【README】本文参考了 docker官方文档安装指南， Install Docker Engine on CentOS | Docker DocumentationInstructions for installing Docker Engine on CentOShttps://docs.docker.com/engine/install/centos/
【1】安装前的工作
1.需要centos7或8上；
// 查看centos版本
[root@centos204 ~]# uname -r
4.18.0-240.el8.x86_64
[root@centos204 ~]# uname -a
Linux centos204 4.18.0-240.el8.x86_64 #1 SMP Fri Sep 25 19:48:47 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux2. 卸载旧版本的docker，若有的话；
sudo yum remove docker \ docker-client \ docker-client-latest \ docker-common \ docker-latest \ docker-latest-logrotate \ docker-logrotate \ docker-selinux \ docker-engine-selinux \ docker-engine
/var/lib/docker 目录中的内容，包括镜像，容器，卷和网络，是受保护的； 现在 docker引擎包称为 docker-ce；
3.docker安装方式有很多种，官方推荐使用 docker 仓库安装，以便于安装和升级工作；参见
https://docs.docker.com/engine/install/centos/#install-using-the-repository【2】基于docker仓库安装docker
在你第一次安装docker引擎到新机器前，你需要安装docker仓库；此后，你可以从仓库中安装和升级docker；
步骤1，安装docker仓库 ；安装 yum-utils 包，提供了 yum-config-manager工具，使用它安装稳定的docker仓库；
sudo yum install -y yum-utilssudo yum-config-manager \
--add-repo \
https://download.docker.com/linux/centos/docker-ce.repo可选：启用夜间或测试仓库；
这些仓库包含在 上述文件docker.repo中，但默认是禁用的；你可以顺着稳定的版本启用它；
启用命令如下：
?启用夜间仓库
sudo yum-config-manager --enable docker-ce-nightly启用测试仓库?
sudo yum-config-manager --enable docker-ce-test?你也可以使用 disable 禁用他们
sudo yum-config-manager --disable docker-ce-nightly
步骤2，安装docker引擎
安装最新版的docker引擎；或者可以安装特定版本的docker引擎；
sudo yum install docker-ce docker-ce-cli containerd.io安装特定版本的docker；
1.列出docker引擎版本；
yum list docker-ce --showduplicates | sort -r2.安装特定版本
sudo yum install docker-ce-<VERSION_STRING> docker-ce-cli-<VERSION_STRING> containerd.io
步骤3， 启动docker；
sudo systemctl start docker
步骤4，运行以下命令验证docker安装正确
?安装成功了；
补充：docker升级；
要升级 Docker 引擎，请下载更新的包文件并重复安装过程 Install Docker Engine on CentOS | Docker Documentation，使用 yum -y upgrade 而不是 yum -y install，并指向新文件。
【3】验证docker
1）验证版本
[root@centos204 ~]# docker --version
Docker version 20.10.9, build c2ea9bc2）配置docker中国区私有仓库
# 配置中国区私有仓库
vim /etc/docker/daemon.json
{
"registry-mirrors":["https://registry.docker-cn.com"]
}
注意registry-mirrors与[]间 不能有空格3）启动docker
systemctl start docker4）查看docker状态
[root@centos204 docker]# systemctl status docker.service
● docker.service - Docker Application Container Engine
Loaded: loaded (/usr/lib/systemd/system/docker.service; disabled; vendor preset: disabled)
// running 证明运行成功了 bingo
Active: active (running) (thawing) since Thu 2021-10-14 11:00:45 EDT; 20s ago
Docs: https://docs.docker.com
Main PID: 14924 (dockerd)
Tasks: 8
Memory: 60.2M
CGroup: /system.slice/docker.service
└─14924 /usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock
Oct 14 11:00:43 centos204 dockerd[14924]: time="2021-10-14T11:00:43.287011628-04:00" level=info msg="Firewalld: docker zone already exists, returning"
Oct 14 11:00:44 centos204 dockerd[14924]: time="2021-10-14T11:00:44.042473792-04:00" level=info msg="Firewalld: interface docker0 already part of docker zone, returning"
Oct 14 11:00:44 centos204 dockerd[14924]: time="2021-10-14T11:00:44.081104218-04:00" level=info msg="Firewalld: interface docker0 already part of docker zone, returning"
Oct 14 11:00:44 centos204 dockerd[14924]: time="2021-10-14T11:00:44.350028734-04:00" level=info msg="Default bridge (docker0) is assigned with an IP address 172.17.0.0/16. Daemon option --bip can be used>
Oct 14 11:00:44 centos204 dockerd[14924]: time="2021-10-14T11:00:44.517659434-04:00" level=info msg="Firewalld: interface docker0 already part of docker zone, returning"
Oct 14 11:00:44 centos204 dockerd[14924]: time="2021-10-14T11:00:44.647868302-04:00" level=info msg="Loading containers: done."
