Deploy to Vercel Skill

This skill guides you through deploying the To-Do List WebApp to Vercel for both frontend and backend.

Prerequisites

• Vercel account (sign up at https://vercel.com)
• Vercel CLI installed: npm install -g vercel
• MongoDB Atlas account for production database (https://www.mongodb.com/cloud/atlas)

Initial Setup

1. Install Vercel CLI

npm install -g vercel

2. Login to Vercel

vercel login

3. Set Up MongoDB Atlas

1. Create a MongoDB Atlas account
2. Create a new cluster
3. Create a database user
4. Whitelist IP addresses (or allow from anywhere: 0.0.0.0/0)
5. Get connection string: mongodb+srv://username:password@cluster.mongodb.net/todolist

Frontend Deployment

1. Configure Frontend Environment

Create frontend/.env.production:

VITE_API_URL=https://your-backend-url.vercel.app/api

2. Build Frontend

cd frontend
npm run build

3. Deploy Frontend

# From frontend directory
vercel

# Or for production
vercel --prod

Follow prompts:

• Set up and deploy: Y
• Which scope: Select your account
• Link to existing project: N (first time)
• Project name: todolist-webapp-frontend
• Directory: ./
• Override settings: N

4. Configure Frontend Environment Variables

In Vercel Dashboard:

1. Go to your frontend project
2. Settings → Environment Variables
3. Add:
   • VITE_API_URL: Your backend API URL

Backend Deployment

1. Configure Backend Environment

The backend is already configured with vercel.json. Ensure it looks like:

{
  "version": 2,
  "builds": [
    {
      "src": "src/index.js",
      "use": "@vercel/node"
    }
  ],
  "routes": [
    {
      "src": "/(.*)",
      "dest": "src/index.js"
    }
  ]
}

2. Deploy Backend

# From backend directory
cd backend
vercel

# Or for production
vercel --prod

3. Configure Backend Environment Variables

In Vercel Dashboard:

1. Go to your backend project
2. Settings → Environment Variables
3. Add all variables from backend/.env.example:
   • MONGODB_URI: Your MongoDB Atlas connection string
   • JWT_SECRET: Generate a secure random string
   • JWT_EXPIRES_IN: 7d
   • NODE_ENV: production
   • FRONTEND_URL: Your frontend Vercel URL
   • PORT: 5000 (optional, Vercel handles this)

4. Redeploy with Environment Variables

After adding environment variables, trigger a new deployment:

cd backend
vercel --prod

Update Frontend with Backend URL

After backend deployment, update frontend environment variable:

1. Go to Frontend project in Vercel Dashboard
2. Settings → Environment Variables
3. Update VITE_API_URL with your backend URL
4. Redeploy frontend:

   cd frontend
   vercel --prod
   

Verification

1. Run Pre-Deployment Check

node .agent/skills/deploy-vercel/scripts/pre-deploy-check.js

2. Manual Verification

1. Frontend: Visit your frontend URL
2. Backend: Visit https://your-backend-url.vercel.app/api/health
3. Test Authentication: Try registering and logging in
4. Test Todo Operations: Create, update, delete todos
5. Check Logs: View logs in Vercel Dashboard

Continuous Deployment

Set Up GitHub Integration

1. Push code to GitHub repository

2. In Vercel Dashboard:

   • Import Git Repository
   • Select your repository
   • Configure:
     • Framework: Vite (frontend) / Other (backend)
     • Root Directory: frontend/ or backend/
     • Build Command: npm run build
     • Output Directory: dist (frontend only)

3. Add environment variables in Vercel

4. Every push to main branch will trigger automatic deployment

Rollback Deployment

Using Vercel CLI

# List recent deployments
vercel ls

# Promote a specific deployment to production
vercel promote <deployment-url>

Using Vercel Dashboard

1. Go to project → Deployments
2. Find the desired deployment
3. Click "..." → Promote to Production

Environment-Specific Deployments

Preview Deployments

Every branch/PR gets a preview deployment automatically:

# Deploy to preview
vercel

Production Deployments

Only deploy to production when ready:

# Deploy to production
vercel --prod

Monitoring

View Logs

# Real-time logs
vercel logs <deployment-url> --follow

# Recent logs
vercel logs <deployment-url>

Check Build Logs

In Vercel Dashboard:

1. Go to project → Deployments
2. Click on a deployment
3. View build logs and function logs

Troubleshooting

Build Fails

1. Check build logs in Vercel Dashboard
2. Ensure dependencies are in dependencies, not devDependencies
3. Verify Node.js version matches (set in package.json engines field)

Environment Variables Not Working

1. Ensure variables are set in Vercel Dashboard
2. Redeploy after adding variables
3. For frontend, variables must start with VITE_

MongoDB Connection Issues

1. Verify connection string is correct
2. Check MongoDB Atlas network access (whitelist 0.0.0.0/0)
3. Verify database user credentials
4. Check MongoDB Atlas cluster status

CORS Errors

Update FRONTEND_URL in backend environment variables:

FRONTEND_URL=https://your-frontend-url.vercel.app

Function Timeout

Vercel has execution time limits:

• Hobby: 10 seconds
• Pro: 60 seconds

Optimize long-running operations or upgrade plan.

Best Practices

1. Use Environment Variables: Never commit secrets to git
2. Test Before Production: Use preview deployments
3. Monitor Performance: Check Vercel Analytics
4. Set Up Alerts: Configure Vercel notifications
5. Use Custom Domains: Set up custom domain for production
6. Enable HTTPS: Vercel provides SSL certificates automatically
7. Implement Health Checks: Use /api/health endpoint
8. Review Logs Regularly: Monitor for errors

Custom Domain Setup

1. Go to Vercel Dashboard → Project → Settings → Domains
2. Add your custom domain
3. Configure DNS records as instructed by Vercel
4. Update environment variables with new domain
5. Redeploy

Cost Optimization

Vercel Free Tier Limits

• 100 GB bandwidth/month
• 100 hours serverless function execution

Optimization Tips

1. Use efficient database queries
2. Implement caching where possible
3. Optimize bundle size (frontend)
4. Use preview deployments sparingly

Useful Commands

# Deploy to preview
vercel

# Deploy to production
vercel --prod

# List deployments
vercel ls

# View logs
vercel logs

# Remove deployment
vercel rm <deployment-name>

# Get deployment info
vercel inspect <deployment-url>

# Set environment variable
vercel env add <NAME>

See Also

• Official documentation: https://vercel.com/docs
• VERCEL_DEPLOYMENT.md in project root
• Vercel CLI reference: https://vercel.com/docs/cli