1 Kubernetes(k8s) 集群升级过程
Kubernetes 使用 kubeadm 工具来管理集群组件的升级。在集群节点层面，升级 Kubernetes(k8s)集群的过程可以分为以下几个步骤：
1）检查当前环境和配置是否满足升级要求。
2）升级master主节点（如果是多master，则master轮着升级）。
3）升级worker工作节点。
4）升级网络插件。
在软件层面，升级 Kubernetes(k8s)集群的过程可以分为以下几个步骤：
1）升级kubeadm
2）节点执行drain操作
3）升级各个组件
4）取消drain操作
5）升级kubelet和kubectl
注意：Kubernetes(k8s)集群升级的时候是不能跨版本升级的，比如：Kubernetes(k8s)集群 1.19.x可以升级为1.20.y，但是Kubernetes(k8s)集群 1.19.x不能直接升级为 1.21.y，只能从一个次版本升级到下一个次版本，或者在次版本相同时升级补丁版本。 也就是说，升级时不可以跳过次版本。 例如，只能从 1.y 升级到 1.y+1，而不能从 1.y 升级到 1.y+2。
2 升级master主节点
2.1 升级kubeadm
Kubernetes(k8s)集群版本是v1.21.0。
$ kubectl get nodes
NAME STATUS ROLES AGE VERSION
ops-master-1 Ready control-plane,master 33m v1.21.0
ops-worker-1 Ready <none> 30m v1.21.0
ops-worker-2 Ready <none> 30m v1.21.0查看可用的kubeadm版本:
yum list --showduplicates kubeadm --disableexcludes=kubernetes
Loaded plugins: fastestmirror, langpacks, releasever-adapter, update-motd
Loading mirror speeds from cached hostfile
Installed Packages
kubeadm.x86_64 1.21.0-0 @k8s
Available Packages
kubeadm.x86_64 1.6.0-0 k8s
kubeadm.x86_64 1.6.1-0 k8s
kubeadm.x86_64 1.6.2-0 k8s
kubeadm.x86_64 1.6.3-0 k8s
kubeadm.x86_64 1.6.4-0 k8s
kubeadm.x86_64 1.6.5-0 k8s
kubeadm.x86_64 1.6.6-0 k8s
kubeadm.x86_64 1.6.7-0 k8s
kubeadm.x86_64 1.6.8-0 k8s
kubeadm.x86_64 1.6.9-0 k8s
kubeadm.x86_64 1.6.10-0 k8s
kubeadm.x86_64 1.6.11-0 k8s
kubeadm.x86_64 1.6.12-0 k8s
kubeadm.x86_64 1.6.13-0 k8s
kubeadm.x86_64 1.7.0-0 k8s
kubeadm.x86_64 1.7.1-0 k8s
kubeadm.x86_64 1.7.2-0 k8s
kubeadm.x86_64 1.7.3-1 k8s
kubeadm.x86_64 1.7.4-0 k8s
kubeadm.x86_64 1.7.5-0 k8s
kubeadm.x86_64 1.7.6-1 k8s
kubeadm.x86_64 1.7.7-1 k8s
kubeadm.x86_64 1.7.8-1 k8s
kubeadm.x86_64 1.7.9-0 k8s
kubeadm.x86_64 1.7.10-0 k8s
kubeadm.x86_64 1.7.11-0 k8s
kubeadm.x86_64 1.7.14-0 k8s
kubeadm.x86_64 1.7.15-0 k8s
kubeadm.x86_64 1.7.16-0 k8s
kubeadm.x86_64 1.8.0-0 k8s
kubeadm.x86_64 1.8.0-1 k8s
kubeadm.x86_64 1.8.1-0 k8s
kubeadm.x86_64 1.8.2-0 k8s
kubeadm.x86_64 1.8.3-0 k8s
kubeadm.x86_64 1.8.4-0 k8s
kubeadm.x86_64 1.8.5-0 k8s
kubeadm.x86_64 1.8.6-0 k8s
kubeadm.x86_64 1.8.7-0 k8s
kubeadm.x86_64 1.8.8-0 k8s
kubeadm.x86_64 1.8.9-0 k8s
kubeadm.x86_64 1.8.10-0 k8s
kubeadm.x86_64 1.8.11-0 k8s
kubeadm.x86_64 1.8.12-0 k8s
kubeadm.x86_64 1.8.13-0 k8s
kubeadm.x86_64 1.8.14-0 k8s
kubeadm.x86_64 1.8.15-0 k8s
kubeadm.x86_64 1.9.0-0 k8s
kubeadm.x86_64 1.9.1-0 k8s
kubeadm.x86_64 1.9.2-0 k8s
kubeadm.x86_64 1.9.3-0 k8s
kubeadm.x86_64 1.9.4-0 k8s
kubeadm.x86_64 1.9.5-0 k8s
kubeadm.x86_64 1.9.6-0 k8s
kubeadm.x86_64 1.9.7-0 k8s
kubeadm.x86_64 1.9.8-0 k8s
kubeadm.x86_64 1.9.9-0 k8s
kubeadm.x86_64 1.9.10-0 k8s
kubeadm.x86_64 1.9.11-0 k8s
kubeadm.x86_64 1.10.0-0 k8s
