Background:

Upgrade is an ongoing thing: Kubernetes 1.16.15 to 1.17.17, and Kubernetes 1.17.17 to 1.18.20

Cluster configuration:

1. Refer to official documentation

Reference: https://kubernetes.io/zh/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade/

2. Confirm the upgradable version and upgrade plan

yum list --showduplicates kubeadm --disableexcludes=kubernetes

The latest version of 1.19 is version 1.19.12-0. K8S-master-03 node should be upgraded first according to personal habits

3. Upgrade the K8S-master-03 node control plane

K8S-master-03 is still executed:

1. Yum upgrades the Kubernetes plugin

Yum install kubeadm-1.19.12-0 kubelet-1.19.12-0 kubectl-1.19.12-0 --disableexcludes=kubernetes

2. The vacated node checks whether the cluster can be upgraded

Still considered a refresher drain command:

kubectl drain k8s-master-03 --ignore-daemonsets
sudo kubeadm upgrade plan

3. Upgrade to 1.19.12

Kubeadm upgrade the apply 1.19.12

Note: It is important to note that the versions of the work node are also 1.18.20. There is no need to boast more versions

[root@k8s-master-03 ~]# sudo systemctl daemon-reload
[root@k8s-master-03 ~]# sudo systemctl restart kubelet
[root@k8s-master-03 ~]# kubectl uncordon k8s-master-03
node/k8s-master-03 uncordoned

4. Upgrade other control plane (K8S-master-01 K8S-master-02)

Sudo yum install kubeadm-1.19.12-0 kubelet-1.19.12-0 kubectl-1.19.12-0 --disableexcludes=kubernetes sudo kubeadm upgrade  node sudo systemctl daemon-reload sudo systemctl restart kubelet

5. Work node upgrade

Sudo yum install kubeadm-1.19.12-0 kubelet-1.19.12-0 kubectl-1.19.12-0 --disableexcludes=kubernetes sudo kubeadm upgrade  node sudo systemctl daemon-reload sudo systemctl restart kubelet

6. Verify the upgrade

 kubectl get nodes

7. Other

Take a look at the plugin log under kube-system to make sure the plugin is working properly

kubectl logs -f kube-controller-manager-k8s-master-01 -n kube-system

Visual inspection is to ignore without a problem…. Well, I’ll leave the Prometheus question. I was ready to install the mainline version as well. The past is ready to unload. If the CLUSeterrole problem occurs, please refer to:Kubernetes 1.16.15 was upgraded to 1.17.17