Twig Function - git commit/branch

Git.php

<?php 

namespace AppBundle\Twig\Extension;

class GitExtension extends \Twig_Extension
{
    public function getFunctions()
    {
        return array(
            new \Twig_SimpleFunction('gitVersion', array($this, 'gitVersion')),
        );
    }

	/**
	 * Return current git version
	 */
	public function gitVersion()
	{
        $hash = exec('git rev-parse --short HEAD');
        $branch = exec('git rev-parse --abbrev-ref HEAD');
        $tag = exec('git describe');
        return $tag. ' ' . $hash . ' on '.$branch;
	}

    /**
     * {@inheritdoc}
     */
    public function getName()
    {
        return 'twig_git';
    }
}

Usage: version: {{ gitVersion() }}