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: