CentOS7 下安装docker

安装必要条件：
操作系统： centos7
卸载旧版本：

```yum remove docker \
                 docker-common \
                 docker-selinux \
                 docker-engine
```

安装docker CE (企业版使用docker EE）

1. 使用镜像仓库进行安装（首次安装需要设置docker镜像仓库）

```
安装所需要的软件包
$ sudo yum install -y yum-utils device-mapper-persistent-data lvm2
```

2. 设置stable镜像仓库。

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

开始docker安装：

1. 更新yum软件包索引

```
#yum installmakecache fast
```

2. 安装最新版本的docker ce

```
# yum install docker-ce
```

3. 启动docker

```

[root@wg001 ~]# systemctl  start docker

```

4. 验证是否安装了docker，方法是运行hello-world 镜像

```
[root@wg001 ~]# docker run hello-world

```

输出内容

```
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/

```

5. 卸载docker ce

```
#yum remove docker-ce
#rm -rf /var/lib/docker
```

安装docker，我们后期会在docker里面安装数据库来使用， 把docker当成虚拟机来练习。