server.js

require('dotenv').config({silent: true});

const express      = require('express');
const compress     = require('compression');
const cookieParser = require('cookie-parser');
const dateFilter   = require('nunjucks-date-filter');
const nunjucks     = require('nunjucks');
const helmet       = require('helmet');
const path         = require('path');
const Sentry       = require('@sentry/node');
const throng       = require('throng');

const { createProxyMiddleware } = require('http-proxy-middleware');

const { handleNotFound } = require('./server/pageNotFound');
const { router }         = require('./server/router');
const tools              = require('./server/tools');
const {
  checkForRedirects,
  loadLocalVars
}                        = require('./server/processRequest');
const {
  prismicMiddleware,
  announcementBarCronJob
}                        = require('./server/prismic');

const {
  API_URL,
  PORT,
  PROD,
  REDIS_URL,
  SENTRY_DSN,
  SENTRY_ENVIRONMENT,
  WEB_CONCURRENCY
} = require('./server/config');

// start up parallel servers in prod
throng({
  workers: WEB_CONCURRENCY,
  lifetime: Infinity
}, start)


function start() {
  const app = express();

  if (SENTRY_DSN) {
    Sentry.init({ dsn: SENTRY_DSN, environment: SENTRY_ENVIRONMENT });
  }

  // rate limit POST requests
  if (REDIS_URL) {
    var redis   = require('redis').createClient(REDIS_URL);
    var limiter = require('express-limiter')(app, redis);

    // rate limit POST requests
    limiter({
      path: '*',
      method: 'post',
      lookup: ['headers.CF-Connecting-IP'],
      // 15 requests per 30 seconds
      total: 15,
      expire: 1000 * 30
    })
  }

  app.set('trust proxy', true);
  // The Sentry request handler must be the first middleware on the app
  app.use(Sentry.Handlers.requestHandler());
  app.use(compress());
  app.use(cookieParser());
  app.use(helmet());
  app.enable('etag');

  app.use(checkForRedirects);

  // check if this is a valid static file
  app.use(express.static('dist', { maxAge: 1000 * 60 * 60 * 24 * 7 }));
  // cache images and static assets for 1 week
  app.use(express.static('content', { maxAge: 1000 * 60 * 60 * 24 * 7 }));

  app.use(prismicMiddleware);
  app.use(loadLocalVars);
  announcementBarCronJob(app)

  if (!PROD) {
    // Proxy for oauth when in dev mode
    app.use('/oauth', createProxyMiddleware({
      target: API_URL || 'https://staging.ionicframework.com',
      changeOrigin: true,
      secure: false
    }));
  }

  // Proxy for Appflow wizard
  const wizardOptions = {
    target: API_URL,
    changeOrigin: true,
    secure: false,
    pathRewrite: {
      '^/api/v1/wizard': '/apps/wizard/request',
    }
  };
  app.use('/api/v1/wizard', createProxyMiddleware(wizardOptions));

  nunjucks.configure('server/pages', {
    express: app,
    noCache: !PROD,
    autoescape: false
  }).addFilter('date', dateFilter);

  app.set('views', path.resolve(__dirname, '/server/pages'));
  app.set('view engine', 'html');

  app.use(router(app));

  // The Sentry error handler must be before any other error middleware
  app.use(Sentry.Handlers.errorHandler());

  app.use(handleNotFound);

  // bind the app to listen for connections on a specified port
  app.listen(PORT, function() {
    console.log('Listening on port ' + PORT);
    // 5 min delay for heroku rolling start to complete
    setTimeout(tools.bustCloudflareCache, 1000 * 60 * 5);
  });
} // end start()