Kubernetes : Remove Nodes2025/01/24 |
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Remove Nodes from existing Kubernetes Cluster. |
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| [1] | Only when deleting a Control Plane node, it is necessary to delete Etcd and load balancing configuration beforehand like follows. |
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[root@ctrl ~]# kubectl get nodes NAME STATUS ROLES AGE VERSION dlp-1.srv.world Ready control-plane 17m v1.31.5 dlp.srv.world Ready control-plane 2d2h v1.31.5 node01.srv.world Ready <none> 2d2h v1.31.5 node02.srv.world Ready <none> 2d2h v1.31.5 node03.srv.world Ready <none> 4m56s v1.31.5[root@ctrl ~]# kubectl get pods -n kube-system | grep etcd kube-system etcd-dlp-1.srv.world 1/1 Running 0 19m kube-system etcd-dlp.srv.world 1/1 Running 4 2d2h # as an example, delete [dlp-1.srv.world] node # access to the Etcd on a Control Plane which is not the delete target and # remove configuration for delete target [root@ctrl ~]# kubectl -n kube-system exec -it etcd-dlp.srv.world -- sh sh-5.2# sh-5.2# etcdctl --endpoints=https://127.0.0.1:2379 --cacert=/etc/kubernetes/pki/etcd/ca.crt --cert=/etc/kubernetes/pki/etcd/peer.crt --key=/etc/kubernetes/pki/etcd/peer.key member list b328c32cc7e9915d, started, dlp-1.srv.world, https://10.0.0.31:2380, https://10.0.0.31:2379, false dd4b95995dc266b1, started, dlp.srv.world, https://10.0.0.30:2380, https://10.0.0.30:2379, false # remove a member which you like to delete sh-5.2# etcdctl --endpoints=https://127.0.0.1:2379 --cacert=/etc/kubernetes/pki/etcd/ca.crt --cert=/etc/kubernetes/pki/etcd/peer.crt --key=/etc/kubernetes/pki/etcd/peer.key member remove b328c32cc7e9915d Member b328c32cc7e9915d removed from cluster 63678238411c70a3 sh-5.2# exit exit
[root@ctrl ~]#
vi /etc/nginx/nginx.conf # remove the target Control Plane stream { upstream k8s-api { server 10.0.0.30:6443; ###server 10.0.0.31:6443; } server { listen 6443; proxy_pass k8s-api; } }[root@ctrl ~]# systemctl reload nginx
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| [2] | Remove a node from the cluster. From this point, the procedure is the same for both the Control Plane and Worker. |
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[root@ctrl ~]# kubectl get nodes NAME STATUS ROLES AGE VERSION dlp-1.srv.world Ready control-plane 17m v1.31.5 dlp.srv.world Ready control-plane 2d2h v1.31.5 node01.srv.world Ready <none> 2d2h v1.31.5 node02.srv.world Ready <none> 2d2h v1.31.5 node03.srv.world Ready <none> 4m56s v1.31.5 # prepare to remove a target node # --ignore-daemonsets ⇒ ignore pods in DaemonSet # --delete-emptydir-data ⇒ ignore pods that has emptyDir volumes # --force ⇒ also remove pods that was created as a pod, not as deployment or others [root@ctrl ~]# kubectl drain dlp-1.srv.world --ignore-daemonsets --delete-emptydir-data --force node/dlp-1.srv.world cordoned Warning: ignoring DaemonSet-managed Pods: kube-system/calico-node-8ckkz, kube-system/kube-proxy-thzrl node/dlp-1.srv.world drained # verify a few minutes later [root@ctrl ~]# kubectl get nodes dlp-1.srv.world NAME STATUS ROLES AGE VERSION dlp-1.srv.world Ready,SchedulingDisabled control-plane 28m v1.31.5 # run delete method [root@ctrl ~]# kubectl delete node dlp-1.srv.world node "dlp-1.srv.world" deleted[root@ctrl ~]# kubectl get nodes NAME STATUS ROLES AGE VERSION dlp.srv.world Ready control-plane 2d2h v1.31.5 node01.srv.world Ready <none> 2d2h v1.31.5 node02.srv.world Ready <none> 2d2h v1.31.5 node03.srv.world Ready <none> 17m v1.31.5 |
| [3] | On the removed Node, Reset kubeadm settings. |
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[root@dlp-1 ~]# kubeadm reset
[reset] Reading configuration from the cluster...
[reset] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -o yaml'
W0124 13:10:24.067304 13255 reset.go:123] [reset] Unable to fetch the kubeadm-config ConfigMap from cluster: failed to get config map: Get "https://10.0.0.25:6443/api/v1/namespaces/kube-system/configmaps/kubeadm-config?timeout=10s": net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
W0124 13:10:24.067662 13255 preflight.go:56] [reset] WARNING: Changes made to this host by 'kubeadm init' or 'kubeadm join' will be reverted.
[reset] Are you sure you want to proceed? [y/N]: y
[preflight] Running pre-flight checks
W0124 13:10:25.789781 13255 removeetcdmember.go:106] [reset] No kubeadm config, using etcd pod spec to get data directory
[reset] Deleted contents of the etcd data directory: /var/lib/etcd
[reset] Stopping the kubelet service
[reset] Unmounting mounted directories in "/var/lib/kubelet"
[reset] Deleting contents of directories: [/etc/kubernetes/manifests /var/lib/kubelet /etc/kubernetes/pki]
[reset] Deleting files: [/etc/kubernetes/admin.conf /etc/kubernetes/super-admin.conf /etc/kubernetes/kubelet.conf /etc/kubernetes/bootstrap-kubelet.conf /etc/kubernetes/controller-manager.conf /etc/kubernetes/scheduler.conf]
The reset process does not clean CNI configuration. To do so, you must remove /etc/cni/net.d
The reset process does not reset or clean up iptables rules or IPVS tables.
If you wish to reset iptables, you must do so manually by using the "iptables" command.
If your cluster was setup to utilize IPVS, run ipvsadm --clear (or similar)
to reset your system's IPVS tables.
The reset process does not clean your kubeconfig files and you must remove them manually.
Please, check the contents of the $HOME/.kube/config file.
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