kubeadm修改证书过期时间

kubeadm搭建的集群证书默认ca是时间，其他组件的证书是一年如果一年没有执行升级的操作就会过期

所以一劳永逸直接修改kubeadm证书时间

下载源码

git clone -b v1.27.3 https://github.com/kubernetes/kubernetes.git

修改证书时间

• ca 证书

code ./staging/src/k8s.io/client-go/util/cert/cert.go

NewSelfSignedCACert这个函数的NotAfter字段

// 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,
    },
    DNSNames:              []string{cfg.CommonName},
    NotBefore:             now.UTC(),
    NotAfter:              now.Add(duration365d * 10).UTC(), // 需要修改的地方
    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)
}

• loopback证书

func GenerateSelfSignedCertKeyWithFixtures(host string, alternateIPs []net.IP, alternateDNS []string, fixtureDirectory string) ([]byte, []byte, error) {
  validFrom := time.Now().Add(-time.Hour) // valid an hour earlier to avoid flakes due to clock skew
  maxAge := time.Minute * 10// one year self-signed certs 这里需要修改

  baseName := fmt.Sprintf("%s_%s_%s", host, strings.Join(ipsToStrings(alternateIPs), "-"), strings.Join(alternateDNS, "-"))
  certFixturePath := filepath.Join(fixtureDirectory, baseName+".crt")
  keyFixturePath := filepath.Join(fixtureDirectory, baseName+".key")
...

• 组件证书

code ./cmd/kubeadm/app/constants/constants.go

CertificateValidity这个变量

// CertificateValidity defines the validity for all the signed certificates generated by kubeadm
CertificateValidity = time.Hour * 24 * 365 // 需要修改的地方

重新编译

make all WHAT=cmd/kubeadm GOFLAGS=-v

make all WHAT=cmd/kube-apiserver GOFLAGS=-v

编译好的二进制文件中在_output/bin/

建议先使用yum等工具安装官方的kubeadm之后进行二进制替换

参考资料

https://blog.51cto.com/legehappy/4895615