关于Kubernetes证书的那点事

本篇文章主要介绍了k8s中用的证书和组件之间是如何进行认证访问的。

k8s证书介绍

众所周知。Kubernetes 需要 PKI 证书才能进行基于 TLS 的身份验证。如果你是使用kubeadm安装的 Kubernetes， 则会自动生成集群所需的证书。但是如果是通过二进制搭建，所有的证书是需要自己生成的，这里我们说说集群必需的证书。

• 服务器单向认证：只需要服务器端提供证书，客户端通过服务器端证书验证服务的身份，但服务器并不验证客户端的身份。这种情况一般适用于对 Internet 开放的服务，例如搜索引擎网站，任何客户端都可以连接到服务器上进行访问，但客户端需要验证服务器的身份，以避免连接到伪造的恶意服务器。
• 双向 TLS 认证：除了客户端需要验证服务器的证书，服务器也要通过客户端证书验证客户端的身份。这种情况下服务器提供的是敏感信息，只允许特定身份的客户端访问

Kubernetes为了安全性，都是采用双向认证。通常我们在部署k8s时候，kubeadm会自动生成集群所需要的证书，下面我们就这些证书一一给大家进行讲解。
这是我们用kubeadm搭建完一个集群后再/etc/kubernetes目录下所生成的文件

[root@VM-4-3-centos etc]# tree kubernetes/
kubernetes/
|-- admin.conf
|-- controller-manager.conf
|-- kubelet.conf
|-- scheduler.conf
|-- manifests
|   |-- etcd.yaml
|   |-- kube-apiserver.yaml
|   |-- kube-controller-manager.yaml
|   `-- kube-scheduler.yaml
|-- pki
|   |-- apiserver.crt
|   |-- apiserver-etcd-client.crt
|   |-- apiserver-etcd-client.key
|   |-- apiserver.key
|   |-- apiserver-kubelet-client.crt
|   |-- apiserver-kubelet-client.key
|   |-- ca.crt
|   |-- ca.key
|   |-- etcd
|   |   |-- ca.crt
|   |   |-- ca.key
|   |   |-- healthcheck-client.crt
|   |   |-- healthcheck-client.key
|   |   |-- peer.crt
|   |   |-- peer.key
|   |   |-- server.crt
|   |   `-- server.key
|   |-- front-proxy-ca.crt
|   |-- front-proxy-ca.key
|   |-- front-proxy-client.crt
|   |-- front-proxy-client.key
|   |-- sa.key
|   `-- sa.pub

下面我们根据这个k8s的组件之间通讯图来一一讲解每个证书的作用。

CA证书

kubeadm安装的集群中我们都是用3套CA证书来管理和签发其他证书，一套CA给ETCD使用，一套是给kubernetes内部组件使用，还有一套是给配置聚合层使用的，当然如果你觉得管理3套CA比较麻烦，您也可以用一套来管理。

etcd证书

ca.crt  ca.key  healthcheck-client.crt  healthcheck-client.key  peer.crt  peer.key  server.crt  server.key

etcd证书位于/etc/kubernetes/pki/etcd目录下，我们根据etcd的yaml配置解释下证书的作用

spec:
  containers:
  - command:
    - etcd
    - --advertise-client-urls=https://10.0.4.3:2379
    - --cert-file=/etc/kubernetes/pki/etcd/server.crt
    - --client-cert-auth=true
    - --data-dir=/var/lib/etcd
    - --initial-advertise-peer-urls=https://10.0.4.3:2380
    - --initial-cluster=vm-4-3-centos=https://10.0.4.3:2380
    - --key-file=/etc/kubernetes/pki/etcd/server.key
    - --listen-client-urls=https://127.0.0.1:2379,https://10.0.4.3:2379
    - --listen-peer-urls=https://10.0.4.3:2380
    - --name=vm-4-3-centos
    - --peer-cert-file=/etc/kubernetes/pki/etcd/peer.crt
    - --peer-client-cert-auth=true
    - --peer-key-file=/etc/kubernetes/pki/etcd/peer.key
    - --peer-trusted-ca-file=/etc/kubernetes/pki/etcd/ca.crt
    - --snapshot-count=10000
    - --trusted-ca-file=/etc/kubernetes/pki/etcd/ca.crt
    image: k8s.gcr.io/etcd:3.3.10
    imagePullPolicy: IfNotPresent
    livenessProbe:
      exec:
        command:
        - /bin/sh
        - -ec
        - ETCDCTL_API=3 etcdctl --endpoints=https://[127.0.0.1]:2379 --cacert=/etc/kubernetes/pki/etcd/ca.crt
          --cert=/etc/kubernetes/pki/etcd/healthcheck-client.crt --key=/etc/kubernetes/pki/etcd/healthcheck-client.key
          get foo
      failureThreshold: 8

