Ubuntu has a very detailed documentation about OpenVPN server configuration. The key feature of this note is script for automatic generation of single-file client configurations (keys and certs are embedded) and sending them by email. Looks interesting? Read below!
I've completed setting up my comfort set of LXC containers and want to save some points I spent a lot of time for or things for copy-paste.
I used the official Ubuntu Server Guide but note at Digital Ocean knowledge base also helped me a lot. I created 3 containers: one for vpn, one for site on Drupal and last one as www proxy for second one with nginx only.
Depends on server configuration, each OpenVPN client needs configuration file (client.conf for *nix and client.ovpn for windows), certificate authority (ca.crt), [optional] tls auth file (ta.key), user crt and key.