I get the same problem. I have used 10hrs to findout.
https://serverless.com/framework/docs/providers/aws/events/apigateway/
// handler.js
'use strict';
module.exports.hello = function(event, context, callback) {
const response = {
statusCode: 200,
headers: {
"Access-Control-Allow-Origin" : "*", // Required for CORS support to work
"Access-Control-Allow-Credentials" : true // Required for cookies, authorization headers with HTTPS
},
body: JSON.stringify({ "message": "Hello World!" })
};
callback(null, response);
};