The Kubernetes project published a guide on 6 October 2026 explaining its move from cgroup v1 to cgroup v2, written by Paco Xu of DaoCloud on the official Kubernetes blog. Cgroups are the Linux kernel feature Kubernetes uses to give containers their share of CPU and memory.
What is changing
These points are stated in the official post:
- cgroup v2 support has been stable since Kubernetes v1.25.
- cgroup v1 moved into maintenance mode in Kubernetes v1.31 and is now deprecated.
- From Kubernetes v1.35, the kubelet does not start on a cgroup v1 node by default. A temporary setting,
failCgroupV1: false, can override this. - That fallback is scheduled for removal in Kubernetes v1.38.
- From v1.35, kubeadm’s preflight check returns an error, not just a warning, when it finds cgroup v1.
What cluster operators need
According to the post, nodes need a Linux kernel of 5.8 or later (5.9 or later is recommended for memory QoS), and a container runtime that supports cgroup v2, such as containerd v1.4 or later or CRI-O v1.20 or later. The kubelet and the runtime must use the same cgroup driver, and the post recommends the systemd driver.
To check a node, the post gives this command. It prints cgroup2fs when cgroup v2 is enabled:
stat -fc %T /sys/fs/cgroup/What this means for learners
This section is our view, not part of the official post.
If you are learning DevOps, this is a good example of why Linux basics matter. Kubernetes runs on Linux nodes, and a change in the kernel layer can stop a cluster upgrade. Interviewers often ask how you would check a node’s health or plan an upgrade, and being able to explain cgroups, container runtimes and the kubelet in plain words is a strong answer.
Practise on a small local cluster: check the cgroup version on a node, read the kubelet configuration, and note what you would change before an upgrade.
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Source: “The Shift to cgroup v2 in Kubernetes: What You Need to Know”, Kubernetes blog, 6 October 2026.
