在创建Dashborad时，查看状态总是ContainerCreating

[root@MyCentos7 k8s]# kubectl get pod --namespace=kube-system
NAME                                    READY     STATUS              RESTARTS   AGE
kubernetes-dashboard-2094756401-kzhnx   0/1       ContainerCreating   0          10m

通过kubectl describe命令查看具体信息（或查看日志/var/log/message）

[root@MyCentos7 k8s]# kubectl describe pod kubernetes-dashboard-2094756401-kzhnx --namespace=kube-system
Name:        kubernetes-dashboard-2094756401-kzhnx
Namespace:    kube-system
Node:        mycentos7-1/192.168.126.131
Start Time:    Tue, 05 Jun 2018 19:28:25 +0800
Labels:        app=kubernetes-dashboard
        pod-template-hash=2094756401
Status:        Pending
IP:        
Controllers:    ReplicaSet/kubernetes-dashboard-2094756401
Containers:
  kubernetes-dashboard:
    Container ID:    
    Image:        daocloud.io/megvii/kubernetes-dashboard-amd64:v1.8.0
    Image ID:        
    Port:        9090/TCP
    Args:
      --apiserver-host=http://192.168.126.130:8080
    State:            Waiting
      Reason:            ContainerCreating
    Ready:            False
    Restart Count:        0
    Liveness:            http-get http://:9090/ delay=30s timeout=30s period=10s #success=1 #failure=3
    Volume Mounts:        <none>
    Environment Variables:    <none>
Conditions:
  Type        Status
  Initialized     True 
  Ready     False 
  PodScheduled     True 
No volumes.
QoS Class:    BestEffort
Tolerations:    <none>
Events:
  FirstSeen    LastSeen    Count    From            SubObjectPath    Type        Reason        Message
  ---------    --------    -----    ----            -------------    --------    ------        -------
  11m        11m        1    {default-scheduler }            Normal        Scheduled    Successfully assigned kubernetes-dashboard-2094756401-kzhnx to mycentos7-1
  11m        49s        7    {kubelet mycentos7-1}            Warning        FailedSync    Error syncing pod, skipping: failed to "StartContainer" for "POD" with ErrImagePull: "image pull failede:latest, this may be because there are no credentials on this request.  details: (open /etc/docker/certs.d/registry.access.redhat.com/redhat-ca.crt: no such file or directory)"

  11m    11s    47    {kubelet mycentos7-1}        Warning    FailedSync    Error syncing pod, skipping: failed to "StartContainer" for "POD" with ImagePullBackOff: "Back-off pulling image \"registry.access.redh

在工作节点（node）上执行
发现此时会pull一个镜像registry.access.redhat.com/rhel7/pod-infrastructure:latest，当我手动pull时，提示如下错误：

[root@MyCentos7-1 k8s]# docker pull registry.access.redhat.com/rhel7/pod-infrastructure:latest
Trying to pull repository registry.access.redhat.com/rhel7/pod-infrastructure ... 
open /etc/docker/certs.d/registry.access.redhat.com/redhat-ca.crt: no such file or directory

通过提示的路径查找该文件，是个软连接，链接目标是/etc/rhsm，查看没有rhsm

[root@MyCentos7-1 ca]# cd /etc/docker/certs.d/registry.access.redhat.com/
[root@MyCentos7-1 registry.access.redhat.com]# ll
总用量 0
lrwxrwxrwx. 1 root root 27 5月  11 14:30 redhat-ca.crt -> /etc/rhsm/ca/redhat-uep.pem

[root@MyCentos7-1 ca]# cd /etc/rhsm
-bash: cd: /etc/rhsm: 没有那个文件或目录

安装rhsm（node上）：

yum install *rhsm*
已加载插件：fastestmirror, langpacks
Loading mirror speeds from cached hostfile
 * base: mirror.lzu.edu.cn
 * extras: mirror.lzu.edu.cn
 * updates: ftp.sjtu.edu.cn
base                                                                                                                                                                                  | 3.6 kB  00:00:00     
extras                                                                                                                                                                                | 3.4 kB  00:00:00     
updates                                                                                                                                                                               | 3.4 kB  00:00:00     
软件包 python-rhsm-1.19.10-1.el7_4.x86_64 被已安装的 subscription-manager-rhsm-1.20.11-1.el7.centos.x86_64 取代
软件包 subscription-manager-rhsm-1.20.11-1.el7.centos.x86_64 已安装并且是最新版本
软件包 python-rhsm-certificates-1.19.10-1.el7_4.x86_64 被已安装的 subscription-manager-rhsm-certificates-1.20.11-1.el7.centos.x86_64 取代
软件包 subscription-manager-rhsm-certificates-1.20.11-1.el7.centos.x86_64 已安装并且是最新版本

但是在/etc/rhsm/ca/目录下依旧没有证书文件，于是反复卸载与安装都不靠谱，后来发现大家所谓yum install *rhsm*其实安装的的是python-rhsm-1.19.10-1.el7_4.x86_64和python-rhsm-certificates-1.19.10-1.el7_4.x86_64，但是在实际安装过程中会有如下提示:

软件包 python-rhsm-1.19.10-1.el7_4.x86_64 被已安装的 subscription-manager-rhsm-1.20.11-1.el7.centos.x86_64 取代
软件包 subscription-manager-rhsm-1.20.11-1.el7.centos.x86_64 已安装并且是最新版本
软件包 python-rhsm-certificates-1.19.10-1.el7_4.x86_64 被已安装的 subscription-manager-rhsm-certificates-1.20.11-1.el7.centos.x86_64 取代
软件包 subscription-manager-rhsm-certificates-1.20.11-1.el7.centos.x86_64 已安装并且是最新版本

罪魁祸首在这里。原来我们想要安装的rpm包被取代了。而取代后的rpm包在安装完成后之创建了目录，并没有证书文件redhat-uep.pem。于是乎，手动下载以上两个包

wget ftp://bo.mirror.garr.it/1/slc/centos/7.1.1503/updates/x86_64/Packages/python-rhsm-1.19.9-1.el7.x86_64.rpm
wget ftp://bo.mirror.garr.it/1/slc/centos/7.1.1503/updates/x86_64/Packages/python-rhsm-certificates-1.19.9-1.el7.x86_64.rpm

如果下载不下来，登陆到 http://rpm.pbone.net/这个网址，里面有个search，在里面搜索上面的两个rpm包，进行下载

注意版本要匹配，卸载安装错的包

yum remove *rhsm*

然后执行安装命令

rpm -ivh *.rpm

rpm -ivh *.rpm
警告：python-rhsm-1.19.9-1.el7.x86_64.rpm: 头V4 DSA/SHA1 Signature, 密钥 ID 192a7d7d: NOKEY
准备中...                          ################################# [100%]
正在升级/安装...
   1:python-rhsm-certificates-1.19.9-1################################# [ 50%]
   2:python-rhsm-1.19.9-1.el7         ################################# [100%]

接着验证手动pull镜像

docker pull registry.access.redhat.com/rhel7/pod-infrastructure:latest
Trying to pull repository registry.access.redhat.com/rhel7/pod-infrastructure ... 
latest: Pulling from registry.access.redhat.com/rhel7/pod-infrastructure
26e5ed6899db: Pull complete 
66dbe984a319: Pull complete 
9138e7863e08: Pull complete 
Digest: sha256:92d43c37297da3ab187fc2b9e9ebfb243c1110d446c783ae1b989088495db931
Status: Downloaded newer image for registry.access.redhat.com/rhel7/pod-infrastructure:latest

问题解决。

再次执行 kubectl  get  pods

过了一会，全部变为running的状态