Definition. An immutable, container-optimised Linux distribution in the tradition of CoreOS Container Linux. Flatcar is updated through atomic image updates, has a read-only root and is designed purely for running containers and Kubernetes nodes. The distribution is now maintained under the umbrella of the CNCF.

Why it matters. Flatcar is an established middle ground: less stripped down than Talos, closer to classic Linux workflows, but still immutable. For teams that run Kubernetes nodes themselves and want to keep SSH workflows, it is a pragmatic default.

Related. Immutable Infrastructure, Talos Linux, Bottlerocket, Kubernetes Worker Node