kubeadm.x86_64 1.10.1-0 k8s
kubeadm.x86_64 1.10.2-0 k8s
kubeadm.x86_64 1.10.3-0 k8s
kubeadm.x86_64 1.10.4-0 k8s
kubeadm.x86_64 1.10.5-0 k8s
kubeadm.x86_64 1.10.6-0 k8s
kubeadm.x86_64 1.10.7-0 k8s
kubeadm.x86_64 1.10.8-0 k8s
kubeadm.x86_64 1.10.9-0 k8s
kubeadm.x86_64 1.10.10-0 k8s
kubeadm.x86_64 1.10.11-0 k8s
kubeadm.x86_64 1.10.12-0 k8s
kubeadm.x86_64 1.10.13-0 k8s
kubeadm.x86_64 1.11.0-0 k8s
kubeadm.x86_64 1.11.1-0 k8s
kubeadm.x86_64 1.11.2-0 k8s
kubeadm.x86_64 1.11.3-0 k8s
kubeadm.x86_64 1.11.4-0 k8s
kubeadm.x86_64 1.11.5-0 k8s
kubeadm.x86_64 1.11.6-0 k8s
kubeadm.x86_64 1.11.7-0 k8s
kubeadm.x86_64 1.11.8-0 k8s
kubeadm.x86_64 1.11.9-0 k8s
kubeadm.x86_64 1.11.10-0 k8s
kubeadm.x86_64 1.12.0-0 k8s
kubeadm.x86_64 1.12.1-0 k8s
kubeadm.x86_64 1.12.2-0 k8s
kubeadm.x86_64 1.12.3-0 k8s
kubeadm.x86_64 1.12.4-0 k8s
kubeadm.x86_64 1.12.5-0 k8s
kubeadm.x86_64 1.12.6-0 k8s
kubeadm.x86_64 1.12.7-0 k8s
kubeadm.x86_64 1.12.8-0 k8s
kubeadm.x86_64 1.12.9-0 k8s
kubeadm.x86_64 1.12.10-0 k8s
kubeadm.x86_64 1.13.0-0 k8s
kubeadm.x86_64 1.13.1-0 k8s
kubeadm.x86_64 1.13.2-0 k8s
kubeadm.x86_64 1.13.3-0 k8s
kubeadm.x86_64 1.13.4-0 k8s
kubeadm.x86_64 1.13.5-0 k8s
kubeadm.x86_64 1.13.6-0 k8s
kubeadm.x86_64 1.13.7-0 k8s
kubeadm.x86_64 1.13.8-0 k8s
kubeadm.x86_64 1.13.9-0 k8s
kubeadm.x86_64 1.13.10-0 k8s
kubeadm.x86_64 1.13.11-0 k8s
kubeadm.x86_64 1.13.12-0 k8s
kubeadm.x86_64 1.14.0-0 k8s
kubeadm.x86_64 1.14.1-0 k8s
kubeadm.x86_64 1.14.2-0 k8s
kubeadm.x86_64 1.14.3-0 k8s
kubeadm.x86_64 1.14.4-0 k8s
kubeadm.x86_64 1.14.5-0 k8s
kubeadm.x86_64 1.14.6-0 k8s
kubeadm.x86_64 1.14.7-0 k8s
kubeadm.x86_64 1.14.8-0 k8s
kubeadm.x86_64 1.14.9-0 k8s
kubeadm.x86_64 1.14.10-0 k8s
kubeadm.x86_64 1.15.0-0 k8s
kubeadm.x86_64 1.15.1-0 k8s
kubeadm.x86_64 1.15.2-0 k8s
kubeadm.x86_64 1.15.3-0 k8s
kubeadm.x86_64 1.15.4-0 k8s
kubeadm.x86_64 1.15.5-0 k8s
kubeadm.x86_64 1.15.6-0 k8s
kubeadm.x86_64 1.15.7-0 k8s
kubeadm.x86_64 1.15.8-0 k8s
kubeadm.x86_64 1.15.9-0 k8s
kubeadm.x86_64 1.15.10-0 k8s
kubeadm.x86_64 1.15.11-0 k8s
kubeadm.x86_64 1.15.12-0 k8s
kubeadm.x86_64 1.16.0-0 k8s
kubeadm.x86_64 1.16.1-0 k8s
kubeadm.x86_64 1.16.2-0 k8s
kubeadm.x86_64 1.16.3-0 k8s
kubeadm.x86_64 1.16.4-0 k8s
kubeadm.x86_64 1.16.5-0 k8s
kubeadm.x86_64 1.16.6-0 k8s
kubeadm.x86_64 1.16.7-0 k8s
kubeadm.x86_64 1.16.8-0 k8s
kubeadm.x86_64 1.16.9-0 k8s
kubeadm.x86_64 1.16.10-0 k8s
kubeadm.x86_64 1.16.11-0 k8s
kubeadm.x86_64 1.16.11-1 k8s
kubeadm.x86_64 1.16.12-0 k8s
kubeadm.x86_64 1.16.13-0 k8s
kubeadm.x86_64 1.16.14-0 k8s
kubeadm.x86_64 1.16.15-0 k8s
kubeadm.x86_64 1.17.0-0 k8s
kubeadm.x86_64 1.17.1-0 k8s
kubeadm.x86_64 1.17.2-0 k8s
