Overridden GlobalVariables object to add more to the twig {{ app }} global variable

AppKernel.php

<?php

use Symfony\Component\HttpKernel\Kernel;
use Symfony\Component\Config\Loader\LoaderInterface;

class AppKernel extends Kernel
{
    // ....

    protected function getKernelParameters()
    {
        $parameters = parent::getKernelParameters();
        $parameters['app.version'] = trim(shell_exec('git describe --tags --always'));

        return $parameters;
    }
}

config.yml

parameters:
    templating.globals.class: Project\AppBundle\Twig\GlobalVariables

GlobalVariables.php

<?php

/**
 * This file is part of the PROJECT
 *
 * (c) Infinite Networks Pty Ltd <http://www.infinite.net.au>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Project\AppBundle\Twig;

use Symfony\Bundle\FrameworkBundle\Templating\GlobalVariables as BaseGlobalVariables;
use Symfony\Component\DependencyInjection\ContainerInterface;

/**
 * An extended value object to store additional global variables to be accessed
 * in Twig.
 */
class GlobalVariables extends BaseGlobalVariables
{
    /**
     * Stores breadcrumbs for display.
     *
     * @var \SplQueue
     */
    public $breadcrumbs;

    /**
     * Stores the current request time.
     *
     * @var \DateTime
     */
    public $date;

    /**
     * Stores an array of date formats to be used inside twig.
     *
     * @var array<string>
     */
    private $formats;

    public function __construct(ContainerInterface $container)
    {
        parent::__construct($container);

        $this->breadcrumbs = new \SplQueue;
        $this->date = new \DateTime;
    }

    public function getFormats()
    {
        if (null === $this->formats) {
            $this->formats = array(
                'date' => $this->container->getParameter('format.date'),
                'datetime' => $this->container->getParameter('format.datetime'),
                'shortdate' => $this->container->getParameter('format.shortdate'),
                'shorttime' => $this->container->getParameter('format.shorttime'),
                'time' => $this->container->getParameter('format.time'),
            );
        }

        return $this->formats;
    }

    /**
     * Returns the application name
     *
     * @return string
     */
    public function getName()
    {
        return $this->container->getParameter('app.name');
    }

    /**
     * Returns the applications short name.
     *
     * @return string
     */
    public function getShortName()
    {
        return $this->container->getParameter('app.short_name');
    }

    /**
     * Returns the detected version of the application.
     *
     * @return string
     */
    public function getVersion()
    {
        return $this->container->getParameter('app.version');
    }
}

Thank you very much