Lightwhale

Lightwhale is an immutable Linux server OS designed for self-hosting Docker and Docker Swarm workloads. It uses overlayfs to layer a writable upper filesystem over an immutable root, applying writable overlays only to key directories (/etc, /var, /home). Persistence is opt-in: writing a magic header to a storage device triggers automatic partitioning and Btrfs formatting on next boot, with optional RAID1 support for multiple disks. Docker's data root is stored directly on the persistent data filesystem. The persistence subsystem runs as an init.d script and proceeds through a well-defined sequence of detection, partitioning, formatting, and mounting steps.