Building a Simple Nest.js Application using Redis

Nest.js is a JavaScript framework used for building efficient, scalable, and static server-side applications. Nest.js is built on top of React for better rendering and abstraction. This enables you to build powerful React applications.

Nest.js allows you to build React applications that support server-side rendering. Traditionally with React, you can only render on the client-side which impacts SEO negatively.

With server-side rendering, pages are rendered during the build-up phase. The content is then served ahead of time to the user or search engine bots.

Goal

This tutorial will show you how to build a Nest.js microservice application that uses Redis as a message transporter.

An overview of a microservice

A microservice is an architectural design that allows one to create small modules/components of an application that can scale on demand. Each component is packaged independently and can communicate and interact with each other through APIs.

Nest.js comes with in-built support for microservice architecture and multiple transport layers. These transport layers are in charge of transferring messages between microservice instances.

We can use Redis as a transport layer protocol for end-to-end connectivity. Redis allows flow control and segmentation between different microservices. As a result, each microservice can connect to different channels, and every channel can have various microservices connected to it.

Let’s now build a Nest.js microservice application using Redis as the transporter.

Prerequisites

• We are going to bundle Nest.js CLI using a Node.js package. Therefore, ensure that you have Node.js installed to have NPM on your computer. The Node.js installer can be downloaded from here.

• Nest.js is bundled and backed by Typescript. So a basic knowledge of Typescript is required.

• To implement a microservice architecture, we are going to use Redis as the transporter. So make sure Redis is installed on your computer.

Let’s get started.

Step 1: Setting the application environment

We will begin by installing the Nest.js CLI using the Node.js package manager.

The Nest CLI is a command-line GUI framework that aids you in configuring, creating, and maintaining your Nest.js applications. This helps with several activities including scaffolding a Nest.js project, serving it in a development context, as well as creating and packaging the production application.

The following command will help us install Nest CLI globally:

npm i -g @nestjs/cli

Now that we have Nest.js CLI ready, we can go ahead to create a Nest.js application template.

Here is a command to set that up:

nest new nest-ms

We need to turn our newly created project into a monorepo. A monorepo refers to a single repository hosting different microservices.

Change directory to nest-ms.

To generate the monorepo in the app, we run the following command inside the nest-ms folder:

nest generate app new_app

After running the command above, you will observe that an apps folder will be created. This will scaffold our project and generate controllers, providers, and services for a Nest.js project.

Step 2: Adding microservices and Redis packages

Install the microservices and redis packages using the following NPM command:

npm install @nestjs/microservices redis

• @nestjs/microservices - It will allow you to set various configurations for our microservice.

• redis - It will help connect with redis currently installed locally.

Step 3: Adding transporter configurations

We will add the configuration for the transporter as follows:

First, navigate to the new_app that you generated with the nest generate app command.

Then go to apps/new-app/src/main.ts and replace the main.ts with the lines of code shown below:

import { NestFactory } from '@nestjs/core';
import { NewAppModule } from './new-app.module';
import { Transport } from '@nestjs/microservices';

async function bootstrap() {
  const app = await NestFactory.createMicroservice(NewAppModule, {
    transport: Transport.REDIS, //setting transporter
    options: {
      url: 'redis://localhost:6379',
    },
  });
  await app.listen();
}
bootstrap();

In the code above, we are creating a microservice and setting the transporter as Redis.

Step 4: Adding client service configurations

In the apps/nest-ms/src/app.service.ts file, add the following code:

import { Injectable } from '@nestjs/common';
import {
  Transport,
  ClientProxy,
  ClientProxyFactory,
} from '@nestjs/microservices';

@Injectable()
export class AppService {
  private client: ClientProxy;

  constructor() {
    this.client = ClientProxyFactory.create({
      transport: Transport.REDIS,
      options: {
        url: 'redis://localhost:6379',
      },
    });
  }
  getHello(): string {
    return 'Hello World!';
  }
}

In the code above, we are setting up the client with a Proxy Factory and using redis as the transporter.

Step 5: Running and testing the application

We use the following command to initiate the Redis server:

sudo systemctl start redis

We can start the application by executing the following command from the project’s root directory:

npm start

We then open another terminal and run the command below:

npm start new-app

In your browser, navigate to http://localhost:3000.

The content of the page should be nearly identical to the image below.

Conclusion

You now have a Nest.js microservice application that uses Redis as a transporter. You can utilize the knowledge and skills gained from this tutorial to craft other powerful applications.

Happy coding!!

Peer Review Contributions by: Mohan Raj