dfx.json

{
  "canisters": {
    "hosting": {
      "frontend": {
        "entrypoint": "dfinity/entrypoint.js"
      },
      "source": [
        "build"
      ],
      "type": "assets"
    }
  },
  "dfx": "0.6.21",
  "networks": {
    "ic": {
      "providers": [
        "https://gw.dfinity.network"
      ],
      "type": "persistent"
    }
  },
  "version": 1
}

entrypoint.js

// located at ./dfinity/entrypoint.js
const canisterId = window.location.hostname.split('.').shift();

console.log('You are being redirected to:');
console.log('%s.ic.fleek.co', canisterId);

window.location.href = `https://${canisterId}.ic.fleek.co`;