• etcd 对外提供服务的服务器证书及私钥

  server.crt  server.key

• etcd 节点之间相互进行认证的 peer 证书、私钥以及验证 peer 的 CA

  ca.crt  ca.key peer.crt  peer.key

• etcd 验证访问其服务的客户端的 CA

  healthcheck-client.crt  healthcheck-client.key 

kube-apiserver证书

 name: kube-apiserver
  namespace: kube-system
spec:
  containers:
  - command:
    - kube-apiserver
    - --advertise-address=10.0.4.3
    - --allow-privileged=true
    - --authorization-mode=Node,RBAC
    - --client-ca-file=/etc/kubernetes/pki/ca.crt
    - --enable-admission-plugins=NodeRestriction
    - --enable-bootstrap-token-auth=true
    - --etcd-cafile=/etc/kubernetes/pki/etcd/ca.crt
    - --etcd-certfile=/etc/kubernetes/pki/apiserver-etcd-client.crt
    - --etcd-keyfile=/etc/kubernetes/pki/apiserver-etcd-client.key
    - --etcd-servers=https://127.0.0.1:2379
    - --insecure-port=0
    - --kubelet-client-certificate=/etc/kubernetes/pki/apiserver-kubelet-client.crt
    - --kubelet-client-key=/etc/kubernetes/pki/apiserver-kubelet-client.key
    - --kubelet-preferred-address-types=InternalIP,ExternalIP,Hostname
    - --proxy-client-cert-file=/etc/kubernetes/pki/front-proxy-client.crt
    - --proxy-client-key-file=/etc/kubernetes/pki/front-proxy-client.key
    - --requestheader-allowed-names=front-proxy-client
    - --requestheader-client-ca-file=/etc/kubernetes/pki/front-proxy-ca.crt
    - --requestheader-extra-headers-prefix=X-Remote-Extra-
    - --requestheader-group-headers=X-Remote-Group
    - --requestheader-username-headers=X-Remote-User
    - --secure-port=6443
    - --service-account-key-file=/etc/kubernetes/pki/sa.pub
    - --service-cluster-ip-range=10.96.0.0/12
    - --tls-cert-file=/etc/kubernetes/pki/apiserver.crt
    - --tls-private-key-file=/etc/kubernetes/pki/apiserver.key
    image: k8s.gcr.io/kube-apiserver:v1.15.2

apiserver证书位于/etc/kubernetes/pki，同样我们通过apiserver的yaml文件来一一解释下每个证书的作用。

• 访问etcd的客户端证书及私钥，这个证书是由etcd的CA证书签发，因此也需要在apiserver中配置etcd的CA证书

  apiserver-etcd-client.key   apiserver-etcd-client.crt   

• 用来签发k8s中其他证书的CA证书及私钥

  ca.crt  ca.key

• apiServer的对外提供服务的服务端证书及私钥

  apiserver.crt   apiserver.key  

• apiserver 访问 kubelet 所需的客户端证书及私钥

  apiserver-kubelet-client.crt  apiserver-kubelet-client.key

  配置聚合层（apiserver扩展）的CA和客户端证书及私钥
  说明：要使聚合层在您的环境中正常工作以支持代理服务器和扩展 apiserver 之间的相互 TLS 身份验证， 需要满足一些设置要求。Kubernetes 和 kube-apiserver 具有多个 CA， 因此请确保代理是由聚合层 CA 签名的，而不是由主 CA 签名的。扩展apiserver为了能够和apiserver通讯，所以需要在apiserver中配置，假如你不需要这个功能可以不配置该证书。

