【Kubernetes详解】（三）搭建Kubernetes Dashboard

╰+攻爆jí腚メ 2023-02-17 02:19 8阅读 0赞

# 一、前言 #

上一篇文章介绍了[从零开始搭建Kubernetes集群][Kubernetes]，本文将介绍一下如何搭建K8S的Dashboard。

简单的说，K8S Dashboard是官方的一个基于WEB的用户界面，专门用来管理K8S集群，并展示集群的状态。K8S集群安装好后默认没有包含Dashboard，我们需要额外创建它。

Dashboard设计的还不错，界面友好，功能也比较强大。如果你厌倦了命令行的操作，全程使用Dashboard也是可行的。

因为我们使用kubeadm搭建的集群会默认开启RABC（角色访问控制机制），所以我们必须要进行额外的设置。关于RABC的概念，网上资料很多，大家务必提前了解。

# 二、RBAC简介 #

RBAC（Role-Based Access Control ）基于角色的访问控制，不懂的可以百度看下  
K8S 1.6引进，是让用户能够访问 k8S API 资源的授权方式【不授权就没有资格访问K8S的资源】

## 2.1、用户 ##

K8S有两种用户：User和Service Account。其中，User给人用，Service Account给进程用，让进程有相关权限。如Dashboard就是一个进程，我们就可以创建一个Service Account给它

## 2.2、角色 ##

Role是一系列权限的集合，例如一个Role可包含读取和列出 Pod的权限【 ClusterRole 和 Role 类似，其权限范围是整个集群】

## 2.3、角色绑定 ##

RoleBinding把角色映射到用户，从而让这些用户拥有该角色的权限【ClusterRoleBinding 和RoleBinding 类似，可让用户拥有 ClusterRole 的权限】

## 2.4、Secret ##

Secret是一个包含少量敏感信息如密码，令牌，或秘钥的对象。把这些信息保存在 Secret对象中，可以在这些信息被使用时加以控制，并可以降低信息泄露的风险  
如下图，灰色是“角色”，蓝色是“用户”，绿色是“角色绑定”，黄色是该角色拥有的权限。简言之 ，角色绑定将角色和用户进行挂钩：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTMwNjgzNzc_size_16_color_FFFFFF_t_70]

# 三、安装Kubernetes-Dashboard #

官方文档：[Web UI (K8S Dashboard)][Web UI _K8S Dashboard]

## 3.1、部署 ##

参考官方文档，在部署好了 k8s 集群环境的前提下，要安装 Kubernetes-Dashboard 只需要一条命令就可以搞定，如下：

kubectl apply -f https://raw.githubusercontent.com/kubernetes/dashboard/v2.0.0/aio/deploy/recommended.yaml

确实如此，但是要通过页面访问还需要进行其他操作

## 3.2、访问 ##

要想通过页面访问，我们可以先大致看下 recommended.yaml，理解下其中的内容

### 3.2.1、recommended.yaml 内容 ###

# Copyright 2017 The Kubernetes Authors.
    #
    # Licensed under the Apache License, Version 2.0 (the "License");
    # you may not use this file except in compliance with the License.
    # You may obtain a copy of the License at
    #
    # http://www.apache.org/licenses/LICENSE-2.0
    #
    # Unless required by applicable law or agreed to in writing, software
    # distributed under the License is distributed on an "AS IS" BASIS,
    # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    # See the License for the specific language governing permissions and
    # limitations under the License.
    
    apiVersion: v1
    kind: Namespace
    metadata:
      name: kubernetes-dashboard
    
    ---
    
    apiVersion: v1
    kind: ServiceAccount
    metadata:
      labels:
        k8s-app: kubernetes-dashboard
      name: kubernetes-dashboard
      namespace: kubernetes-dashboard
    
    ---
    
    kind: Service
    apiVersion: v1
    metadata:
      labels:
        k8s-app: kubernetes-dashboard
      name: kubernetes-dashboard
      namespace: kubernetes-dashboard
    spec:
      ports:
        - port: 443
          targetPort: 8443
      selector:
        k8s-app: kubernetes-dashboard
    
