kubeadm 默认证书为一年，一年过期后，会导致api service不可用，使用过程中会出现：x509: certificate has expired or is not yet valid.
方案一 通过修改kubeadm 调整证书过期时间
修改代码，调整过期时间
克隆代码：git clone https://github.com/kubernetes/kubernetes.git, 切换到指定的tag或者版本修改vendor/k8s.io/client-go/util/cert/cert.go文件，git diff 对比如下：
diff --git a/staging/src/k8s.io/client-go/util/cert/cert.go b/staging/src/k8s.io/client-go/util/cert/cert.go index fb7f5fa..e800962 100644 --- a/staging/src/k8s.io/client-go/util/cert/cert.go +++ b/staging/src/k8s.io/client-go/util/cert/cert.go @@ -104,7 +104,7 @@ func NewSignedCert(cfg Config, key *rsa.PrivateKey, caCert *x509.Certificate, ca IPAddresses: cfg.AltNames.IPs, SerialNumber: serial, NotBefore: caCert.NotBefore, - NotAfter: time.Now().Add(duration365d).UTC(), + NotAfter: time.Now().Add(duration365d * 10).UTC(), KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature, ExtKeyUsage: cfg.Usages, } @@ -149,7 +149,7 @@ func GenerateSelfSignedCertKey(host string, alternateIPs []net.IP, alternateDNS CommonName: fmt.Sprintf("%s-ca@%d", host, time.Now().Unix()), }, NotBefore: time.Now(), - NotAfter: time.Now().Add(time.Hour * 24 * 365), + NotAfter: time.Now().Add(time.Hour * 24 * 3650), KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature | x509.KeyUsageCertSign, BasicConstraintsValid: true,
编译代码
这里我们可以使用官方容器对代码进行编译。
k8s.gcr.io/kube-cross:v1.12.5-1，如果不能翻墙的用户，可以拉取我个人下的镜像skymyyang/kube-cross:v1.12.5-1
docker pull skymyyang/kube-cross:v1.12.5-1
编译
docker run --rm -v 你修改后的代码目录:/go/src/k8s.io/kubernetes -it skymyyang/kube-cross:v1.12.5-1 bash cd /go/src/k8s.io/kubernetes # 编译kubeadm, 这里主要编译kubeadm 即可 make all WHAT=cmd/kubeadm GOFLAGS=-v # 编译kubelet # make all WHAT=cmd/kubelet GOFLAGS=-v # 编译kubectl # make all WHAT=cmd/kubectl GOFLAGS=-v #编译完产物在 _output/bin/kubeadm 目录下 #将kubeadm 文件拷贝出来，替换系统中的kubeadm
替换证书
#用新的kubeadm 替换官方的kubeadm chmod +x kubeadm && cp -f kubeadm /usr/bin #备份原有的证书 mv /etc/kubernetes/pki /etc/kubernetes/pki.old #生成新的证书，kubeadm.yaml 指定你自己服务器上的 kubeadm alpha phase certs all --config ~/kubeadm.yaml #备份原有的conf文件 mv /etc/kubernetes/*conf /etc/kubernetes/*conf-old #根据新证书重新生成新的配置文件 kubeadm alpha phase kubeconfig all --config ~/kubeadm.yaml #替换老的config文件 cp -f /etc/kubernetes/admin.conf ~/.kube/config
方案二 启用自动轮换kubelet 证书
kubelet证书分为server和client两种， k8s 1.9默认启用了client证书的自动轮换，但server证书自动轮换需要用户开启
增加 kubelet 参数
# 在/etc/systemd/system/kubelet.service.d/10-kubeadm.conf 增加如下参数 Environment="KUBELET_EXTRA_ARGS=--feature-gates=RotateKubeletServerCertificate=true"
增加 controller-manager 参数
# 在/etc/kubernetes/manifests/kube-controller-manager.yaml 添加如下参数 - command: - kube-controller-manager - --experimental-cluster-signing-duration=87600h0m0s - --feature-gates=RotateKubeletServerCertificate=true - ....