kubeadm.x86_64 1.17.3-0 k8s
kubeadm.x86_64 1.17.4-0 k8s
kubeadm.x86_64 1.17.5-0 k8s
kubeadm.x86_64 1.17.6-0 k8s
kubeadm.x86_64 1.17.7-0 k8s
kubeadm.x86_64 1.17.7-1 k8s
kubeadm.x86_64 1.17.8-0 k8s
kubeadm.x86_64 1.17.9-0 k8s
kubeadm.x86_64 1.17.11-0 k8s
kubeadm.x86_64 1.17.12-0 k8s
kubeadm.x86_64 1.17.13-0 k8s
kubeadm.x86_64 1.17.14-0 k8s
kubeadm.x86_64 1.17.15-0 k8s
kubeadm.x86_64 1.17.16-0 k8s
kubeadm.x86_64 1.17.17-0 k8s
kubeadm.x86_64 1.18.0-0 k8s
kubeadm.x86_64 1.18.1-0 k8s
kubeadm.x86_64 1.18.2-0 k8s
kubeadm.x86_64 1.18.3-0 k8s
kubeadm.x86_64 1.18.4-0 k8s
kubeadm.x86_64 1.18.4-1 k8s
kubeadm.x86_64 1.18.5-0 k8s
kubeadm.x86_64 1.18.6-0 k8s
kubeadm.x86_64 1.18.8-0 k8s
kubeadm.x86_64 1.18.9-0 k8s
kubeadm.x86_64 1.18.10-0 k8s
kubeadm.x86_64 1.18.12-0 k8s
kubeadm.x86_64 1.18.13-0 k8s
kubeadm.x86_64 1.18.14-0 k8s
kubeadm.x86_64 1.18.15-0 k8s
kubeadm.x86_64 1.18.16-0 k8s
kubeadm.x86_64 1.18.17-0 k8s
kubeadm.x86_64 1.18.18-0 k8s
kubeadm.x86_64 1.18.19-0 k8s
kubeadm.x86_64 1.18.20-0 k8s
kubeadm.x86_64 1.19.0-0 k8s
kubeadm.x86_64 1.19.1-0 k8s
kubeadm.x86_64 1.19.2-0 k8s
kubeadm.x86_64 1.19.3-0 k8s
kubeadm.x86_64 1.19.4-0 k8s
kubeadm.x86_64 1.19.5-0 k8s
kubeadm.x86_64 1.19.6-0 k8s
kubeadm.x86_64 1.19.7-0 k8s
kubeadm.x86_64 1.19.8-0 k8s
kubeadm.x86_64 1.19.9-0 k8s
kubeadm.x86_64 1.19.10-0 k8s
kubeadm.x86_64 1.19.11-0 k8s
kubeadm.x86_64 1.19.12-0 k8s
kubeadm.x86_64 1.19.13-0 k8s
kubeadm.x86_64 1.19.14-0 k8s
kubeadm.x86_64 1.19.15-0 k8s
kubeadm.x86_64 1.19.16-0 k8s
kubeadm.x86_64 1.20.0-0 k8s
kubeadm.x86_64 1.20.1-0 k8s
kubeadm.x86_64 1.20.2-0 k8s
kubeadm.x86_64 1.20.4-0 k8s
kubeadm.x86_64 1.20.5-0 k8s
kubeadm.x86_64 1.20.6-0 k8s
kubeadm.x86_64 1.20.7-0 k8s
kubeadm.x86_64 1.20.8-0 k8s
kubeadm.x86_64 1.20.9-0 k8s
kubeadm.x86_64 1.20.10-0 k8s
kubeadm.x86_64 1.20.11-0 k8s
kubeadm.x86_64 1.20.12-0 k8s
kubeadm.x86_64 1.20.13-0 k8s
kubeadm.x86_64 1.20.14-0 k8s
kubeadm.x86_64 1.20.15-0 k8s
kubeadm.x86_64 1.21.0-0 k8s
kubeadm.x86_64 1.21.1-0 k8s
kubeadm.x86_64 1.21.2-0 k8s
kubeadm.x86_64 1.21.3-0 k8s
kubeadm.x86_64 1.21.4-0 k8s
kubeadm.x86_64 1.21.5-0 k8s
kubeadm.x86_64 1.21.6-0 k8s
kubeadm.x86_64 1.21.7-0 k8s
kubeadm.x86_64 1.21.8-0 k8s
kubeadm.x86_64 1.21.9-0 k8s
kubeadm.x86_64 1.21.10-0 k8s
kubeadm.x86_64 1.21.11-0 k8s
kubeadm.x86_64 1.21.12-0 k8s
kubeadm.x86_64 1.21.13-0 k8s
kubeadm.x86_64 1.21.14-0 k8s
kubeadm.x86_64 1.22.0-0 k8s
kubeadm.x86_64 1.22.1-0 k8s
kubeadm.x86_64 1.22.2-0 k8s
kubeadm.x86_64 1.22.3-0 k8s
kubeadm.x86_64 1.22.4-0 k8s
kubeadm.x86_64 1.22.5-0 k8s
kubeadm.x86_64 1.22.6-0 k8s
kubeadm.x86_64 1.22.7-0 k8s
kubeadm.x86_64 1.22.8-0 k8s
kubeadm.x86_64 1.22.9-0 k8s
