docker安装

1、卸载旧版本的Docker

yum remove docker \
    docker-client \
    docker-client-latest \
    docker-common \
    docker-latest \
    docker-latest-logrotate \
    docker-logrotate \
    docker-engine

2、配置Docker的yum库

首先要安装一个yum工具，这个命令可能会失败
yum install -y yum-utils
报错信息

[root@hcss-ecs-a901 yum.repos.d]# yum makecache
Loaded plugins: fastestmirror
Determining fastest mirrors
Could not retrieve mirrorlist http://mirrorlist.centos.org?arch=x86_64&release=7&repo=sclo-rh error was
14: curl#6 - "Could not resolve host: mirrorlist.centos.org; Unknown error"


 One of the configured repositories failed (Unknown),
 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=<repoid> ...

     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 <repoid>
        or
            subscription-manager repos --disable=<repoid>

     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=<repoid>.skip_if_unavailable=true

Cannot find a valid baseurl for repo: centos-sclo-rh/x86_64

如果失败就按照
以下步骤

• 1、先进入目录 /etc/yum.repos.d
  cd /etc/yum.repos.d
• 2、4.编辑 CentOS-Base.repo 文件（必选）
  vi /etc/yum.repos.d/CentOS-Base.repo
  替换内容为：

[base]
name=CentOS-$releasever - Base
baseurl=https://mirrors.aliyun.com/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

[updates]
name=CentOS-$releasever - Updates
baseurl=https://mirrors.aliyun.com/centos/$releasever/updates/$basearch/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

[extras]
name=CentOS-$releasever - Extras
baseurl=https://mirrors.aliyun.com/centos/$releasever/extras/$basearch/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

[centosplus]
name=CentOS-$releasever - Plus
baseurl=https://mirrors.aliyun.com/centos/$releasever/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=https://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

• 3、清理yum缓存
  yum clean all
• 4、重新生产yum缓存
  yum makecache
  如果你执行了以上这些步骤未能解决的话请看这篇博客
  https://blog.csdn.net/qq_43768851/article/details/140112143

安装成功后，执行命令，配置Docker的yum源：

yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo

如果你安装出现网络不可用的情况
1、执行以下命令

yum-config-manager --save --setopt=download.docker.com_linux_centos_docker-ce.rep.skip_if_unavailable=true

执行后出现界面

2、在执行docker安装

yum install docker-ce

3、安装成功