Goal is to have MCO ability to apply existing content generated in rendered config on top of Customer Base Image in containerized format.

Customer Base Image is a container image containing rhcos image + (hotfix or user content).

In today's MCO working model, final content that it applies on the node like ignition configs, kargs, extensions, cluster proxy config etc gets rendered into rendered config. To switch to layering model, we would need to apply these content as a container layer on top of the Base OS container image. Base OS container image can be just rhcos image or Customer Base Image.

Some of the related work was done in the MCO repo layering branch in epic https://issues.redhat.com/browse/MCO-188 .