kubeadm.x86_64 1.22.10-0 k8s
kubeadm.x86_64 1.22.11-0 k8s
kubeadm.x86_64 1.22.12-0 k8s
kubeadm.x86_64 1.22.13-0 k8s
kubeadm.x86_64 1.22.14-0 k8s
kubeadm.x86_64 1.22.15-0 k8s
kubeadm.x86_64 1.22.16-0 k8s
kubeadm.x86_64 1.22.17-0 k8s
kubeadm.x86_64 1.23.0-0 k8s
kubeadm.x86_64 1.23.1-0 k8s
kubeadm.x86_64 1.23.2-0 k8s
kubeadm.x86_64 1.23.3-0 k8s
kubeadm.x86_64 1.23.4-0 k8s
kubeadm.x86_64 1.23.5-0 k8s
kubeadm.x86_64 1.23.6-0 k8s
kubeadm.x86_64 1.23.7-0 k8s
kubeadm.x86_64 1.23.8-0 k8s
kubeadm.x86_64 1.23.9-0 k8s
kubeadm.x86_64 1.23.10-0 k8s
kubeadm.x86_64 1.23.11-0 k8s
kubeadm.x86_64 1.23.12-0 k8s
kubeadm.x86_64 1.23.13-0 k8s
kubeadm.x86_64 1.23.14-0 k8s
kubeadm.x86_64 1.23.15-0 k8s
kubeadm.x86_64 1.23.16-0 k8s
kubeadm.x86_64 1.23.17-0 k8s
kubeadm.x86_64 1.24.0-0 k8s
kubeadm.x86_64 1.24.1-0 k8s
kubeadm.x86_64 1.24.2-0 k8s
kubeadm.x86_64 1.24.3-0 k8s
kubeadm.x86_64 1.24.4-0 k8s
kubeadm.x86_64 1.24.5-0 k8s
kubeadm.x86_64 1.24.6-0 k8s
kubeadm.x86_64 1.24.7-0 k8s
kubeadm.x86_64 1.24.8-0 k8s
kubeadm.x86_64 1.24.9-0 k8s
kubeadm.x86_64 1.24.10-0 k8s
kubeadm.x86_64 1.24.11-0 k8s
kubeadm.x86_64 1.24.12-0 k8s
kubeadm.x86_64 1.24.13-0 k8s
kubeadm.x86_64 1.24.14-0 k8s
kubeadm.x86_64 1.24.15-0 k8s
kubeadm.x86_64 1.24.16-0 k8s
kubeadm.x86_64 1.24.17-0 k8s
kubeadm.x86_64 1.25.0-0 k8s
kubeadm.x86_64 1.25.1-0 k8s
kubeadm.x86_64 1.25.2-0 k8s
kubeadm.x86_64 1.25.3-0 k8s
kubeadm.x86_64 1.25.4-0 k8s
kubeadm.x86_64 1.25.5-0 k8s
kubeadm.x86_64 1.25.6-0 k8s
kubeadm.x86_64 1.25.7-0 k8s
kubeadm.x86_64 1.25.8-0 k8s
kubeadm.x86_64 1.25.9-0 k8s
kubeadm.x86_64 1.25.10-0 k8s
kubeadm.x86_64 1.25.11-0 k8s
kubeadm.x86_64 1.25.12-0 k8s
kubeadm.x86_64 1.25.13-0 k8s
kubeadm.x86_64 1.25.14-0 k8s
kubeadm.x86_64 1.26.0-0 k8s
kubeadm.x86_64 1.26.1-0 k8s
kubeadm.x86_64 1.26.2-0 k8s
kubeadm.x86_64 1.26.3-0 k8s
kubeadm.x86_64 1.26.4-0 k8s
kubeadm.x86_64 1.26.5-0 k8s
kubeadm.x86_64 1.26.6-0 k8s
kubeadm.x86_64 1.26.7-0 k8s
kubeadm.x86_64 1.26.8-0 k8s
kubeadm.x86_64 1.26.9-0 k8s
kubeadm.x86_64 1.27.0-0 k8s
kubeadm.x86_64 1.27.1-0 k8s
kubeadm.x86_64 1.27.2-0 k8s
kubeadm.x86_64 1.27.3-0 k8s
kubeadm.x86_64 1.27.4-0 k8s
kubeadm.x86_64 1.27.5-0 k8s
kubeadm.x86_64 1.27.6-0 k8s
kubeadm.x86_64 1.28.0-0 k8s
kubeadm.x86_64 1.28.1-0 k8s
kubeadm.x86_64 1.28.2-0 k8s 升级kubeadm到1.21.9-0版本:
$ yum install -y kubeadm-1.21.9-0 --disableexcludes=kubernetes
Loaded plugins: fastestmirror, langpacks, releasever-adapter, update-motd
Loading mirror speeds from cached hostfile
Resolving Dependencies
--> Running transaction check
---> Package kubeadm.x86_64 0:1.21.0-0 will be updated
---> Package kubeadm.x86_64 0:1.21.9-0 will be an update
