title: Why .env should not be loaded in production in Symfony4?
body: <p>The front controller <code>index.php</code> <a href="https://github.com/symfony/recipes/blob/master/symfony/framework-bundle/3.3/public/index.php#L10" rel="nofollow noreferrer">has by default</a>:</p>
  
  <pre><code>// The check is to ensure we don't use .env in production
  if (!isset($_SERVER['APP_ENV'])) {
      (new Dotenv())-&gt;load(__DIR__.'/../.env');
  }
  </code></pre>
  
  <p>What's the reason behind this? Why <code>.env</code> file should be ignored in the production environment?</p>