A nice easy to read guide: https://codeopolis.com/posts/installing-wireguard-in-docker/
The github page including readme: https://github.com/linuxserver/docker-wireguard
Recommended - set up a Dynamic DNS such as DuckDNS first: https://sensorsiot.github.io/IOTstack/Accessing-your-Device-from-the-internet/
Make sure your Raspbian build is up to date, or at least a recent build (check with uname -a), this is useful to avoid header errors later on:
sudo apt update
sudo apt full-upgrade
sudo reboot
Once complete, run ~/IOTstack/menu.sh to add wireguard to IOTstack. This will append the container details to ~/IOTstack/docker-compose.yml ready for the stack to be started (don't start yet)
Edit docker-compose.yml with your parameters:
sudo nano ~/IOTstack/docker-compose.yml
and as needed change your timezone, peers, server url etc.. This is where you put you DuckDNS server if you made one. More info on the Wireguard github.
Alternatively you may choose to use compose-override.yml as per the guide here, but please note the caveats:
https://sensorsiot.github.io/IOTstack/Custom/
Now up the stack to start the container:
docker compose up -d
Check the logs to make sure wireguard is running properly, I like to use Portainer and go to "Container>Wireguard>Logs".
If you see an error about headers, check the troubleshooting guide.
All being well you will see a QR code in the log output. Download the Wireguard app to your phone, scan the QR code and your VPN connection is set up. There are other methods to set up not covered here. Yor config files are at ~/IOTstack/services/wireguard/config.
Now you are on your phone, switch to mobile data (to simulate being on another network) and enable the VPN. You should be able to browse to local IP addresses such as 192.168.1.x as if you were inside your home WiFi network. This means you have it set up correctly. Note, you will need to forward port 51820 on your router.
Github page: https://github.com/linuxserver/docker-wireguard#application-setup
Nice youtube video: https://youtu.be/GZRTnP4lyuo
Header error: Make sure you updated your Raspian build as per the above instructions. Otherwise Google is your friend.