Introduction: –

In the dynamic realm of web development, selecting the appropriate framework can significantly impact your project’s success. Nest JS stands out as a formidable contender, boasting a harmonious mix of adaptability, performance, and developer-centric features. In this blog post, we will delve into how NestJS, with its resilient ecosystem and user- friendly attributes, streamlines the incorporation of authentication and authorization mechanisms, ensuring the effective security of your applications.

What is Nest JS?

Nest.JS is a framework for building efficient and scalable server-side applications using modern JavaScript or TypeScript. Nest JS is made using Node.js, a popular platform for web development. It uses Node.js’ ability to handle many tasks at once, making it a strong and trustworthy choice for building web applications.

Nest features: –

let’s briefly go over the key features of Nest: modules, controllers, and services.

• Modules are crucial for organizing and structuring a Nest app. You need at least one root module to create an app. Each module can have controllers, services, and even include other modules.
• Nest employs the dependency injection pattern to connect modules with their dependencies. Making a class injectable involves using the @Injectable decorator. Subsequently, in a module or controller, Nest utilizes constructor-based dependency injection to provide the class.
• Controllers manage incoming HTTP requests, validate parameters, and send responses back to the client. It’s important to keep controllers clean and straightforward, and the next Nest feature helps achieve that.
• Services encapsulate the majority of business logic and app functionality in Nest projects. For any intricate logic, it’s recommended to use services. Essentially, services belong to a primary category of classes referred to as providers.
• A provider is essentially a class injected as a dependency. Other examples of providers that might be utilized include classes such as repositories, factories, helpers, and so on.

Getting Started With Nest js :-

When you’re prepared, let’s start a new Nest project. Initially, we’ll set up the Nest CLI.

npm install -g @nestjs/cli

Then, we will create a new project:

nest new my-api-project

once installation is completed, navigate to the project and start it:

cd nestjs-authetication
npm run start:dev

You can then launch the app in your browser by visiting http://localhost:3000/. You should see a nice “Hello World!” message.

The app will reload automatically after any changes you make. If you want to restart the app manually, use npm run start command instead.

Authentication and Authorization: –

Understanding Authentication and Authorization:

Before delving into implementation details, let’s clarify the concepts of authentication and authorization:

• Authentication: Authentication verifies the identity of a user, typically through credentials such as username/password or tokens. Once authenticated, users receive a unique identifier (e.g., session token, JWT) to access protected resources.
• Authorization: Authorization determines whether an authenticated user has the necessary permissions to perform certain actions or access specific resources within an application.

Implementing Authentication in Nest JS: –

Start by installing the required dependencies for JWT-based authentication:

npm install @nestjs/jwt passport passport-jwt

Configure JWT Module:

Configure the JWT module in your Nest JS application by providing a secret key and defining required options such as expiration time:

import { JwtModule } from '@nestjs/jwt';
import { JwtModule } from '@nestjs/jwt';
@Module({
imports: [
JwtModule.register({
secret: 'your_secret_key',
signOptions: { expiresIn: '1h' },
}),
],
})
export class AppModule {}
export class AppModule {}

Create Authentication Service:

Create an authentication service responsible for validating user credentials and generating JWT tokens:

@Injectable()
export class AuthService {
 constructor(private readonly usersService: UsersService, private readonly jwtService: JwtService) {}
 async validateUser(username: string, password: string): Promise {
  const user = await this.usersService.findOne(username);
  if (user && await bcrypt.compare(password, user.password)) {
	const { password, ...result } = user;
	return result;
  }
  return null;
 }
 async login(user: any) {
  const payload = { username: user.username, sub: user.userId };
  return {
	access_token: this.jwtService.sign(payload),
  };
 }
}

Implement Authentication Endpoint:

Create an authentication controller with an endpoint for user login:

@Controller('auth')
export class AuthController {
 constructor(private readonly authService: AuthService) {}
 @Post('login')
 async login(@Body() loginUserDto: LoginUserDto) {
  return this.authService.login(loginUserDto);
 }

Implementing Authorization in Nest JS:

After users are authenticated, it’s essential to establish authorization mechanisms to manage access to resources within your application. Nest JS offers features for role-based access control (RBAC), permission-based access control, and additional authorization functionalities.

Role-Based Access Control (RBAC):

Enforce Role-Based Access Control (RBAC) by linking roles to users and limiting access according to role permissions. Define roles and permissions within your application and employ middleware or guards to ensure adherence to authorization rules.

Permission-Based Access Control:

For finer control, implement permission-based access control, assigning specific permissions to each resource and granting users explicit permissions. Employ middleware or guards to verify permissions before granting access.

Conclusion:

Securing web applications requires effective authentication and authorization. Nest JS simplifies the implementation of these crucial components, thanks to its modular architecture and comprehensive ecosystem. Utilizing authentication strategies like JWT and integrating authorization logic through middleware or guards ensures the protection of Nest JS applications from unauthorized access and potential security threats.