Не могу сделать запрос из firebase hosting

Развернул функцию в cloud.functions:

const cors = require('cors')({origin: true});
const functions = require('firebase-functions');

exports.hello = functions.https.onRequest((req, res) => {
  cors(req, res, () => {
          console.log('Привет мир!');
          // Send Response
          res.status(200).send('Привет мир!');
      });
});

в firebase.json добавил обращение к функции hello, при запросе по адресу mysite.web.app/hello:

{
  "hosting": {
    "public": "build/web",
    "ignore": [
      "firebase.json",
      "**/.*",
      "**/node_modules/**"
    ],
    "headers": [ {
      "source" : "*",
      "headers" : [ {
        "key" : "Access-Control-Allow-Origin",
        "value" : "*"
      } ]
    }],
    "rewrites": [
      {
        "source": "/hello",
        "function": "hello"
      },
      {
        "source": "/bigben/bigben",
        "function": "bigben"
      },
      {
        "source": "**",
        "destination": "/index.html"
      }
    ]
  }
}

При запросе все равно выходит ошибка:

Access to fetch at 'https://accounts.google.com/ServiceLogin?service=ah&passive=true&continue=https://uc.appengine.google.com/_ah/conflogin%3Fcontinue%3Dhttps://us-central1-mysite.cloudfunctions.net/hello/hello' (redirected from 'https://mysite.web.app/hello') from origin 'https://mysite.web.app' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.