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

<?php
// determine current key
$url = Zend_Controller_Front::getInstance()->getRequest()->getRequestUri();
$currentKey = isset($this->navkey) ? $this->navkey : $url;

$item = $this->navigation->keys("menu");
?>
<?php if ($this->auth()->isAuthenticated()): ?>
<ul class="nav nav-stacked" >
  <?php
  $activeSet = false;
  foreach ($item as $itemName) {
      if($itemName[0] == "_") {
          ?>
          <li class="section-end"></li>
          <?php
          continue;
      }

      $item = $this->navigation->menu->$itemName;
      $active = false;
      $url = "";

      if (is_string($item)) {
          $active = !$activeSet && $this->baseUrl($item) == $currentKey;
          $url = $this->baseUrl($item);
      } else {
          $url = $this->baseUrl(isset($item->route) ? $item->route : "");
          $itemName = isset($item->title) ? $item->title : $itemName;
          $active = !$activeSet && (isset($item->key) ? $item->key : $url) === $currentKey;
      }
      $activeSet = $activeSet || $active;
      ?>
    <li class="<?= $active ? "active" : "" ?>">
      <a href="<?= $url ?>"><?= $itemName ?></a>
    </li>
      <?php
      $class = "";
  }
  ?>
</ul>
<? endif ?>