K8s部署使用错误排查

发表于 2022-11-01 更新于 2023-12-05 本文字数： 1.6k 阅读时长 ≈ 1 分钟

ImagePullBackOff

错误

在mac上使用minikube, 创建pod出现如下 ImagePullBackOff:

Normal   Pulling    8s               kubelet            Pulling image "docker.io/nginx:1.23"
Warning  Failed     8s               kubelet            Failed to pull image "docker.io/nginx:1.23": rpc error: code = Unknown desc = Error response from daemon: Get "https://registry-1.docker.io/v2/": dial tcp: lookup registry-1.docker.io on 192.168.64.1:53: server misbehaving
Warning  Failed     8s               kubelet            Error: ErrImagePull
Normal   BackOff    6s (x2 over 7s)  kubelet            Back-off pulling image "docker.io/nginx:1.23"
Warning  Failed     6s (x2 over 7s)  kubelet            Error: ImagePullBackOff

解决方案

参见: 解决方案

登录minikube的节点
```
$ minikube ssh
```

在minikube node上手动 pull docker image, 如下, 发现问题仍然重现

$ docker pull docker.io/nginx
Using default tag: latest
Error response from daemon: Get "https://registry-1.docker.io/v2/": dial tcp: lookup registry-1.docker.io on 192.168.64.1:53: server misbehaving

修改minikube node上的resolv.conf文件的nameserver:

$ sudo vi /etc/resolv.conf
nameserver 8.8.8.8
search .

重新尝试手动pull image, 发现问题解决:

$ docker pull docker.io/nginx:1.23
1.23: Pulling from library/nginx
Digest: sha256:943c25b4b66b332184d5ba6bb18234273551593016c0e0ae906bab111548239f
Status: Downloaded newer image for nginx:1.23
docker.io/library/nginx:1.23

退出node, 在Mac上重新检查pod状态, 问题解决🎉🎉🎉:

davywalkerdeMacBook-Pro:~ davywalker$ k get po
NAME                              READY   STATUS    RESTARTS   AGE
hello-minikube-67b8c7bdfd-965qn   1/1     Running   0          87s

为啥叫”ImagePullBackOff”??

参见文章 Kubernetes ImagePullBackOff error: what you need to know 说明.

The status ImagePullBackOff means that a Pod couldn’t start,
because Kubernetes couldn’t pull a container image.
The ‘BackOff’ part means that Kubernetes will keep trying to pull the image,
with an increasing delay (‘back-off’).

这里的”BackOff”就是”退避”的意思, 当拉取失败时, kubelet应该有个退避算法来重试拉取. 具体退避算法是啥, 有待后续钻研. 🤔