Getting Invalid Host header with azure deployment

I am getting Invalid host header error with azure deployment of my web version of expo app. The docker image works perfectly fine in my local. Upon googling I see that we will need to add the below lines:

module.exports = {
  //...
  devServer: {
    allowedHosts: 'all',
  },
}; 

These lines need to be added into webpack.config.js. But the problem is expo does not expose webpack.config.js so how get around this problem??