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Backend Development Guide

Learn how to develop, test, and deploy the backend service for the DISCover Program template.

Overview​

The backend service is built with:

  • Express.js for the web server
  • Supabase for database and authentication
  • Cookie-based session management
  • CORS protection for secure client communication

Project Setup​

Environment Variables​

Create a .env file with the following variables:

FRONTEND_URL=your_DEPLOYED_frontend_url_on_vercel
FRONTEND_URL_DEV=localhost:3001
SUPABASE_URL=your_supabase_url
SUPABASE_ANON_KEY=your_supabase_key
PORT=3000
API_URL=http://localhost:5050
NODE_ENV=development

Authentication Flow​

The backend handles these auth routes:

POST / auth / signup; // Create new user account
POST / auth / login; // Log in existing user
POST / auth / logout; // Log out user
GET / auth / verify; // Verify email after signup
GET / auth / me; // Get current user details
GET / auth / users; // Get all users (protected route)
GET / auth / google; // Initiate Google OAuth
GET / auth / callback; // Handle OAuth callback
POST / auth / callback; // Process OAuth tokens

Session Management​

  • Sessions are managed using HTTP-only cookies
  • The authMiddleware validates sessions by:
    1. Checking for authorization header or cookie
    2. Validating token with Supabase
    3. Attaching user data to request

Development Process​

Git Workflow​

  1. Create feature branch from main:
git checkout -b feature/your-feature
  1. Make changes and commit:
git add .
git commit -m "feat: description of changes"
  1. Push and create PR:
git push origin feature/your-feature
  1. Request review from CODEOWNERS

Code Quality​

The repository enforces:

  • Linting with ESLint
  • Formatting with Prettier
  • GitHub Actions for CI/CD
  • Protected main branch
  • Required PR reviews

Running Locally​

Start development server:

npm run dev

Run tests:

npm test

Error Handling​

Use consistent error responses:

// 400 Bad Request
res.status(400).json({
  error: "Specific error message",
});

// 401 Unauthorized
res.status(401).json({
  error: "Authentication failed",
});

// 500 Server Error
res.status(500).json({
  error: "Internal server error",
});

Common Issues​

  1. CORS errors

    • Check FRONTEND_URL in .env
    • Ensure credentials are enabled

  2. Auth errors

    • Verify Supabase keys
    • Check cookie settings
    • Validate token format

  3. Database errors

    • Confirm Supabase connection
    • Check table permissions
    • Validate query syntax

Deployment​

  1. Set production environment variables
  2. Build the application:
npm run build
  1. Start production server:
npm start

Resources​