makeManifest.js

let base = {
  "short_name": "Kakidashi",
  "name": "Kakidashi Tool",
  "icons": [
    {
      "src": "favicon.ico",
      "sizes": "64x64 32x32 24x24 16x16",
      "type": "image/x-icon"
    },
    {
      "src": "logo192.png",
      "type": "image/png",
      "sizes": "192x192"
    },
    {
      "src": "logo512.png",
      "type": "image/png",
      "sizes": "512x512"
    }
  ],
  "start_url": ".",
  "display": "standalone",
  "theme_color": "#000000",
  "background_color": "#ffffff"
}

exports.handler = function (event, context, callback) {
  start_url = event.queryStringParameters.start_url
  base.start_url = start_url
  callback(null, {
    statusCode: 200,
    body: JSON.stringify(base)
  })
}