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add a blog about KubeletCgroupDriverFromCRI feature
Signed-off-by: Peter Hunt <pehunt@redhat.com>
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content/en/blog/_posts/2024-08-21-cgroup-driver-from-cri.md
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--- | ||
layout: blog | ||
title: "Configuring Kubernetes just got easier: cgroup driver from CRI" | ||
date: 2024-07-01 | ||
slug: cgroup driver from CRI to betra | ||
author: > | ||
Peter Hunt (Red Hat) | ||
--- | ||
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Historically, a pain point for users running new Kubernetes clusters has been | ||
the cgroup driver. On Linux systems, there are two different cgroup drivers: | ||
`cgroupfs` and `systemd`. In the past, both the Kubelet and CRI implementation | ||
(like CRI-O or containerd) needed to be configured to use the same cgroup | ||
driver, or else the Kubelet would exit with an error. This was a source of | ||
headaches for many cluster admins. However, there is light at the end of the | ||
tunnel! | ||
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## `KubeletCgroupDriverFromCRI` Feature Gate | ||
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In v1.28.0, the SIG-Node community introduced the feature gate | ||
`KubeletCgroupDriverFromCRI`, which instructs the Kubelet to ask the CRI | ||
implementation which cgroup driver to use. It took a couple of releases for | ||
support to land in the major two CRI implementations, but as of v1.31.0, this | ||
feature is now beta! | ||
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In addition to setting the feature gate, a cluster admin needs to ensure their | ||
CRI implementation is new enough: | ||
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- containerd: Support has been added in v2.0.0 | ||
- CRI-O: Support has been added in v1.28.0 | ||
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Then, they should ensure their CRI implementation is configured to the | ||
`cgroup_driver` they would like to use. | ||
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## Future Work | ||
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Eventually, support for the Kubelet's `cgroupDriver` configuration field will be | ||
dropped, and the Kubelet will fail to start if the CRI implementation isn't new | ||
enough to have support for this feature. For now, the Kubelet's `cgroupDriver` | ||
field is used as a fallback in case the CRI implementation is not new enough, | ||
and this behavior will also be dropped. |