Docswrite sub directory hostings for firebase

firebase.function.js

exports.blog = functions.https.onRequest((request, response) => {
  let url = new URL(request.url);
    url.hostname = "blog.docswrite.blog"; // use your docswrite url 
    url.pathname = url.pathname.replace('/blog', '');
    fetch(url, request).then(d => d.text()).then(res => response.send(res));
});

firebase.json

"hosting": {
  // ...

  // Add the "rewrites" attribute within "hosting"
  "rewrites": [ {
    "source": "/blog/*",
    "function": "blog"
  } ]
}