code/origin_request/index.js
const HEADER_NAME = 'x-original-host';
exports.handler = (event, _, callback) => {
const request = event.Records[0].cf.request;
const originalHost = request.headers[HEADER_NAME][0].value;
const labels = originalHost.split('.');
// Use left-most label to build S3 path.
const path = `/${labels[0]}`;
request.origin.s3.path = path;
callback(null, request);
};