创建好yaml文件以后，为了将它发布到kubernetes集群中，在Master节点执行以下命令时，显示我们想要创建的RC已经创建成功
#kubectl create -f filename.yam
replicationcontroller "rcname" created
但是当查看Pods时，却显示不存在
#kubectl get pods
No resources found.
解决办法是编辑/etc/kubernetes/apiserver 去除 KUBE_ADMISSION_CONTROL 中的 SecurityContextDeny,ServiceAccount ，并重启kube-apiserver.service服务
#vim /etc/kubernetes/apiserver
KUBE_ADMISSION_CONTROL="--admission-control=NamespaceLifecycle,NamespaceExists,LimitRanger,ResourceQuota"
#systemctl restart kube-apiserver.service
删除RC，重新执行前面的步骤就可以看到Pods的生成了
#kubectl delete -f filename.yam
replicationcontroller "rcname" deleted
#kubectl create -f filename.yam
replicationcontroller "rcname" created
#kubectl get pods
NAME READY STATUS RESTARTS AGE
mysql-sgvzt 0/1 ContainerCreating 0 3s
若是Pod一直卡在ContainerCreating状态，可以用以下命令查看具体原因
#kubectl describe pod mysql-sgvzt
Name: mysql-sgvzt
Namespace: default
Node: 127.0.0.1/127.0.0.1
Start Time: Thu, 26 Apr 2018 13:45:25 +0800
Labels: app=mysql
Status: Pending
IP:
Controllers: ReplicationController/mysql
Containers:
mysql:
Container ID:
Image: docker.io/mysql
Image ID:
Port: 3306/TCP
State: Waiting
Reason: ContainerCreating
Ready: False
Restart Count: 0
Volume Mounts: <none>
Environment Variables:
MYSQL_ROOT_PASSWORD: 123456
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
--------- -------- ----- ---- ------------- -------- ------ -------
30m 30m 1 {default-scheduler } Normal Scheduled Successfully assigned mysql-sgvzt to 127.0.0.1
30m 4m 10 {kubelet 127.0.0.1} Warning FailedSync Error syncing pod, skipping: failed to "StartContainer" for "POD" with ErrImagePull: "image pull failed for registry.access.redhat.com/rhel7/pod-infrastructure: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)"
29m 1s 132 {kubelet 127.0.0.1} Warning FailedSync Error syncing pod, skipping: failed to "StartContainer" for "POD" with ImagePullBackOff: "Back-off pulling image \"registry.access.redhat.com/rhel7/pod-infrastructure:latest\""
根据结果，可以明显看到失败原因，缺少了/etc/docker/certs.d/registry.access.redhat.com/redhat-ca.crt
pod, skipping: failed to "StartContainer" for "POD" with ErrImagePull: "image pull failed for registry.access.redhat.com/rhel7/pod-infrastructure: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
而这个缺失的文件是由python-rhsm-certificates提供的，所以我们只需要用yum安装他就行了
yum install -y *rhsm*
如果依然报错，可参考下面的方案：
wget http://mirror.centos.org/centos/7/os/x86_64/Packages/python-rhsm-certificates-1.19.10-1.el7_4.x86_64.rpm
rpm2cpio python-rhsm-certificates-1.19.10-1.el7_4.x86_64.rpm | cpio -iv --to-stdout ./etc/rhsm/ca/redhat-uep.pem | tee /etc/rhsm/ca/redhat-uep.pem
这两个命令会生成/etc/rhsm/ca/redhat-uep.pem文件.
顺得的话会得到下面的结果。
[root@localhost]# 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
删除原来创建的rc
[root@localhost /]# kubectl delete -f mysql-rc.yaml
重新创建
[root@localhost /]# kubectl create -f mysql-rc.yaml
replicationcontroller "mysql" created
再次查看状态
[root@localhost /]# kubectl get pod
NAME READY STATUS RESTARTS AGE
mysql-b8m2q 1/1 Running 0 27m
作者：JensenWong
链接：https://www.jianshu.com/p/e601d79357c6
來源：简书
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