Using BullMQ in NestJS Project

Introduction

This document covers how to integrate BullMQ into a NestJS project to manage queues. BullMQ is a robust library built on top of Redis, providing reliable job processing capabilties.

Prerequisites

• Node.js and npm installed
• NestJS CLI installed( npm install -g @nestjs/cli)
• Redis server running

NOTE:- Ensure you are using Node.js version 18 for compatibility.

Step 1: Set Up Your NestJS Project

1. Create a new Project

 nest new ${project_name}

2. Navigate to the project

cd project_name  // navigate to existing project or newly created project.

Step 2: Install Required Packages

1. Install BullMQ and Redis packages

  npm install @nestjs/bullmq @nestjs/bull bullmq bull ioredis

Step 3: Configure BullMQ

1. Configure the BullModule in AppModule:

// app.module.ts
import { Module } from '@nestjs/common';
import { BullModule } from '@nestjs/bullmq';
@Module({
 imports: [
   BullModule.forRoot({
     connection: {
       host: 'localhost',// or pass your own redis host
       port: 6379, // or pass your own redis port
     },
   }),
   BullQueueModule
 ],
   controllers: [],// Add your controller if any
 providers: []// Add your service,
 })
 export class AppModule{}

Step 4: Create a BullMQ Queue Module

1. Generate a new module, service and controller for BullMQ implementation

 nest g module bull-queue
 nest g service bull-queue
 nest g controller bull-queue

2. Set up the queue in the module:

  // bull-queue.module.ts
  import {Module} from '@nestjs/common'
  import {BullModule} from '@nestjs/bullmq'
  import {BullQueueService} from './bull-queue.service';
  import { BullQueueController } from './bull-queue.controller';


  @Module({
   import:[
   BullModule.registerQueue({
     name:'mail-queue'
   })],
   providers:[BullQueueService],
   exports:[BullQueueService],
   controllers:[BullQueueController]
  })
  export class BullQueueModule {}

3. Implement the queue service:

 //bull-queue.service.ts
 import {Injectable} from '@nestjs/common';
 import {InjectQueue} from '@nestjs/bull';
 import {Queue} from 'bullmq'

 @Injectable()
 export class BullQueueService{
   constructor(@InjectQueue('mail-queue') private readonly myQueue: Queue){}
   async addJobsInBulk(jobs: { serverName: string, to: string; subject: string; message: any }[])
   const bulkJobs= jobs.map(job=>({
     name:"sendMail", // name of the job
     data:{
       serverName:job.serverName,
       to:job.to,
       subject: job.subject,
       message:job.message
     }
   }))
   await this.myQueue.addBulk(bulkJobs)// addBulk is used to push list of jobs at a time in queue
 }

Note use await this.myQueue.add('job-name', data) to add single job to the queue.

4. Implement the controller to handle job creation:

  import { Controller, Post, Body } from '@nestjs/common';
  import { BullQueueService } from './bull-queue.service';
  @controller('bull-queue')
  export class BullQueueController{
   constructor(private readonly bullQueueService:BullQueueService){}
   @Post('add-job')
   async addJob(@Body() data: { serverName: string; to: string; subject: string; message: any }[],){
     await this.bullQueueService.addJobsInBulk(data);
     return {message:'JOb added to the queue successfully'}
   }
  }

Step 6: Running the Application:

1. Start the NestJS application:

  npm run start

2. Test the Queue by Sending a POST Request: Use a tool like postman and send a request to http://localhost:3000/bull-queue/add-job

[
  {
 "serverName":"XYZ", "to":"xyz@gmail.com","subject":"testing mail server","message":"<h1>Hi</h1>"
},]