docker安装

国内源：

$ sudo yum-config-manager 
    --add-repo 
    https://mirrors.ustc.edu.cn/docker-ce/linux/centos/docker-ce.repo

安装依赖包：

$ sudo yum install -y yum-utils 
           device-mapper-persistent-data 
           lvm2

--打开
yum-config-manager --enable docker-ce-nightly
--关闭
yum-config-manager --disable docker-ce-nightly

更新 yum 软件源缓存，并安装 docker-ce。

$ sudo yum makecache fast
$ sudo yum install docker-ce

启动docker-CE

$ sudo systemctl enable docker
$ sudo systemctl start docker

验证docker安装是否成功

$ docker run hello-world

若输出：

[root@cent7-zuoys ~]# systemctl enable docker
Created symlink from /etc/systemd/system/multi-user.target.wants/docker.service to /usr/lib/systemd/system/docker.service.
[root@cent7-zuoys ~]# systemctl start docker
[root@cent7-zuoys ~]# docker run hello-world
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
1b930d010525: Pull complete 
Digest: sha256:2557e3c07ed1e38f26e389462d03ed943586f744621577a99efb77324b0fe535
Status: Downloaded newer image for hello-world:latest

Hello from Docker!
This message shows that your installation appears to be working correctly.

To generate this message, Docker took the following steps:
 1. The Docker client contacted the Docker daemon.
 2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
    (amd64)
 3. The Docker daemon created a new container from that image which runs the
    executable that produces the output you are currently reading.
 4. The Docker daemon streamed that output to the Docker client, which sent it
    to your terminal.

To try something more ambitious, you can run an Ubuntu container with:
 $ docker run -it ubuntu bash

Share images, automate workflows, and more with a free Docker ID:
 https://hub.docker.com/

For more examples and ideas, visit:
 https://docs.docker.com/get-started/

说明，安装成功。