--> Finished Dependency Resolution
Dependencies Resolved
============================================================================================================================================================================================================
Package Arch Version Repository Size
============================================================================================================================================================================================================
Updating:
kubeadm x86_64 1.21.9-0 k8s 9.1 M
Transaction Summary
============================================================================================================================================================================================================
Upgrade 1 Package
Total download size: 9.1 M
Downloading packages:
No Presto metadata available for k8s
f41c806d2113e9b88efd9f70e3a07da3cd0597f5361f7842058e06b9601ff7fc-kubeadm-1.21.9-0.x86_64.rpm | 9.1 MB 00:00:01
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Updating : kubeadm-1.21.9-0.x86_64 1/2
Cleanup : kubeadm-1.21.0-0.x86_64 2/2
Verifying : kubeadm-1.21.9-0.x86_64 1/2
Verifying : kubeadm-1.21.0-0.x86_64 2/2
Updated:
kubeadm.x86_64 0:1.21.9-0
Complete!kubeadm upgrade plan验证升级计划，COMPONENT CURRENT TARGET ：告诉我们组件可以从当前版本升级到的版本。
$ kubeadm upgrade plan
kubeadm upgrade plan
[upgrade/config] Making sure the configuration is correct:
[upgrade/config] Reading configuration from the cluster...
[upgrade/config] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -o yaml'
[preflight] Running pre-flight checks.
[upgrade] Running cluster health checks
[upgrade] Fetching available versions to upgrade to
[upgrade/versions] Cluster version: v1.21.0
[upgrade/versions] kubeadm version: v1.21.9
I1210 20:34:17.564937 5980 version.go:254] remote version is much newer: v1.28.4; falling back to: stable-1.21
[upgrade/versions] Target version: v1.21.14
[upgrade/versions] Latest version in the v1.21 series: v1.21.14
Components that must be upgraded manually after you have upgraded the control plane with 'kubeadm upgrade apply':
COMPONENT CURRENT TARGET
kubelet 3 x v1.21.0 v1.21.14
Upgrade to the latest version in the v1.21 series:
COMPONENT CURRENT TARGET
kube-apiserver v1.21.0 v1.21.14
kube-controller-manager v1.21.0 v1.21.14
kube-scheduler v1.21.0 v1.21.14
kube-proxy v1.21.0 v1.21.14
CoreDNS v1.8.0 v1.8.0
etcd 3.4.13-0 3.4.13-0
You can now apply the upgrade by executing the following command:
kubeadm upgrade apply v1.21.14
Note: Before you can perform this upgrade, you have to update kubeadm to v1.21.14.
