在《使用VirtualBox安装CentOS 7和Kubernetes》章节中，我们已经成功地使用VirtualBox虚拟机安装了CentOS 7.9、Docker和Kubernetes，现在我们继续安装Dashboard服务，以便于我们可以更直观地了解Kubernetes。

查找Dashboard版本

我们可在GitHub中Dashboard的Release页面查找Dashboard的可用版本：https://github.com/kubernetes/dashboard/releases?after=v2.0.0

此时，我们使用v2.4.0版本即可。在下方的“Installation”部分我们可以看到该版本的安装命令：

kubectl apply -f https://raw.githubusercontent.com/kubernetes/dashboard/v2.4.0/aio/deploy/recommended.yaml

尝试执行该命令，会发生如下错误：

The connection to the server raw.githubusercontent.com was refused - did you specify the right host or port?

这是因为域名“raw.githubusercontent.com”无法被解析。因此我们只能手动下载配置文件。

下载recommended.yaml配置文件

首先，我们访问Dashboard项目主页，找到“v2.4.0”版本的Tag。

然后，我们切换到该Tag，并找到“/aio/deploy”目录下的“recommended.yaml”配置文件。

最后，我们复制该配置文件的内容，并写入到本地文件中：

vi recommended.yaml

文件的内容为：

# 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:v2.4.0
          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
    spec:
      securityContext:
        seccompProfile:
          type: RuntimeDefault
      containers:
        - name: dashboard-metrics-scraper
          image: kubernetesui/metrics-scraper:v1.0.7
          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: {}

拉取所需的Docker镜像

我们首先通过以下命令，列出Dashboard所需要的镜像：

cat recommended.yaml | grep image:

其输出结果为：

          image: kubernetesui/dashboard:v2.4.0
          image: kubernetesui/metrics-scraper:v1.0.7

可知我们需要两个镜像，我们首先将这两个镜像拉取到本地，以加速后续的安装过程。
在拉取镜像之前，我们先配置Docker官方在国内的加速。我们打开“/etc/docker/daemon.json”配置文件：

vi /etc/docker/daemon.json

然后增加镜像站配置：

{
    "exec-opts": [
        "native.cgroupdriver=systemd"
    ],
    "registry-mirrors": [
        "https://registry.docker-cn.com"
    ]
}

现在我们分别拉取这两个镜像。与镜像站建立连接可能需要一些时间，我们需要耐心等待。
首先拉取“kubernetesui/dashboard:v2.4.0”镜像：

docker image pull kubernetesui/dashboard:v2.4.0

拉取成功后的输出为：

v2.4.0: Pulling from kubernetesui/dashboard
5a24d13191c9: Pull complete
476e0d029a85: Pull complete
Digest: sha256:526850ae4ea9aba360e72b6df69fd3126b129d446efe83ac5250282b85f95b7f
Status: Downloaded newer image for kubernetesui/dashboard:v2.4.0
docker.io/kubernetesui/dashboard:v2.4.0

然后拉取“kubernetesui/metrics-scraper:v1.0.7”镜像：

docker image pull kubernetesui/metrics-scraper:v1.0.7

拉取成功后的输出为：

v1.0.7: Pulling from kubernetesui/metrics-scraper
18dd5eddb60d: Pull complete
1930c20668a8: Pull complete
Digest: sha256:36d5b3f60e1a144cc5ada820910535074bdf5cf73fb70d1ff1681537eef4e172
Status: Downloaded newer image for kubernetesui/metrics-scraper:v1.0.7
docker.io/kubernetesui/metrics-scraper:v1.0.7

修改recommended.yaml配置

现在，我们需要修改“recommended.yaml”的配置，是为了两个目的：

• 修改服务配置，使用NodePort网络将主机端口映射给POD，使我们后续在宿主机可以直接访问Dashboard页面。
• 修改镜像的拉取策略，使之当本地有镜像时使用本地镜像，而不是每次尝试重新拉取。

首先，我们为Dashboard服务配置NodePort。我们修改Service配置（在配置文件中“kind: Service”的片段中），通过NodePort将主机端口映射到POD，使其可被外网访问。这么做主要是因为我们的POD部署在虚拟机中，以此来使我们可以在宿主机中通过浏览器访问Dashboard页面。
我们需要在“metadata.spec”下增加“type”属性，并将其的值设置为“NodePort”，同时在“ports”定义的端口中增加“nodePort”属性，指定使用的主机端口，主机端口需要在30000~32767之间，这里我们使用30443端口，如下所示：

