CentOS7.x上yum安装Docker CE问题记录

前段时间在腾讯云上买了几台CentOS7.5的云服务器，在上面准备安装docker以防服务器到期以后环境转移的尴尬。

安装步骤如下：

1. 更新yum包到最新  sudo yum update
2. 安装需要的软件包， yum-util 提供yum-confifig-manager功能，另外两个是devicemapper驱动依赖的  sudo yum install -y yum-utils device-mapper-persistent-data lvm2
3. 设置yum源为阿里云  sudo yum-config-manager --add-repo http://mirrors.aliyun.com/docker- ce/linux/centos/docker-ce.repo
4. 更新并安装Docker CE   sudo yum makecache fast     sudo yum install docker-ce
   此处出现异常 

   http://mirrors.aliyun.com/docker-/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found
   Trying other mirror.
   To address this issue please refer to the below wiki article 

   https://wiki.centos.org/yum-errors

   If above article doesn't help to resolve this issue please use https://bugs.centos.org/.

    One of the configured repositories failed (added from: http://mirrors.aliyun.com/docker-),
    and yum doesn't have enough cached data to continue. At this point the only
    safe thing yum can do is fail. There are a few ways to work "fix" this:

        1. Contact the upstream for the repository and get them to fix the problem.

        2. Reconfigure the baseurl/etc. for the repository, to point to a working
           upstream. This is most often useful if you are using a newer
           distribution release than is supported by the repository (and the
           packages for the previous distribution release still work).

        3. Run the command with the repository temporarily disabled
               yum --disablerepo=mirrors.aliyun.com_docker- ...

        4. Disable the repository permanently, so yum won't use it by default. Yum
           will then just ignore the repository until you permanently enable it
           again or use --enablerepo for temporary usage:

               yum-config-manager --disable mirrors.aliyun.com_docker-
           or
               subscription-manager repos --disable=mirrors.aliyun.com_docker-

        5. Configure the failing repository to be skipped, if it is unavailable.
           Note that yum will try to contact the repo. when it runs most commands,
           so will have to try and fail each time (and thus. yum will be be much
           slower). If it is a very temporary problem though, this is often a nice
           compromise:

               yum-config-manager --save --setopt=mirrors.aliyun.com_docker-.skip_if_unavailable=true。网上的网友大多的解释如下然而我去查看了docker-ce.pro文件的内容并未发现以上问题检查/etc/yum.repos.d路径后发现多出来一个mirrors.aliyun.com_docker-.repo文件，删除后就正常了。

5. 删除后继续安装 

6. 安装成功