k8s单节点改为高可用和更新证书

• master单节点添加master节点
• apiServer添加域名更新证书
• 更新kubenertes证书有效期

环境

kubernetes v1.22.12

使用kubeadm安装的集群

#添加节点

#生成节点添加token(在master运行)

#创建join token.  Create join token
kubeadm token create --print-join-command
#kubeadm join IP:6443 --token xxx --discovery-token-ca-cert-hash sha256:xxx

#创建用于添加master节点的证书.  Create certificate-key for add master node
kubeadm init phase upload-certs --upload-certs

#添加节点(在添加节点运行)

#安装kubelet

export Ver=1.22.12 #与master版本一致
curl -s http://elvin.vip/ks/k8s/kubelet.sh |bash

#查看往期快速创建k8s文章 https://www.cnblogs.com/elvi/p/8976305.html

#添加node节点

#添加node节点，运行上面生成的
kubeadm join IP:6443 --token xxx --discovery-token-ca-cert-hash sha256:xxx

#添加master节点

#添加master节点，添加上面创建的certificate-key
kubeadm join IP:6443 --token xxx --discovery-token-ca-cert-hash sha256:xxx \
    --control-plane --certificate-key xxx 

#master节点配置kubectl凭证
mkdir -p $HOME/.kube
ln -fs /etc/kubernetes/admin.conf $HOME/.kube/config

#node lable
kubectl label node $(hostname) node-role.kubernetes.io/master=
#view nodes
kubectl get nodes

#添加Endpoint

若添加master节点报错且有如下提示，则需要添加Endpoint

Please ensure that:
* The cluster has a stable controlPlaneEndpoint address.
* The certificates that must be shared among control plane instances are provided.

master单节点添加master节点报错提示没controlPlaneEndpoint

Endpoint地址需要添加到apiServer证书认证地址里

为保证Endpoint能被新节点能访问,可使用7层代理、DNS轮询或添加到hosts解析

单节点添加master节点后保证Endpoint高可用, 即达到master节点高可用

#echo "masterIP  myk8s.api.io" >>/etc/hosts

#查看kubeadm-config
kubectl -n kube-system get cm kubeadm-config -o yaml

#修改kubeadm-config,添加如 controlPlaneEndpoint: myk8s.api.io:6443
kubectl edit cm kubeadm-config -n kube-system

#添加位置，与版本号缩进一致
controlPlaneEndpoint: myk8s.api.io:6443
kubernetesVersion: v1.22.12

#添加域名更新apiServer证书

添加Endpoint使用域名或IP后，需要更新证书

域名或IP添加到certSANs部分，如下

apiVersion: v1
data:
  ClusterConfiguration: |
    apiServer:
      certSANs:
      - myk8s.api.io
    certificatesDir: /etc/kubernetes/pki
    controlPlaneEndpoint: myk8s.api.io:6443
    kubernetesVersion: v1.22.12

#导出kubeadm配置

kubectl -n kube-system get configmap kubeadm-config \
  -o jsonpath='{.data.ClusterConfiguration}' > kubeadm-init.yaml

#查看配置
cat kubeadm-init.yaml

#创建新的apiServer证书

#移除apiserver证书
mv /etc/kubernetes/pki/apiserver.{crt,key} /tmp/ 

#创建新的apiserver证书
kubeadm init phase certs apiserver --config kubeadm-init.yaml 

#查看证书包含的域名和IP
openssl x509 -in /etc/kubernetes/pki/apiserver.crt -text |grep DNS

#重启apiserver生效
docker ps |awk '/kube-apiserver/{print $1}' |xargs docker restart

#更新kubenertes证书有效期

#查看有效期
kubeadm certs check-expiration

#更新有效期
kubeadm certs renew all 

#重启服务生效
docker ps |awk '/k8s_kube-|etcd/{print $1}' |xargs docker restart