Comment by thesnide
I'm also doing bootable images. But the old way with a r/o initrd, that does then mount the rootfs.
The rootfs can be mkfs and rsynced nicely.
That said, the article is awesome and the idea very clever.
But more to do streaming replication that dd catchup.
initrd with native OverlayFS kernel support is very versatile. ;)
Yet the btrfs, CephFS, or ZFS all have snapshot syncing tricks that make state mirrors far more practical and safe to pull off. =3