Gulp task for static rendering for Este

staticRender.js

gulp.task('static-render', done => {
  args.production = true;

  const pages = {
    '/': 'index.html',
    '/foo-bla-bar': '404.html'
  };

  const fetch = path => new Promise((resolve, reject) => {
    require('http').get({host: 'localhost', path, port: 8000}, res => {
      // Explicitly treat incoming data as utf8 (avoids issues with multi-byte).
      res.setEncoding('utf8');
      let body = '';
      res.on('data', data => body += data);
      res.on('end', () => resolve(body));
    }).on('error', reject);
  });

  const staticRender = () => {
    const promises = Object.keys(pages)
      .map(path => fetch(path).then(html => {
        require('fs')
          .writeFile('build/' + pages[path], html.replace(/_assets\//g, ''));
      }));
    return Promise.all(promises);
  };

  runSequence('clean', 'build', () => {
    const proc = require('child_process').spawn('node', ['./src/server']);
    proc.stdout.on('data', data => {
      if (data.indexOf('Server started') === -1) return;
      staticRender().then(() => {
        done();
        proc.kill();
      });
    });
  });
});