一、问题描述

https://download.docker.com/linux/centos/7/x86_64/stable/Packages/docker-ce-18.09.9.ce-3.el7.x86_64.rpm: [Errno 12] Timeout on https://download.docker.com/linux/centos/7/x86_64/stable/Packages/docker-ce-18.09.9.ce-3.el7.x86_64.rpm: (28, Operation too slow. Less than 1000 bytes/sec transferred the last 30 seconds)
Trying other mirror.
docker-ce-18.09.9.ce-3.el7.x86 FAILED                                          
https://download.docker.com/linux/centos/7/x86_64/stable/Packages/docker-ce-18.09.9.ce-3.el7.x86_64.rpm: [Errno 12] Timeout on https://download.docker.com/linux/centos/7/x86_64/stable/Packages/docker-ce-18.09.9.ce-3.el7.x86_64.rpm: (28, Operation too slow. Less than 1000 bytes/sec transferred the last 30 seconds)
Trying other mirror.
docker-ce-18.09.9.ce-3.el7.x86 FAILED                                          
https://download.docker.com/linux/centos/7/x86_64/stable/Packages/docker-ce-18.09.9.ce-3.el7.x86_64.rpm: [Errno 14] curl#6 - "Could not resolve host: download.docker.com; Unknown error"
Trying other mirror.

问题原因：这是由于国内访问不到docker官方镜像。

二、解决方案

解决方案：使用阿里云镜像源。

方法一：

sudo yum-config-manager --add-repo http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo

方法二：

vim /etc/yum.repos.d/docker-ce.repo

[docker-ce-stable]
name=Docker CE Stable - $basearch
baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/$releasever/$basearch/stable
enabled=1
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg

[docker-ce-stable-debuginfo]
name=Docker CE Stable - Debuginfo $basearch
baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/$releasever/debug-$basearch/stable
enabled=0
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg

[docker-ce-stable-source]
name=Docker CE Stable - Sources
baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/$releasever/source/stable
enabled=0
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg

[docker-ce-test]
name=Docker CE Test - $basearch
baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/$releasever/$basearch/test
enabled=0
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg

[docker-ce-test-debuginfo]
name=Docker CE Test - Debuginfo $basearch
baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/$releasever/debug-$basearch/test
enabled=0
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg

[docker-ce-test-source]
name=Docker CE Test - Sources
baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/$releasever/source/test
enabled=0
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg

[docker-ce-nightly]
name=Docker CE Nightly - $basearch
baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/$releasever/$basearch/nightly
enabled=0
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg

[docker-ce-nightly-debuginfo]
name=Docker CE Nightly - Debuginfo $basearch
baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/$releasever/debug-$basearch/nightly
enabled=0
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg

[docker-ce-nightly-source]
name=Docker CE Nightly - Sources
baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/$releasever/source/nightly
enabled=0
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg

更多详细内容请参考：