_____________________________________________________________________
The table below shows the current state of component configs as understood by this version of kubeadm.
Configs that have a "yes" mark in the "MANUAL UPGRADE REQUIRED" column require manual config upgrade or
resetting to kubeadm defaults before a successful upgrade can be performed. The version to manually
upgrade to is denoted in the "PREFERRED VERSION" column.
API GROUP CURRENT VERSION PREFERRED VERSION MANUAL UPGRADE REQUIRED
kubeproxy.config.k8s.io v1alpha1 v1alpha1 no
kubelet.config.k8s.io v1beta1 v1beta1 no
_____________________________________________________________________
2.2 升级各个组件
上一步是升级kubeadm ,接下来升级各个组件（kube-apiserver，kube-controller-manager等等），
kubeadm upgrade apply v1.21.9升级各个组件到1.21.9版本，如果etcd这个组件不想升级，可以加上选项:kubeadm upgrade apply v1.21.9 --etcd-upgrade=false。
可以提前drain节点，后面drain也可以。
腾空节点：通过将节点标记为不可调度并腾空节点为节点作升级准备：kubectl drain --ignore-daemonsets。
$ kubectl drain ops-master-1 --ignore-daemonsets
node/k8scloude1 cordoned
error: unable to drain node "k8scloude1", aborting command...
There are pending nodes to be drained:
k8scloude1
error: cannot delete Pods with local storage (use --delete-emptydir-data to override): kube-system/metrics-server-bcfb98c76-j4gs8, kubernetes-dashboard/dashboard-metrics-scraper-7f458d9467-9knf9
因为有本地数据，需要加--delete-emptydir-data选项。
$ kubectl drain ops-master-1 --ignore-daemonsets --delete-emptydir-data
node/ops-master-1 already cordoned
WARNING: ignoring DaemonSet-managed Pods: kube-system/calico-node-whfb8, kube-system/kube-proxy-srhgz
node/ops-master-1 drained升级各个组件，--etcd-upgrade=false表示etcd数据库不升级。
$ kubeadm upgrade apply v1.21.9 --etcd-upgrade=false
[upgrade/config] Making sure the configuration is correct:
[upgrade/config] Reading configuration from the cluster...
[upgrade/config] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -o yaml'
[preflight] Running pre-flight checks.
[upgrade] Running cluster health checks
[upgrade/version] You have chosen to change the cluster version to "v1.21.9"
[upgrade/versions] Cluster version: v1.21.0
[upgrade/versions] kubeadm version: v1.21.9
[upgrade/confirm] Are you sure you want to proceed with the upgrade? [y/N]: y
[upgrade/prepull] Pulling images required for setting up a Kubernetes cluster
[upgrade/prepull] This might take a minute or two, depending on the speed of your internet connection
[upgrade/prepull] You can also perform this action in beforehand using 'kubeadm config images pull'
[upgrade/apply] Upgrading your Static Pod-hosted control plane to version "v1.21.9"...
Static pod: kube-apiserver-ops-master-1 hash: 94a1393eb20a9652cea984f5907ed147
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
[upgrade/staticpods] Writing new Static Pod manifests to "/etc/kubernetes/tmp/kubeadm-upgraded-manifests053748490"
[upgrade/staticpods] Preparing for "kube-apiserver" upgrade
[upgrade/staticpods] Renewing apiserver certificate
[upgrade/staticpods] Renewing apiserver-kubelet-client certificate
[upgrade/staticpods] Renewing front-proxy-client certificate
[upgrade/staticpods] Renewing apiserver-etcd-client certificate
[upgrade/staticpods] Moved new manifest to "/etc/kubernetes/manifests/kube-apiserver.yaml" and backed up old manifest to "/etc/kubernetes/tmp/kubeadm-backup-manifests-2023-12-10-20-38-23/kube-apiserver.yaml"
[upgrade/staticpods] Waiting for the kubelet to restart the component
[upgrade/staticpods] This might take a minute or longer depending on the component/version gap (timeout 5m0s)
Static pod: kube-apiserver-ops-master-1 hash: 94a1393eb20a9652cea984f5907ed147
Static pod: kube-apiserver-ops-master-1 hash: 94a1393eb20a9652cea984f5907ed147
Static pod: kube-apiserver-ops-master-1 hash: 26e768b6e5881ba632db749b44ed30c5
[apiclient] Found 1 Pods for label selector component=kube-apiserver
[upgrade/staticpods] Component "kube-apiserver" upgraded successfully!
