protected function getBaseUrl()
    {
        if (isset($this->baseUrl)) {
            return $this->baseUrl;
        }

        $this->baseUrl = $this->container->getParameter('tenside.self_update.base_url');

        if (false === strpos($this->baseUrl, '://')) {
            $this->baseUrl = (extension_loaded('openssl') ? 'https' : 'http') . '://' . $this->baseUrl;
        }

        return $this->baseUrl;
    }