  front-proxy-client.crt front-proxy-ca.key front-proxy-client.key

  ```
  * 验证 service account token 的公钥

  sa.pub

  到这里，集群生成的所有证书介绍完了，那么像kube-controller-mananger、kube-scheduler、kube-proxy、kubele这些组件也是需要访问apiserver的，那么他们是怎么通讯的呢？下面我们可以看看这些组件是如何和apiserver进行通讯的。
  
  # kube-controller-mananger
  还是和之前一样，我们通过kube-controller-mananger的yaml文件配置来看看是如何访问apiserver。

  spec:
  containers:
  • command:
    • kube-controller-manager
    • –allocate-node-cidrs=true
    • –authentication-kubeconfig=/etc/kubernetes/controller-manager.conf
    • –authorization-kubeconfig=/etc/kubernetes/controller-manager.conf
    • –bind-address=127.0.0.1
    • –client-ca-file=/etc/kubernetes/pki/ca.crt
    • –cluster-cidr=10.244.0.0/16
    • –cluster-signing-cert-file=/etc/kubernetes/pki/ca.crt
    • –cluster-signing-key-file=/etc/kubernetes/pki/ca.key
    • –controllers=*,bootstrapsigner,tokencleaner
    • –kubeconfig=/etc/kubernetes/controller-manager.conf
    • –leader-elect=true
    • –node-cidr-mask-size=24
    • –requestheader-client-ca-file=/etc/kubernetes/pki/front-proxy-ca.crt
    • –root-ca-file=/etc/kubernetes/pki/ca.crt
    • –service-account-private-key-file=/etc/kubernetes/pki/sa.key
    • –use-service-account-credentials=true
      image: k8s.gcr.io/kube-controller-manager:v1.15.2

      你会发现在yaml中配置了/etc/kubernetes/controller-manager.conf这个配置文件，而不是配置controller-manager的客户端证书之类的。Kubernetes 这里的设计是这样的，kube-controller-mananger、kube-scheduler、kube-proxy、kubelet等组件，采用一个kubeconfig 文件中配置的信息来访问 kube-apiserver。该文件中包含了 kube-apiserver 的地址，验证 kube-apiserver 服务器证书的 CA 证书，自己的客户端证书和私钥等访问信息，这样组件只需要配置这个kubeconfig就行。
      
      由于创建工作负载的时候，我们有时候会用到service accout，那么这里需要和apiserver认证，所以我们需要在controller-manager
      
      配置上sa私钥，当然需要和apiserver通讯，自然需要配置上kubernates的CA证书
      
      下面我们看看controller-manager.conf这个文件配置的证书和秘钥是什么。

      [root@VM-4-3-centos kubernetes]# cat controller-manager.conf
      apiVersion: v1
      clusters:

• cluster:
  certificate-authority-data: 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
  server: https://10.0.4.3:6443
  name: kubernetes
  contexts:
• context:
  cluster: kubernetes
  user: system:kube-controller-manager
  name: system:kube-controller-manager@kubernetes
  current-context: system:kube-controller-manager@kubernetes
  kind: Config
  preferences: {}
  users:
• name: system:kube-controller-manager
  user:
  client-certificate-data: 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
  client-key-data: 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

  我们解析下certificate-authority-data这个内容看看是不是CA的证书

  [root@VM-4-3-centos kubernetes]# echo “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”|base64 -d

—–BEGIN CERTIFICATE—–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—–END CERTIFICATE—–
[root@VM-4-3-centos kubernetes]# cat pki/ca.crt
—–BEGIN CERTIFICATE—–
MIICyDCCAbCgAwIBAgIBADANBgkqhkiG9w0BAQsFADAVMRMwEQYDVQQDEwprdWJl
cm5ldGVzMB4XDTIwMDgyMDAyMzAwNVoXDTMwMDgxODAyMzAwNVowFTETMBEGA1UE
AxMKa3ViZXJuZXRlczCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAJwh
