Vercel Deployment

This skill helps you deploy and configure Next.js applications on Vercel following best practices.

Quick Deploy Checklist

• Environment variables set in Vercel dashboard
• Build command configured (default: next build)
• Output directory correct (default: .next)
• Node.js version specified (20.x recommended)
• Database accessible from Vercel's network
• Secrets not committed to git

Environment Variables

Setting Variables

Vercel Dashboard (Recommended for secrets):

1. Project Settings → Environment Variables
2. Add variable with appropriate scope:
   • Production: Only production deployments
   • Preview: PR and branch previews
   • Development: Local vercel dev

Via CLI:

vercel env add VARIABLE_NAME production
vercel env pull .env.local  # Pull to local

Variable Naming

# Server-only (never exposed to browser)
DATABASE_URL=
SESSION_SECRET=
ANTHROPIC_API_KEY=

# Client-exposed (prefixed with NEXT_PUBLIC_)
NEXT_PUBLIC_APP_URL=
NEXT_PUBLIC_ANALYTICS_ID=

Size Limits

Context	Limit
Total per deployment	64 KB
Edge Functions	5 KB per variable
Single variable	64 KB max

Required Variables for This Project

# Authentication (required)
SESSION_SECRET=your-32-char-minimum-secret-here

# AI Integration (required for chat)
ANTHROPIC_API_KEY=sk-ant-api...

# Database (if using external)
DATABASE_URL=file:./data/app.db

# Push Notifications (optional)
VAPID_PUBLIC_KEY=
VAPID_PRIVATE_KEY=
VAPID_SUBJECT=mailto:admin@example.com

# OAuth (optional)
GOOGLE_CLIENT_ID=
GOOGLE_CLIENT_SECRET=
GITHUB_CLIENT_ID=
GITHUB_CLIENT_SECRET=
APPLE_CLIENT_ID=
APPLE_CLIENT_SECRET=

vercel.json Configuration

{
  "buildCommand": "npm run build",
  "framework": "nextjs",
  "regions": ["iad1"],
  "headers": [
    {
      "source": "/api/(.*)",
      "headers": [
        { "key": "Cache-Control", "value": "no-store, must-revalidate" }
      ]
    },
    {
      "source": "/(.*)",
      "headers": [
        { "key": "X-Content-Type-Options", "value": "nosniff" },
        { "key": "X-Frame-Options", "value": "DENY" },
        { "key": "X-XSS-Protection", "value": "1; mode=block" }
      ]
    }
  ],
  "redirects": [
    {
      "source": "/old-path",
      "destination": "/new-path",
      "permanent": true
    }
  ],
  "rewrites": [
    {
      "source": "/api/v1/:path*",
      "destination": "/api/:path*"
    }
  ]
}

TypeScript Configuration (New in 2025)

// vercel.ts - Type-safe configuration
import { defineConfig } from '@vercel/config';

export default defineConfig({
  regions: ['iad1'],

  headers: async () => [
    {
      source: '/api/:path*',
      headers: [
        { key: 'Cache-Control', value: 'no-store' },
      ],
    },
  ],

  redirects: async () => [
    {
      source: '/old',
      destination: '/new',
      permanent: true,
    },
  ],
});

Edge Functions

When to Use Edge

Good for:

• Authentication/authorization
• A/B testing
• Geolocation-based content
• Request/response transforms
• Simple, fast operations

Not suitable for:

• Database connections (use serverless instead)
• Long-running operations
• Large dependencies

Edge Function Example

// src/middleware.ts
import { NextResponse } from 'next/server';
import type { NextRequest } from 'next/server';

export const config = {
  matcher: ['/api/:path*', '/protected/:path*'],
};

export function middleware(request: NextRequest) {
  // Check auth token
  const token = request.cookies.get('session')?.value;

  if (!token && request.nextUrl.pathname.startsWith('/protected')) {
    return NextResponse.redirect(new URL('/login', request.url));
  }