[upgrade/staticpods] Preparing for "kube-controller-manager" upgrade
[upgrade/staticpods] Renewing controller-manager.conf certificate
[upgrade/staticpods] Moved new manifest to "/etc/kubernetes/manifests/kube-controller-manager.yaml" and backed up old manifest to "/etc/kubernetes/tmp/kubeadm-backup-manifests-2023-12-10-20-38-23/kube-controller-manager.yaml"
[upgrade/staticpods] Waiting for the kubelet to restart the component
[upgrade/staticpods] This might take a minute or longer depending on the component/version gap (timeout 5m0s)
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: dfcbd862b8c83e8fbd17b289c6d2d47b
Static pod: kube-controller-manager-ops-master-1 hash: 0074b909bb20d0a0ab9caa7f07b66191
[apiclient] Found 1 Pods for label selector component=kube-controller-manager
[upgrade/staticpods] Component "kube-controller-manager" upgraded successfully!
[upgrade/staticpods] Preparing for "kube-scheduler" upgrade
[upgrade/staticpods] Renewing scheduler.conf certificate
[upgrade/staticpods] Moved new manifest to "/etc/kubernetes/manifests/kube-scheduler.yaml" and backed up old manifest to "/etc/kubernetes/tmp/kubeadm-backup-manifests-2023-12-10-20-38-23/kube-scheduler.yaml"
[upgrade/staticpods] Waiting for the kubelet to restart the component
[upgrade/staticpods] This might take a minute or longer depending on the component/version gap (timeout 5m0s)
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: f77a726558e477a8bc7504218c9d2ccd
Static pod: kube-scheduler-ops-master-1 hash: 07614ccea2a58fd20ecb645d2901f0c9
[apiclient] Found 1 Pods for label selector component=kube-scheduler
[upgrade/staticpods] Component "kube-scheduler" upgraded successfully!
[upgrade/postupgrade] Applying label node-role.kubernetes.io/control-plane='' to Nodes with label node-role.kubernetes.io/master='' (deprecated)
[upgrade/postupgrade] Applying label node.kubernetes.io/exclude-from-external-load-balancers='' to control plane Nodes
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.21" in namespace kube-system with the configuration for the kubelets in the cluster
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to get nodes
[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstrap-token] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstrap-token] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy
[upgrade/successful] SUCCESS! Your cluster was upgraded to "v1.21.9". Enjoy!
[upgrade/kubelet] Now that your control plane is upgraded, please proceed with upgrading your kubelets if you haven't already done so.现在ops-master-1节点是不可调度状态的。
$ kubectl get node
NAME STATUS ROLES AGE VERSION
ops-master-1 Ready,SchedulingDisabled control-plane,master 49m v1.21.0
ops-worker-1 Ready <none> 46m v1.21.0
ops-worker-2 Ready <none> 46m v1.21.0解除ops-master-1节点的保护：通过将节点标记为可调度，让其重新上线。
$ kubectl uncordon ops-master-1
node/ops-master-1 uncordoned现在ops-master-1节点是Ready状态的。
$ kubectl get node
NAME STATUS ROLES AGE VERSION
ops-master-1 Ready control-plane,master 53m v1.21.0
ops-worker-1 Ready <none> 50m v1.21.0
ops-worker-2 Ready <none> 50m v1.21.02.2 升级 kubelet 和 kubectl
升级 kubelet 和 kubectl到1.21.9版本。
$ yum install -y kubelet-1.21.9-0 kubectl-1.21.9-0 --disableexcludes=kubernetes重新加载配置文件并重启 kubelet。
$ systemctl daemon-reload ;systemctl restart kubelet此时op-master-1节点的版本就变为v1.21.9了，k8s集群的master节点升级成功，如果有多个master，则步骤一样，但是第二个master节点不需要执行kubeadm upgrade apply v1.21.9命令，第二台master节点把kubeadm upgrade apply v1.21.9变为kubeadm upgrade node。
$ kubectl get node
NAME STATUS ROLES AGE VERSION
ops-master-1 Ready control-plane,master 143m v1.21.9
ops-worker-1 Ready <none> 140m v1.21.0
ops-worker-2 Ready <none> 140m v1.21.03 升级worker工作节点
3.1 升级kubeadm
$ yum install -y kubeadm-1.21.9-0 --disableexcludes=kubernetes通过将节点标记为不可调度并腾空节点，为节点作升级准备。
如果本地有数据，建议使用--delete-emptydir-data选项。
$ kubectl drain ops-worker-1 --ignore-daemonsets
node/ops-worker-1 cordoned
WARNING: ignoring DaemonSet-managed Pods: kube-system/calico-node-g6ntb, kube-system/kube-proxy-nf2rm
evicting pod kube-system/coredns-59d64cd4d4-qf9rx
pod/coredns-59d64cd4d4-qf9rx evicted
node/ops-worker-1 evictedkubectl get node
NAME STATUS ROLES AGE VERSION
ops-master-1 Ready control-plane,master 144m v1.21.9
ops-worker-1 Ready,SchedulingDisabled <none> 141m v1.21.0
ops-worker-2 Ready <none> 141m v1.21.0对于工作节点， kubeadm upgrade node 命令会升级本地的 kubelet 配置。
$ kubeadm upgrade node
[upgrade] Reading configuration from the cluster...