l8eWyJPlIjpj9S7OUIdRMeqWC0og+7xPzbPd8sKcSzfjZ7GsKmQyoB8hBseiUCuL
j/myYyNM62LHkFJl271sEYWf8KbY/5cmtRacFyL8Jri3KB/uxvgfQ/1xL+g7RdAq
FBYVG3mi+5OZ+LLrfULQNjzkhMYehHCtsCFfI0ayjbibMTPbKOyhn5wpuLg8/9We
SSJr5Nkg+dtXrRgNXzSisRLAQy2gDs7Ni3tJIZ64nDgHjJrKmGGgjlIc7TEtaTug
rym+/vjEYgcqNXGjF6zBeOQW5nMuHt+ZeazagT2A3dP8FcyDYVkHRUwDDH0Y9Ves
NPP2fxTG5UfXV9EtYRMCAwEAAaMjMCEwDgYDVR0PAQH/BAQDAgKkMA8GA1UdEwEB
/wQFMAMBAf8wDQYJKoZIhvcNAQELBQADggEBADj6KauPGgoVyFBgMS1YbUEEqGBj
7r0hnorSn9ZxvU1fC5RFtPGt8B4aN4OtLkTDRz9fgEsVbtWh1tWYDHYAz7aCbEYk
LE0+G6P2JqGN7HykwNAdZuA/zzhNuQJfxcdnjTyHEfWg+y8GuKbjIMPtRU9N9lZh
FSyLlb3ozKXmDC+dnHxG1xMnzB3NSA+Xxi7d5GjA1ze3aqqes6meN53XZqdx167H
/3A6Wz66xPOg8ylPSUktymMG51d91lu1bebXPLmvg4+pAxWadbFgmLGFtPMTEw+Z
HDvs+q640H9biz+OWdewHcQq4MohCWnl8aW5IaeRamfY/sg/1wSW2FmxebA=
—–END CERTIFICATE—–

从解码可以发现，kubeconfig配置的就是kubernates的CA证书，client-certificate-data和client-key-data就是controller-manager用来访问apiserver的客户端证书和秘钥，只不过kubeconfig对内容进行了base64编码。这个就是整个controller-manager和apiserver证书认证的方式。

# kube-scheduler
kube-scheduler也是同样的原理，也是在yaml中配置一个kubeconfig来进行访问apiserver

[root@VM-4-3-centos kubernetes]# cat scheduler.conf
apiVersion: v1
clusters:

• cluster:
  certificate-authority-data: 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
  server: https://10.0.4.3:6443
  name: kubernetes
  contexts:
• context:
  cluster: kubernetes
  user: system:kube-scheduler
  name: system:kube-scheduler@kubernetes
  current-context: system:kube-scheduler@kubernetes
  kind: Config
  preferences: {}
  users:
• name: system:kube-scheduler
  user:
  client-certificate-data: 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
  client-key-data: LS0tLS1CRUdJTiBSU0EgUFJJVkFURSBLRVktLS0tLQpNSUlFcEFJQkFBS0NBUUVBekVyYVRwK0JlZTJtNHpkczZCOU1vVEdKZVhEc3NCYnBQTlA2UnF2QlFwNzZFa2N0ClVuWEgwbHFUMEtQcTlSMWkwWjBiZmJBUzRZUVNUS2JzWVI3S3ZHdURGMlZLeXRWMk1FQkp2R25yQ0oyaURCLysKVlNTTGVSbzVRbmRURE9kcUJmN040ZTdDRlRzUERvS2VJbDNmOUY2aHBJQngvNmlYMjB6aHVUaDY1T1MxYUlEMApmM2hYSStPZm9nbDAvc3loZkV5Tmp0YmxMN1h2OW16U21hdG1YR2RkYU4vb01qQ3ZyTjZiNUhwQzV1bkUxbTBqCmxpQ1hqM3FRNENMb3RTZXJPRUhpdmVIc0wwYTBuV0JQM2x1VnNJUmp2aWJwNG9NV0xtcW1DdEIrbmh6WFpkQnoKZWFsM2R4djU3SVU5S1ZvUUpGMmtvOG1UaUo3SFhxekUyWGNXTHdJREFRQUJBb0lCQVFDbmJhVlRFSGlkdy82bApjMVJIUFBlaG1DYXlKN0ZqYzdOOWpjRXRVREJZZUZBODBLYTlVUmdPTnZ1ejM5TjlSYk1xVlpjbFFEdUpKYU9WCnZLdzN3SE9wVG5lbW9mWlZHL0w4QW9RcjdhYVpiZzlUM3BpamtRclptbnRaRk5BMDRDZk5lQkdsMi9hbVRidSsKU2FCdVMvOXltR2ZqbVAxVTZRaGp5N09uQ0RuNEFsMmw1SXJpUCtlSTgxS3ZjVjRWUWNhcmtQL0F5SityQm56SgpSZjNRSFBRL2pFaUVRMm9kKzQ4N1FzSWNZVlcwZ0FmQ3pKN05NMUJMeTE0Yy8zUFJRS3JLZTdXT3AwM2Z3QmkxCk5TRlc1dmxSUkpnTDduSHQ4TkdsSUhHRE5VT29KR0UvVnppekJUVFpQRS9nOEkxZ1FLYko5b3ZSdXJQa0J6VGsKRHNGQ281bEJBb0dCQU5qalNTVXIybFo0Z1B6MEZ6bnBMTEFBaVhBSDkwZFlBb1BQSUhoWDR2WmtRUjE4Ykx2NgoraXVSR2dMTkQyckV4dHk3dE1tcTQrZkt2S1VXRWorOVR0KzNqWTVmTFdCeWhNTk1uaXN2eDFsdkxlZnFybkRvCnlkODdPb0p3TnZZdit2YitQR3NGaU51SHdXUTR4Wit3WTFaYitCUnB5UVJNUEs1TnVEbDRFMXZQQW9HQkFQRWkKRitwS1VJSmE0NGZuWDk3L1lHalh6Z1lWTEQ4RkRRMTh4dmY3TG43UEhUNzJoK1VCaXJFV29uK2RmcDFBZS95