Kubernetes集群的CA认证

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kube-apiserver默认配置

查看一下kube-apiserver的一些启动配置项，确认存放地址。

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[root@CentOS7-Node1 manifests]# ll
total 16
-rw-------. 1 root root 1759 Dec 10 12:15 etcd.yaml
-rw-------. 1 root root 2602 Dec 10 12:15 kube-apiserver.yaml
-rw-------. 1 root root 2531 Dec 10 12:15 kube-controller-manager.yaml
-rw-------. 1 root root 1119 Dec 10 12:15 kube-scheduler.yaml
[root@CentOS7-Node1 manifests]# pwd
/etc/kubernetes/manifests

可以通过查看yaml文件的方式查看

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[root@CentOS7-Node1 manifests]# cat kube-apiserver.yaml 
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    component: kube-apiserver
    tier: control-plane
  name: kube-apiserver
  namespace: kube-system
spec:
  containers:
  - command:
    - kube-apiserver
    - --advertise-address=10.211.55.7
    - --allow-privileged=true
    - --authorization-mode=Node,RBAC
    - --client-ca-file=/etc/kubernetes/pki/ca.crt #指定CA根证书文件
    - --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 #指定ApiServer证书文件
    - --tls-private-key-file=/etc/kubernetes/pki/apiserver.key #指定ApiServer私钥文件
    image: k8s.gcr.io/kube-apiserver:v1.16.0
    imagePullPolicy: IfNotPresent
    livenessProbe:
      failureThreshold: 8
      httpGet:
        host: 10.211.55.7
        path: /healthz
        port: 6443
        scheme: HTTPS
      initialDelaySeconds: 15
      timeoutSeconds: 15
    name: kube-apiserver
    resources:
      requests:
        cpu: 250m
    volumeMounts:
    - mountPath: /etc/ssl/certs
      name: ca-certs
      readOnly: true
    - mountPath: /etc/pki
      name: etc-pki
      readOnly: true
    - mountPath: /etc/kubernetes/pki
      name: k8s-certs
      readOnly: true
  hostNetwork: true
  priorityClassName: system-cluster-critical
  volumes:
  - hostPath:
      path: /etc/ssl/certs
      type: DirectoryOrCreate
    name: ca-certs
  - hostPath:
      path: /etc/pki
      type: DirectoryOrCreate
    name: etc-pki
  - hostPath:
      path: /etc/kubernetes/pki
      type: DirectoryOrCreate
    name: k8s-certs
status: {}

我们注意到有如下三个启动参数：

  • --client-ca-file: 指定CA根证书文件为/etc/kubernetes/pki/ca.pem，内置CA公钥用于验证某证书是否是CA签发的证书
  • --tls-private-key-file: 指定ApiServer私钥文件为/etc/kubernetes/pki/apiserver-key.pem
  • --tls-cert-file：指定ApiServer证书文件为/etc/kubernetes/pki/apiserver.pem
直接获取nodes节点

用默认的CA认证尝试一下从其他节点查看pods的信息，直接来获取master节点的pods信息。

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[root@CentOS7-Node2 Workspace]# kubectl --server=https://10.211.55.7:6443 get nodes
Please enter Username: # 这里会提示需要输入用户名，但我们并不知道用户名是什么？
通过CA认证方式

然后我们尝试用默认的CA认证，首先把master节点上的CA文件copy到我们的其他节点去。

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scp /etc/kubernetes/pki/ca.crt root@10.211.55.8:/home/parallels/Workspace/
scp /etc/kubernetes/pki/apiserver-kubelet-client.crt root@10.211.55.8:/home/parallels/Workspace/
scp /etc/kubernetes/pki/apiserver-kubelet-client.key root@10.211.55.8:/home/parallels/Workspace/

通过设置certificate-authority、client-certificate、client-key来访问。

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[root@CentOS7-Node2 Workspace]# kubectl --server=https://10.211.55.7:6443 \
--certificate-authority=/home/parallels/Workspace/ca.crt  \
--client-certificate=/home/parallels/Workspace/apiserver-kubelet-client.crt \
--client-key=/home/parallels/Workspace/apiserver-kubelet-client.key \
get nodes
NAME            STATUS   ROLES    AGE     VERSION
centos7-node1   Ready    master   5h28m   v1.16.2
centos7-node2   Ready    <none>   149m    v1.16.2

操作成功！

参考地址：