Flatcar Container Linux, a continuation of the CoreOS project, focuses on backward compatibility with a fixed set of software, relying on containers for customization. However, scenarios requiring extensions beyond the original design have emerged. Luckily, Flatcar has evolved with systemd-sysext to facilitate reliable infrastructure automation. This innovative solution allows for user-provided software integration at the OS level without compromising system integrity. This approach streamlines the deployment of custom Docker/containerd versions and cloud vendor tools, enhancing user flexibility while maintaining system stability. These advancements represent a significant shift towards a more modular and user-friendly OS, setting Flatcar apart as a leading innovator in the field.
https://www.flatcar.org/blog/2024/04/os-innovation-with-systemd-sysext/