kubeadm leaves backup files after a successful upgrade

[davidwtf]

What happened?

When I successfully upgraded the cluster using kubeadm, I found the /etc/kubernetes/tmp, which contains the backup files, was left.

~]# du -h /etc/kubernetes/tmp/
20K	/etc/kubernetes/tmp/kubeadm-backup-manifests-2024-06-06-18-02-44
32M	/etc/kubernetes/tmp/kubeadm-backup-etcd-2024-06-06-18-02-44/etcd/member/snap
123M	/etc/kubernetes/tmp/kubeadm-backup-etcd-2024-06-06-18-02-44/etcd/member/wal
155M	/etc/kubernetes/tmp/kubeadm-backup-etcd-2024-06-06-18-02-44/etcd/member
155M	/etc/kubernetes/tmp/kubeadm-backup-etcd-2024-06-06-18-02-44/etcd
155M	/etc/kubernetes/tmp/kubeadm-backup-etcd-2024-06-06-18-02-44
16K	/etc/kubernetes/tmp/kubeadm-backup-manifests-2024-06-06-18-13-10
32M	/etc/kubernetes/tmp/kubeadm-backup-etcd-2024-06-06-18-13-10/etcd/member/snap
123M	/etc/kubernetes/tmp/kubeadm-backup-etcd-2024-06-06-18-13-10/etcd/member/wal
155M	/etc/kubernetes/tmp/kubeadm-backup-etcd-2024-06-06-18-13-10/etcd/member
155M	/etc/kubernetes/tmp/kubeadm-backup-etcd-2024-06-06-18-13-10/etcd
155M	/etc/kubernetes/tmp/kubeadm-backup-etcd-2024-06-06-18-13-10
4.0K	/etc/kubernetes/tmp/kubeadm-kubelet-config3316271885
16K	/etc/kubernetes/tmp/kubeadm-backup-manifests-2024-06-06-18-22-34
32M	/etc/kubernetes/tmp/kubeadm-backup-etcd-2024-06-06-18-22-34/etcd/member/snap
123M	/etc/kubernetes/tmp/kubeadm-backup-etcd-2024-06-06-18-22-34/etcd/member/wal
155M	/etc/kubernetes/tmp/kubeadm-backup-etcd-2024-06-06-18-22-34/etcd/member
155M	/etc/kubernetes/tmp/kubeadm-backup-etcd-2024-06-06-18-22-34/etcd
155M	/etc/kubernetes/tmp/kubeadm-backup-etcd-2024-06-06-18-22-34
4.0K	/etc/kubernetes/tmp/kubeadm-kubelet-config3278283034
463M	/etc/kubernetes/tmp/

What did you expect to happen?

I would like to know if this is intended or if it's a bug.
Maybe the document https://kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade/ should make it clear that the user needs to remove the backup files manually.

How can we reproduce it (as minimally and precisely as possible)?

Upgrade the cluster with kubeadm.

Anything else we need to know?

No response

Kubernetes version

$ kubectl version
Client Version: v1.28.8
Kustomize Version: v5.0.4-0.20230601165947-6ce0bf390ce3
Server Version: v1.28.8

upgraded from v1.25.16 to v1.26.15 to 1.27.12 to 1.27.8

Cloud provider

OS version

# On Linux:
$ cat /etc/os-release
# paste output here
$ uname -a
# paste output here

# On Windows:
C:\> wmic os get Caption, Version, BuildNumber, OSArchitecture
# paste output here

Install tools

Container runtime (CRI) and version (if applicable)

Related plugins (CNI, CSI, ...) and versions (if applicable)

[k8s-ci-robot]

This issue is currently awaiting triage.

If a SIG or subproject determines this is a relevant issue, they will accept it by applying the triage/accepted label and provide further guidance.

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[davidwtf]

/sig cluster-lifecycle

[neolit123]

I would like to know if this is intended or if it's a bug.

it's by design. we never discussed the option to cleanup as users can easily do that.

Maybe the document https://kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade/ should make it clear that the user needs to remove the backup files manually.

please log a ticket in kubernetes/website, also PRs to adjust the docs are welcome.
the exact place to note this is here:
https://kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade/#recovering-from-a-failure-state

/close

[k8s-ci-robot]

@neolit123: Closing this issue.

In response to this:

I would like to know if this is intended or if it's a bug.

it's by design. we never discussed the option to cleanup as users can easily do that.

Maybe the document https://kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade/ should make it clear that the user needs to remove the backup files manually.

please log a ticket in kubernetes/website, also PRs to adjust the docs are welcome.
the exact place to note this is here:
https://kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade/#recovering-from-a-failure-state

/close

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.