ImagePullBackOff一般是拉取镜像问题，排查方法：
1、kubectl get pod -o wide 查看pod在哪个节点
2、kubectl describe pod pod名 查看pod的详细信息
看到报错信息：Failed to pull image "harbor.zhongdian.com/baseimage/alpine:latest": rpc error: code = Unknown desc = Error response from daemon: Get https://harbor.zhongdian.com/v2/: x509: certificate is valid for hexiao.18qy.cn, not harbor.zhongdian.com
3、这个报错是Harbor证书问题，发现新加节点忘记加Harbor证书了。