add note for cgroup v1 deprecation during kubelet upgrade #53082
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lmktfy
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Nov 4, 2025
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Thanks.
I recommend aligning closer to our style guide.
Also, make it clear that this advice is for Linux nodes. Other OS are available.
| If you are using cgroups v1, you should migrate to cgroups v2. | ||
| To explicitly enable cgroups v1 support for kubelet v1.35 or newer, | ||
| you must set the kubelet configuration option 'FailCgroupV1' to 'false'. You must also explicitly skip this validation. | ||
| For more information, see https://git.k8s.io/enhancements/keps/sig-node/5573-remove-cgroup-v1. |
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We should link to the docs about the deprecation, not to the KEP.
| If you are using cgroups v1, you should migrate to cgroups v2. | ||
| To explicitly enable cgroups v1 support for kubelet v1.35 or newer, | ||
| you must set the kubelet configuration option 'FailCgroupV1' to 'false'. You must also explicitly skip this validation. | ||
| For more information, see https://git.k8s.io/enhancements/keps/sig-node/5573-remove-cgroup-v1. |
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We should link to the docs about the deprecation, not to the KEP.
| ### Upgrade kubelet and kubectl | ||
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| {{< note >}} | ||
| FailCgroupV1 is a kubelet configuration option that is set to 'true' by default. |
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Style and wording nit:
Suggested change
| FailCgroupV1 is a kubelet configuration option that is set to 'true' by default. | |
| On Linux nodes, the kubelet defaults to supporting only cgroups v2. | |
| For Kubernetes {{< skew currentVersion >}} the `FailCgroupV1` kubelet configuration option is set to true by default. |
| ### Upgrade kubelet and kubectl | ||
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| {{< note >}} | ||
| FailCgroupV1 is a kubelet configuration option that is set to 'true' by default since v1.35. |
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Style and wording nit:
Suggested change
| FailCgroupV1 is a kubelet configuration option that is set to 'true' by default since v1.35. | |
| On Linux nodes, the kubelet defaults to supporting only cgroups v2. | |
| For Kubernetes {{< skew currentVersion >}} the `FailCgroupV1` kubelet configuration option is set to true by default. |
| The cgroups v1 support is deprecated and will be removed in a future release. | ||
| If you are using cgroups v1, you should migrate to cgroups v2. | ||
| To explicitly enable cgroups v1 support for kubelet v1.35 or newer, | ||
| you must set the kubelet configuration option 'FailCgroupV1' to 'false'. You must also explicitly skip this validation. |
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Suggested change
| you must set the kubelet configuration option 'FailCgroupV1' to 'false'. You must also explicitly skip this validation. | |
| you **must** set the kubelet configuration option `FailCgroupV1` to false. You must also explicitly skip this kubeadm validation. |
| The cgroups v1 support is deprecated and will be removed in a future release. | ||
| If you are using cgroups v1, you should migrate to cgroups v2. | ||
| To explicitly enable cgroups v1 support for kubelet v1.35 or newer, | ||
| you must set the kubelet configuration option 'FailCgroupV1' to 'false'. You must also explicitly skip this validation. |
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Suggested change
| you must set the kubelet configuration option 'FailCgroupV1' to 'false'. You must also explicitly skip this validation. | |
| you **must** set the kubelet configuration option `FailCgroupV1` to false. You must also explicitly skip this kubeadm validation. |
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| {{< note >}} | ||
| FailCgroupV1 is a kubelet configuration option that is set to 'true' by default since v1.35. | ||
| If you are using cgroups v1, kubelet will fail to start if the FailCgroupV1 is not set.. |
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Suggested change
| If you are using cgroups v1, kubelet will fail to start if the FailCgroupV1 is not set.. | |
| If you are using cgroups v1 and the `FailCgroupV1` setting is not set to true, | |
| the kubelet reports an error and fails to start. |
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| {{< note >}} | ||
| FailCgroupV1 is a kubelet configuration option that is set to 'true' by default. | ||
| If you are using cgroups v1, kubelet will fail to start if the FailCgroupV1 is not set. |
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Suggested change
| If you are using cgroups v1, kubelet will fail to start if the FailCgroupV1 is not set. | |
| If you are using cgroups v1 and the `FailCgroupV1` setting is not set to true, | |
| the kubelet reports an error and fails to start. |
neolit123
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Nov 6, 2025
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instead of including similar text in multiple places, can we include a note that links to a central blog post or a document that covers the problem?
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Description
refer to kubernetes/system-validators#58 (comment)
Issue
xref: kubernetes/kubernetes#134744