I'm looking for methods and software to help create a variant of lubuntu that will restore itself to an install state and/or update on every boot. I'm thinking of doing things like putting the root filesystem on a squashfs and using unionfs and tmpfs to make root writable, but automagically restorable. I'm thinking of updating the squashfs with rsync. Perhaps there are other ways to approach the problem. Perhaps root needn't be writable at all. All thoughts welcome.

The home dir would be writable in the usual way.

The goal, if it matters, is a Linux that's simple to maintain from the home office, but that functions correctly for customers. We have some custom software that we wish for customers to be able to run trivially on equipment we provide. Ideally these devices would have a "restore to factory" function that would put it back the way we intended. If this is part of the normal boot cycle, so much the better.

Why lubuntu? Personal preference for this application. It has a usable desktop, but doesn't take up much ram.