Oct 14 11:00:45 centos204 dockerd[14924]: time="2021-10-14T11:00:45.016948340-04:00" level=info msg="Docker daemon" commit=79ea9d3 graphdriver(s)=overlay2 version=20.10.9
Oct 14 11:00:45 centos204 dockerd[14924]: time="2021-10-14T11:00:45.017100694-04:00" level=info msg="Daemon has completed initialization"
Oct 14 11:00:45 centos204 systemd[1]: Started Docker Application Container Engine.
Oct 14 11:00:45 centos204 dockerd[14924]: time="2021-10-14T11:00:45.111491314-04:00" level=info msg="API listen on /var/run/docker.sock"5）测试案例：从docker仓库中查询mysql镜像
[root@centos204 docker]# docker search mysql
NAME DESCRIPTION STARS OFFICIAL AUTOMATED
mysql MySQL is a widely used, open-source relation… 11533 [OK]
mariadb MariaDB Server is a high performing open sou… 4381 [OK]
mysql/mysql-server Optimized MySQL Server Docker images. Create… 853 [OK]
centos/mysql-57-centos7 MySQL 5.7 SQL database server 91
mysql/mysql-cluster Experimental MySQL Cluster Docker images. Cr… 88
centurylink/mysql Image containing mysql. Optimized to be link… 59 [OK]
databack/mysql-backup Back up mysql databases to... anywhere! 51
prom/mysqld-exporter 43 [OK]
deitch/mysql-backup REPLACED! Please use http://hub.docker.com/r… 41 [OK]
tutum/mysql Base docker image to run a MySQL database se… 35
linuxserver/mysql A Mysql container, brought to you by LinuxSe… 32
schickling/mysql-backup-s3 Backup MySQL to S3 (supports periodic backup… 31 [OK]
mysql/mysql-router MySQL Router provides transparent routing be… 23
centos/mysql-56-centos7 MySQL 5.6 SQL database server 20
arey/mysql-client Run a MySQL client from a docker container 19 [OK]
fradelg/mysql-cron-backup MySQL/MariaDB database backup using cron tas… 16 [OK]
yloeffler/mysql-backup This image runs mysqldump to backup data usi… 7 [OK]
genschsa/mysql-employees MySQL Employee Sample Database 7 [OK]
openshift/mysql-55-centos7 DEPRECATED: A Centos7 based MySQL v5.5 image… 6
devilbox/mysql Retagged MySQL, MariaDB and PerconaDB offici… 3
idoall/mysql MySQL is a widely used, open-source relation… 3 [OK]
ansibleplaybookbundle/mysql-apb An APB which deploys RHSCL MySQL 2 [OK]
jelastic/mysql An image of the MySQL database server mainta… 2
widdpim/mysql-client Dockerized MySQL Client (5.7) including Curl… 1 [OK]
centos/mysql-80-centos7 MySQL 8.0 SQL database server