NodeJS GCloud Pub/Sub module


A Google Cloud Pub/Sub library for the NestJS framework. Easily subscribe or publish to topics in Google Pub/Sub.

Features

- Module for sending messages on topics
- Microservice to subscribe to topics in controllers

Todo

- Add Module for subscribing to topics
- Add Microservice client for sending messages on topics

Installation

Yarn

``bash
yarn add @ecobee/nodejs-gcloud-pubsub-module
`

NPM

`bash
npm install @ecobee/nodejs-gcloud-pubsub-module --save
`

Usage

Please refer to the interfaces file to understand parameter and object requirements.

$3

Publishing topics follows the classic NestJS pattern of importing a module and injecting a service via dependency injection

#### Module Setup

Import this module into your module

`ts
import { Module } from '@nestjs/common';
import { GcloudPubSubModule } from 'nodejs-gcloud-pubsub-module'
import * as path from 'path';

@Module({
imports: [
GcloudPubSubModule.forRoot(moduleOptions: GcloudPubSubModuleOptions),
],
})
export class AppModule {}
`

If you need to populate the moduleOptions with dynamic configuration data use the forRootAsync method. The following example pulls configuration objects using the nestjs-config module

`ts
import { Module } from '@nestjs/common'
import { GcloudPubSubModule } from 'nodejs-gcloud-pubsub-module'
import { ConfigService } from 'nestjs-config'
import * as path from 'path'

@Module({
imports: [
GcloudPubSubModule.forRootAsync({
useFactory: (config: ConfigService) => {
const authOptions = config.get('pubsub.authOptions')
const publishOptions = config.get('pubsub.publishOptions')
return {
authOptions / Authentication options /,
publishOptions / Message publishing options (Optional) /,
}
},
inject: [ConfigService],
}),
],
})
export class AppModule {}
`

#### Service

With the module imported you can now publish messages to topics

`ts
import { Injectable } from '@nestjs/common'
import { GcloudPubSubService } from 'nodejs-gcloud-pubsub-module'

const topic = 'projects/MyProjectId/topics/MyTopic'

@Injectable()
export class MyService {
constructor(private readonly gcloudPubSubService: GcloudPubSubService) {}

async publish(payload: PubSubMessage) {
const serializedPayload = JSON.stringify(payload)
return await this.gcloudPubSubService.publishMessage(topic, serializedPayload)
}
}
`

$3

To subscribe to pubsub message topics we leverage a custom NestJS Microservice. This has the benefit of allowing us to decorate our controllers as we would for standard HTTP requests.

Using a Microservice alongside HTTP can be accomplished by creating a Hybrid NestJS application. Refer to this example to see how this is accomplished.

#### Microservice setup

`ts
import { NestFactory } from '@nestjs/core'
import { GCloudPubSubServer } from 'nodejs-gcloud-pubsub-module'
import { ApplicationModule } from './app.module'

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

const GCloudPubSubServerOptions = {
authOptions: {/ Authentication options /}),
subscriptionIds: ['subscription-name'],
subscriberOptions: {/ https://googleapis.dev/nodejs/pubsub/latest/global.html#SubscriberOptions /}
}

app.connectMicroservice({
strategy: new GCloudPubSubServer(GCloudPubSubServerOptions),
})

await app.startAllMicroservicesAsync()
await app.listen(3001)
}
bootstrap()
`

#### Controller

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

@Controller('mycontroller')
export class EntitlementController {
@EventPattern('subscription-name')
async handleCreateEntitlement(message: Message) {
const { data } = message
const messageData = JSON.parse(data.toString())
// do stuff with the message
message.ack()
}
}
``