rpm-ostree

OSTree is an upgrade system for Linux-based operating systems that performs atomic upgrades of complete filesystem trees. 
It is not a package system; rather, it is intended to complement them. 
A primary model is composing packages on a server, and then replicating them to clients.

The underlying architecture might be summarized as "git for operating system binaries". 
It operates in userspace, and will work on top of any Linux filesystem.

rpm: "Red Hat Package Manager" but now "RPM Package Manager".
Build rpm:
https://docs.google.com/document/d/1KrxNdQOUY3Jzw0GDA1P3VcXbMAn-JYy_pc6Bz4IdKTQ/edit
https://docs.fedoraproject.org/en-US/quick-docs/creating-rpm-packages/
https://docs.fedoraproject.org/en-US/packaging-guidelines/
https://fedoranews.org/alex/tutorial/rpm/

Ref:
https://ostree.readthedocs.io/en/latest/manual/introduction/