The OS image we currently produce is unsuitable as a base for building Flatcar specific sysext images: it lacks package information and portage configuration. During the image build process our low-level build automation removes this information from the OS image to keep it lean.

In order to build sysext images suitable for running on a specific OS release, the image build needs to be extended to produce artifacts retaining this information.

Part of the work is already in progress here: flatcar/scripts#858

This issue builds on that work with the aim to make it more generally usable for all future Flatcar / version specific sysext builds.