OpenVPN in a Docker container on a Raspberry Pi

Install Docker on the Pi
Clone the OpenVPN for Docker repository
Enter the docker-openvpn folder
Build the image

docker build -t your-prefix/open-vpn .

Follow the README in the repo or these slightly modified instructions below:

Initialise the data volume

export OVPN_DATA="ovpn-data"
export OVPN_IMAGE="your-prefix/open-vpn"
docker volume create --name ${OVPN_DATA}
docker run -v ${OVPN_DATA}:/etc/openvpn --rm ${OVPN_IMAGE} ovpn_genconfig -u udp://your.server.vpn
docker run -v ${OVPN_DATA}:/etc/openvpn --rm -it ${OVPN_IMAGE} ovpn_initpki
# (this can take a while)

Start the server

docker run -v ${OVPN_DATA}:/etc/openvpn -d -p 1194:1194/udp --cap-add=NET_ADMIN --restart=always ${OVPN_IMAGE}

Generate a client certificate with a passphrase

docker run -v ${OVPN_DATA}:/etc/openvpn --rm -it ${OVPN_IMAGE} easyrsa build-client-full your-client-name

Retrieve the client configuration with embedded certificates for the use within OpenVPN Connect

docker run -v ${OVPN_DATA}:/etc/openvpn --rm ${OVPN_IMAGE} ovpn_getclient your-client-name > your-client-name.ovpn

Fetch the .ovpn file from your server
Archive with the passphrase password

zip -er your-client-name.zip your-client-name.ovpn

Distribute the zip to the 'client' and send the passphrase in a separate channel.

To access your VPN server from outside your home, configure NAT (or Port Forwarding) on your router and specify port 1194 and the (static) IP address of your VPN server. Then use the configured VPN client to connect, either by IP address or domain name.