一、讲解示例 kubernetes-dashboard.yaml

# ------------------- Dashboard Secret ------------------- #
apiVersion: v1
kind: Secret
metadata:
  labels:
    k8s-app: kubernetes-dashboard
  name: kubernetes-dashboard-certs
  namespace: kube-system
type: Opaque

---
# ------------------- Dashboard Service Account ------------------- #
apiVersion: v1
kind: ServiceAccount
metadata:
  labels:
    k8s-app: kubernetes-dashboard
  name: kubernetes-dashboard
  namespace: kube-system

---
# ------------------- Dashboard Role & Role Binding ------------------- #
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: kubernetes-dashboard-minimal
  namespace: kube-system
rules:
  # Allow Dashboard to create 'kubernetes-dashboard-key-holder' secret.
- apiGroups: [""]
  resources: ["secrets"]
  verbs: ["create"]
  # Allow Dashboard to create 'kubernetes-dashboard-settings' config map.
- apiGroups: [""]
  resources: ["configmaps"]
  verbs: ["create"]
  # Allow Dashboard to get, update and delete Dashboard exclusive secrets.
- apiGroups: [""]
  resources: ["secrets"]
  resourceNames: ["kubernetes-dashboard-key-holder", "kubernetes-dashboard-certs"]
  verbs: ["get", "update", "delete"]
  # Allow Dashboard to get and update 'kubernetes-dashboard-settings' config map.
- apiGroups: [""]
  resources: ["configmaps"]
  resourceNames: ["kubernetes-dashboard-settings"]
  verbs: ["get", "update"]
  # Allow Dashboard to get metrics from heapster.
- apiGroups: [""]
  resources: ["services"]
  resourceNames: ["heapster"]
  verbs: ["proxy"]
- apiGroups: [""]
  resources: ["services/proxy"]
  resourceNames: ["heapster", "http:heapster:", "https:heapster:"]
  verbs: ["get"]
  
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: kubernetes-dashboard-minimal
  namespace: kube-system
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: kubernetes-dashboard-minimal
subjects:
- kind: ServiceAccount
  name: kubernetes-dashboard
  namespace: kube-system
 
---
# ------------------- Dashboard Deployment ------------------- #
kind: Deployment
apiVersion: apps/v1beta2
metadata:
  labels:
    k8s-app: kubernetes-dashboard
  name: kubernetes-dashboard
  namespace: kube-system
spec:
  replicas: 1
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      k8s-app: kubernetes-dashboard
  template:
    metadata:
      labels:
        k8s-app: kubernetes-dashboard
    spec:
      containers:
      - name: kubernetes-dashboard
        image: registry.cn-hangzhou.aliyuncs.com/kube_containers/kubernetes-dashboard-amd64
        ports:
        - containerPort: 8443
          protocol: TCP
        args:
          - --auto-generate-certificates
          # Uncomment the following line to manually specify Kubernetes API server Host
          # If not specified, Dashboard will attempt to auto discover the API server and connect
          # to it. Uncomment only if the default does not work.
          # - --apiserver-host=http://my-address:port
        volumeMounts:
        - name: kubernetes-dashboard-certs
          mountPath: /certs
          # Create on-disk volume to store exec logs
        - mountPath: /tmp
          name: tmp-volume
        livenessProbe:
          httpGet:
            scheme: HTTPS
            path: /
            port: 8443
          initialDelaySeconds: 30
          timeoutSeconds: 30
      volumes:
      - name: kubernetes-dashboard-certs
        secret:
          secretName: kubernetes-dashboard-certs
      - name: tmp-volume
        emptyDir: {}
      serviceAccountName: kubernetes-dashboard
      # Comment the following tolerations if Dashboard must not be deployed on master
      tolerations:
      - key: node-role.kubernetes.io/master
        effect: NoSchedule
---
# ------------------- Dashboard Service ------------------- #
kind: Service
apiVersion: v1
metadata:
  labels:
    k8s-app: kubernetes-dashboard
  name: kubernetes-dashboard
  namespace: kube-system
spec:
  type: NodePort
  ports:
    - port: 443
      targetPort: 8443
      nodePort: 30001
  selector:
    k8s-app: kubernetes-dashboard

二、文件资源对象

2.0 该文件主要有如下资源(倒序)

• Service： 暴露容器中的服务
• Deployment： 创建容器的控制器的控制器
• RoleBinding： 角色绑定，绑定角色和服务账户
• Role： 角色，指定角色权限
• ServiceAccount： 创建服务账户
• Secret： 提供令牌，访问API服务器所用

2.1 Deployment：

• spec.template.spec.serviceAccountName：kubernetes-dashboard，意思是产生的容器归属于kubernetes-dashboard服务账户。
• spec.template.spec.volumes.secret.secret：kubernetes-dashboard-certs，意思是产生的容器默认挂载该令牌访问API服务资源。
• 简单的说：Web UI容器属于kubernetes-dashboard服务账户，该容器访问API服务器令牌为kubernetes-dashboard-certs

2.2 Role：

• 规定了 kubernetes-dashboard-minimal该角色的权限，比如rules[0],对于URL资源型的secret,该角色可以创建，不可删该查。

2.3 RoleBinding：

• 声明了服务账户kubernetes-dashboard享有 kubernetes-dashboard-minimal该角色的权限

2.4 综上所述：

• Web UI容器绑定了如下两个资源：
• Secret：让dashboard容器访问API能够认证通过，
• ServiceAccount： 认证通过后dashboard容器会有什么权限

三.《实验》权限验证

我们来看一下kubernetes-dashboard该服务账户的认证令牌

[root@k8s-master k8s]# kubectl describe sa kubernetes-dashboard -n kube-system | grep Token
Tokens:              kubernetes-dashboard-token-gthpd

