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Kubernetes upgrade notes: 1.34.x to 1.35.x

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Upgrade notes to Kubernetes 1.35 (esp. if you use my Kubernetes Ansible roles)

If you used my Kubernetes the Not So Hard Way With Ansible blog posts to setup a Kubernetes (K8s) cluster this notes might be helpful for you (and maybe for others too that manage a K8s cluster on their own e.g.). I’ll only mention changes that might be relevant because they will either be interesting for most K8s administrators anyways (even in case they run a fully managed Kubernetes deployment) or if it’s relevant if you manage your own bare-metal/VM based on-prem Kubernetes deployment. I normally skip changes that are only relevant for GKE, AWS EKS, Azure or other cloud providers.

I’ve a general upgrade guide Kubernetes the Not So Hard Way With Ansible - Upgrading Kubernetes that worked quite well for me for the last past K8s upgrades. So please read that guide if you want to know HOW the components are updated. This post here is esp. for the 1.34.x to 1.35.x upgrade and WHAT was interesting for me.

As usual I normally don’t update a production system before the .2 release of a new major version is released. In my experience the .0 and .1 are just too buggy (well, it got way better meanwhile but you don’t want do experiments in production, right? 😉). Nevertheless it’s important to test new releases (and even beta or release candidates if possible) already in development environments and report bugs!

I only upgrade from the latest version of the former major release. At the time writing this blog post 1.34.8 was the latest 1.34.x release. After reading the 1.34 CHANGELOG to figure out if any important changes where made between the current 1.34.x and latest 1.34.8 release I didn’t see anything that prevented me updating and I don’t needed to change anything.

So I did the 1.34.8 update first. If you use my Ansible roles that basically only means to change k8s_ctl_release variable from 1.34.x to 1.34.8 (for the controller nodes) and the same for k8s_worker_release (for the worker nodes). Deploy the changes for the control plane and worker nodes as described in my upgrade guide.

Hint: To save some time, IMHO it should be good enough to only update the controller nodes to the latest 1.34.x release as it’s mostly the kube-apiserver that stores the state of the Kubernetes cluster in etcd and that state is quite important. That’s what I normally do. Upgrading to the next major release can then be done for all nodes as usual. But if you want to be absolutely sure just upgrade the whole cluster to the latest 1.34.x release first.

After that everything still worked as expected, I continued with the next step.

As it’s normally no problem (and actually the supported method) to have a newer kubectl utility that is only one major version ahead of the server version I updated kubectl from 1.32.x to latest 1.33.x using my kubectl Ansible role.

While my roles are not using kubeadm to manage my K8s cluster, it’s recommended to have at least etcd 3.5.24 running but 3.5.26 is definitely the better option (see below). I updated my etcd role to current 3.5.26 and updated my etcd deployment accordingly. See Upgrading Kubernetes - etcd for more information how to upgrade etcd.

NOTE 1: There is already etcd 3.6.x available. But for K8s 1.35 I’ll stay with etcd 3.5 for now. etcd 3.6.x has some breaking changes that needs to be addressed first. Upgrading etcd to 3.6.x is planned with the next major release upgrade.

NOTE 2: If you use etcd for Kubernetes and want to upgrade to etcd v3.6 you DEFINITELY want to upgrade to etcd v3.5.26 first! For further information:

containerd was updated from 2.2.1 to 2.3.0. I updated my containerd role accordingly. Please read the CHANGELOG for potential breaking changes. From my experience the upgrade “just works”. But if you upgrade that role before version 0.17.0+2.2.1 then please check the CHANGELOG.

containerd >= 2.0 is also a prerequisite to use user namespace isolation which got enabled by default as of Kubernetes 1.33.

runc was upgraded from 1.3.2 to 1.4.2. I’ve updated my runc role accordingly. Release notes for runc are in runc releases but shouldn’t be that interesting.

With runc >= 1.2 and containerd >= 2.0 (as mentioned above) User Namespaces are finally supported. Together with Kubernetes release > v1.33 user namespace isolation finally arrived out of the box and you should consider using it.

And finally the CNI plugins are updated from 1.8.0 to 1.9.1. Again I updated my CNI role accordingly. The release notes for CNI 1.9.1 might be worth a read but only if you want to go deeper 😉

Since K8s 1.14 there are also searchable release notes available. You can specify the K8s version and a K8s area/component (e.g. kubelet, apiserver, …) and immediately get an overview what changed in that regard. Quite nice! 😉

NOTE: If you use etcd for Kubernetes and want to upgrade to etcd v3.6 you DEFINITELY want to upgrade to etcd v3.5.26 first! For further information:

I guess most users wont be affected by any Urgent Upgrade Notes. Here are the potentially important ones:

  • Removed the --pod-infra-container-image flag from kubelet command line.
  • cgroups v1 wont work out of the box anymore. kubelet wont start if cgroups v1 is detected. This most probably only affects users running Kubernetes on older Linux distributions that do not support cgroups v1.

All important stuff is listed in the Kubernetes v1.35: Timbernetes release announcement.

The following list of changes and features only contains stuff that I found useful and interesting. That means I’m normally not mentioning any Kubernetes internals that have changed but mostly stuff that is interesting for administrators and operation. This is mainly to remember myself what changed 😉 See the full Kubernetes v1.35 Changelog for all changes.

  • etcd: Updated to v3.5.26

If you use CSI then also check the CSI Sidecar Containers documentation. Every sidecar container contains a matrix which version you need at a minimum, maximum and which version is recommend to use with whatever K8s version.

Nevertheless if your K8s update to v1.35 worked fine I would recommend to also update the CSI sidecar containers sooner or later.

Now I finally upgraded the K8s controller and worker nodes to version 1.35.x as described in Kubernetes the Not So Hard Way With Ansible - Upgrading Kubernetes.

That’s it for today! Happy upgrading! 😉

Updated on 2026-05-18
 Kubernetes, Update, Upgrade, Ansible
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