起因:

在使用curl 命令进行自动化安装Docker的执行脚本过程中报错如下

# Executing docker install script, commit: 93d2499759296ac1f9c510605fef85052a2c32be
Warning: the "docker" command appears to already exist on this system.
 
If you already have Docker installed, this script can cause trouble, which is
why we're displaying this warning and provide the opportunity to cancel the
installation.
 
If you installed the current Docker package using this script and are using it
again to update Docker, you can safely ignore this message.
 
You may press Ctrl+C now to abort this script.
+ sleep 20
+ sh -c 'yum install -y -q yum-utils'
http://mirrors.cloud.aliyuncs.com/centos/7/os/x86_64/repodata/repomd.xml: [Errno 14] curl#6 - "Could not resolve host: mirrors.cloud.aliyuncs.com; Unknown error"
Trying other mirror.
http://mirrors.cloud.aliyuncs.com/epel/7/x86_64/repodata/repomd.xml: [Errno 14] curl#6 - "Could not resolve host: mirrors.cloud.aliyuncs.com; Unknown error"
Trying other mirror.
http://mirrors.cloud.aliyuncs.com/centos/7/extras/x86_64/repodata/repomd.xml: [Errno 14] curl#6 - "Could not resolve host: mirrors.cloud.aliyuncs.com; Unknown error"
Trying other mirror.
http://mirrors.cloud.aliyuncs.com/centos/7/updates/x86_64/repodata/repomd.xml: [Errno 14] curl#6 - "Could not resolve host: mirrors.cloud.aliyuncs.com; Unknown error"
Trying other mirror.

问题解决:

可以按照如下步骤进行修改即可

进入 cd /etc/yum.repos.d/ 该目录下

修改文件 CentOS-Base.repo 和 epel.repo 中所有

http://mirrors.cloud.aliyuncs.com 为 http://mirrors.aliyun.com/centos

最后运行 yum -y update 即可

修改后 重新执行上面curl命令