Casync

casync (content-addressable synchronisation) is a Linux software utility designed to distribute frequently-updated file system images over the Internet.

Utility
According to the creator Lennart Poettering, casync is inspired by rsync and Git, as well as tar. casync is aimed to be used for Internet of things (IoT), container, virtual machine (VM), portable services, and operating system (OS) images, as well as backups and home directory synchronization. casync splits images into variable size segments, uses sha256 checksums, and aims to work with content delivery networks (CDNs). Available for Linux only, packages are available for Ubuntu, Fedora and Arch Linux.

Similar software
Similar software that delivers file system images are:
 * Docker with a layered tarballs
 * OSTree