UwpTMER6Q2ZLUDdiM0R3YkxPbmRKcHdLWnUrUjdBaEs5RGFlVEJ3Y2FkRDFpTzNoME5RSVFoVFJPaVJRclN4RWpmCllXVnRmUXFuSUJhS3pMSnRCakVtakRDcXJ2QjJ3QTRza1Z5d09WZWhBb0dBTWZWb3k5OG1FL1QrQVVaWWMwWjYKdksvaStLTmRHbG56ZWxranFaVFUrdHh0QTFXOTFpOGhvUmR6WG1ITncxSkFYR2dBWk5Pd1c1d2ZpQWRsZkxrbQppZkhGOFoySzNrU0N3Rm5OdFRUMFBtMlZyVzRwY0dpdTEzVFZMV2Fid21tYTdYbnlnTlJ0aWVQamNDcURteDBPClJMNDZqcmt2VElZakZDTmk1Qm44bTVFQ2dZQmNHdUs1cW1Nd041bGJpd1J5d0dkS0JNeDhSRkFmVGtXYkZrTkYKNjVycDh5Qy9zUmxkWHdaaitEcGZ0bi9yZnZzZEVhQlBFY2FGOFhZbEd3WDh6N0UyOHhBVVFxVkRtdFBUd2xOTApmcnNPcTJWMk5UUWdNclNuQTdWV1A1QlJ2d29jcjc2YktJUXZzb0N1TzV4T3R4ZzdZL2IraStQQWxBdHVIcFh6CnFwaHNvUUtCZ1FERkxITzFwTTNPNlRWN3cybThKWVI0WGxBUWtLZkRPMlFGaDB0bGM1bk1rZUdZbHZFUUlZdVMKS2liV3NJNHVwMHFRcFZjdHF2VU9wc2V1Rk5ZdGVRQzF6YncxNWp4a0xEMm9Gb2c1Yk9WRXk3ekZERU1kVmdpRwpEbjhkbHN3SWp0bUF1SDFGOWdBbGR1V1M0cXkyV0I0SlRPZjBlTDVOM1dTWkRzcm91anA5NlE9PQotLS0tLUVORCBSU0EgUFJJVkFURSBLRVktLS0tLQo=

  同理，解析certificate-authority-data也是kubernates的CA证书，client-certificate-data和client-key-data就是kube-scheduler用来访问apiserver的客户端证书和秘钥
  
  # kube-proxy
  在这里我们并未发现kube-proxy的kubeconfig，kube-proxy也是需要访问apiserver的，那么是如何进行认证的。还是从yaml文件进行分析一下，如果需要认证，肯定会在yaml中配置对应的证书或者包含证书的文件或token

  [root@VM-4-3-centos run]# kubectl get pod kube-proxy-6bf2t -n kube-system -o yaml
  …..
  containers:
  • command:
    • /usr/local/bin/kube-proxy
    • –config=/var/lib/kube-proxy/config.conf
    • –hostname-override=$(NODE_NAME)
      env:
    • name: NODE_NAME
      valueFrom:
      fieldRef:
      apiVersion: v1
      fieldPath: spec.nodeName
      image: k8s.gcr.io/kube-proxy:v1.15.2
      imagePullPolicy: IfNotPresent
      name: kube-proxy
      resources: {}
      securityContext:
      privileged: true
      terminationMessagePath: /dev/termination-log
      terminationMessagePolicy: File
      volumeMounts:
    • mountPath: /var/lib/kube-proxy
      name: kube-proxy
    • mountPath: /run/xtables.lock
      name: xtables-lock
    • mountPath: /lib/modules
      name: lib-modules
      readOnly: true
    • mountPath: /var/run/secrets/kubernetes.io/serviceaccount
      name: kube-proxy-token-rd92l
      readOnly: true
      dnsPolicy: ClusterFirst
      …..
      volumes:
  • configMap:
    defaultMode: 420
    name: kube-proxy
    name: kube-proxy
  • hostPath:
    path: /run/xtables.lock
    type: FileOrCreate
    name: xtables-lock
  • hostPath:
    path: /lib/modules
    type: “”
    name: lib-modules
  • name: kube-proxy-token-rd92l
    secret:
    defaultMode: 420
    secretName: kube-proxy-token-rd92l
    kube-proxy挂载一个secret，这边猜测这个就是用来进行认证的。我们查看下这个token
    [root@VM-4-3-centos run]# kubectl get secret -n kube-system kube-proxy-token-rd92l -o yaml
    apiVersion: v1
    data:
    ca.crt: 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
    namespace: a3ViZS1zeXN0ZW0=