    ---
    
    apiVersion: v1
    kind: Secret
    metadata:
      labels:
        k8s-app: kubernetes-dashboard
      name: kubernetes-dashboard-certs
      namespace: kubernetes-dashboard
    type: Opaque
    
    ---
    
    apiVersion: v1
    kind: Secret
    metadata:
      labels:
        k8s-app: kubernetes-dashboard
      name: kubernetes-dashboard-csrf
      namespace: kubernetes-dashboard
    type: Opaque
    data:
      csrf: ""
    
    ---
    
    apiVersion: v1
    kind: Secret
    metadata:
      labels:
        k8s-app: kubernetes-dashboard
      name: kubernetes-dashboard-key-holder
      namespace: kubernetes-dashboard
    type: Opaque
    
    ---
    
    kind: ConfigMap
    apiVersion: v1
    metadata:
      labels:
        k8s-app: kubernetes-dashboard
      name: kubernetes-dashboard-settings
      namespace: kubernetes-dashboard
    
    ---
    
    kind: Role
    apiVersion: rbac.authorization.k8s.io/v1
    metadata:
      labels:
        k8s-app: kubernetes-dashboard
      name: kubernetes-dashboard
      namespace: kubernetes-dashboard
    rules:
      # Allow Dashboard to get, update and delete Dashboard exclusive secrets.
      - apiGroups: [""]
        resources: ["secrets"]
        resourceNames: ["kubernetes-dashboard-key-holder", "kubernetes-dashboard-certs", "kubernetes-dashboard-csrf"]
        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.
      - apiGroups: [""]
        resources: ["services"]
        resourceNames: ["heapster", "dashboard-metrics-scraper"]
        verbs: ["proxy"]
      - apiGroups: [""]
        resources: ["services/proxy"]
        resourceNames: ["heapster", "http:heapster:", "https:heapster:", "dashboard-metrics-scraper", "http:dashboard-metrics-scraper"]
        verbs: ["get"]
    
    ---
    
    kind: ClusterRole
    apiVersion: rbac.authorization.k8s.io/v1
    metadata:
      labels:
        k8s-app: kubernetes-dashboard
      name: kubernetes-dashboard
    rules:
      # Allow Metrics Scraper to get metrics from the Metrics server
      - apiGroups: ["metrics.k8s.io"]
        resources: ["pods", "nodes"]
        verbs: ["get", "list", "watch"]
    
    ---
    
    apiVersion: rbac.authorization.k8s.io/v1
    kind: RoleBinding
    metadata:
      labels:
        k8s-app: kubernetes-dashboard
      name: kubernetes-dashboard
      namespace: kubernetes-dashboard
    roleRef:
      apiGroup: rbac.authorization.k8s.io
      kind: Role
      name: kubernetes-dashboard
    subjects:
      - kind: ServiceAccount
        name: kubernetes-dashboard
        namespace: kubernetes-dashboard
    
    ---
    
    apiVersion: rbac.authorization.k8s.io/v1
    kind: ClusterRoleBinding
    metadata:
      name: kubernetes-dashboard
    roleRef:
      apiGroup: rbac.authorization.k8s.io
      kind: ClusterRole
      name: kubernetes-dashboard
    subjects:
      - kind: ServiceAccount
        name: kubernetes-dashboard
        namespace: kubernetes-dashboard
    