  // Add headers
  const response = NextResponse.next();
  response.headers.set('X-Request-Id', crypto.randomUUID());

  return response;
}

Edge Runtime in API Routes

// src/app/api/edge-example/route.ts
export const runtime = 'edge';

export async function GET(request: Request) {
  // Limited to edge-compatible APIs
  return Response.json({ timestamp: Date.now() });
}

Build Configuration

package.json Scripts

{
  "scripts": {
    "build": "next build",
    "postbuild": "npm run db:generate"
  }
}

Build Environment

# Set Node.js version
# In Vercel Dashboard → Settings → General → Node.js Version
# Or in package.json:
{
  "engines": {
    "node": "20.x"
  }
}

Build Output

# Check build locally
npm run build

# Analyze bundle
ANALYZE=true npm run build

Database Considerations

SQLite on Vercel

SQLite with better-sqlite3 works in Vercel's serverless functions, but:

• Filesystem is read-only except /tmp
• Data doesn't persist between invocations
• Not suitable for production data storage

Production Database Options

1. Turso (SQLite edge database)

   import { createClient } from '@libsql/client';
   
   const db = createClient({
     url: process.env.TURSO_DATABASE_URL!,
     authToken: process.env.TURSO_AUTH_TOKEN,
   });
   

2. Vercel Postgres

   import { sql } from '@vercel/postgres';
   
   const result = await sql`SELECT * FROM users`;
   

3. PlanetScale (MySQL)

4. Neon (Postgres)

Preview Deployments

Branch Previews

Every git push creates a preview deployment:

• https://<project>-<branch>-<team>.vercel.app
• Separate environment variables for preview

Preview Environment Variables

# Different values for preview vs production
# In Vercel Dashboard, set both:

DATABASE_URL (Production): postgres://prod-db...
DATABASE_URL (Preview): postgres://staging-db...

Commenting on PRs

Vercel automatically comments on PRs with:

• Preview URL
• Build status
• Performance metrics

Troubleshooting

Build Failures

# Check build locally first
npm run build

# Common issues:
# - Missing environment variables
# - TypeScript errors
# - ESLint errors (strict mode)
# - Missing dependencies

Environment Variable Issues

# Verify variables are set
vercel env ls

# Pull to local for debugging
vercel env pull .env.local

Function Timeout

// Increase timeout (max 60s on Pro, 10s on Hobby)
// In vercel.json:
{
  "functions": {
    "api/long-running.ts": {
      "maxDuration": 60
    }
  }
}

Memory Issues

// Increase memory (affects cost)
{
  "functions": {
    "api/heavy-processing.ts": {
      "memory": 1024
    }
  }
}

Monitoring

Vercel Analytics

// src/app/layout.tsx
import { Analytics } from '@vercel/analytics/react';

export default function RootLayout({ children }) {
  return (
    <html>
      <body>
        {children}
        <Analytics />
      </body>
    </html>
  );
}

Speed Insights

import { SpeedInsights } from '@vercel/speed-insights/next';

export default function RootLayout({ children }) {
  return (
    <html>
      <body>
        {children}
        <SpeedInsights />
      </body>
    </html>
  );
}

Function Logs

# View logs via CLI
vercel logs <deployment-url>

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

Domains

Custom Domain Setup

1. Vercel Dashboard → Domains
2. Add domain
3. Configure DNS:
   • A record: 76.76.21.21
   • Or CNAME: cname.vercel-dns.com
4. SSL automatically provisioned

Redirects

// vercel.json
{
  "redirects": [
    {
      "source": "/:path((?!api/).*)",
      "has": [{ "type": "host", "value": "old-domain.com" }],
      "destination": "https://new-domain.com/:path",
      "permanent": true
    }
  ]
}

Security

Protected Routes

Use middleware for authentication checks (see Edge Functions above).

Rate Limiting

Implement application-level rate limiting since Vercel doesn't provide built-in rate limiting for serverless functions.

Secrets Management

• Never commit .env files
• Use Vercel's encrypted environment variables
• Rotate secrets regularly
• Different secrets for preview vs production

References

• Vercel Documentation
• Environment Variables
• Edge Functions
• Next.js on Vercel