Troubleshooting·Certified Kubernetes Administrator
Resetting and Rejoining a Node with kubeadm
Take a node out of a cluster and put it back, and take a machine all the way back to bare Ubuntu. Covers what kubeadm reset does not clean up, why removing a node needs two commands rather than one, and the package purge that silently does nothing.
Installation and Cluster Builds Guide 13 of 103 Intermediate
- OSUbuntu 26.04 LTS
- Kubernetes1.36.4
- containerd2.2.6
- Calicov3.32.1
- TimeAbout 30 min
- Reviewed21 August 2026
Written against the versions above. Container and sandbox IDs, timings and package versions are specific to this run.
| Server Name | IP Address | OS | Roles | CPU | RAM | HDD |
|---|---|---|---|---|---|---|
| CKA3001 | 192.168.0.185 | Ubuntu 26.04 LTS | Control Plane Node | 2 Core | 4 GB | 50 GB |
| CKA3001-NODE01 | 192.168.0.186 | Ubuntu 26.04 LTS | Worker Node (removed and rejoined) | 2 Core | 4 GB | 50 GB |
Before you start
- A cluster with at least one worker you are willing to disturb.
sudoon the node andkubectlaccess to the control plane.- If the node runs anything you care about, somewhere else for it to go. Removing the only worker leaves its pods Pending.
- Know which you want: taking a node out of a cluster is not the same as taking a machine back to bare Ubuntu. The first is two commands, the second is closer to eight.
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Removing a node takes two commands, not one
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Reset the machine, and read what it tells you
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Expect noisy errors during reset on a node that had a CNI
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Rejoin with a fresh token
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Going further: back to bare Ubuntu
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The package purge that silently does nothing
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Reboot, because interfaces outlive the packages