k8s（kubernetes）服務部署dashboard時出現ImagePullBackOff/CrashLoopBackOff解決辦法

部署服務時鏡像拉取過程當中出現:ImagePullBackOff
kubectl describe pods kubernetes-dashboard-975499656-krwl7 -n kube-system
查看pod的詳細狀況

Events:
  Type     Reason     Age                    From                Message
  ----     ------     ----                   ----                -------
  Normal   Scheduled  4m38s                  default-scheduler   Successfully assigned kube-system/kubernetes-dashboard-975499656-krwl7 to k8s-node2
  Normal   Pulling    2m32s (x4 over 4m38s)  kubelet, k8s-node2  Pulling image "k8s.gcr.io/kubernetes-dashboard-amd64:v1.10.1"
  Warning  Failed     2m16s (x4 over 4m22s)  kubelet, k8s-node2  Failed to pull image "k8s.gcr.io/kubernetes-dashboard-amd64:v1.10.1": rpc error: code = Unknown desc = Error response from daemon: Get https://k8s.gcr.io/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
  Warning  Failed     2m16s (x4 over 4m22s)  kubelet, k8s-node2  Error: ErrImagePull
  Normal   BackOff    112s (x6 over 4m22s)   kubelet, k8s-node2  Back-off pulling image "k8s.gcr.io/kubernetes-dashboard-amd64:v1.10.1"
  Warning  Failed     99s (x7 over 4m22s)    kubelet, k8s-node2  Error: ImagePullBackOff

分析：這個拉取的國外的鏡像源，是有點慢，網絡很差的時候常常會出現這種狀況，能夠提早把須要的鏡像下載好
解決辦法:
更換國內鏡像源，搜索須要下載的鏡像
①編輯文件 /etc/docker/daemon.json 加入"registry-mirrors":["https://docker.mirrors.ustc.edu.cn"]

重載配置文件重啓docker生效

systemctl daemon-reload 
systemctl restart docker

②搜索須要的鏡像，如:k8s.gcr.io/kubernetes-dashboard-amd64:v1.10.1

③拉取指定鏡像

④tag爲配置文件中須要的鏡像名k8s.gcr.io/kubernetes-dashboard-amd64:v1.10.1

docker tag loveone/kubernetes-dashboard-amd64:v1.10.1 k8s.gcr.io/kubernetes-dashboard-amd64:v1.10.1

完成後再試一次(注意最好每一個節點都作這樣的操做，由於調度器隨機選擇節點部署，簡而言之是在被部署的節點上操做)
從新部署
①kubectl delete -f kubernetes-dashboard.yaml,
②kubectl apply -f kubernetes-dashboard.yaml 或者 kubectl create -f kubernetes-dashboard.yaml --save-config
出現以下報錯

kubectl logs kubernetes-dashboard-975499656-xlx5b -n kube-system

• 查看pod日誌以下
  Error from server: Get https://192.168.40.131:10250/containerLogs/kube-system/kubernetes-dashboard-975499656-xlx5b/kubernetes-dashboard: dial tcp 192.168.40.131:10250: connect: no route to host
  
• 分析:因而可知，部署服務時訪問節點131的10250端口鏈接被拒絕，推測多是防火牆的緣由
• 解決辦法:
  ①查看服務端口是否被佔用，!是否已經啓起來了；
  能夠看到，端口啓動正常；
  ②telnet測試一下端口（我這裏是master機器上測試的）
  
  果真不通
  ③查看節點1的防火牆狀態
  果真是防火牆的緣由
  
  
  
  再試端口就通了
  
  從新部署試試
  成功