    ---
    
    kind: Deployment
    apiVersion: apps/v1
    metadata:
      labels:
        k8s-app: kubernetes-dashboard
      name: kubernetes-dashboard
      namespace: kubernetes-dashboard
    spec:
      replicas: 1
      revisionHistoryLimit: 10
      selector:
        matchLabels:
          k8s-app: kubernetes-dashboard
      template:
        metadata:
          labels:
            k8s-app: kubernetes-dashboard
        spec:
          containers:
            - name: kubernetes-dashboard
              image: kubernetesui/dashboard:v2.0.0
              imagePullPolicy: Always
              ports:
                - containerPort: 8443
                  protocol: TCP
              args:
                - --auto-generate-certificates
                - --namespace=kubernetes-dashboard
                # 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
              securityContext:
                allowPrivilegeEscalation: false
                readOnlyRootFilesystem: true
                runAsUser: 1001
                runAsGroup: 2001
          volumes:
            - name: kubernetes-dashboard-certs
              secret:
                secretName: kubernetes-dashboard-certs
            - name: tmp-volume
              emptyDir: { }
          serviceAccountName: kubernetes-dashboard
          nodeSelector:
            "kubernetes.io/os": linux
          # Comment the following tolerations if Dashboard must not be deployed on master
          tolerations:
            - key: node-role.kubernetes.io/master
              effect: NoSchedule
    
    ---
    
    kind: Service
    apiVersion: v1
    metadata:
      labels:
        k8s-app: dashboard-metrics-scraper
      name: dashboard-metrics-scraper
      namespace: kubernetes-dashboard
    spec:
      ports:
        - port: 8000
          targetPort: 8000
      selector:
        k8s-app: dashboard-metrics-scraper
    
    ---
    
    kind: Deployment
    apiVersion: apps/v1
    metadata:
      labels:
        k8s-app: dashboard-metrics-scraper
      name: dashboard-metrics-scraper
      namespace: kubernetes-dashboard
    spec:
      replicas: 1
      revisionHistoryLimit: 10
      selector:
        matchLabels:
          k8s-app: dashboard-metrics-scraper
      template:
        metadata:
          labels:
            k8s-app: dashboard-metrics-scraper
          annotations:
            seccomp.security.alpha.kubernetes.io/pod: 'runtime/default'
        spec:
          containers:
            - name: dashboard-metrics-scraper
              image: kubernetesui/metrics-scraper:v1.0.4
              ports:
                - containerPort: 8000
                  protocol: TCP
              livenessProbe:
                httpGet:
                  scheme: HTTP
                  path: /
                  port: 8000
                initialDelaySeconds: 30
                timeoutSeconds: 30
              volumeMounts:
              - mountPath: /tmp
                name: tmp-volume
              securityContext:
                allowPrivilegeEscalation: false
                readOnlyRootFilesystem: true
                runAsUser: 1001
                runAsGroup: 2001
          serviceAccountName: kubernetes-dashboard
          nodeSelector:
            "kubernetes.io/os": linux
          # Comment the following tolerations if Dashboard must not be deployed on master
          tolerations:
            - key: node-role.kubernetes.io/master
              effect: NoSchedule
          volumes:
            - name: tmp-volume
              emptyDir: { }

#### 3.2.1.1、recommended中包括了下面几个组件 ####

*  Dashboard Service
 *  Dashboard Deployment
 *  Dashboard Role
 *  RoleBinding
 *  Dashboard Service Account
 *  Dashboard Secret

**Dashboard Service**

kind: Service
    ...
    k8s-app: kubernetes-dashboard
    ...
    spec:
      type: NodePort
      ports:
        - port: 443 
          targetPort: 8443
          nodePort: 30000

Dashboard 对外提供服务设置，也指定了nodePort，这样我们可以通过物理机上的30000端口进行访问

**Dashboard Deployment**

kind: Deployment
    ...
    k8s-app: kubernetes-dashboard
    ....

Dashboard的Deployment指定了其使用的ServiceAccount是kubernetes-dashboard。并且还将Secret kubernetes-dashboard-certs通过volumes挂在到pod内部的/certs路径。为何要挂载Secret ？原因是创建Secret 时会自动生成token。请注意参数–auto-generate-certificates，其表示Dashboard会自动生成证书。

**Dashboard Role**

kind: Role
    apiVersion: rbac.authorization.k8s.io/v1
    metadata:
      labels:
        k8s-app: kubernetes-dashboard
      name: kubernetes-dashboard
      namespace: kubernetes-dashboard
    rules:
    ...

