Kubernetes v1.35 Sneak Peek

Kubernetes v1.35 Sneak Peek As the release of Kubernetes v1.35 approaches, the Kubernetes project continues to evolve. Features may be deprecated, removed, or replaced to improve the project's overall health. This blog post outlines planned changes for the v1.35 release that the release team believes you should be aware of to ensure the continued smooth operation of your Kubernetes cluster(s), and to keep you up to date with the latest developments. The information below is based on the current status of the v1.35 release and is subject to change before the final release date. Deprecations and removals for Kubernetes v1.35 cgroup v1 support On Linux nodes, container runtimes typically rely on cgroups (short for "control groups"). Support for using cgroup v2 has been stable in Kubernetes since v1.25, providing an alternative to the original v1 cgroup support. While cgroup v1 provided the initial resource control mechanism, it suffered from well-known inconsistencies and limitations. Adding support for cgroup v2 allowed use of a unified control group hierarchy, improved resource isolation, and served as the foundation for modern features, making legacy cgroup v1 support ready for removal. The removal of cgroup v1 support will only impact cluster administrators running nodes on older Linux distributions that do not support cgroup v2; on those nodes, the kubelet will fail to start. Administrators must migrate their nodes to systems with cgroup v2 enabled. More details on compatibility requirements will be available in a blog post soon after the v1.35 release. To learn more, read about cgroup v2 ; you can also track the switchover work via KEP-5573: Remove cgroup v1 support . Deprecation of ipvs mode in kube-proxy Many releases ago, the Kubernetes project implemented an ipvs mode in kube-proxy . It was adopted as a way to provide high-performance service load balancing, with better performance than the existing iptables mode. However, maintaining feature parity between ipvs and other kube-proxy modes became difficult, due to technical complexity and diverging requirements. This created significant technical debt and made the ipvs backend impractical to support alongside newer networking capabilities. The Kubernetes project intends to deprecate kube-proxy ipvs mode in the v1.35 release, to streamline the kube-proxy codebase. For Linux nodes, the recommended kube-proxy mode is already nftables . You can find more in KEP-5495: Deprecate ipvs mode in kube-proxy Kubernetes is deprecating containerd v1.y support While Kubernetes v1.35 still supports containerd 1.7 and other LTS releases of containerd, as a consequence of automated cgroup driver detection, the Kubernetes SIG Node community has formally agreed upon a final support timeline for containerd v1.X. Kubernetes v1.35 is the last release to offer this support (aligned with containerd 1.7 EOL). This is a final warning that if you are using containerd 1.X, you must switch to 2.0 or later before upgrading Kubernetes to the next version. You are able to monitor the kubelet_cri_losing_support metric to determine if any nodes in your cluster are using a containerd version that will soon be unsupported. You can find more in the official blog...

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