@algoan/nestjs-google-pubsub-microservice

A Nest Google PubSub Microservice.

NestJS Google Cloud PubSub Micro-service

A custom NestJS Microservice transport strategy using Google Cloud PubSub.

Installation

npm install --save @algoan/pubsub @algoan/nestjs-google-pubsub-microservice

Usage

To start a new Google Cloud PubSub server:

Server setup:

// main.ts
import { GooglePubSubOptions } from '@algoan/pubsub';
import { INestMicroservice } from '@nestjs/common';
import { NestFactory } from '@nestjs/core';
import { GCPubSubServer } from '@algoan/nestjs-google-pubsub-microservice';
import { AppModule } from './app.module';

async function bootstrap() {
  const options: GooglePubSubOptions = {
    projectId: 'test',
    subscriptionsPrefix: 'test-app',
  }

  const app: INestMicroservice = await NestFactory.createMicroservice(AppModule, {
    strategy: new GCPubSubServer(options)
  })

  await app.listen();

  console.log('Server running!')
}
bootstrap()

Controller:

import { EmittedMessage } from '@algoan/pubsub';
import { Controller } from '@nestjs/common';
import { EventPattern, Payload } from '@nestjs/microservices';
import { AppService } from './app.service';

@Controller()
export class AppController {
  constructor(private readonly appService: AppService) {}

  /**
   * Handle the test event
   * @param data Payload sent
   */
  @EventPattern('test_event')
  public async handleTestEvent(@Payload() data: EmittedMessage<{ hello: string }>): Promise<void> {
    /**
     * Handle data emitted by Google PubSub
     */
    this.appService.handleTestEvent(data);
  }
}

EventPattern extras

You can add ListenOptions to the subscription by adding extras to the EventPattern decorator. For example, if you want a different topic name:

/**
  * Handle the test event
  * @param data Payload sent
  */
@EventPattern('test_event', { topicName: 'different_topic' })
public async handleTestEvent(@Payload() data: EmittedMessage<{ hello: string }>): Promise<void> {
  /**
    * Handle data emitted by Google PubSub
    */
  this.appService.handleTestEvent(data);
}

When the application will start and look for event patterns, it will get or create the different_topic topic from Google Cloud.

API

This module uses @algoan/pubsub library which by default automatically acknowledges emitted messages.

GCPubSubServer(options)

Create a new Server instance of Google PubSub. It retrieves all message handlers patterns and creates subscriptions.

• options: Algoan PubSub options. More information here.
• options.listenOptions: Global options which will be applied to all subscriptions.
• options.topicsNames: Only subscribe to topics included in this whitelist.

Other NestJS Google Cloud PubSub server

Other modules implementing Google Cloud PubSub with NestJS microservices:

• crallen/nestjs-google-pubsub
• ecobee/nodejs-gcloud-pubsub-module