创建 rbac 对象
创建rbac对象，允许节点轮换kubelet server证书：
cat > ca-update.yaml << EOF apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRole metadata: annotations: rbac.authorization.kubernetes.io/autoupdate: "true" labels: kubernetes.io/bootstrapping: rbac-defaults name: system:certificates.k8s.io:certificatesigningrequests:selfnodeserver rules: - apiGroups: - certificates.k8s.io resources: - certificatesigningrequests/selfnodeserver verbs: - create --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRoleBinding metadata: name: kubeadm:node-autoapprove-certificate-server roleRef: apiGroup: rbac.authorization.k8s.io kind: ClusterRole name: system:certificates.k8s.io:certificatesigningrequests:selfnodeserver subjects: - apiGroup: rbac.authorization.k8s.io kind: Group name: system:nodes EOF kubectl create –f ca-update.yaml
如果证书已经过期，如何进行重新签发证书
针对kubeadm 1.13.x 及以上处理
准备kubeadm.conf 配置文件一份
apiVersion: kubeadm.k8s.io/v1beta1 kind: ClusterConfiguration kubernetesVersion: v1.14.1 #-->这里改成你集群对应的版本 imageRepository: registry.cn-hangzhou.aliyuncs.com/google_containers #这里使用国内的镜像仓库，否则在重新签发的时候会报错：could not fetch a Kubernetes version from the internet: unable to get URL "https://dl.k8s.io/release/stable-1.txt"
重新签发命令
kubeadm alpha certs renew all --config=/root/kubeadm.conf 运行如上命令会重新生成以下证书 #-- /etc/kubernetes/pki/apiserver.key #-- /etc/kubernetes/pki/apiserver.crt #-- /etc/kubernetes/pki/apiserver-etcd-client.key #-- /etc/kubernetes/pki/apiserver-etcd-client.crt #-- /etc/kubernetes/pki/apiserver-kubelet-client.key #-- /etc/kubernetes/pki/apiserver-kubelet-client.crt #-- /etc/kubernetes/pki/front-proxy-client.key #-- /etc/kubernetes/pki/front-proxy-client.crt #-- /etc/kubernetes/pki/etcd/healthcheck-client.key #-- /etc/kubernetes/pki/etcd/healthcheck-client.crt #-- /etc/kubernetes/pki/etcd/peer.key #-- /etc/kubernetes/pki/etcd/peer.crt #-- /etc/kubernetes/pki/etcd/server.key #-- /etc/kubernetes/pki/etcd/server.crt
完成后重启kube-apiserver,kube-controller,kube-scheduler,etcd这4个容器
针对kubeadm 1.13.0（不包含1.13.0） 以下处理
移动证书和配置【注意！必须移动，不然会使用现有的证书，不会重新生成】
cd /etc/kubernetes mkdir ./pki_bak mkdir ./pki_bak/etcd mkdir ./conf_bak mv pki/apiserver* ./pki_bak/ mv pki/front-proxy-client.* ./pki_bak/ mv pki/etcd/healthcheck-client.* ./pki_bak/etcd/ mv pki/etcd/peer.* ./pki_bak/etcd/ mv pki/etcd/server.* ./pki_bak/etcd/ mv ./admin.conf ./conf_bak/ mv ./kubelet.conf ./conf_bak/ mv ./controller-manager.conf ./conf_bak/ mv ./scheduler.conf ./conf_bak/
创建证书
kubeadm alpha phase certs all --apiserver-advertise-address=${MASTER_API_SERVER_IP} --apiserver-cert-extra-sans=主机内网ip,主机公网ip
运行如上命令会重新生成以下证书
#-- /etc/kubernetes/pki/apiserver.key
#-- /etc/kubernetes/pki/apiserver.crt
#-- /etc/kubernetes/pki/apiserver-etcd-client.key
#-- /etc/kubernetes/pki/apiserver-etcd-client.crt
#-- /etc/kubernetes/pki/apiserver-kubelet-client.key
#-- /etc/kubernetes/pki/apiserver-kubelet-client.crt
#-- /etc/kubernetes/pki/front-proxy-client.key
#-- /etc/kubernetes/pki/front-proxy-client.crt
#-- /etc/kubernetes/pki/etcd/healthcheck-client.key
#-- /etc/kubernetes/pki/etcd/healthcheck-client.crt
#-- /etc/kubernetes/pki/etcd/peer.key
#-- /etc/kubernetes/pki/etcd/peer.crt
#-- /etc/kubernetes/pki/etcd/server.key
#-- /etc/kubernetes/pki/etcd/server.crt
不移动证书会有如下提示
#[certificates] Using the existing apiserver certificate and key.
#[certificates] Using the existing apiserver-kubelet-client certificate and key.
#[certificates] Using the existing front-proxy-client certificate and key.
#[certificates] Using the existing etcd/server certificate and key.
#[certificates] Using the existing etcd/peer certificate and key.
#[certificates] Using the existing etcd/healthcheck-client certificate and key.
#[certificates] Using the existing apiserver-etcd-client certificate and key.
#[certificates] valid certificates and keys now exist in "/etc/kubernetes/pki"
#[certificates] Using the existing sa key.
