Enter username, server, password, ip address in etc/ppp/chap-secrets
# Secrets for authentication using CHAP
# client server secret IP addresses
user1 pptpd pass%word *
docker build -t vpn .
docker run -d --name vpn_pptp --privileged -p 1723:1723 vpn
You can add --restart=always parametr for restarting container after reboot