Request a login (username and password) for the Rentouch-Docker-Hub from Rentouch if you do not already have one.
docker login harbor3.piplanning.io
If your server does not have a connection to the internet:
Install the updated offline installable images
Request a download link from rentouch for the updated .tar archived docker images.
Move the .tar archive to the server on which you are installing pi-server.
Input the command:(this may takes a minute...)
docker load -i pi-server-images_1.8.0.tar
Update PI-Server config files
On the host-system download the newest version (checkout https://binaries.rentouch.ch/on-premise to see all versions) of the PI-Server docker archive and extract it:
wget https://binaries.rentouch.ch/on-premise/pi-server-docker_1.8.0.tar
mkdir -p pi-server-docker_1.8.0 && tar -xf pi-server-docker_1.8.0.tar -C pi-server-docker_1.8.0
cd pi-server-docker_1.8.0
Run the updater. You have to pass the path to your PI-Server folder (which contains the docker-compose and all the data) as the first argument.