fssonca/todoAppBackend

LambdaTodoApp

A serverless Todo application backend built with AWS Lambda, Serverless Framework, and DynamoDB. This application supports user registration, login with email verification, JWT authentication, and CRUD operations for managing todos.

Features

• User Registration: Users can register using their email, which receives a verification code for authentication.
• Email Verification: Sends a six-digit verification code via EmailJS.
• JWT Authentication: After email verification, users receive a JWT for authorization in further requests.
• Todo Management: Users can create, view, complete, and delete todo items. Each todo has a name, description, priority, due date, and completion status.
• Serverless: Fully serverless application using AWS Lambda, DynamoDB, and Serverless Framework.

Tech Stack

• AWS Lambda - For serverless functions
• AWS DynamoDB - Database to store user, login code, and todo information
• EmailJS - To send verification codes to user email addresses
• JWT - For secure user authentication and authorization
• Serverless Framework - To deploy and manage AWS resources
• TypeScript - For type safety and maintainability

Project Structure

.
├── src
│   ├── handlers             # Lambda function handlers
│   │   ├── createTodo.ts
│   │   ├── deleteTodo.ts
│   │   ├── getAllTodos.ts
│   │   ├── completeTodo.ts
│   │   ├── registerUser.ts
│   │   ├── userLogin.ts
│   │   └── verifyEmail.ts
│   ├── services             # Business logic and helper functions
│   │   ├── authMiddleware.ts
│   │   ├── authService.ts
│   │   ├── codeService.ts
│   │   └── smtpService.ts
│   └── utils                # Utility functions and constants
├── serverless.yml           # Serverless configuration file
└── package.json             # Node.js dependencies and scripts

Prerequisites

• Node.js (v14 or higher)
• Serverless Framework installed globally:

  npm install -g serverless

• AWS CLI configured with sufficient permissions to deploy Lambda functions and manage DynamoDB tables.

Environment Variables

Create a .env file in the root directory with the following environment variables:

JWT_SECRET=your_jwt_secret
EMAILJS_PUBLIC_KEY=your_emailjs_public_key
EMAILJS_PRIVATE_KEY=your_emailjs_private_key
EMAILJS_SERVICE_ID=your_emailjs_service_id
EMAILJS_TEMPLATE_ID=your_emailjs_template_id

Setup Instructions

1. Install dependencies:

   npm install

2. Compile TypeScript:

   npm run build

3. Deploy the application:

   serverless deploy

   This will deploy the Lambda functions, configure API Gateway routes, and create necessary DynamoDB tables (Users, Todos, and LoginCodes).

API Endpoints

Function	Path	Method	Description
Register User	/register-user	POST	Registers a new user with email
Login User	/login	POST	Initiates login by sending a code to email
Verify Code	/verify-email	POST	Verifies the login code and returns a JWT
Get Todos	/todos	GET	Retrieves all todos for an authenticated user
Create Todo	/todos	POST	Creates a new todo
Complete Todo	/todos/complete	POST	Marks a todo as complete
Delete Todo	/todos	DELETE	Deletes a specified todo

Authentication Workflow

1. User Registration: Users initiate login by providing their email. A verification code is sent via EmailJS.
2. Email Verification: The user submits the verification code. If valid, a JWT is issued.
3. JWT Authorization: The JWT is used to authorize requests for creating, viewing, completing, and deleting todos.

Key Files and Functions

serverless.yml

This file configures the Serverless Framework, defining the provider, environment variables, IAM permissions, and the Lambda functions.

• IAM Role Permissions:
  • DynamoDB: Permissions to read and write to the Users, Todos, and LoginCodes tables.
  • SES: Permission to send emails using Amazon SES (optional, since EmailJS is used here).

src/handlers/*.ts

Each file in the handlers folder is a Lambda function handler for specific API endpoints. For example:

• createTodo.ts: Handles the creation of a new todo item.
• userLogin.ts: Sends a login code to the user's email or validates an entered code.
• verifyEmail.ts: Verifies the email code and issues a JWT if successful.

src/services/authMiddleware.ts

A middleware function to authenticate incoming requests by decoding the JWT and extracting the user’s email. This middleware is used to secure todo-related endpoints.

src/services/smtpService.ts

A service to send emails using EmailJS. It is used to send the six-digit login code to users' email addresses.

Example Requests

Register User (POST /register-user)

{
  "email": "user@example.com"
}

Login User (POST /login)

• Request to send code:

  {
    "email": "user@example.com"
  }

• Request to verify code:

  {
    "email": "user@example.com",
    "sixDigitCode": "123456"
  }

Create Todo (POST /todos)

Headers: Authorization: Bearer <JWT_TOKEN>

{
  "name": "Sample Task",
  "description": "This is a sample task",
  "priority": 3,
  "dueDate": "2024-12-31"
}

Complete Todo (POST /todos/complete)

Headers: Authorization: Bearer <JWT_TOKEN>

{
  "todoId": "unique-todo-id"
}

Delete Todo (DELETE /todos)

Headers: Authorization: Bearer <JWT_TOKEN>

{
  "todoId": "unique-todo-id"
}

Local Testing

To test the functions locally, you can use the Serverless framework's offline capabilities or invoke functions directly with sample payloads.

Invoke a Function Locally

For example, to test createTodo:

serverless invoke local -f createTodo -p path/to/sample-event.json

Deployment

To update the deployed Lambda functions, run:

serverless deploy

License

This project is licensed under the MIT License.