Introducing ue-rs, minimal and secure rewrite of update engine in Flatcar (asg2025)

Introduce ue-rs, a fresh project that aims to be a drop-in reimplementation of update engine, written in Rust. The goal of ue-rs is to have a minimal, secure and robust implementation of update engine, required by A/B update mechanism of Flatcar Container Linux. Just like the existing update engine, it downloads OS update payloads from a Nebraska server, parses its Omaha protocol, verifies signatures, etc. This project, however, is different from the original update engine in the following aspects. First, it aims to be minimal, by reducing heavyweight legacies in the update engine. Moreover, written in Rust, it brings a huge advantage for security, especially memory safety, in contrast to the original update engine, which is written mainly in C++ and bash. Finally, in addition to traditional OS update payloads, it supports systemd-sysext OEM, which is supported by Flatcar. Licensed to the public under https://creativecommons.org/licenses/by/4.0/de/ about this event: https://cfp.all-systems-go.io/all-systems-go-2025/talk/JAC3DH/