Kubernetes : ノードを削除する2025/01/24

	既存の Kubernetes クラスターからノードを削除する場合は以下のように設定します。
[1]	Control Plane ノードを削除する場合のみ、事前に Etcd の削除やロードバランス設定の削除を実行します。

[root@ctrl ~]#

kubectl get nodes

NAME               STATUS   ROLES           AGE     VERSION
dlp-1.srv.world    Ready    control-plane   10m     v1.32.6
dlp.srv.world      Ready    control-plane   8h      v1.32.6
node01.srv.world   Ready    <none>          8h      v1.32.6
node02.srv.world   Ready    <none>          8h      v1.32.6
node03.srv.world   Ready    <none>          2m21s   v1.32.6

[root@ctrl ~]#

kubectl get pods -n kube-system | grep etcd

etcd-dlp-1.srv.world                      1/1     Running   0          10m
etcd-dlp.srv.world                        1/1     Running   3          8h

# 例として [dlp-1.srv.world] を削除する
# 削除しない方の Control Plane で起動している Etcd へアクセスして
# 削除対象ノードの設定を削除する

[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 
58023a79f50482a2, 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

# 削除したいノードのメンバーを削除
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 58023a79f50482a2 
Member 58023a79f50482a2 removed from cluster 63678238411c70a3

sh-5.2# exit 
exit

[root@ctrl ~]#

vi /etc/nginx/nginx.conf

# 対象ノードの設定を削除
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

[2]	ノードをクラスターから削除します。以降は Control Plane / Worker 共に同じ手順です。

[root@ctrl ~]#

kubectl get nodes

NAME               STATUS   ROLES           AGE     VERSION
dlp-1.srv.world    Ready    control-plane   12m     v1.32.6
dlp.srv.world      Ready    control-plane   8h      v1.32.6
node01.srv.world   Ready    <none>          8h      v1.32.6
node02.srv.world   Ready    <none>          8h      v1.32.6
node03.srv.world   Ready    <none>          4m36s   v1.32.6

# 対象ノードを安全に削除するための事前準備
# --ignore-daemonsets ⇒ DeamonSet の Pod は無視
# --delete-emptydir-data ⇒ emptyDir ボリュームを持つ Pod は無視
# --force ⇒ 単体で作成された Pod も削除

[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: calico-system/calico-node-cdfjw, calico-system/csi-node-driver-5phrh, kube-system/kube-proxy-kdj8v
node/dlp-1.srv.world drained

# 一定時間経過後に確認
# 時間は環境によって異なる

[root@ctrl ~]#

kubectl get nodes dlp-1.srv.world

NAME              STATUS                     ROLES           AGE   VERSION
dlp-1.srv.world   Ready,SchedulingDisabled   control-plane   14m   v1.32.6

# 削除処理を実行

[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   8h      v1.32.6
node01.srv.world   Ready    <none>          8h      v1.32.6
node02.srv.world   Ready    <none>          8h      v1.32.6
node03.srv.world   Ready    <none>          6m49s   v1.32.6

[3]	削除したノードで、kubeadm の設定をリセットしておきます。

[root@dlp-1 ~]#

kubeadm reset

[reset] Reading configuration from the "kubeadm-config" ConfigMap in namespace "kube-system"...
[reset] Use 'kubeadm init phase upload-config --config your-config.yaml' to re-upload it.
W0703 19:14:22.103943    7600 reset.go:143] [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
W0703 19:14:22.104357    7600 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
W0703 19:14:23.191123    7600 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.