Kubernetes : Remove Nodes2025/05/20 |
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. |
[root@ctrl ~]# kubectl get nodes NAME STATUS ROLES AGE VERSION dlp-1.srv.world Ready control-plane 117m v1.31.9 dlp.srv.world Ready control-plane 3h3m v1.31.9 node01.srv.world Ready <none> 178m v1.31.9 node02.srv.world Ready <none> 177m v1.31.9 node03.srv.world Ready <none> 38s v1.31.9[root@ctrl ~]# kubectl get pods -n kube-system | grep etcd etcd-dlp-1.srv.world 1/1 Running 0 120m etcd-dlp.srv.world 1/1 Running 2 3h5m # 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 41771c7b1d23e5, 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 41771c7b1d23e5 Member 41771c7b1d23e5 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. |
[root@ctrl ~]# kubectl get nodes NAME STATUS ROLES AGE VERSION dlp-1.srv.world Ready control-plane 124m v1.31.9 dlp.srv.world Ready control-plane 3h9m v1.31.9 node01.srv.world Ready <none> 3h4m v1.31.9 node02.srv.world Ready <none> 3h3m v1.31.9 node03.srv.world Ready <none> 6m49s v1.31.9 # 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-m9cc9, kube-system/kube-proxy-4r2xt 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 125m v1.31.9 # 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 3h11m v1.31.9 node01.srv.world Ready <none> 3h6m v1.31.9 node02.srv.world Ready <none> 3h5m v1.31.9 node03.srv.world Ready <none> 8m46s v1.31.9 |
[3] | On the removed Node, Reset kubeadm settings. |
[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' W0520 12:50:42.776277 36142 reset.go:123] [reset] Unable to fetch the kubeadm-config ConfigMap from cluster: failed to get node registration: failed to get corresponding node: nodes "dlp-1.srv.world" not found W0520 12:50:42.776743 36142 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 W0520 12:50:44.299139 36142 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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