centos7下安装docker

$ yum install -y yum-utils \
 device-mapper-persistent-data \
 lvm2
$ yum-config-manager \
 --add-repo \
 https://download.docker.com/linux/centos/docker-ce.repo

安装最新的Docker CE版本
$ yum install docker-ce docker-ce-cli containerd.io

如需指定版本安装执行下述命令：
$ yum list docker-ce --showduplicates | sort -r

$ yum install docker-ce-<VERSION_STRING> docker-ce-cli-<VERSION_STRING> containerd.io

说明：<VERSION_STRING>，取第二列中的第一个：或第一个数字到-之间的字符串，如18.09.6、18.06.2.ce等。

3.启动

启动
systemctl start docker
查看状态
systemctl status docker

4运行hello world，查看是否正常运行

[root@localhost ~]# docker run hello-world

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/

配置随机启动，看个人需求

systemctl enable docker