I recently set up some public computers with Ubuntu at a hackerspace. People kept logging into their Gmail etc. and forgetting to log out. For their own benefit I changed the computers to use overlayfs so on reboot all changes from the base filesystem (Ubuntu 24.04 + packages + updates) are lost. I'm looking for tips on configuration. Keep in mind that because our users tend to be fairly technical I am not attempting to outright prevent changes, just prevent them by default.

Here are the current details:

• The machines have a wallpaper warning users that all changes are wiped on reboot
• The normal automatic update system is disabled (updates through it won't persist)
• I install updates and reboot on a cronjob at 5am every day (this uses overlayroot-chroot)
• The overlay is implemented as an encrypted filesystem on a separate partition, with the key generated on boot and held in memory
• Documentation is taped to the desktop computer itself educating users on how to make persistent changes