The simple yet easy way to boot and running GNU/Linux system READ-ONLY using OverlayFS.
Applying overlay via systemd service method, not via initramfs hook method.
####2 Modes :
- DipFrizz Mode
- KeepSession Mode
####A note about OverlayFS :
-
From https://www.kernel.org/doc/Documentation/filesystems/overlayfs.txt :
Objects that are not directories (files, symlinks, device-special files etc.) are presented either from the upper or lower filesystem as appropriate. When a file in the lower filesystem is accessed in a way the requires write-access, such as opening for write access, changing some metadata etc., the file is first copied from the lower filesystem to the upper filesystem (copy_up). Note that creating a hard-link also requires copy_up, though of course creation of a symlink does not.
It doesn't operate at block-level. Means, it doesn't really fit for editing big files. Except, you use fast storage media (SSD) and or patient enough to wait for first "copy up" process.