CentOS 7 yum安装 k8s 创建Pod一直处于ContainerCreating状态 问题解决

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CentOS 7 yum安装 k8s 创建Pod一直处于ContainerCreating状态 问题解决

优惠码发放 2020-04-17 18:47:26 浏览742

CentOS 7 yum安装 k8s 创建Pod一直处于ContainerCreating状态 问题解决

阅读目录
问题描述
本文内容
问题分析与解决
原因分析与其他方案
参考
问题描述
使用CentOS7的 yum 包管理器安装了 Kubernetes 集群,使用 kubectl 创建服务成功后,执行 kubectl get pods,发现AGE虽然在不断增加,但状态始终不变

本文内容
分析问题原因
给出直接解决此问题的方式 (不完美)
给出其他方案
且听我娓娓道来~

问题分析与解决
kubectl 提供了 describe 子命令来输出指定的一个/多个资源的详细信息。

执行 kubectl describe pod mytomcat-9lcq5,查看问题 Pod 的状态信息,输出如下:

[root@kube-master app]# kubectl describe pod mytomcat-9lcq5
Name: mytomcat-9lcq5
Namespace: default
Node: kube-node-2/192.168.87.145
Start Time: Fri, 17 Apr 2020 15:53:50 +0800
Labels: app=mytomcat
Status: Pending
IP:
Controllers: ReplicationController/mytomcat
Containers:
mytomcat:

Container ID:        
Image:            tomcat:9-jre8-alpine
Image ID:            
Port:            8080/TCP
State:            Waiting
  Reason:            ContainerCreating
Ready:            False
Restart Count:        0
Volume Mounts:        <none>
Environment Variables:    <none>

Conditions:
Type Status
Initialized True
Ready False
PodScheduled True
No volumes.
QoS Class: BestEffort
Tolerations:
Events:
FirstSeen LastSeen Count From SubObjectPath Type Reason Message
--------- -------- ----- ---- ------------- -------- ------ -------
5m 5m 1 {default-scheduler } Normal Scheduled Successfully assigned mytomcat-9lcq5 to kube-node-2
4m 4m 1 {kubelet kube-node-2} 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: (Get https://registry.access.redhat.com/v1/_ping: net/http: TLS handshake timeout)"

3m 3m 1 {kubelet kube-node-2} 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: (Network timed out while trying to connect to https://registry.access.redhat.com/v1/repositories/rhel7/pod-infrastructure/images. You may want to check your internet connection or if you are behind a proxy.)"

2m 2m 1 {kubelet kube-node-2} 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: (Error: image rhel7/pod-infrastructure:latest not found)"

3m 1m 3 {kubelet kube-node-2} 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""

通过查看最下方的输出信息,Successfully assigned mytomcat-9lcq5 to kube-node-2 说明这个 Pod 分配到 kube-node-2 这个主机上了,然后在这个主机上创建 Pod 失败,

原因是 image pull failed for registry.access.redhat.com/rhel7/pod-infrastructure:latest, this may be because there are no credentials on this request.

通过以上信息,我们了解到通过红帽自家的 docker 仓库 pull 镜像,需要使用 CA 证书进行认证,才能 pull 成功

docker的证书在 /etc/docker/certs.d 目录下,根据上边的错误提示域名是 registry.access.redhat.com,证书在这个目录中

经过 ll 命令查看,发现 /etc/docker/certs.d/registry.access.redhat.com/redhat-ca.crt 是一个软链接(软链接是什么?),指向到 /etc/rhsm/ca/redhat-uep.pem,

熟悉软连接的我们知道,处于红色闪烁状态的目标是不存在,需要生成 /etc/rhsm/ca/redhat-uep.pem 证书文件

生成证书:

openssl s_client -showcerts -servername registry.access.redhat.com -connect registry.access.redhat.com:443 /null 2>/dev/null | openssl x509 -text > /etc/rhsm/ca/redhat-uep.pem

生成证书命令执行有时会出现 unable to load certificate 139930742028176:error:0906D06C:PEM routines:PEM_read_bio:no start line:pem_lib.c:707:Expecting: TRUSTED CERTIFICATE 问题,重新执行就好

命令执行完毕后,查看软链接指向的证书文件:

[root@kube-node-2 registry.access.redhat.com]# ll /etc/rhsm/ca/redhat-uep.pem
-rw-r--r-- 1 root root 9233 Apr 17 16:55 /etc/rhsm/ca/redhat-uep.pem
证书文件已经存在,我们去 k8s 管理节点 kube-master 主机删除刚才的 Pods,等待 Pod 重新创建成功 (第二个节点因为网络问题没有拉成功镜像……)

至此完成 Pod 的创建

但是还有存在些问题的,当前国内网络环境访问外边的网络偶尔会有问题,导致创建 Pod 失败,通过 describe 描述还是同样的信息提示,但是查看证书文件却存在且有内容

原因分析与其他方案
k8s 管理节点分配创建 Pod 到执行节点,到达执行节点后,拉取红帽 docker 仓库的 Pod基础镜像 pod-infrastructure:latest,由于其仓库使用 https 需要验证证书,证书不存在导致失败

另外就是因为拉取的镜像是红帽 docker 仓库中的,在国内网络环境下握手失败,无法下载镜像

所以问题就成了 如何解决 k8s pod-infrastructure 镜像拉取失败,这里给出一个方案,步骤如下:

拉取 docker 官方仓库其他人上传的 pod-infrastructure 镜像,docker pull tianyebj/pod-infrastructure
添加tag标签,改为私有仓库地址,如:docker tag tianyebj/pod-infrastructure 10.2.7.70:5000/dev/pod-infrastructure
push镜像到私有仓库,如:docker push 10.2.7.70:5000/dev/pod-infrastructure

修改所有 worker 节点的 /etc/kubernetes/kubelet,修改 registry.access.redhat.com/rhel7/pod-infrastructure 为刚才设置的 tag 标签
sed -i "s#registry.access.redhat.com/rhel7/pod-infrastructure#<私有仓库pod-infrastructure镜像tag>#" /etc/kubernetes/kubelet

重启所有 worker 节点的 kubelet,systemctl restart kubelet,即可
注意事项:

上传的镜像要设为公开镜像,否则 kubelet 自己没权限拉镜像的,另外也可以去 ssh 登录 worker 节点登录仓库,执行docker pull <私有仓库pod-infrastructure镜像tag>
最后的效果:

参考
https://github.com/CentOS/sig-atomic-buildscripts/issues/329
https://cloud.tencent.com/developer/article/1156329

原文地址https://www.cnblogs.com/hellxz/p/k8s-pod-always-container-creating-status-problem.html