nginx.conf

    map $host $host_or_hyphen {
        default $host;
        "" -;
    }
    log_format lighttpd
        '$remote_addr $host_or_hyphen $remote_user [$time_local] "$request" '
        '$status $body_bytes_sent "$http_referer" "$http_user_agent"';
    access_log /var/log/nginx/access.log lighttpd;