I tried to setup a OpenVPN Server on a LXD alpine-linux container.
So as i understand it correctly the tun/tap device is provided by LXD. But the OpenVPN server have problems to access the device:
TUN/TAP device tap0 opened
Note: Cannot set tx queue length on tap0: Operation not permitted (errno=1)
I don’t think installing openvpn in a container represents any specific issues. I set up the openvpn container using macvlan, so it get’s its IP address from the router. I have arranged for the router to forward openvpn’s required ports to the openvpn server, and once connected, I can then interact directly with all internal devices (except the lxd host). I installed using the openvpn-access-server (https://openvpn.net/index.php/access-server/overview.html), and it worked ‘out of the box’, but If you install openvpn by hand, it should work the same way.