Backup

#What to backup?

In your backup software you need as minimum these real data :

1. /etc/hosts (but I guess you already added /etc/)
2. /opt/docker-proxy/nginx_config/ for the generated Nginx vhosts and certificates
3. optional: /opt/docker-proxy/docker-hosts.cfg

For 2+3) The project are just a few text files and shell scripts. If you add /opt/docker-proxy/ you backup a few kilobytes of data.