    token: ZXlKaGJHY2lPaUpTVXpJMU5pSXNJbXRwWkNJNklpSjkuZXlKcGMzTWlPaUpyZFdKbGNtNWxkR1Z6TDNObGNuWnBZMlZoWTJOdmRXNTBJaXdpYTNWaVpYSnVaWFJsY3k1cGJ5OXpaWEoyYVdObFlXTmpiM1Z1ZEM5dVlXMWxjM0JoWTJVaU9pSnJkV0psTFhONWMzUmxiU0lzSW10MVltVnlibVYwWlhNdWFXOHZjMlZ5ZG1salpXRmpZMjkxYm5RdmMyVmpjbVYwTG01aGJXVWlPaUpyZFdKbExYQnliM2g1TFhSdmEyVnVMWEprT1RKc0lpd2lhM1ZpWlhKdVpYUmxjeTVwYnk5elpYSjJhV05sWVdOamIzVnVkQzl6WlhKMmFXTmxMV0ZqWTI5MWJuUXVibUZ0WlNJNkltdDFZbVV0Y0hKdmVIa2lMQ0pyZFdKbGNtNWxkR1Z6TG1sdkwzTmxjblpwWTJWaFkyTnZkVzUwTDNObGNuWnBZMlV0WVdOamIzVnVkQzUxYVdRaU9pSmhOemRrTjJKaE1TMW1Zek5pTFRRM1lUTXRZV00wWkMweVpXRmtPVEV6WkRVd09ESWlMQ0p6ZFdJaU9pSnplWE4wWlcwNmMyVnlkbWxqWldGalkyOTFiblE2YTNWaVpTMXplWE4wWlcwNmEzVmlaUzF3Y205NGVTSjkuSTRuR0UxOVhJakFPU0lKcWZyb3A2azhHcXBickxBeVFzQ3NoeFhxMEc3RklTZmJudS1TTW9xV1pHUjU0S2hwREdlaGd6WkQwMGVGZG14bEM1ZzBIc2ZzZE40V0tmVFI1ZjY1b3kzTnVvWUxxcUIzUzgySUxLelJHREVBNHpwWmFXeG1lRmtzdU1mdl9UWDRjSGdtYUI3V0ZQZzJ5RWtxV0VPa3kwT0hOWnIxNmd4Mzl3S1owWDRhQ29FOVd0cGlZU1BKYU5SdmtVbENfNTlPZHJTYnBCYnlkd2JOaWVaRjdhcWRBbFdWQ3JXQkRfWmlCaHNnZklVYUpEcVg5TWtRbUpjVS1Yb2pzWUpXNFpNejZ3OEZFTHY4THpCazRLTUc5V185aG5Jc3FfVlFUM2xDek5iSHlNSktWeXZ1VlVrblo5X3AwaTJGQlpDeGVVdlpVazdrd01R
    kind: Secret
    metadata:
    annotations:
    kubernetes.io/service-account.name: kube-proxy
    kubernetes.io/service-account.uid: a77d7ba1-fc3b-47a3-ac4d-2ead913d5082
    creationTimestamp: “2020-08-20T02:30:48Z”
    name: kube-proxy-token-rd92l
    namespace: kube-system
    resourceVersion: “196”
    selfLink: /api/v1/namespaces/kube-system/secrets/kube-proxy-token-rd92l
    uid: c9ff07a0-4176-4053-a93c-11c7d0aff285
    type: kubernetes.io/service-account-token

    从上面token的内容，这个里面包含一个CA证书是kubernates查到ca证书，token就是用来和apiserver通讯的客户端证书和秘钥
    
    # kubelet
    kubelet和其他组件类似，用的kubeconfig来进行认证的，都是用kubernates的CA生成。

    [root@VM-4-3-centos kubernetes]# cat kubelet.conf
    apiVersion: v1
    clusters:
• cluster:
  certificate-authority-data: LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCk1JSUN5RENDQWJDZ0F3SUJBZ0lCQURBTkJna3Foa2lHOXcwQkFRc0ZBREFWTVJNd0VRWURWUVFERXdwcmRXSmwKY201bGRHVnpNQjRYRFRJd01EZ3lNREF5TXpBd05Wb1hEVE13TURneE9EQXlNekF3TlZvd0ZURVRNQkVHQTFVRQpBeE1LYTNWaVpYSnVaWFJsY3pDQ0FTSXdEUVlKS29aSWh2Y05BUUVCQlFBRGdnRVBBRENDQVFvQ2dnRUJBSndoCmw4ZVd5SlBsSWpwajlTN09VSWRSTWVxV0Mwb2crN3hQemJQZDhzS2NTemZqWjdHc0ttUXlvQjhoQnNlaVVDdUwKai9teVl5Tk02MkxIa0ZKbDI3MXNFWVdmOEtiWS81Y210UmFjRnlMOEpyaTNLQi91eHZnZlEvMXhMK2c3UmRBcQpGQllWRzNtaSs1T1orTExyZlVMUU5qemtoTVllaEhDdHNDRmZJMGF5amJpYk1UUGJLT3lobjV3cHVMZzgvOVdlClNTSnI1TmtnK2R0WHJSZ05YelNpc1JMQVF5MmdEczdOaTN0SklaNjRuRGdIakpyS21HR2dqbEljN1RFdGFUdWcKcnltKy92akVZZ2NxTlhHakY2ekJlT1FXNW5NdUh0K1plYXphZ1QyQTNkUDhGY3lEWVZrSFJVd0RESDBZOVZlcwpOUFAyZnhURzVVZlhWOUV0WVJNQ0F3RUFBYU1qTUNFd0RnWURWUjBQQVFIL0JBUURBZ0trTUE4R0ExVWRFd0VCCi93UUZNQU1CQWY4d0RRWUpLb1pJaHZjTkFRRUxCUUFEZ2dFQkFEajZLYXVQR2dvVnlGQmdNUzFZYlVFRXFHQmoKN3IwaG5vclNuOVp4dlUxZkM1UkZ0UEd0OEI0YU40T3RMa1REUno5ZmdFc1ZidFdoMXRXWURIWUF6N2FDYkVZawpMRTArRzZQMkpxR043SHlrd05BZFp1QS96emhOdVFKZnhjZG5qVHlIRWZXZyt5OEd1S2JqSU1QdFJVOU45bFpoCkZTeUxsYjNvektYbURDK2RuSHhHMXhNbnpCM05TQStYeGk3ZDVHakExemUzYXFxZXM2bWVONTNYWnFkeDE2N0gKLzNBNld6NjZ4UE9nOHlsUFNVa3R5bU1HNTFkOTFsdTFiZWJYUExtdmc0K3BBeFdhZGJGZ21MR0Z0UE1URXcrWgpIRHZzK3E2NDBIOWJpeitPV2Rld0hjUXE0TW9oQ1dubDhhVzVJYWVSYW1mWS9zZy8xd1NXMkZteGViQT0KLS0tLS1FTkQgQ0VSVElGSUNBVEUtLS0tLQo=
