kubernetes创建pod失败

[zhangsc]

集群搭建好后，我创建命名空间 development.yaml内容如下：
[root@localhost demo]# cat development.yaml
apiVersion: v1
kind: Namespace
metadata:
   name: development

[root@localhost demo]# kubectl create -f development.yaml
namespace/development created

然后创建一个Pod, busybox.yaml内容如下：
[root@localhost demo]# cat busybox.yaml
apiVersion: v1
kind: Pod
metadata:
   name: busybox
   namespace: development
spec:
   containers:
   - image: busybox
     command: 
       - sleep
       - "3600"
     name: busybox

[root@localhost demo]# kubectl create -f busybox.yaml
pod/busybox created
[root@localhost demo]# kubectl get pods --namespace=development
NAME      READY   STATUS             RESTARTS   AGE
busybox   0/1     ImagePullBackOff   0          47s

busybox的状态是ImagePullBackOff，猜测是busybox的镜像没有拉下来，想问一下，修改哪个配置文件才能将busybox的镜像下载下来，谢谢