【Kubernetes】部署K8s-dashboard v1.10.1

一、官方kubernetes-dashboard.yaml簡介###

①首先認識一下官方的kubernetes-dashboard.yaml，我們先下載：
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

該文件分為以下幾部分：
Dashboard Secret
Dashboard Service Account
Dashboard Role & Role Binding
Dashboard Deployment
Dashboard Service
這里，我們簡單的對各個部分的功能進行介紹：

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

---

如上定義了Dashboard的用戶，其類型為ServiceAccount，名稱為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

---

如上定義了Dashboard 的角色，其角色名稱為kubernetes-dashboard-minimal，rules中清晰的列出了其擁有的多個權限。通過名稱我們可以猜到，這個權限級別是比較低的。
如上定義了Dashboard的角色綁定，其名稱為kubernetes-dashboard-minimal，roleRef中為被綁定的角色，也叫kubernetes-dashboard-minimal，subjects中為綁定的用戶：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

---

將其中的鏡像替換成國內的鏡像：
k8s.gcr.io/kubernetes-dashboard-amd64 替換成

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。並且還將Secret kubernetes-dashboard-certs通過volumes掛在到pod內部的/certs路徑。為何要掛載Secret ？原因是創建Secret 時會自動生成token。請注意參數--auto-generate-certificates，其表示Dashboard會自動生成證書。

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

重新安裝dashboard

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

查看Pod 的狀態為running說明dashboard已經部署成功：

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

Dashboard 會在 kube-system namespace 中創建自己的 Deployment 和 Service：

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

遇到的錯誤：###

完成了上述操作卻發現還是CrashLoopBackOff的錯誤

使用命令查看錯誤原因：

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

發現pod運行在副節點k8s-node1上，需要將dashboard調度到master節點上去。
輸入命令，為master節點添加label

kubectl label node k8s-master type=master

在kubernetes-dashboard.yaml中添加nodeSelecor定義：

配置完成之后，再重新安裝dashboard，發現問題得到了解決。

三、訪問Dashboard###

根據官方文檔，目前訪問Dashboard有四種方式：
①NodePort
②kubectl proxy
③API Server
④Ingress
以上四種方式，我測試了前兩種，目前NodePort和kubectl proxy可用。
①使用NodePort

為kubernetes-dashboard.yaml添加Service后，就可以使用NodePort訪問Dashboard。在我們的物理機上，使用Firefox訪問https://192.168.56.101:30001/，結果如下圖所示：

選擇令牌方式獲取token登錄:

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

②使用kubectl proxy
這里，我主要介紹一下最便捷的kubectl proxy方式。在Master上執行kubecll proxy，然后使用如下地址訪問Dashboard：

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

但限制就是必須在Master上訪問，這顯然是個坑，我們的目標是在我們真實的物理機上去訪問Master的Dashboard。
所以，在主節點上，我們執行kubectl proxy --address=192.168.56.101 --disable-filter=true開啟代理。

其中：
address表示外界可以使用192.168.56.101來訪問Dashboard，我們也可以使用0.0.0.0
disable-filter=true表示禁用請求過濾功能，否則我們的請求會被拒絕，並提示 Forbidden (403) Unauthorized。
我們也可以指定端口，具體請查看kubectl proxy --help
如下圖所示，proxy默認對Master的8001端口進行監聽：
這樣，我們就可以使用如下地址訪問登錄界面：

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

遇到的問題：獲取的token值登錄無效###

我們回想本文第三小節對kubernetes-dashboard.yaml的介紹，現在就理解了為什么其角色的名稱為kubernetes-dashboard-minimal。一句話，這個Role的權限不夠！
這個報錯的原因是因為我們沒有權限去訪問Kubernetes儀表盤。
1⃣️我們可以在Bash中運行如下命令來解決上述問題：

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

或者
2⃣️我們可以更改RoleBinding修改為ClusterRoleBinding，並且修改roleRef中的kind和name，使用cluster-admin這個非常牛逼的CusterRole（超級用戶權限，其擁有訪問kube-apiserver的所有權限）。如下：

修改后，重新安裝kubernetes-dashboard.yaml，Dashboard就可以擁有訪問整個K8S 集群API的權限。
3⃣️kubernetes-dashboard卸載

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

參考鏈接：
kubernetes部署dashboard可視化插件.
kubernetes安裝dashboard步驟.
Centos7 單節點上安裝kubernetes-dashboard過程.
kubeadm部署kubernetes 1.13.1集群.
dashboard-ui.
kubernetes github.