【Kubernetes】部署K8s-dashboard v1.10.1

一、官方kubernetes-dashboard.yaml简介###

①首先认识一下官方的kubernetes-dashboard.yaml，我们先下载：
https://github.com/kubernetes/dashboard/blob/v1.10.0/src/deploy/recommended/kubernetes-dashboard.yaml

[root@K8s-Master test]# wget https://raw.githubusercontent.com/kubernetes/dashboard/v1.10.1/src/deploy/recommended/kubernetes-dashboard.yaml

该文件分为以下几部分：
Dashboard Secret
Dashboard Service Account
Dashboard Role & Role Binding
Dashboard Deployment
Dashboard Service
这里，我们简单的对各个部分的功能进行介绍：

# ------------------- 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

---

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

# ------------------- 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

---

如上定义了Dashboard 的角色，其角色名称为kubernetes-dashboard-minimal，rules中清晰的列出了其拥有的多个权限。通过名称我们可以猜到，这个权限级别是比较低的。
如上定义了Dashboard的角色绑定，其名称为kubernetes-dashboard-minimal，roleRef中为被绑定的角色，也叫kubernetes-dashboard-minimal，subjects中为绑定的用户：kubernetes-dashboard。

# ------------------- Dashboard Deployment ------------------- #

kind: Deployment
apiVersion: apps/v1
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: k8s.gcr.io/kubernetes-dashboard-amd64:v1.10.1
        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

---

将其中的镜像替换成国内的镜像：
k8s.gcr.io/kubernetes-dashboard-amd64 替换成

image: registry.cn-hangzhou.aliyuncs.com/google_containers/kubernetes-dashboard-amd64:v1.10.0

如上可以看到，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 Service ------------------- #

kind: Service
apiVersion: v1
metadata:
  labels:
    k8s-app: kubernetes-dashboard
  name: kubernetes-dashboard
  namespace: kube-system
spec:
  ports:
    - port: 443
      targetPort: 8443
  selector:
    k8s-app: kubernetes-dashboard

二、部署Dashboard###

kubectl create -f kubernetes-dashboard.yaml

重新安装dashboard

kubectl delete -f kubernetes-dashboard.yaml
kubectl create -f kubernetes-dashboard.yaml

查看Pod 的状态为running说明dashboard已经部署成功：

kubectl get pod --namespace=kube-system -o wide | grep dashboard
kubectl get pods --all-namespaces

Dashboard 会在 kube-system namespace 中创建自己的 Deployment 和 Service：

kubectl get deployment kubernetes-dashboard --namespace=kube-system
kubectl get service kubernetes-dashboard --namespace=kube-system

遇到的错误：###

完成了上述操作却发现还是CrashLoopBackOff的错误

使用命令查看错误原因：

kubectl --namespace=kube-system describe pod <pod_name>

发现pod运行在副节点k8s-node1上，需要将dashboard调度到master节点上去。
输入命令，为master节点添加label

kubectl label node k8s-master type=master

在kubernetes-dashboard.yaml中添加nodeSelecor定义：

配置完成之后，再重新安装dashboard，发现问题得到了解决。

三、访问Dashboard###

根据官方文档，目前访问Dashboard有四种方式：
①NodePort
②kubectl proxy
③API Server
④Ingress
以上四种方式，我测试了前两种，目前NodePort和kubectl proxy可用。
①使用NodePort

为kubernetes-dashboard.yaml添加Service后，就可以使用NodePort访问Dashboard。在我们的物理机上，使用Firefox访问https://192.168.56.101:30001/，结果如下图所示：

选择令牌方式获取token登录:

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

②使用kubectl proxy
这里，我主要介绍一下最便捷的kubectl proxy方式。在Master上执行kubecll proxy，然后使用如下地址访问Dashboard：

http://localhost:8001/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy

但限制就是必须在Master上访问，这显然是个坑，我们的目标是在我们真实的物理机上去访问Master的Dashboard。
所以，在主节点上，我们执行kubectl proxy --address=192.168.56.101 --disable-filter=true开启代理。

其中：
address表示外界可以使用192.168.56.101来访问Dashboard，我们也可以使用0.0.0.0
disable-filter=true表示禁用请求过滤功能，否则我们的请求会被拒绝，并提示 Forbidden (403) Unauthorized。
我们也可以指定端口，具体请查看kubectl proxy --help
如下图所示，proxy默认对Master的8001端口进行监听：
这样，我们就可以使用如下地址访问登录界面：

http://192.168.56.101:8001/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy/#!/login

遇到的问题：获取的token值登录无效###

我们回想本文第三小节对kubernetes-dashboard.yaml的介绍，现在就理解了为什么其角色的名称为kubernetes-dashboard-minimal。一句话，这个Role的权限不够！
这个报错的原因是因为我们没有权限去访问Kubernetes仪表盘。
1⃣️我们可以在Bash中运行如下命令来解决上述问题：

kubectl create clusterrolebinding kubernetes-dashboard --clusterrole=cluster-admin --serviceaccount=kube-system:kubernetes-dashboard

或者
2⃣️我们可以更改RoleBinding修改为ClusterRoleBinding，并且修改roleRef中的kind和name，使用cluster-admin这个非常牛逼的CusterRole（超级用户权限，其拥有访问kube-apiserver的所有权限）。如下：

修改后，重新安装kubernetes-dashboard.yaml，Dashboard就可以拥有访问整个K8S 集群API的权限。
3⃣️kubernetes-dashboard卸载

kubectl delete deployment kubernetes-dashboard --namespace=kube-system 
kubectl delete service kubernetes-dashboard  --namespace=kube-system 
kubectl delete role kubernetes-dashboard-minimal --namespace=kube-system 
kubectl delete rolebinding kubernetes-dashboard-minimal --namespace=kube-system
kubectl delete sa kubernetes-dashboard --namespace=kube-system 
kubectl delete secret kubernetes-dashboard-certs --namespace=kube-system
kubectl delete secret kubernetes-dashboard-csrf --namespace=kube-system
kubectl delete secret kubernetes-dashboard-key-holder --namespace=kube-system

参考链接：
kubernetes部署dashboard可视化插件.
kubernetes安装dashboard步骤.
Centos7 单节点上安装kubernetes-dashboard过程.
kubeadm部署kubernetes 1.13.1集群.
dashboard-ui.
kubernetes github.