Scalr\Model\Entity\Script::fetchVariables PHP Method

    public static function fetchVariables($content)
    {
        $text = preg_replace('/(\\\\%)/si', '$$scalr$$', $content);
        preg_match_all("/\\%([^\\%\\s]+)\\%/si", $text, $matches);
        return $matches[1];
    }

 public function save()
 {
     $this->variables = [];
     $variables = Script::fetchVariables($this->content);
     if (!empty($variables)) {
         $builtin = array_keys(\Scalr_Scripting_Manager::getScriptingBuiltinVariables());
         foreach ($variables as $var) {
             if (!in_array($var, $builtin)) {
                 $this->variables[$var] = ucwords(str_replace("_", " ", $var));
             }
         }
     }
     parent::save();
 }