vercel-hello-world | vercel-pack

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vercel-hello-world | vercel-pack

Vercel Hello World

Overview

Deploy a minimal project to Vercel with a static page and a serverless API route. Confirms your CLI auth, project structure, and deployment pipeline work end to end.

Prerequisites

Completed vercel-install-auth setup
Vercel CLI installed and authenticated
Node.js 18+

Instructions

Step 1: Create Project Structure

mkdir my-vercel-app && cd my-vercel-app
npm init -y

Create the static landing page:

<!-- public/index.html -->
<!DOCTYPE html>
<html>
<head><title>Hello Vercel</title></head>
<body>
  <h1>Hello from Vercel</h1>
  <p id="result">Loading...</p>
  <script>
    fetch('/api/hello')
      .then(r => r.json())
      .then(d => document.getElementById('result').textContent = d.message);
  </script>
</body>
</html>

Step 2: Create Serverless API Route

// api/hello.ts
import type { VercelRequest, VercelResponse } from '@vercel/node';

export default function handler(req: VercelRequest, res: VercelResponse) {
  res.status(200).json({
    message: 'Hello from Vercel Serverless Function!',
    timestamp: new Date().toISOString(),
    region: process.env.VERCEL_REGION || 'local',
  });
}

Install the types:

npm install --save-dev @vercel/node typescript

Step 3: Add vercel.json Configuration

{
  "rewrites": [
    { "source": "/api/(.*)", "destination": "/api/$1" }
  ],
  "headers": [
    {
      "source": "/api/(.*)",
      "headers": [
        { "key": "Cache-Control", "value": "s-maxage=0, stale-while-revalidate" }
      ]
    }
  ]
}

Step 4: Deploy Preview

# Deploy to a preview URL (not production)
vercel

# Output:
# Vercel CLI 39.x.x
# 🔗 Linked to your-team/my-vercel-app
# 🔍 Inspect: https://vercel.com/your-team/my-vercel-app/xxx
# ✅ Preview: https://my-vercel-app-xxx.vercel.app

Step 5: Test the Deployment

# Test static page
curl -s https://my-vercel-app-xxx.vercel.app/ | head -5

# Test API route
curl -s https://my-vercel-app-xxx.vercel.app/api/hello | jq .
# {
#   "message": "Hello from Vercel Serverless Function!",
#   "timestamp": "2026-03-22T12:00:00.000Z",
#   "region": "iad1"
# }

Step 6: Promote to Production

# Deploy directly to production
vercel --prod

# Or promote the preview deployment
vercel promote https://my-vercel-app-xxx.vercel.app

Vercel System Environment Variables

These are available in every function at runtime:

Variable	Value
`VERCEL`	`"1"` — always set on Vercel
`VERCEL_ENV`	`"production"`, `"preview"`, or `"development"`
`VERCEL_URL`	Deployment URL (no protocol)
`VERCEL_REGION`	Function region (e.g., `iad1`)
`VERCEL_GIT_COMMIT_SHA`	Git commit hash
`VERCEL_GIT_COMMIT_MESSAGE`	Git commit message

Output

Static page served from Vercel CDN
Serverless API route returning JSON at /api/hello
Preview URL for testing before production
Production deployment live on your domain

Error Handling

Error	Cause	Solution
`404 NOT_FOUND` on `/api/hello`	File not in `api/` directory	Move file to project root `api/` folder
`FUNCTION_INVOCATION_FAILED`	Runtime error in handler	Check function logs: `vercel logs <url>`
`BUILD_FAILED`	TypeScript compilation error	Run `npx tsc --noEmit` locally first
`NO_RESPONSE_FROM_FUNCTION`	Handler didn't call `res.send/json`	Ensure all code paths return a response
`FUNCTION_PAYLOAD_TOO_LARGE`	Response body > 4.5 MB	Paginate or stream the response

Resources

Next Steps

Proceed to vercel-local-dev-loop for development workflow setup.