Click packages cannot be installed as a non-root user on focal
Click packages in Ubuntu Touch based on Ubuntu 16.04 are installed using PackageKit. click provides a PackageKit plugin which allows the root-level daemon to install packages on behalf of the user. This means that click packages can be installed by a user without root-level privileges. In other words, you don't need to use sudo
to install a click.
This is especially good since installing a click requires multiple steps: first you must install the package, then it must be provisioned for every user. This allows multiple versions of a single click to be installed at once, and each user on the system can have a different version. If only Ubuntu Touch was a multi-user system...
Unfortunately, external PackageKit plugins were removed from PackageKit between the version included in 16.04 and 20.04. This means that our plugin is, well, useless. This left us with two options: rewrite the PackageKit plugin as a built-in backend for the new version or replace the PackageKit daemon with one of our own.
We're not sure we'd be able to meet the maintenance requirements of a PackageKit backend, nor the requirements to have it included in the upstream PackageKit. Therefore, we believe we should write our own click daemon for the installation of click packages.