app.js

/**
 * Copyright 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.
 */

// [START app]
'use strict';

// [START setup]
const express = require('express');
const crypto = require('crypto');

const app = express();
app.enable('trust proxy');

// By default, the client will authenticate using the service account file
// specified by the GOOGLE_APPLICATION_CREDENTIALS environment variable and use
// the project specified by the GCLOUD_PROJECT environment variable. See
// https://googlecloudplatform.github.io/gcloud-node/#/docs/google-cloud/latest/guides/authentication
// These environment variables are set automatically on Google App Engine
const Datastore = require('@google-cloud/datastore');

// Instantiate a datastore client
const datastore = Datastore();
// [END setup]

// [START insertVisit]
/**
 * Insert a visit record into the database.
 *
 * @param {object} visit The visit record to insert.
 */
function insertVisit (visit) {
  return datastore.save({
    key: datastore.key('visit'),
    data: visit
  });
}
// [END insertVisit]

// [START getVisits]
/**
 * Retrieve the latest 10 visit records from the database.
 */
function getVisits () {
  const query = datastore.createQuery('visit')
    .order('timestamp', { descending: true })
    .limit(10);

  return datastore.runQuery(query)
    .then((results) => {
      const entities = results[0];
      return entities.map((entity) => `Time: ${entity.timestamp}, AddrHash: ${entity.userIp}`);
    });
}
// [END getVisits]

app.get('/', (req, res, next) => {
  // Create a visit record to be stored in the database
  const visit = {
    timestamp: new Date(),
    // Store a hash of the visitor's ip address
    userIp: crypto.createHash('sha256').update(req.ip).digest('hex').substr(0, 7)
  };

  insertVisit(visit)
    // Query the last 10 visits from Datastore.
    .then(() => getVisits())
    .then((visits) => {
      res
        .status(200)
        .set('Content-Type', 'text/plain')
        .send(`Last 10 visits:\n${visits.join('\n')}`)
        .end();
    })
    .catch(next);
});

// [START listen]
const PORT = process.env.PORT || 8080;
app.listen(process.env.PORT || 8080, () => {
  console.log(`App listening on port ${PORT}`);
  console.log('Press Ctrl+C to quit.');
});
// [END listen]
// [END app]

module.exports = app;