[upgrade] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -o yaml'
[preflight] Running pre-flight checks
[preflight] Skipping prepull. Not a control plane node.
[upgrade] Skipping phase. Not a control plane node.
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[upgrade] The configuration for this node was successfully updated!
[upgrade] Now you should go ahead and upgrade the kubelet package using your package manager.通过将ops-worker-1节点标记为可调度，让其重新上线。
$ kubectl uncordon ops-worker-1
node/ops-worker-1 uncordoned$ kubectl get nodes
NAME STATUS ROLES AGE VERSION
ops-master-1 Ready control-plane,master 145m v1.21.9
ops-worker-1 Ready <none> 142m v1.21.0
ops-worker-2 Ready <none> 142m v1.21.03.2 升级kubelet和kubectl
升级kubelet和kubectl到1.21.9版本。
$ yum install -y kubelet-1.21.9-0 kubectl-1.21.9-0 --disableexcludes=kubernetes
Loaded plugins: fastestmirror, langpacks, releasever-adapter, update-motd
Loading mirror speeds from cached hostfile
Resolving Dependencies
--> Running transaction check
---> Package kubectl.x86_64 0:1.21.0-0 will be updated
---> Package kubectl.x86_64 0:1.21.9-0 will be an update
---> Package kubelet.x86_64 0:1.21.0-0 will be updated
---> Package kubelet.x86_64 0:1.21.9-0 will be an update
--> Finished Dependency Resolution
Dependencies Resolved
============================================================================================================================================================================================================
Package Arch Version Repository Size
============================================================================================================================================================================================================
Updating:
kubectl x86_64 1.21.9-0 k8s 9.6 M
kubelet x86_64 1.21.9-0 k8s 20 M
Transaction Summary
============================================================================================================================================================================================================
Upgrade 2 Packages
Total download size: 30 M
Downloading packages:
No Presto metadata available for k8s
(1/2): f53d5be18ac04fa2eebe0f27a984fbc1197a31f1ed4e92c3762f0f584fcd502c-kubectl-1.21.9-0.x86_64.rpm | 9.6 MB 00:00:00
(2/2): 6e68c2e2eb926e163f53a7d64000334c6cae982841fffee350f5003793a63a9c-kubelet-1.21.9-0.x86_64.rpm | 20 MB 00:00:01
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Total 28 MB/s | 30 MB 00:00:01
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Updating : kubelet-1.21.9-0.x86_64 1/4
Updating : kubectl-1.21.9-0.x86_64 2/4
Cleanup : kubectl-1.21.0-0.x86_64 3/4
Cleanup : kubelet-1.21.0-0.x86_64 4/4
Verifying : kubectl-1.21.9-0.x86_64 1/4
Verifying : kubelet-1.21.9-0.x86_64 2/4
Verifying : kubelet-1.21.0-0.x86_64 3/4
Verifying : kubectl-1.21.0-0.x86_64 4/4
Updated:
kubectl.x86_64 0:1.21.9-0 kubelet.x86_64 0:1.21.9-0
Complete!重新加载配置文件并重启kubelet。
$ systemctl daemon-reload ;systemctl restart kubelet
systemctl daemon-reload ;systemctl restart kubelet$ kubectl get nodes
NAME STATUS ROLES AGE VERSION
ops-master-1 Ready control-plane,master 145m v1.21.9
ops-worker-1 Ready <none> 142m v1.21.9
ops-worker-2 Ready <none> 142m v1.21.0节点ops-worker-2升级步骤和ops-worker-1节点一模一样。
等节点ops-worker-2升级完成后，整个Kubernetes(k8s) 集群就升级完毕了，版本都是v1.21.9。
$ kubectl get nodes
NAME STATUS ROLES AGE VERSION
ops-master-1 Ready control-plane,master 147m v1.21.9
ops-worker-1 Ready <none> 144m v1.21.9
ops-worker-2 Ready <none> 144m v1.21.9