule
  ]
})

Package versions:

@nestjs/core@8.2.6
@nestjs/common@8.2.6
@golevelup/nestjs-rabbitmq@1.18.1

Is anybody else seeing this behaviour?

[WonderPanda]

I think it should probably be fine for us to move all the logic from onModuleInit to onApplicationBootstrap like you suggested.

@ckfngod I don’t think the order of the imports actually matters in your case, its more likely that its just a lucky thing with the timing that you happen to see a difference when you reorder the array

[ckfngod]

@underfisk @WonderPanda Thanks for the responses. Yeah it looks like it’s definitely lucky timing, wasn’t able to get it to work in my sample app. I’m seeing issues specifically with this in combination with a GRPC microservice. Rabbit consumers will begin processing events before the GRPC service is ready so as the application starts up it will throw a bunch of errors but afterwards it works fine.

Sample app is here: https://github.com/ckfngod/rabbitmq-app-init-issue

Start up the app to assert the queue, stop the app, publish a couple events to the queue then start the app again and you should see the issue.