重新编译kubeadm，修改默认证书时间

女爷i 2021-11-09 02:18 388阅读 0赞

## 参考 ##

*  [kubeadm alpha certs renew][]
 *  [Kubeadm1.14 证书调整][Kubeadm1.14]

kubeadm 部署的 kubernetes 集群，默认的证书有效时间是1年，需要每年手工更新。

## 1. 重新编译kubeadm ##

### 1.1 准备 ###

# 下载对应的kubernetes源代码，这里采用 "v1.14.1" 版本
    wget https://codeload.github.com/kubernetes/kubernetes/tar.gz/v1.14.1
    
    # untar
    tar -zxvf kubernetes-1.14.1.tar.gz
    cd kubernetes-1.14.1
    
    # 进入源代码目录
    cd kubernetes-1.14.1

### 1.2 修改源代码-cert.go ###

*  文件：`staging/src/k8s.io/client-go/util/cert/cert.go`
 *  `NewSelfSignedCACert` 方法，签发以下证书，且默认为10年有效期：
    
     *  front-proxy-ca.crt
     *  front-proxy-client.crt
     *  ca.crt
     *  etcd/ca.crt
     *  etcd/peer.crt

# 1.14.0版本开始，此文件不需要修改
    vim staging/src/k8s.io/client-go/util/cert/cert.go
    
    const duration365d = time.Hour * 24 * 365
    
    // Config contains the basic fields required for creating a certificate
    type Config struct {
            CommonName   string
            Organization []string
            AltNames     AltNames
            Usages       []x509.ExtKeyUsage
    }
    
    // AltNames contains the domain names and IP addresses that will be added
    // to the API Server's x509 certificate SubAltNames field. The values will
    // be passed directly to the x509.Certificate object.
    type AltNames struct {
            DNSNames []string
            IPs      []net.IP
    }
    
    // NewSelfSignedCACert creates a CA certificate
    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(),
                    # 默认已调整有效期为10年；
                    # 但只影响部分证书：
                    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)
    }

### 1.3 修改源代码-pki\_helpers.go ###

*  ，以下证书由 `NewSignedCert` 方法签发，但签发的证书默认只有一年有效期：
    
     *  apiserver.crt
     *  apiserver-etcd-client.crt
     *  etcd/server.crt
     *  etcd/healthcheck-client.crt
     *  apiserver-kubelet-client.crt

# `NewSignedCert` 方法：
    # 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
    vim cmd/kubeadm/app/util/pkiutil/pki_helpers.go
    
    // NewSignedCert creates a signed certificate using the given CA certificate and key
    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,
                    # 修改签发相关证书的默认有效期为10年
                    // NotAfter:     time.Now().Add(duration365d).UTC(),
                    NotAfter:     time.Now().Add(duration365d * 10).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)
    }

### 1.4 编译 ###

# go环境已经准备好
    # kubeadm
    make WHAT=cmd/kubeadm GOFLAGS=-v
    
    # 补充：编译kubelet
    # make all WHAT=cmd/kubelet GOFLAGS=-v
    
    # 补充：编译kubectl
    # make all WHAT=cmd/kubectl GOFLAGS=-v
    
    # 编译生成的二进制文件在 _output/bin/ 目录下

### 1.5 更新kubeadm ###

# 将kubeadm 文件拷贝替换系统中原有kubeadm
    cp /usr/bin/kubeadm /usr/bin/kubeadm.origin
    cp _output/bin/kubeadm /usr/bin/kubeadm

## 2. 更新证书 ##

### 2.1 更新 kube-master (任一)节点证书 ###

*  `1.13.x` 版本(含)之后的处理方式；
 *  不更新 `kubeadm` 的情况下，也可手动更新证书，但更新的证书有效期默认仍是一年。

# 备份
    cp -r /etc/kubernetes/pki /etc/kubernetes/pki.origin
    
    # 更新证书；
    # "--config" 指定 "kubeadm" 的配置文件，建议使用部署集群时使用的配置文件；
    # 其他参数可参考官方文档
    cd /etc/kubernetes/pki
    kubeadm alpha certs renew all --config=/root/kubeadm/kubeadm-config.yaml
    
    # 验证
    openssl x509 -in apiserver.crt -text -noout | grep Not
    
    # 关于kubeconfig：$HOME/.kube/config
    # service account的密钥是以rsa密钥对形式生成，没有过期时间

### 2.2 (optional) HA集群其余mater节点证书更新 ###

*  在已更新证书的master节点运行脚本，将更新的证书同步到其余master节点

# 如果可以，请提前在被同步master节点做备份
    cat certificate.sh
    #!/bin/bash
    # 2019-05-27 v0.1
    # scp certificate files from the first control plane node to the rest.
    
    USER=root # customizable
    CONTROL_PLANE_IPS="100.64.198.137 100.64.198.138"
    for host in ${CONTROL_PLANE_IPS}; do
        scp /etc/kubernetes/pki/ca.crt "${USER}"@$host:/etc/kubernetes/pki/
        scp /etc/kubernetes/pki/ca.key "${USER}"@$host:/etc/kubernetes/pki/
        scp /etc/kubernetes/pki/sa.key "${USER}"@$host:/etc/kubernetes/pki/
        scp /etc/kubernetes/pki/sa.pub "${USER}"@$host:/etc/kubernetes/pki/
        scp /etc/kubernetes/pki/front-proxy-ca.crt "${USER}"@$host:/etc/kubernetes/pki/
        scp /etc/kubernetes/pki/front-proxy-ca.key "${USER}"@$host:/etc/kubernetes/pki/
        scp /etc/kubernetes/pki/etcd/ca.crt "${USER}"@$host:/etc/kubernetes/pki/etcd/ca.crt
        scp /etc/kubernetes/pki/etcd/ca.key "${USER}"@$host:/etc/kubernetes/pki/etcd/ca.key
        scp /etc/kubernetes/admin.conf "${USER}"@$host:/etc/kubernetes/
    done

## 3. 补充：go 环境 ##

# download，根据需要选择版本
    wget https://studygolang.com/dl/golang/go1.12.1.linux-amd64.tar.gz
    
    # untar
    tar -zxvf go1.12.1.linux-amd64.tar.gz -C /usr/local
    
    # edit /etc/profile，在文件末尾添加如下内容
    vim /etc/profile
    # go setting
    export GOROOT=/usr/local/go
    export GOPATH=/usr/local/gopath
    export PATH=$PATH:$GOROOT/bin
    
    # enable /etc/profile
    source /etc/profile

转载于:https://www.cnblogs.com/netonline/p/11207765.html

[kubeadm alpha certs renew]: https://v1-14.docs.kubernetes.io/docs/reference/setup-tools/kubeadm/kubeadm-alpha/#cmd-certs-renew
[Kubeadm1.14]: http://team.jiunile.com/blog/2019/05/k8s-kubeadm14-ca-upgrade.html