server.js

/**
 * Copyright 2015-2016, Google, Inc.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

'use strict';

const express = require('express');
const multer = require('multer'); // Use multer to parse muti-part forms.
const UpdateCacheUrlProvider = require('amp-toolbox-update-cache');
const upload = multer();
const app = express();

app.use(express.static('public'));

app.post('/api/cache/generate-update-url', upload.array(), (req, res) => {
  // Get parameters from request.
  const privateKey = req.body.privatekey;
  const url = req.body.url;

  // Generate update-cache URLs.
  const updateCacheUrlProvider = UpdateCacheUrlProvider.create(privateKey);
  const timestamp = Math.round((new Date()).getTime() / 1000) + 60;

  updateCacheUrlProvider.calculateFromOriginUrl(url, timestamp)
    .then(refreshUrlInfos => {
      // Append CORS headers.
      const requestingOrigin = req.headers.origin;
      const requestingSourceOrigin = req.query.__amp_source_origin;
      res.header('Access-Control-Allow-Origin', requestingOrigin);
      res.header('Access-Control-Allow-Credentials', 'true');
      res.setHeader('Access-Control-Expose-Headers', 'AMP-Access-Control-Allow-Source-Origin');
      res.setHeader('AMP-Access-Control-Allow-Source-Origin', requestingSourceOrigin);

      // Sends generated URLs on the response.
      res.send(JSON.stringify({items: refreshUrlInfos}));
    });
});

const port = process.env.PORT || 3000;
app.listen(port, () => {
  console.log('Example app listening on port', port,'!');
});