Docker是一个建设企业及数据中心服务仓库的进程，通过裸金属机和虚拟机承载的MAC、windows和linux系统提供本地和远程软件服务，涉及应用软件镜像、系统镜像、虚拟化仓库（虚拟机）。它承载着灵活的、轻量级的、可移植的、松散耦合、可扩展的、安全的特性。
部署环境：
系统：Centos8
[root@localhost
~]# uname -r
4.18.0-193.14.2.el8_2.x86_64
[root@localhost
~]# cat /etc/redhat-release
CentOS Linux
release 8.2.2004 (Core)
软件：Docker_CE latest
[root@localhost
~]# docker -v
Docker
version 19.03.12, build 48a66213fe
卸载老docker版本（防止老版本docker的依赖包影响安装）
[root@localhost
~]# yum remove docker
docker-client
docker-client-latest
docker-common
docker-latest
docker-latest-logrotate
docker-logrotate
docker-engine
i.通过国内mirrors获取docker-ce资源
阿里云：https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
中国科技技术大学：https://mirrors.ustc.edu.cn/docker-ce/linux/centos/docker-ce.repo
Docker官方下载：https://download.docker.com/linux/centos/docker-ce.repo
ii.下载docker-ce的repo
[root@localhost
~]# yum-config-manager --add-repo https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
iii.更新yum缓存
[root@localhost
~]# dnf makecache //dnf 相对于yum来说是轻量级的，它们同为包管理器（安装、更新、删除），降低对内存的消耗;
iv.问题：解决containerd.io版本过低
[root@localhost
~]# dnf install
https://download.docker.com/linux/fedora/30/x86_64/stable/Packages/containerd.io-1.2.6-3.3.fc30.x86_64.rpm
v.安装docker-ce的依赖包
[root@localhost
~]# dnf install -y yum-utils device-mapper-persistent-data lvm2
vi.安装docker-ce数据包
[root@localhost
~]# dnf install -y docker-ce
vii.开启docker服务
[root@localhost
~]# systemctl start docker
viii.docker服务加入开机启动
[root@localhost
~]# systemctl enable docker
Created
symlink /etc/systemd/system/multi-user.target.wants/docker.service → /usr/lib/systemd/system/docker.service.
ix.问题：docker服务无法启动
docker的/etc/docker/daemon.json文本内容，如下：
{
"registry-mirrors":
["https://5***0wdp.mirror.aliyuncs.com"], //远程镜像服务器地址
"insecure-registries":
["192.168.1.102:4000"] }， //通过http协议访问仓库管理web
"graph":"/data/docker" //自定义docker软件的安装目录
}
用逗号“,”分割，避免service无法启动；
一般情况，docker状态命令“systemctl status docker”log提示failed信息，由于目录/usr/lib/systemd/system/docker.service和/etc/docker/daemon.json 存在错误配置；
x.查看docker状态
[root@localhost
~]# systemctl status docker
●
docker.service - Docker Application Container Engine
Loaded: loaded
(/usr/lib/systemd/system/docker.service; enabled; vendor preset: disabled)
Active:
active (running) since Mon 2020-08-03 21:40:17 CST;
18s ago
Docs:
https://docs.docker.com
Main PID:
35838 (dockerd)
Tasks: 10
Memory: 41.8M
CGroup:
/system.slice/docker.service
└─35838
/usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock
Aug 03 21:40:16
localhost.localdomain dockerd[35838]:
time="2020-08-03T21:40:16.780989114+08:00" level=i>
Aug 03
21:40:16 localhost.localdomain dockerd[35838]:
time="2020-08-03T21:40:16.801029788+08:00" level=w>
Aug 03
21:40:16 localhost.localdomain dockerd[35838]:
time="2020-08-03T21:40:16.801065229+08:00" level=w>
Aug 03
21:40:16 localhost.localdomain dockerd[35838]:
time="2020-08-03T21:40:16.801194904+08:00" level=i>
Aug 03
21:40:17 localhost.localdomain dockerd[35838]:
time="2020-08-03T21:40:17.301292877+08:00" level=i>
Aug 03
21:40:17 localhost.localdomain dockerd[35838]: time="2020-08-03T21:40:17.666918985+08:00"
level=i>
Aug 03
21:40:17 localhost.localdomain dockerd[35838]:
time="2020-08-03T21:40:17.697215147+08:00" level=i>
Aug 03
21:40:17 localhost.localdomain dockerd[35838]:
time="2020-08-03T21:40:17.697472227+08:00" level=i>
Aug 03
21:40:17 localhost.localdomain dockerd[35838]:
time="2020-08-03T21:40:17.717429365+08:00" level=i>
Aug 03
21:40:17 localhost.localdomain systemd[1]: Started Docker Application Container
Engine.
xi.检查docker版本
[root@localhost
~]# docker -v
Docker version
19.03.12, build 48a66213fe
参考Docker官方文档：https://docs.docker.com/engine/install/centos/