  server: https://10.0.4.3:6443
  name: kubernetes
  contexts:
• context:
  cluster: kubernetes
  user: system:node:vm-4-3-centos
  name: system:node:vm-4-3-centos@kubernetes
  current-context: system:node:vm-4-3-centos@kubernetes
  kind: Config
  preferences: {}
  users:
• name: system:node:vm-4-3-centos
  user:
  client-certificate-data: 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
  client-key-data: 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

  这边我们会给每个节点生成一份客户端的证书和私钥，master上用的是kubelet.conf ，节点上的kubelet.conf如下，直接指向一个kubelet-client-current.pem文件，这里包含了证书和私钥，每一个节点都不一样。因此每个节点都会有一个自己的客户端证书和私钥。

  [root@VM-4-9-centos ~]# cat /etc/kubernetes/kubelet.conf
  apiVersion: v1
  clusters:
• cluster:
  certificate-authority-data: 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
  server: https://10.0.4.3:6443
  name: default-cluster
  contexts:
• context:
  cluster: default-cluster
  namespace: default
  user: default-auth
  name: default-context
  current-context: default-context
  kind: Config
  preferences: {}
  users:
• name: default-auth
  user:
  client-certificate: /var/lib/kubelet/pki/kubelet-client-current.pem
  client-key: /var/lib/kubelet/pki/kubelet-client-current.pem
  [root@VM-4-9-centos pki]# cat /var/lib/kubelet/pki/kubelet-client-current.pem

—–BEGIN CERTIFICATE—–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—–END CERTIFICATE—–
—–BEGIN EC PRIVATE KEY—–
MHcCAQEEIN75eP2QG76VLv/nRWiLzW9Fg9hCzeb33BrZ5n9PhwhToAoGCCqGSM49
AwEHoUQDQgAEnVBvcPAVFSMhhpoHE0ZOJ5c5sYp0Ysbz8dV3Bc2RVIhYsYGTP1Cw
Vo6HUiyJDqDkV/FEGd5aHJBM6AyYPTK/KQ==
—–END EC PRIVATE KEY—–

现在有一个问题就是，k8s中节点可能有几万个，那么是如何快速给节点自动生成客户端证书和秘钥然后配置给kubelet呢？

[root@VM-4-11-centos pki]# ps -ef | grep kubelet
root 14746 1 0 Aug20 ? 17:50:19 /usr/bin/kubelet –bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf –kubeconfig=/etc/kubernetes/kubelet.conf –config=/var/lib/kubelet/config.yaml –cgroup-driver=cgroupfs –network-plugin=cni –pod-infra-container-image=k8s.gcr.io/pause:3.1

查看kubelet进程可以发现还有一个kubeconfig是bootstrap-kubelet.conf，我们来看看这个文件配置的是什么？

[root@VM-4-11-centos pki]# cat /etc/kubernetes/bootstrap-kubelet.conf
apiVersion: v1
clusters:

• cluster:
  certificate-authority-data: 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
  server: https://10.0.4.3:6443
  name: kubernetes
  contexts:
• context:
  cluster: kubernetes
  user: tls-bootstrap-token-user
  name: tls-bootstrap-token-user@kubernetes
  current-context: tls-bootstrap-token-user@kubernetes
  kind: Config
  preferences: {}
  users:
• name: tls-bootstrap-token-user
  user:
  token: qsciu5.l8b4382ue1m8e61x
  ```
  Kubernetes 提供了 TLS bootstrapping 的方式来简化 Kubelet 证书的生成过程。其原理是预先提供一个 bootstrapping token，kubelet 通过该 kubelet 调用 kube-apiserver 的证书签发 API 来生成 自己需要的证书。要启用该功能，需要在 kube-apiserver 中启用 –enable-bootstrap-token-auth ，并创建一个 kubelet 访问 kube-apiserver 使用的 bootstrap token secret。如果使用 kubeadmin 安装，可以使用 kubeadm token create命令来创建 token。

