kubeadm升级集群(1.3.4 to 1.14.x)

1. 检查可用于升级的版本，并验证当前集群是否可升级。要跳过互联网检查，请传入可选参数[version].

kubeadm upgrade plan [version] [flags]

默认情况下kubeadm 访问的https://dl.k8s.io/release/stable.txt 地址会被rewrite https://storage.googleapis.com/kubernetes-release/release/stable.txt获取当前的稳定版本，需要提子。

2. master 安装需要升级到特定版本的kubeadm版本

yum install kubeadm-1.14.3-0.x86_64

3. 在master节点上执行升级集群的configmap操作

kubeadm upgrade apply 1.14.3

看到如下结果表示成功：

[kubelet] Creating a ConfigMap "kubelet-config-1.14" in namespace kube-system with the configuration for the kubelets in the cluster
[kubelet-start] Downloading configuration for the kubelet from the "kubelet-config-1.14" ConfigMap in the kube-system namespace
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[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 "v1.14.3". Enjoy!

[upgrade/kubelet] Now that your control plane is upgraded, please proceed with upgrading your kubelets if you haven't already done so.

4. 升级节点配置

从集群ConfigMap kubelet-config-1.x下载kubelet配置，其中X是kubelet的次要版本。

从集群中kubelete-config-1.x，形式的ConfigMap下载kubelet配置，其中X是kubelet的次版本。

kubeadm upgrade node config [flags]

例如：

 # Downloads the kubelet configuration from the ConfigMap in the cluster. Uses a specific desired kubelet version.
  kubeadm upgrade node config --kubelet-version 1.14.0
  
  # Simulates the downloading of the kubelet configuration from the ConfigMap in the cluster with a specific desired
  # version. Does not change any state locally on the node.
  kubeadm upgrade node config --kubelet-version 1.14.0 --dry-run

成功后会看到一下提示:

[kubelet-start] Downloading configuration for the kubelet from the "kubelet-config-1.14" ConfigMap in the kube-system namespace
[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.

5.升级节点的kubeadm版本到v1.14.3

yum install kubeadm-1.14.3-0.x86_64

安装完成后重启kubelet

详细参考