背景
1 台 master 加入集群后發現忘了修改主機名,而在 k8s 集群中修改節點主機名非常麻煩,不如將 master 退出集群改名並重新加入集群(前提是用的是高可用集群)。
操作步驟
ssh 登錄另外一台 master 節點將要改名的 master 節點移出集群。
kubectl drain blog-k8s-n0
kubectl delete node blog-k8s-n0
登錄已退出集群的 master 服務器重置 kubelet 配置並重新加入集群。
kubeadm reset
kubeadm join k8s-api:6443 --token ****** \
--discovery-token-ca-cert-hash ****** \
--control-plane --certificate-key ****** \
--v=5
加入失敗,錯誤信息如下:
I0109 21:26:48.440711 3893 etcd.go:107] etcd endpoints read from pods: https://10.0.1.81:2379,https://10.0.1.32:2379,https://10.0.1.33:2379
I0109 21:26:48.455921 3893 etcd.go:166] etcd endpoints read from etcd: https://10.0.1.81:2379,https://10.0.1.32:2379,https://10.0.1.33:2379
I0109 21:26:48.455975 3893 etcd.go:125] update etcd endpoints: https://10.0.1.81:2379,https://10.0.1.32:2379,https://10.0.1.33:2379
I0109 21:27:08.469938 3893 etcd.go:388] Failed to get etcd status for https://10.0.1.81:2379: failed to dial endpoint https://10.0.1.81:2379 with maintenance client: context deadline exceeded
failed to dial endpoint https://10.0.1.81:2379 with maintenance client: context deadline exceeded
etcd cluster is not healthy
從錯誤信息看 etcd 集群不知道 10.0.1.81 已經退出 k8s 集群,etcd 集群中還保存着 10.0.1.81 的信息,所以在加入時連接 10.0.1.81 失敗。
登錄其中一台正常的 master ,進入 etcd 容器:
docker exec -it $(docker ps -f name=etcd_etcd -q) /bin/sh
查看 etcd 集群的成員列表,果然其中還有那台已經退出集群的服務器 blog-k8s-n0
$ etcdctl --endpoints 127.0.0.1:2379 --cacert /etc/kubernetes/pki/etcd/ca.crt --cert /etc/kubernetes/pki/etcd/server.crt --key /etc/kubernetes/pki/etcd/server.key member list
12637f5ec2bd02b8, started, blog-k8s-n0, https://10.0.1.81:2380, https://10.0.1.81:2379, false
17d58f8d29164d23, started, k8s-master1, https://10.0.1.32:2380, https://10.0.1.32:2379, false
19441808830db070, started, k8s-master2, https://10.0.1.33:2380, https://10.0.1.33:2379, false
在容器中將這台服務器從 etcd 集群中移除
etcdctl --endpoints 127.0.0.1:2379 --cacert /etc/kubernetes/pki/etcd/ca.crt --cert /etc/kubernetes/pki/etcd/server.crt --key /etc/kubernetes/pki/etcd/server.key member remove 12637f5ec2bd02b8
移除之后之前退出集群的服務器就能成功加入集群。