采用TLS bootstrapping 生成证书的流程如下：

1. 调用 kube-apiserver 生成一个 bootstrap token。
   将该 bootstrap token 写入到一个 kubeconfig 文件中，作为 kubelet 调用 kube-apiserver 的客户端验证方式。
2. 通过 –bootstrap-kubeconfig 启动参数将 bootstrap token 传递给 kubelet 进程。
3. Kubelet 采用 bootstrap token 调用 kube-apiserver API，生成自己所需的服务器和客户端证书。
4. 证书生成后，Kubelet 采用生成的证书和 kube-apiserver 进行通信，并删除本地的 kubeconfig 文件，以避免 bootstrap token 泄漏风险。

Service Account 认证

前面我们有说在kube-apiserver 和 kube-controller-manager分配配置的sa的公钥和私钥，这里就是用来对service account来进行认证的，我们一般在RBAC中来限制service account的访问限制。kubernetes 会为该 service account 生成一个 JWT token，并使用 secret 将该 service account token 加载到 pod 上。pod 中的应用可以使用 service account token 来访问 api server。service account 证书被用于生成和验证 service account token。该证书的用法和前面介绍的其他证书不同，因为实际上使用的是其公钥和私钥，而并不需要对证书进行验证。下面是service account的认证方式

这里参考大佬的文章根据集群的实际部署对k8s的证书进行了梳理，加深对这方面的知识了解，有什么问题请大家多多指正。

参考链接

https://mp.weixin.qq.com/s/IbxRTQBOeKtL8AlC3R65Rw

https://kubernetes.io/zh/docs/setup/best-practices/certificates/