k8s升級，此次升級是1.12.0 至1.13.0

準備

# 首先升級master節點的基礎元件kubeadm、kubelet、kubectl
apt-get update && apt-get upgrade  kubeadm

# 更新到1.13.0後，在master執行,執行一次

kubeadm upgrade plan

[upgrade/versions] Latest version in the v1.12 series: v1.13.0

External components that should be upgraded manually before you upgrade the control plane with 'kubeadm upgrade apply':
COMPONENT CURRENT AVAILABLE
Etcd 3.2.22 3.2.24

Components that must be upgraded manually after you have upgraded the control plane with 'kubeadm upgrade apply':
COMPONENT CURRENT AVAILABLE
Kubelet 1 x v1.12.0 v1.13.0
2 x v1.13.0 v1.13.0

Upgrade to the latest version in the v1.12 series:

COMPONENT CURRENT AVAILABLE
API Server v1.12.0 v1.13.0
Controller Manager v1.12.0 v1.13.0
Scheduler v1.12.0 v1.13.0
Kube Proxy v1.12.0 v1.13.0
CoreDNS 1.2.2 1.2.6

You can now apply the upgrade by executing the following command:
kubeadm upgrade apply v1.13.0

需要先升級etcd服務，我們的版本是3.2.22，需要升級到3.2.24

# 更新
 kubeadm upgrade apply v1.13.0
# 備份etcd資料(以防萬一)
 etcdctl snapshot save backup.db
 
# 檢視備份的狀態
 etcdctl --write-out=table snapshot status backup.db
 
# 下載新的etcd，這裡我們部署1.13.0的kubernetes需要的是3.2.24
# (https://github.com/etcd-io/etcd/releases/download/v3.2.24/etcd-v3.2.24-linux-amd64.tar.gz)

  wget https://github.com/etcd-io/etcd/releases/download/v3.2.24/etcd-v3.2.24-linux-amd64.tar.gz

#由於之前部署的是三節點的etcd叢集，所以可以做到無縫升級，一個節點一個節點進行升級，每個節點恢復正常後在升級下一個節點；
# 停掉當前節點
 systemctl stop etcd

# 將下載好的檔案解壓，然後替換之前的etcd和etcdctl，替換完成後啟動etcd

 systemctl start etcd

# 每個節點替換完成後檢查服務狀態

 etcdctl endpoint health
 

Upgrade master and node packages

kubectl drain node_name --ignore-daemonsets

#master節點需要加上--ignore-daemonsets，node節點不用

#更新
apt-get update
apt-get upgrade -y  kubeadm

#更新過程中要保證服務不中斷，輪詢替換更新

Upgrade kubelet on each node

# On each node except the master node, upgrade the kubelet config:

kubeadm upgrade node config --kubelet-version $(kubelet --version | cut -d  ' '  -f 2) 

# Restart the kubelet process:

systemctl restart kubelet

# Verify that the new version of the kubelet is running on the node:

systemctl status kubelet

# Bring the node back online by marking it schedulable:

kubectl uncordon $NODE

# verify that all nodes are available again by running the following command from anywhere kubectl can access the cluster:

kubectl get nodes


#The STATUS column should show Ready for all your nodes, and the version number should be updated.

Rolling update

# 如果升級失敗了，一般會自動回滾到之前的版本，如果出現異常沒有回退到之前的版本，可以再次執行kubeadm upgrade
kubeadm upgrade apply v1.12.0 --force