How can I use openvpn?

This is how I got openvpn client work from startup:

yum install openvpn

systemctl enable openvpn@[conf_name].service

systemctl start openvpn@[conf_name].service

Then, make sure openvpn starts after Docker service.

nano /etc/systemd/system/multi-user.target.wants/openvpn@[conf_name].service

[Unit]
Description=OpenVPN Robust And Highly Flexible Tunneling Application On %I
Requires=docker.service
After=network.target docker.service

Then check if tun0 is up:

ifconfig