然后，我们修改镜像的拉取策略，使其优先使用本地镜像。
镜像拉取策略的配置为“imagePullPolicy”，其有三个候选值，分别为：

• Always，表示总是拉取远端镜像。
• IfNotPresent，当本地没有镜像时才拉取远端镜像。
• Never，总是使用本地镜像。

我们需要在配置中找到“imagePullPolicy”，并将值改为“IfNotPresent”：

创建Dashboard

执行以下命令，创建Dashboard：

kubectl apply -f recommended.yaml

其输出结果如下：

namespace/kubernetes-dashboard created
serviceaccount/kubernetes-dashboard created
service/kubernetes-dashboard created
secret/kubernetes-dashboard-certs created
secret/kubernetes-dashboard-csrf created
secret/kubernetes-dashboard-key-holder created
configmap/kubernetes-dashboard-settings created
role.rbac.authorization.k8s.io/kubernetes-dashboard created
clusterrole.rbac.authorization.k8s.io/kubernetes-dashboard created
rolebinding.rbac.authorization.k8s.io/kubernetes-dashboard created
clusterrolebinding.rbac.authorization.k8s.io/kubernetes-dashboard created
deployment.apps/kubernetes-dashboard created
service/dashboard-metrics-scraper created
deployment.apps/dashboard-metrics-scraper created

然后我们来查看一下Dashboard相关POD的运行情况。

kubectl get pods -n kubernetes-dashboard

其中“-n”用以指定所查询的POD所属的命名空间，等同于“--namespace”。
其输出结果为：

NAME                                         READY   STATUS    RESTARTS   AGE
dashboard-metrics-scraper-799d786dbf-9b6cw   1/1     Running   0          19s
kubernetes-dashboard-674846bfb9-p5sz9        1/1     Running   0          19s

可见两个POD都处于运行态，现在我们可以尝试在宿主机通过虚拟机的IP和之前配置的NodePort端口来访问Dashboard的页面。注意需要通过https访问：

访问Dashboard需要登录。那么接下来，我们来创建一个用户，来访问这个页面。

创建admin用户

首先，我们创建“admin-user.yaml”文件：

vi admin-user.yaml

将以下内容输入到文件中：

apiVersion: v1
kind: ServiceAccount
metadata:
  name: admin-user
  namespace: kube-system

然后我们执行以下命令来创建用户：

kubectl apply -f admin-user.yaml

输出结果如下：

serviceaccount/admin-user created

表示我们已成功创建了用户，然后我们为用户绑定角色。
首先创建“admin-user-role-binding.yaml”：

vi admin-user-role-binding.yaml

将以下内容输入到文件：

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: kube-system

然后执行以下命令为用户绑定角色：

kubectl apply -f admin-user-role-binding.yaml

输出结果如下：

clusterrolebinding.rbac.authorization.k8s.io/admin-user created

现在，我们执行以下命令来查看用户的Token：

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

其输出结果为：

Name:         admin-user-token-7nl67
Namespace:    kube-system
Labels:       <none>
Annotations:  kubernetes.io/service-account.name: admin-user
              kubernetes.io/service-account.uid: 84e2459e-03d9-4ee0-ace9-5cc51ea48392

Type:  kubernetes.io/service-account-token

Data
====
ca.crt:     1099 bytes
namespace:  11 bytes
token:      eyJhbGciOiJSUzI1NiIsImtpZCI6ImZoSTlyQmFOV0dYeFB5S1RSUmh1cDJTejVYY2pNSFBjbG1UemRYSjZRdDQifQ.eyJpc3MiOiJrdWJlcm5ldGVzL3NlcnZpY2VhY2NvdW50Iiwia3ViZXJuZXRlcy5pby9zZXJ2aWNlYWNjb3VudC9uYW1lc3BhY2UiOiJrdWJlLXN5c3RlbSIsImt1YmVybmV0ZXMuaW8vc2VydmljZWFjY291bnQvc2VjcmV0Lm5hbWUiOiJhZG1pbi11c2VyLXRva2VuLTdubDY3Iiwia3ViZXJuZXRlcy5pby9zZXJ2aWNlYWNjb3VudC9zZXJ2aWNlLWFjY291bnQubmFtZSI6ImFkbWluLXVzZXIiLCJrdWJlcm5ldGVzLmlvL3NlcnZpY2VhY2NvdW50L3NlcnZpY2UtYWNjb3VudC51aWQiOiI4NGUyNDU5ZS0wM2Q5LTRlZTAtYWNlOS01Y2M1MWVhNDgzOTIiLCJzdWIiOiJzeXN0ZW06c2VydmljZWFjY291bnQ6a3ViZS1zeXN0ZW06YWRtaW4tdXNlciJ9.sAPC2v71g3JfvlCeSRJMKK-67MP1f6PyGI7sX0nPs_jgk-somRYQNydV6Qdb07ZlW3Czy1nvbxT2nM9E1OhXXW7YqHW2P5R8SrDy6dR2N0IzZCatcY6ZLXwaFTo8aCVQ67U90mLBvsVlHOJQ1lX8J9ElMuG64YKzORn4mStBbgCfKRINoFQctLCGIqfko9GAHZiKC3DYfbeE1VBtNHvrhkfJP2VjCz44_4s3sSlFoOMVRdEE2OOq2fZ-h2KlQo3t4PtqtDBUnIBX9Yf7E2QUooatkXlhrtQ7z4lEwcLmyxyWVF1O6d1DEudDjZ6Zkgd4nSYj62MXcb4pnDb9DJIAqQ

可以看到，输出结果的最下方即为Token。现在我们将Token复制到Dashboard登录页面的输入框中：

点击登录，即可登录到Dashboard。