Correctly Configuring publicPath for React Applications

When serving React apps, an incorrect publicPath can cause broken assets, failed loading, and routing issues. Here’s how to properly configure it for different deployment scenarios.

Understanding publicPath

publicPath determines:

• Where your assets are served from
• How files are referenced in your built HTML/CSS
• The base URL for all your application’s assets

Common Symptoms of Incorrect publicPath

• Blank white screen in production
• 404 errors for JavaScript/CSS files
• Broken images and static assets
• Failed API requests
• Routing malfunctions

Configuration Solutions

1. Webpack Configuration (for custom setups)

// webpack.config.js
module.exports = {
  output: {
    publicPath: '/', // Default for root domain
    publicPath: '/my-app/', // For subdirectory
    publicPath: 'https://cdn.example.com/', // For CDN
  }
}

2. Create React App Solutions

Option A: package.json homepage field

{
  "homepage": "https://example.com/subdirectory"
}

Option B: Environment variables

# .env
PUBLIC_URL=/subdirectory

3. For Different Environments

Development:

publicPath: '/'

Production:

publicPath: process.env.PUBLIC_URL || '/'

Testing:

publicPath: './' // Relative paths

Deployment-Specific Configurations

GitHub Pages

{
  "homepage": "https://username.github.io/repo-name",
  "scripts": {
    "predeploy": "npm run build",
    "deploy": "gh-pages -d build"
  }
}

Netlify/Vercel

// No special config needed for root deployments
// For preview deployments:
publicPath: process.env.PUBLIC_URL || '/'

AWS S3/CloudFront

publicPath: process.env.CDN_URL || '/'

Dynamic Path Resolution

For advanced scenarios:

// webpack.config.js
const publicPath = process.env.NODE_ENV === 'production'
  ? 'https://cdn.example.com/'
  : '/';

module.exports = {
  output: { publicPath }
}

Troubleshooting Techniques

1. Inspect built index.html:

• Check if asset paths match your deployment structure

1. Verify environment variables:

   echo $PUBLIC_URL

3. Test locally:

   serve -s build --listen 5000

4. Check network tab:

• Look for failed resource loading

Best Practices

1. Set publicPath early in project setup
2. Use environment variables for flexibility
3. Test in staging before production
4. Document your deployment requirements
5. Consider using relative paths for more portable builds

Common Fixes for Specific Issues

Problem: Assets loading from wrong path
Solution:

publicPath: process.env.PUBLIC_URL || '/'

Problem: Routing breaks on refresh
Solution:

// webpack.config.js
publicPath: '/'
// plus proper server configuration to serve index.html for all routes

Problem: CDN assets not loading
Solution:

publicPath: 'https://your-cdn-url.com/'