@dbc-tech/nest-dapr

Develop NestJs microservices using Dapr pubsub and bindings.

Description

Dapr Module for Nest built on top of the Dapr JS SDK.

Installation

npm i --save @dbc-tech/nest-dapr

Requirements

Install Dapr as per getting started guide. Ensure Dapr is running with

dapr --version

Output:

CLI version: 1.7.1
Runtime version: 1.7.4

Quick start

The following scaffolds a Nest project with the nest-dapr package and demonstrates using Nest with Dapr using RabbitMQ pubsub & queue bindings.

Install Nest CLI

npm install -g @nestjs/cli

Scaffold Nest project

nest new nest-dapr
cd nest-dapr/

Install nest-dapr package

npm i --save @dbc-tech/nest-dapr

Import DaprModule in AppModule class

@Module({
  imports: [DaprModule.register()],
  controllers: [AppController],
  providers: [AppService],
})
export class AppModule {}

Import DaprClient from @dapr/dapr package and add dependency to AppController class

import { DaprClient } from '@dapr/dapr';
import { Controller, Get } from '@nestjs/common';
import { AppService } from './app.service';

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

  @Get()
  getHello(): string {
    return this.appService.getHello();
  }
}

Create pubsub & topic names used for pubsub operations and message interface

const pubSubName = 'my-pubsub';
const topicName = 'my-topic';

interface Message {
  hello: string;
}

@Controller()

Create endpoint to publish topic message

@Post('pubsub')
async pubsub(): Promise<boolean> {
  const message: Message = { hello: 'world' };

  return this.daprClient.pubsub.publish(pubSubName, topicName, message);
}

Create pubsub handler which will subscribe to the topic and log the received message

@DaprPubSub(pubSubName, topicName)
pubSubHandler(message: Message): void {
  console.log(`Received topic:${topicName} message:`, message);
}

Create Dapr pubsub component in components folder

apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
  name: my-pubsub
  namespace: default
spec:
  type: pubsub.rabbitmq
  version: v1
  metadata:
  - name: host
    value: amqp://guest:guest@localhost:5674

Save file as components/rabbitmq-pubsub.yaml

Create docker-compose.yml in the project root used to run RabbitMQ

version: '3.9'
services:
  pubsub:
    image: rabbitmq:3-management-alpine
    ports:
      - 5674:5672
      - 15674:15672

Start RabbitMQ

docker-compose up

Create script to bootstrap your Nest project using Dapr sidecar. Update package.json and add script

"scripts": {
  ..
  "start:dapr": "dapr run --app-id nest-dapr --app-protocol http --app-port 50001 --dapr-http-port 50000 --components-path ./components npm run start"
},

Start Nest app with Dapr

npm run start:dapr

Invoke endpoint to publish the message

curl -X POST localhost:3000/pubsub

This should publish a message to RabbitMQ which should be consumed by the handler and written to the console:

== APP == Received topic:my-topic message: { hello: 'world' }

Full example

import { DaprClient } from '@dapr/dapr';
import { DaprPubSub } from '@dbc-tech/nest-dapr';
import { Controller, Get, Post } from '@nestjs/common';
import { AppService } from './app.service';

const pubSubName = 'my-pubsub';
const topicName = 'my-topic';

interface Message {
  hello: string;
}

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

  @Get()
  getHello(): string {
    return this.appService.getHello();
  }

  @Post('pubsub')
  async pubsub(): Promise<boolean> {
    const message: Message = { hello: 'world' };

    return this.daprClient.pubsub.publish(pubSubName, topicName, message);
  }

  @DaprPubSub(pubSubName, topicName)
  pubSubHandler(message: Message): void {
    console.log(`Received topic:${topicName} message:`, message);
  }
}