project1.md

Project1 - Requirements Document

Objective

The objective of this project is to implement basic user/password authentication in a Nest.js application. This authentication system will allow users to authenticate with a username and password stored in a JSON file.

Requirements

Step 1: Generate a Nest Project

• Install the Nest CLI globally if not already installed:

  npm install -g @nestjs/cli

  • Use yarn
• Create Project 1

  nest new project1
  cd project1

Step 2: Create Authentication Service and Module

• Create an authentication service to handle user authentication::

  nest generate service auth

• Create an authentication module to organize authentication-related components:

  nest generate module auth

• Create an authentication controller

  nest generate controller auth

Step 3: Implement Authentication Logic

• Implement the logic for basic authentication in the authentication service (auth.service.ts). Store login/password pairs in a JSON and validate user credentials against it.

  // auth/auth.service.ts
  import { Injectable } from '@nestjs/common';
  
  @Injectable()
  export class AuthService {
  private readonly users = [
    { username: 'user1', password: 'password1' },
    { username: 'user2', password: 'password2' },
  ];
  
  async login(username: string, password: string): Promise<boolean> {
    const user = this.users.find(
      (user) => user.username === username && user.password === password,
    );
  
    if (user) {
      return true; // Login successful
    }
    return false; // Invalid credentials
  }
  }

  • Create the middleware

  // auth/auth.middleware.ts
  import { Injectable, NestMiddleware } from '@nestjs/common';
  import { Request, Response, NextFunction } from 'express';
  @Injectable()
  export class AuthMiddleware implements NestMiddleware {
   
    use(req: Request, res: Response, next: NextFunction) {
      // Implement logic to check for valid authentication credentials in the request headers
  
      const authHeader = req.headers.authorization;
      if (!authHeader || authHeader !== 'Bearer your_access_token') {
        return res.status(401).json({ message: 'Unauthorized' });
      }
  
      next();
    }
  }

  • Update the app module

  // src/app.module.ts
  import { Module } from '@nestjs/common';
  import { AuthModule } from './auth/auth.module';
  import { AuthController } from './auth/auth.controller'; // Import the AuthController
  
  @Module({
    imports: [AuthModule],
    controllers: [AuthController], // Include the AuthController
  })
  export class AppModule {}

  • Update the controller

  // auth/auth.controller.ts
  import { Controller, Post, Body } from '@nestjs/common';
  import { AuthService } from './auth.service';
  @Controller()
  export class AuthController {
    constructor(private readonly authService: AuthService) {}
  
    @Post('login')
    async login(@Body() body: { username: string, password: string }) {
      // Assuming you have a method named `login` in your AuthService
      const result = await this.authService.login(body.username, body.password);
      if (result) {
        return { message: 'Login successful' };
      } else {
        return { message: 'Invalid credentials' };
      }
    }
  }

Example Structure

Your project structure might look like this:

 project1/
 ├── src/
 │   ├── auth/
 │   │   ├── auth.controller.ts
 │   │   ├── auth.middleware.ts
 │   │   ├── auth.module.ts
 │   │   └── auth.service.ts
 │   ├── app.module.ts
 │   ├── main.ts
 │   └── ...
 └── ...
 

Testing

Start the server

yarn start

Send a request with valid credentials

curl -X POST -H "Content-Type: application/json" -d '{"username": "user1", "password": "password1"}' http://localhost:3000/login

Expect: {"message":"Login successful"}%

Send a request with invalid credentials

curl -X POST -H "Content-Type: application/json" -d '{"username": "user1", "password": "wrongpassword"}' http://localhost:3000/login

Expect: {"message":"Invalid credentials"}%

Test Assignment

1. Extend this to support uploading a file, and store the file to disk. Create the curl and include the curl in a test script so that the end to end file upload test can be called from within the project using a simple script.

   curl -X POST -F "file=@/path/to/your/file.txt" http://localhost:3000/upload
   

2. Extend the upload functionality to write to a Google Storage bucket. The file should reside in Google storage after the curl call.

3. Create a React client

   npx create-react-app my-react-client
   

• Build a ui that does login, logout, and upload.