public function validateServerName($attribute)
{
if (!preg_match('/^[а-яa-z0-9.-]{2,255}$/', $this->{$attribute})) {
$this->addError($attribute, \Yii::t('skeeks/cms', 'Use only lowercase letters and numbers. Example {site} (2-255 characters)', ['site' => 'site.ru']));
}
}