We need some packages from the unmaintained repository, but the UCS installation at the docker container has this variable set to “no”
I try to create a join script which will set this variable, but our join script will not be deploied inside the container.
What could we do?
The join script is not run inside the container. It is run on the outside (because not all containers can run join scripts - not all containers are based on appbox).
You want a script that is run inside the container. In this case, setup would be the correct one.
I used this opportunity to add a snippet to our documentation about the various scripts:
https://wiki.univention.de/index.php/Docker_Apps/Container_Scripts#setup_in_UCS_based_containers
Note that for appbox Apps, you could just download the packages on a full UCS server with unmaintained enabled (ucr set repository/online/unmaintained=yes && apt update && apt download ...) and then upload these packages to your repository in the App Center.