icingaweb2/application/layouts/scripts/parts/navigation.phtml

<?php

use Icinga\Web\Url;
use Icinga\Web\Menu;

// Don't render a menu for unauthenticated users unless menu is auth aware
if (! $this->auth()->isAuthenticated()) {
    return;
}

// Current url
$url = Url::fromRequest()->remove('_render')->getRelativeUrl();
$menu = Menu::fromConfig();
?>
<div id="menu" data-base-target="_main">
  <form action="<?= $this->href('search') ?>" method="get">
    <input type="text" name="q" class="search" placeholder="Search..." autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" />
  </form>
<?= $this->partial('parts/menu.phtml', array(
    'items' => $menu->getChildren(),
    'url'   => $url
)) ?>
</div>