protected function hostNameForConfigFile($server_name = null, $server =null)
    {
        $server_name = $server_name ? $server_name: $this->getServerName();
        $server = $server ? $server: $this->getServer();
        $this->checkServerName($server_name);
        $this->checkServer($server);
        return snake_case($server_name) . '_' . $server;
    }