public function getOutput(): string
    {
        $log_file = $this->config->getLogFile();
        if (!file_exists($log_file)) {
            $msg = "Server output log file does not exists '$log_file'";
            $this->logger->error("Get server output failed: $msg");
            throw new Exception\RuntimeException($msg);
        } elseif (!is_readable($log_file)) {
            $msg = "Cannot read log file do to missing read permission '$log_file'";
            $this->logger->error("Get server output failed: $msg");
            throw new Exception\RuntimeException($msg);
        }
        $output = file_get_contents($log_file);

        return $output;
    }