Edge SEO Engineering: Injecting Structured Schema and Dynamic Metadata via Cloudflare Workers and Fastly VCL

Puntos clave

1. Understand the model. Edge functions run at the CDN, modifying responses before they reach the user.
2. Inject metadata. Add or modify title, description, and canonical tags at the edge.
3. Add schema markup. Inject JSON-LD structured data based on URL patterns.
4. Handle redirects. Implement 301/302 redirects at the edge for fast response times.
5. A/B test metadata. Serve different metadata to different user segments.
6. Monitor edge performance. Edge functions add latency; measure and optimize.
7. Version control edge code. Store worker scripts in Git and deploy via CI/CD.
8. Test before deploy. Use staging environments to validate edge changes.

Architecture

Requests hit the CDN edge, where a worker inspects the URL and modifies the response. Metadata and schema are injected into the HTML. Redirects are handled before reaching the origin. Changes deploy globally in seconds.

Production configuration

export default {
  async fetch(request, env) {
    const url = new URL(request.url);
    const response = await fetch(request);
    const html = await response.text();
    // inject metadata based on path
    const title = getTitleForPath(url.pathname);
    const schema = getSchemaForPath(url.pathname);
    const modified = html
      .replace(/<title>.*<\/title>/, `<title>${title}</title>`)
      .replace('</head>', `${schema}</head>`);
    return new Response(modified, response);
  }
};

export default {
  async fetch(request) {
    const url = new URL(request.url);
    const redirects = {
      '/old-page': '/new-page',
      '/legacy': '/modern',
    };
    if (redirects[url.pathname]) {
      return Response.redirect(url.origin + redirects[url.pathname], 301);
    }
    return fetch(request);
  }
};

wrangler deploy
# test edge function
curl -s -o /dev/null -w '%{http_code}' https://example.com/old-page
# verify metadata
curl -s https://example.com/products | grep -o '<title>.*</title>'
# check schema
curl -s https://example.com/products | grep -o 'application/ld+json'

Edge cases from production

• Edge functions add latency; keep them fast and avoid heavy computation.
• Caching can serve stale metadata; set appropriate cache headers.
• Bot detection at the edge can block crawlers; whitelist known bots.
• Edge changes can break pages; test thoroughly before deploying.

Preguntas frecuentes