Best way to approach updatable custom cms?
I currently have to work with an old cakePHP 1.3 cms tailored for a specific customers. The guy I'm doing development for wants to upgrade and move to another framework and create a new cms. Because this is such a niche specific cms we want to add ability to update the cms from the admin panel, over the air - there are 70-100+ websites at all times up and running and updating them manually is not viable. And probably have modules that would be separate but easily installable from the admin panel. Whats the best approach here? Any good examples already working in the wild? First thing that popped into my mind is opencart with the ocmod for custom mods, the problem being updates for it.