安装步骤：

    1. 下载docker-ce的repo
      1. curl https://download.docker.com/linux/centos/docker-ce.repo -o /etc/yum.repos.d/docker-ce.repo

      2. 安装依赖（相比centos7的关键步骤）
      1. yum install https://download.docker.com/linux/fedora/30/x86_64/stable/Packages/containerd.io-1.2.6-3.3.fc30.x86_64.rpm

      3. 安装docker-ce
    1. yum install docker-ce
    1. 启动docker
      1. systemctl start docker
      5.验证安装成功
    1. docker version