I ran bash vst-install.sh --nginx no --apache no --phpfpm no --named yes --remi yes --vsftpd no --proftpd no --iptables no --fail2ban no --quota no --exim no --dovecot no --spamassassin no --clamav no --softaculous no --mysql no --postgresql no in container with minimal Ubuntu 18.04 to use it only as a DNS slave.

But nginx repos were added, nginx, roundcube etc. packages were installed. They are not needed and were explicitly disable by cli arguements.