Appears to launch and run without the environment variables had to steal a little code from the OVPN one and modify it to suit SoftEther VPN.
The docker run command I issue to run it without rockstor is
docker run -d -e "SPW=test123" -e "HPW=test123" --cap-add NET_ADMIN -p 500:500/udp -p 4500:4500/udp -p 1701:1701/tcp -p 1194:1194/udp -p 5555:5555/tcp -p 992:992/tcp siomiz/softethervpn
However I can not figure out how to pass 2 variables that are user defineable to the docker container.
The variables are in the below format.
All optional: -e PSK: Pre-Shared Key (PSK), if not set: "notasecret" (without quotes) by default. -e USERS: Multiple usernames and passwords may be set with the following pattern: username:password;user2:pass2;user3:pass3. Username and passwords are separated by :. Each pair of username:password should be separated by ;. If not set a single user account with a random username ("user[nnnn]") and a random weak password is created. -e SPW: Server management password. :warning: -e HPW: "DEFAULT" hub management password. :warning:
see https://hub.docker.com/r/siomiz/softethervpn/ for a further explanation.