nestjs-google-pubsub

Subscribe to Google Cloud PubSub topics using NestJS's EventMessage handlers.

Installation

# NPM
npm install nestjs-google-pubsub

# Yarn
yarn add nestjs-google-pubsub

Usage

The PubSubServer follows the same microservice convention used by other NestJS integrations:

import { NestFactory } from '@nestjs/core';
import { PubSubServer } from 'nestjs-google-pubsub';
import { AppModule } from './app.module';

async function bootstrap() {
  const app = await NestFactory.createMicroservice(AppModule, {
    strategy: new PubSubServer({
      projectId: 'my-gcp-project',
      // other PubSub client options
      topics: {
        'my-topic': {
          subscriptionId: 'my-subscription'
        }
      }
    })
  });
  app.listen(() => console.log('Microservice is listening'));
}
bootstrap();

Next, set up a handler somewhere in your app:

import { Message } from '@google-cloud/pubsub';
import { Controller } from '@nestjs/common';
import { EventPattern } from '@nestjs/microservices';

@Controller()
export class MyController {
  @EventPattern('my-topic')
  async handleMyTopicEvent(data: Message) {
    // business logic
  }
}

Configuration

The PubSubServer constructor takes in an options object that supports all of the same fields that the PubSub client supports. For more information on these options, visit the PubSub documentation.

The only required option in the configuration is a map of topic IDs to subscription IDs. To be consistent with how other message queue systems work, the topic ID is specified in the EventPattern decorator. For PubSub, we also need the subscription ID. This can be specified in the topics field of the configuration object.

const app = await NestFactory.createMicroservice(AppModule, {
  strategy: new PubSubServer({
    topics: {
      'my-topic': {
        subscriptionId: 'my-subscription'
      }
    }
  })
});