使用kubeadm安装的k8s，所有的证书都是放在 /etc/kubernetes/pki这个目录下的，我们可以查看每个证书的时间，会发现ca证书除外，其他组件证书都是默认一年有效期，ca类型的证书的有效期为10年。
root@k8smaster1:~# kubeadm alpha certs check-expiration
[check-expiration] Reading configuration from the cluster...
[check-expiration] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -oyaml'
CERTIFICATE EXPIRES RESIDUAL TIME CERTIFICATE AUTHORITY EXTERNALLY MANAGED
admin.conf Dec 15, 2021 09:27 UTC 337d no
apiserver Dec 15, 2021 09:27 UTC 337d ca no
apiserver-etcd-client Dec 15, 2021 09:27 UTC 337d etcd-ca no
apiserver-kubelet-client Dec 15, 2021 09:27 UTC 337d ca no
controller-manager.conf Dec 15, 2021 09:27 UTC 337d no
etcd-healthcheck-client Dec 15, 2021 09:27 UTC 337d etcd-ca no
etcd-peer Dec 15, 2021 09:27 UTC 337d etcd-ca no
etcd-server Dec 15, 2021 09:27 UTC 337d etcd-ca no
front-proxy-client Dec 15, 2021 09:27 UTC 337d front-proxy-ca no
scheduler.conf Dec 15, 2021 09:27 UTC 337d no
CERTIFICATE AUTHORITY EXPIRES RESIDUAL TIME EXTERNALLY MANAGED
ca Dec 13, 2030 09:27 UTC 9y no
etcd-ca Dec 13, 2030 09:27 UTC 9y no
front-proxy-ca Dec 13, 2030 09:27 UTC 9y no
服务器的k8smaster1上需要安装两个工具git和go (这里就省略了)
下载对应的源码版本
cd /usr/local/src/
git clone -b v1.18.5 --depth=1 https://github.com/kubernetes/kubernetes.git
cd kubernetes
# 修改 cmd/kubeadm/app/constans/constans.go 文件
# 找到 CertificateValidity = time.Hour * 24 * 365, 修改为下面一行内容
CertificateValidity = time.Hour * 24 * 365 * 10
# 编译kubeadm
cd /usr/local/src/kubernetes/
root@k8smaster1:/usr/local/src/kubernetes# make WHAT=cmd/kubeadm
+++ [0112 17:59:21] Building go targets for linux/amd64:
./vendor/k8s.io/code-generator/cmd/deepcopy-gen
+++ [0112 17:59:39] Building go targets for linux/amd64:
./vendor/k8s.io/code-generator/cmd/defaulter-gen
+++ [0112 17:59:53] Building go targets for linux/amd64:
./vendor/k8s.io/code-generator/cmd/conversion-gen
+++ [0112 18:00:19] Building go targets for linux/amd64:
./vendor/k8s.io/kube-openapi/cmd/openapi-gen
+++ [0112 18:00:41] Building go targets for linux/amd64:
./vendor/github.com/go-bindata/go-bindata/go-bindata
warning: ignoring symlink /usr/local/src/kubernetes/_output/local/go/src/k8s.io/kubernetes
go: warning: "k8s.io/kubernetes/vendor/github.com/go-bindata/go-bindata/..." matched no packages
+++ [0112 18:00:42] Building go targets for linux/amd64:
cmd/kubeadm
# 编译完生成_output目录
# 备份之前的kubeadm,然后用新的
root@k8smaster1:/usr/local/src/kubernetes# mv /usr/bin/kubeadm /usr/bin/kubeadm.old
root@k8smaster1:/usr/local/src/kubernetes# cp _output/bin/kubeadm /usr/bin/kubeadm
# 备份之前的证书，重新生成证书
root@k8smaster1:/usr/local/src/kubernetes# cp -rf /etc/kubernetes/pki/ /etc/kubernetes/pki.old
root@k8smaster1:/usr/local/src/kubernetes# cd /etc/kubernetes/
root@k8smaster1:/etc/kubernetes# ls
admin.conf controller-manager.conf kubelet.conf manifests pki pki.old scheduler.conf
root@k8smaster1:/etc/kubernetes# cd pki
root@k8smaster1:/etc/kubernetes/pki# ls
apiserver.crt apiserver-etcd-client.key apiserver-kubelet-client.crt ca.crt etcd front-proxy-ca.key front-proxy-client.key sa.pub
apiserver-etcd-client.crt apiserver.key apiserver-kubelet-client.key ca.key front-proxy-ca.crt front-proxy-client.crt sa.key
root@k8smaster1:/etc/kubernetes/pki# kubeadm alpha certs renew all
[renew] Reading configuration from the cluster...
[renew] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -oyaml'
certificate embedded in the kubeconfig file for the admin to use and for kubeadm itself renewed
certificate for serving the Kubernetes API renewed
certificate the apiserver uses to access etcd renewed
certificate for the API server to connect to kubelet renewed
certificate embedded in the kubeconfig file for the controller manager to use renewed
certificate for liveness probes to healthcheck etcd renewed
certificate for etcd nodes to communicate with each other renewed
certificate for serving etcd renewed
certificate for the front proxy client renewed
certificate embedded in the kubeconfig file for the scheduler manager to use renewed
# 再次查看组件中的证书有效时间，已经为10年了
root@k8smaster1:/etc/kubernetes/pki# kubeadm alpha certs check-expiration
[check-expiration] Reading configuration from the cluster...
[check-expiration] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -oyaml'
CERTIFICATE EXPIRES RESIDUAL TIME CERTIFICATE AUTHORITY EXTERNALLY MANAGED
admin.conf Jan 10, 2031 10:10 UTC 9y no
apiserver Jan 10, 2031 10:10 UTC 9y ca no
apiserver-etcd-client Jan 10, 2031 10:10 UTC 9y etcd-ca no
apiserver-kubelet-client Jan 10, 2031 10:10 UTC 9y ca no
controller-manager.conf Jan 10, 2031 10:10 UTC 9y no
etcd-healthcheck-client Jan 10, 2031 10:10 UTC 9y etcd-ca no
etcd-peer Jan 10, 2031 10:10 UTC 9y etcd-ca no
etcd-server Jan 10, 2031 10:10 UTC 9y etcd-ca no
front-proxy-client Jan 10, 2031 10:10 UTC 9y front-proxy-ca no
scheduler.conf Jan 10, 2031 10:10 UTC 9y no
CERTIFICATE AUTHORITY EXPIRES RESIDUAL TIME EXTERNALLY MANAGED
ca Dec 13, 2030 09:27 UTC 9y no
etcd-ca Dec 13, 2030 09:27 UTC 9y no
front-proxy-ca Dec 13, 2030 09:27 UTC 9y no
