How to add a blog at /blog with a Cloudflare Worker

const ORIGIN_HOST = 'o--your-blog-id.outrankblog.com';
const PREFIX = '/blog';

const rewriteLocation = (location, url) => {
  try {
    const target = new URL(location, `https://${ORIGIN_HOST}`);
    if (target.hostname !== ORIGIN_HOST) return location;
    return `${url.origin}${PREFIX}${target.pathname === '/' ? '' : target.pathname}${target.search}`;
  } catch {
    return location;
  }
};

export default {
  async fetch(request) {
    const url = new URL(request.url);
    if (url.pathname !== PREFIX && !url.pathname.startsWith(`${PREFIX}/`)) {
      return fetch(request);
    }
    if (url.pathname === `${PREFIX}/`) {
      return Response.redirect(`${url.origin}${PREFIX}${url.search}`, 301);
    }
    const upstream = new URL(request.url);
    upstream.hostname = ORIGIN_HOST;
    upstream.pathname = url.pathname.slice(PREFIX.length) || '/';
    const headers = new Headers(request.headers);
    headers.set('X-Forwarded-Host', url.hostname);
    headers.set('X-Forwarded-Proto', 'https');
    headers.set('X-Outrank-Base-Path', PREFIX);
    const response = await fetch(upstream.toString(), {
      method: request.method,
      headers,
      body: request.method === 'GET' || request.method === 'HEAD' ? undefined : request.body,
      redirect: 'manual',
    });
    const proxied = new Response(response.body, response);
    const location = proxied.headers.get('Location');
    if (location) proxied.headers.set('Location', rewriteLocation(location, url));
    return proxied;
  },
};

Example only. In your dashboard, Outrank shows this code with your blog’s own address filled in.