查看该令牌

[root@k8s-master k8s]# kubectl describe secret kubernetes-dashboard-token-gthpd -n kube-system | grep ^token
token:      eyJhbGciOiJSUzI1NiI......htI0PbXnmUG6HHL-KAtR4nw

如果使用该令牌登录Web UI会如何？答案是啥资源信息也看不了

为什么呢？如上图，集群下有命名空间namespaces、节点nodes、持久化存储卷pv、角色Role、存储类Store class，叫做集群资源，也叫全局资源;
命名空间下有Jobpod、DaemonSet、Deployment、Pods、RS、RC、Service、Secret等等局部资源
如果要查看他们，必须有权限访问这些资源信息，回头看看Role部署文件声明的Rule，的确有部分访问权限，例如secrets的删改查，很遗憾该令牌所对应的服务账户被绑定的并非集群角色，绑定的方式并非集群绑定，WebUI的集群资源必须被ClusterBinding，角色必须为ClusterRole，所以也就啥都没,还报一堆警告。

那我们从系统中找个有集群角色的服务账户实验一下
集群绑定资源可以查询绑定的角色和服务账户
1.我们先找一个集群角色绑定资源

[root@k8s-master k8s]# kubectl get clusterrolebinding system:controller:namespace-controller
找打了namespace-controller服务账户和system:controller:namespace-controller集群角色

2.看下集群角色有什么权限，并验证

[root@k8s-master k8s]# kubectl get clusterrole system:controller:namespace-controller -o yaml
rules:
- apiGroups:
  - ""
  resources:
  - namespaces    !对命名空间只有查删,没有增改
  verbs:
  - delete
  - get
  - list
  - watch
- apiGroups:
  - ""
  resources:
  - namespaces/finalize
  - namespaces/status
  verbs:
  - update
- apiGroups:
  - '*'
  resources:
  - '*'
  verbs:               !对所有资源只有查删,没有增改
  - delete
  - deletecollection
  - get
  - list

从上面可知，这个角色对所有资源只有查删，不能增改!!!,来验证一下…
3获取密钥

[root@m ~]# kubectl get sa namespace-controller -n kube-system -o yaml
secret： namespace-controller-token-gb4hf
[root@k8s-master k8s]# kubectl describe secret namespace-controller-token-gb4hf -n kube-system

4.web登录，选择令牌登录

很好，可以查到所有资源，跟预期一致
4.1试试创建新命名空间

很好，果然不能创建(增)资源
4.2 试试删除资源

[root@k8s-master k8s]# kubectl get pods --watch
NAME                   READY   STATUS    RESTARTS   AGE
test-c478db4fb-w6c68   1/1     Running   0          16m

可以看到有一个容器test-c478db4fb-w6c68正在运行，那么我们现在在Web删除他，–watch参数是实时监控

回到黑屏终端，可以见到命令行实时监控输出的信息

[root@k8s-master k8s]# kubectl get pods --watch
NAME                   READY   STATUS    RESTARTS   AGE
test-c478db4fb-w6c68   1/1     Running   0          16m
test-c478db4fb-w6c68   1/1     Terminating   0          19m
test-c478db4fb-sqs9q   0/1     Pending       0          0s
test-c478db4fb-sqs9q   0/1     Pending       0          0s
test-c478db4fb-w6c68   1/1     Terminating   0          19m
test-c478db4fb-sqs9q   0/1     ContainerCreating   0          1s
test-c478db4fb-w6c68   0/1     Terminating         0          19m
test-c478db4fb-sqs9q   1/1     Running             0          9s
test-c478db4fb-w6c68   0/1     Terminating         0          19m
test-c478db4fb-w6c68   0/1     Terminating         0          19m

很好，test-c478db4fb-w6c68被结束，就是删除成功，其他资源类似，不再举例。
那么有一个问题，test-c478db4fb-sqs9q这个是什么？因为这个容器我是通过RS部署的，所以被删除会有一个替代它。

验证结束: 确实只有查删、不能增改

四、超级权限

那么最后一个问题，我想要root权限，不想受那么多限制咋办？
同样，我们也在clusterrolebinding找，但你不用找了，我直接告诉你，集群角色：cluster-admin拥有超级权限，但是很遗憾这个集群绑定没有指定服务账户，所以现在我们需要创建ClusterRoleBinding和ServiceAccount

[root@k8s-master ~]# vi k8s-admin.yaml
apiVersion: v1
kind: ServiceAccount
metadata:
  name: dashboard-admin
  namespace: kube-system
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
  name: dashboard-admin
subjects:
  - kind: ServiceAccount
    name: dashboard-admin
    namespace: kube-system
roleRef:
  kind: ClusterRole
  name: cluster-admin
  apiGroup: rbac.authorization.k8s.io
  
[root@k8s-master ~]# kubectl create -f k8s-admin.yaml
!1.查看服务账户对应的secret
[root@k8s-master k8s]# kubectl describe sa -n kube-system dashboard-admin | greo ^Tokens 
Tokens:              dashboard-admin-token-xxxxx
!2.获取令牌
[root@k8s-master k8s]# kubectl describe secret dashboard-admin-token-np46j -n kube-system | grep ^token
token:      eyJhbGciOiJSUzI1NiIsI......f2NkjH0YsBD7QEjRiQxp0Cv35rHC0pXuyRtDDKM7VE_RppJoY06WCRzAwZGCOBE1H6A
!3.接下来令牌登录即可获取k8s资源所有权，你就是集群最靓的仔

五、回顾

很好，相信你已经有了比较清晰思路