//https://docs.docker.com/install/linux/docker-ce/centos/

To get started with Docker CE on CentOS, make sure you meet the prerequisites, then install Docker.

// meet vt. 滿足；遇見；對付 prerequisite n.先決條件

Prerequisites

OS requirements

To install Docker CE, you need a maintained version of CentOS 7. Archived versions aren’t supported or tested.

The centos-extras repository must be enabled. This repository is enabled by default, but if you have disabled it, you need to re-enable it.

The overlay2 storage driver is recommended.

Uninstall old versions

Older versions of Docker were called docker or docker-engine. If these are installed, uninstall them, along with associated dependencies.

$ 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

It’s OK if yum reports that none of these packages are installed. //如果yum 報告這些包都沒有安裝，那也沒關系

The contents of /var/lib/docker/, including images, containers, volumes, and networks, are preserved. The Docker CE package is now called docker-ce.

//preserved [pr?‘z??vd] adj. 保藏的；

Install Docker CE

You can install Docker CE in different ways, depending on your needs:

• Most users set up Docker’s repositories and install from them, for ease of installation and upgrade tasks. This is the recommended approach.

• Some users download the RPM package and install it manually and manage upgrades completely manually. This is useful in situations such as installing Docker on air-gapped systems with no access to the internet. //氣隙系統（Air-gapped）是一種將電腦進行完全隔離（不與互聯網以及任何其他聯網設備連接）以保護數據安全的系統

• In testing and development environments, some users choose to use automated convenience scripts to install Docker.

Get Docker CE for CentOS