如题，执行docker安装命令报错：
[root@centos ~]# yum install docker-ce
Loaded plugins: fastestmirror, security
Setting up Install Process
Loading mirror speeds from cached hostfile
https://download.docker.com/linux/centos/7/i386/stable/repodata/repomd.xml: [Errno 14] PYCURL ERROR 22 - "The requested URL returned error: 404 Not Found"
Trying other mirror.
To address this issue please refer to the below knowledge base article https://access.redhat.com/articles/1320623 If above article doesn't help to resolve this issue please open a ticket with Red Hat Support. Error: Cannot retrieve repository metadata (repomd.xml) for repository: docker-ce-stable. Please verify its path and try again
看起来镜像链接失效了。看了下之前的docker-ce仓库配置：
[root@centos ~]# ll /etc/yum.repos.d/docker*
-rw-r--r-- root root Oct : /etc/yum.repos.d/docker-ce.repo
我们看到10月19号有记录，删掉它，再试试
[root@centos ~]# rm /etc/yum.repos.d/docker-ce.repo
rm: remove regular file `/etc/yum.repos.d/docker-ce.repo'? y
[root@centos ~]# yum install docker-ce
Loaded plugins: fastestmirror, security
Setting up Install Process
Loading mirror speeds from cached hostfile
No package docker-ce available.
Error: Nothing to do
看来还是不行，继续找原因：
[root@centos ~]# uname -r
2.6.-.el6.i686
[root@centos ~]# cat /etc/redhat-release
CentOS release 6.9 (Final)
呵呵，docker要求centos是3.10以上才行，歇菜。