k8s master节点更换ip 重签证书

一、开始

证书的修改，必须要 apiserver 服务可用

旧IP：

新IP： 

修改/etc/hosts解析（所有节点）：

vim /etc/hosts
 
k8s-master 10.0.0.10
k8s-node-1 10.0.0.11
k8s-node-2 10.0.0.12

二、备份 kubernetes 目录

cp -r /etc/kubernetes{,-bak}

三、查看证书内的 ip

for i in $(find /etc/kubernetes/pki -type f -name "*.crt");do echo ${i} && openssl x509 -in ${i} -text | grep 'Address'

可以看到，只有 apiserver 和 etcd 的证书里面是包含了 ip 的

/etc/kubernetes/pki/ca.crt
/etc/kubernetes/pki/front-proxy-ca.crt
/etc/kubernetes/pki/etcd/ca.crt
/etc/kubernetes/pki/etcd/server.crt
                DNS:k8s-master, DNS:localhost, IP Address:10.0.0.1, IP Address:127.0.0.1, IP Address:0:0:0:0:0:0:0:1
/etc/kubernetes/pki/etcd/healthcheck-client.crt
/etc/kubernetes/pki/etcd/peer.crt
                DNS:k8s-master, DNS:localhost, IP Address:10.0.0.1, IP Address:127.0.0.1, IP Address:0:0:0:0:0:0:0:1
/etc/kubernetes/pki/apiserver.crt
                DNS:k8s-master, DNS:kubernetes, DNS:kubernetes.default, DNS:kubernetes.default.svc, DNS:kubernetes.default.svc.cluster.local, DNS:lb-vip, IP Address:10.96.0.1, IP Address:10.0.0.1
/etc/kubernetes/pki/apiserver-kubelet-client.crt
/etc/kubernetes/pki/front-proxy-client.crt
/etc/kubernetes/pki/apiserver-etcd-client.crt

四、生成集群配置

kubeadm config view > /root/kubeadm.yaml

更换IP：

vim kubeadm.yaml

apiServer:
  extraArgs:
    authorization-mode: Node,RBAC
  timeoutForControlPlane: 4m0s
  # 增加下面的配置
  certSANs:
  - 10.0.0.10
  # 增加上面的配置
apiVersion: kubeadm.k8s.io/v1beta2
certificatesDir: /etc/kubernetes/pki
clusterName: kubernetes
controlPlaneEndpoint: lb-vip:6443
controllerManager: {}
dns:
  type: CoreDNS
etcd:
  local:
    dataDir: /var/lib/etcd
    # 增加下面的配置
    serverCertSANs:
    - 10.0.0.10
    peerCertSANs:
    - 10.0.0.10
    # 增加上面的配置
imageRepository: registry.aliyuncs.com/google_containers
kind: ClusterConfiguration
kubernetesVersion: v1.17.3
networking:
  dnsDomain: cluster.local
  podSubnet: 172.10.0.0/16
  serviceSubnet: 10.96.0.0/12
scheduler: {}

五、删除原有的证书

需要保留 ca ，sa，front-proxy 这三个证书

rm -rf /etc/kubernetes/pki/{apiserver*,front-proxy-client*}
rm -rf /etc/kubernetes/pki/etcd/{healthcheck*,peer*,server*}

六、重新生成证书

kubeadm init phase certs all --config /root/kubeadm.yaml

再次查看证书内的 ip

for i in $(find /etc/kubernetes/pki -type f -name "*.crt");do echo ${i} && openssl x509 -in ${i} -text | grep 'DNS:';done

/etc/kubernetes/pki/etcd/ca.crt
/etc/kubernetes/pki/etcd/server.crt
                DNS:k8s-master, DNS:localhost, IP Address:10.0.0.10, IP Address:127.0.0.1, 
/etc/kubernetes/pki/etcd/peer.crt
                DNS:k8s-master, DNS:localhost, IP Address:10.0.0.10, IP Address:127.0.0.1, 
/etc/kubernetes/pki/etcd/healthcheck-client.crt
/etc/kubernetes/pki/ca.crt
/etc/kubernetes/pki/front-proxy-ca.crt
/etc/kubernetes/pki/apiserver.crt
                DNS:k8s-master, DNS:kubernetes, DNS:kubernetes.default, DNS:kubernetes.default.svc, DNS:kubernetes.default.svc.cluster.local, DNS:lb-vip, IP Address:10.96.0.1, IP Address:10.0.0.10
/etc/kubernetes/pki/apiserver-kubelet-client.crt
/etc/kubernetes/pki/front-proxy-client.crt
/etc/kubernetes/pki/apiserver-etcd-client.crt

七、将配置更新到 configmap 中

这样，以后有升级，或者增加其他 ip 时，也会将配置的 CertSANs 的 ip 保留下来，方便以后删减

kubeadm init phase upload-config kubeadm --config kubeadm.yaml

八、检查

# 检查kubeadm.config配置的ip是否为新节点IP
 
kubectl get cm -A|grep kubeadm
kubectl get cm -A kubeadm-config -o yaml
 
#检查所有容器健康状态
 
kubectl get pod -A

node节点IP更换，证书会自动重新签发