如上定义了Dashboard 的角色，其角色名称为 kubernetes-dashboard，rules中清晰的列出了其拥有的多个权限。

**RoleBinding**

apiVersion: rbac.authorization.k8s.io/v1
    kind: RoleBinding
    metadata:
      labels:
        k8s-app: kubernetes-dashboard
      name: kubernetes-dashboard
      namespace: kubernetes-dashboard
    roleRef:
      apiGroup: rbac.authorization.k8s.io
      kind: Role
      name: kubernetes-dashboard
    subjects:
      - kind: ServiceAccount
        name: kubernetes-dashboard
        namespace: kubernetes-dashboard

Dashboard的角色绑定，其名称为 kubernetes-dashboard，roleRef 中为被绑定的角色，subjects中为绑定的用户：kubernetes-dashboard

**Dashboard Service Account**

apiVersion: v1
    kind: ServiceAccount
    metadata:
      labels:
        k8s-app: kubernetes-dashboard
      name: kubernetes-dashboard
      namespace: kubernetes-dashboard

如上定义了Dashboard的用户，其类型为ServiceAccount，名称为kubernetes-dashboard

**Dashboard Secret**

apiVersion: v1
    kind: Secret
    ...

### 3.3.2、web 页面 ###

通过暴露的NodePort: 30000 访问 dashboard，页面如图(我这里通过 firefox 才能访问，chrome 都不行)：https://localhost:30000/  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTMwNjgzNzc_size_16_color_FFFFFF_t_70 1]  
这里有两种登录方式：

*  Token
 *  Kubeconfig

我们使用 Token 的方式登录，获取 Token 方式如下：

kubectl -n kubernetes-dashboard describe secret $(kubectl -n kubernetes-dashboard get secret | grep kubernetes-dashboard | awk '{print $1}')

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTMwNjgzNzc_size_16_color_FFFFFF_t_70 2]  
复制token，点击登录即可

## 3.3、到这里还没有完 ##

通过3.2的步骤会出现下面问题：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTMwNjgzNzc_size_16_color_FFFFFF_t_70 3]  
出现上述问题的原因是因为，kubernetes-dashboard 这个账户的角色权限不够

解决：

### 3.3.3、创建dashboard-adminuser.yaml ###

cat > dashboard-adminuser.yaml << EOF apiVersion: v1 kind: ServiceAccount metadata: name: admin-user namespace: kubernetes-dashboard --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRoleBinding metadata: name: admin-user roleRef: apiGroup: rbac.authorization.k8s.io kind: ClusterRole name: cluster-admin subjects: - kind: ServiceAccount name: admin-user namespace: kubernetes-dashboard EOF

### 3.3.2、创建登录用户 ###

kubectl apply -f dashboard-adminuser.yaml

说明：上面创建了一个叫 admin-user 的服务账号，并放在kubernetes-dashboard 命名空间下，并将 cluster-admin 角色绑定到admin-user账户，这样admin-user账户就有了管理员的权限。默认情况下，kubeadm创建集群时已经创建了cluster-admin角色，我们直接绑定即可。

### 3.3.3、查看admin-user账户的token ###

kubectl -n kubernetes-dashboard describe secret $(kubectl -n kubernetes-dashboard get secret | grep admin-user | awk '{print $1}')

重新登录即可  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTMwNjgzNzc_size_16_color_FFFFFF_t_70 4]

# 四、一些命令 #

# 查看dashboard的角色(Role)
    kubectl get role -n kubernetes-dashboard
    # 查看dashboard的账户
    kubectl get ServiceAccount -n kubernetes-dashboard
    # 查看secret
    kubectl get secret -n kuberntes-dashboard
    # 查看集群的角色(ClusterRole)
    kubectl get ClusterRole -n kubernetes-dashboard

[Kubernetes]: https://blog.csdn.net/u013068377/article/details/106611209
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[Web UI _K8S Dashboard]: https://kubernetes.io/docs/tasks/access-application-cluster/web-ui-dashboard/
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