生成新配置文件
kubeadm alpha phase kubeconfig all --apiserver-advertise-address=${MASTER_API_SERVER_IP}
将新生成的admin配置文件覆盖掉原本的admin文件
mv $HOME/.kube/config $HOME/.kube/config.old cp -i /etc/kubernetes/admin.conf $HOME/.kube/config chown $(id -u):$(id -g) $HOME/.kube/config sudo chmod 777 $HOME/.kube/config
完成后重启kube-apiserver,kube-controller,kube-scheduler,etcd这4个容器
如果有多台master，则将第一台生成的相关证书拷贝到其余master即可。
kubeadm 1.14 证书调整教程
kubeadm部署的kubernets证书一直都是个诟病，默认都只有一年有效期，kubeadm 1.14.x安装后有部分证书还是一年有效期，但个别证书已修改为10年有效期，但对我们使用来说，一年有效期还是一个比较的坑，需要进行调整。
修改kubeadm 1.14.x源码，调整证书过期时间
kubeadm1.14.x 安装过后crt证书如下所示
/etc/kubernetes/pki/apiserver.crt /etc/kubernetes/pki/front-proxy-ca.crt #10年有效期 /etc/kubernetes/pki/ca.crt #10年有效期 /etc/kubernetes/pki/apiserver-etcd-client.crt /etc/kubernetes/pki/front-proxy-client.crt #10年有效期 /etc/kubernetes/pki/etcd/server.crt /etc/kubernetes/pki/etcd/ca.crt #10年有效期 /etc/kubernetes/pki/etcd/peer.crt #10年有效期 /etc/kubernetes/pki/etcd/healthcheck-client.crt /etc/kubernetes/pki/apiserver-kubelet-client.crt
如上所示，除了标注说明的证书为10年有效期，其余都是1年有效期，我们查看下原先调整证书有效期的源码，克隆kubernetes 源码，切换到1.14.1 tag 查看：
代码目录： staging/src/k8s.io/client-go/util/cert/cert.go
const duration365d = time.Hour * 24 * 365 func NewSelfSignedCACert(cfg Config, key crypto.Signer) (*x509.Certificate, error) { now := time.Now() tmpl := x509.Certificate{ SerialNumber: new(big.Int).SetInt64(0), Subject: pkix.Name{ CommonName: cfg.CommonName, Organization: cfg.Organization, }, NotBefore: now.UTC(), //这里已经调整为10年有效期 NotAfter: now.Add(duration365d * 10).UTC(), KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature | x509.KeyUsageCertSign, BasicConstraintsValid: true, IsCA: true, } certDERBytes, err := x509.CreateCertificate(cryptorand.Reader, &tmpl, &tmpl, key.Public(), key) if err != nil { return nil, err } return x509.ParseCertificate(certDERBytes) }
如上所示，通过NewSelfSignedCACert这个方法签发的证书都默认为10年有效期了，但这个只影响部分证书，但这样还没满足我们的需求，个别证书的有效期调整，在经过对源码的分析后，找到了如下的逻辑：
发现部分证书是通过NewSignedCert这个方法签发，而这个方法签发的证书默认只有一年有效期，查看代码逻辑：
代码: cmd/kubeadm/app/util/pkiutil/pki_helpers.go
const duration365d = time.Hour * 24 * 365 func NewSignedCert(cfg *certutil.Config, key crypto.Signer, caCert *x509.Certificate, caKey crypto.Signer) (*x509.Certificate, error) { serial, err := rand.Int(rand.Reader, new(big.Int).SetInt64(math.MaxInt64)) if err != nil { return nil, err } if len(cfg.CommonName) == 0 { return nil, errors.New("must specify a CommonName") } if len(cfg.Usages) == 0 { return nil, errors.New("must specify at least one ExtKeyUsage") } certTmpl := x509.Certificate{ Subject: pkix.Name{ CommonName: cfg.CommonName, Organization: cfg.Organization, }, DNSNames: cfg.AltNames.DNSNames, IPAddresses: cfg.AltNames.IPs, SerialNumber: serial, NotBefore: caCert.NotBefore, // 只有一年有效期 NotAfter: time.Now().Add(duration365d).UTC(), KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature, ExtKeyUsage: cfg.Usages, } certDERBytes, err := x509.CreateCertificate(cryptorand.Reader, &certTmpl, caCert, key.Public(), caKey) if err != nil { return nil, err } return x509.ParseCertificate(certDERBytes) }
至此，调整NewSignedCert这个方法，重新进行编译，将证书有效期调整为你想要的任何时间。
原文链接：
http://icyxp.github.io/blog/2019/05/k8s-kubeadm14-ca-upgrade.html