DeviceDetection.js

'use strict';

/* This is an origin request function */
exports.handler = (event, context, callback) => {
    const request = event.Records[0].cf.request;
    const headers = request.headers;

    /*
     * Serve different versions of an object based on the device type.
     * NOTE: 1. You must configure your distribution to cache based on the
     *          CloudFront-Is-*-Viewer headers. For more information, see
     *          the following documentation:
     *          http://docs.aws.amazon.com/console/cloudfront/cache-on-selected-headers
     *          http://docs.aws.amazon.com/console/cloudfront/cache-on-device-type
     *       2. CloudFront adds the CloudFront-Is-*-Viewer headers after the viewer
     *          request event. To use this example, you must create a trigger for the
     *          origin request event.
     */

    const desktopPath = '/desktop';
    const mobilePath = '/mobile';
   

    if (headers['cloudfront-is-desktop-viewer']
        && headers['cloudfront-is-desktop-viewer'][0].value === 'true') {
        request.uri = desktopPath + request.uri;
    } else if (headers['cloudfront-is-mobile-viewer']
               && headers['cloudfront-is-mobile-viewer'][0].value === 'true') {
        request.uri = mobilePath + request.uri;
    } 
    console.log(`Request uri set to "${request.uri}"`);

    callback(null, request);
};