一、前言
最近在一個集羣上安裝 Docker，本來多麼簡單的事卻因爲網絡原因以及系統版本變得曲折了，也由於找到了不適合的解決方案，饒了一個彎，所以特此記錄一下安裝過程，防止重複踩坑。
==系統版本：Centos 7.2.1511==
二、下載與上傳
由於服務器不能連接外網，所以服務器使用的是公司自帶的 yum 倉庫，但是倉庫內沒有 Docker 安裝包，所以需要自己下載。
下載地址：https://yum.dockerproject.org/repo/main/centos/7/Packages/
下載文件：
下載完成後，上傳到服務器等待安裝
三、安裝
依次輸入如下命令：
$ sudo yum -y localinstall docker-engine-selinux-1.13.1-1.el7.centos.noarch.rpm
$ sudo yum -y localinstall docker-engine-1.13.1-1.el7.centos.x86_64.rpm這裏使用yum -y localinstall命令，而不是rpm -ivh，是因爲它會自動從倉庫中下載並安裝相應的依賴包，那麼如果指定的倉庫中有系統對應的版本，安裝就應該是沒問題的，但是我所使用的倉庫中沒有7.2.1511版本的安裝包，在該目錄下有一個readme文件（通過瀏覽器打開），內容如下：
This directory (and version of CentOS) is deprecated. For normal users,
you should use /7/ and not /7.2.1511/ in your path. Please see this FAQ
concerning the CentOS release scheme:
https://wiki.centos.org/FAQ/General
If you know what you are doing, and absolutely want to remain at the 7.2.1511
level, go to http://vault.centos.org/ for packages.
Please keep in mind that 7.2.1511 no longer gets any updates, nor
any security fix's.嗯，大概意思就是讓我使用版本7目錄下的…
==由於對應版本的安裝包不存在時發生的異常見附錄1==
四、修改 yum 獲取的版本
使用如下命令進入修改界面：
sudo vi /etc/yum.repos.d/CentOS-Base.repo原文件如下：
[base]
name=CentOS-$releasever - Base
baseurl=http://s7repo01/centos/7.2.1511/os/$basearch/
gpgcheck=1
gpgkey=http://s7repo01/centos/RPM-GPG-KEY-CentOS-7
#released updates
[updates]
name=CentOS-$releasever - Updates
baseurl=http://s7repo01/centos/7.2.1511/updates/$basearch/
gpgcheck=1
gpgkey=http://s7repo01/centos/RPM-GPG-KEY-CentOS-7
#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
baseurl=http://s7repo01/centos/7.2.1511/extras/$basearch/
gpgcheck=1
gpgkey=http://s7repo01/centos/RPM-GPG-KEY-CentOS-7
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus
baseurl=http://s7repo01/centos/7.2.1511/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://s7repo01/centos/RPM-GPG-KEY-CentOS-7將所有的baseurl屬性修改爲版本7對應的目錄路徑，baseurl屬性修改後如下：
baseurl=http://s7repo01/centos/7/centosplus/$basearch/注：只修改版本號即可，對應的倉庫地址可能與此不同，能訪問則不必修改。
五、繼續安裝
繼續使用如下命令安裝：
$ sudo yum -y localinstall docker-engine-selinux-1.13.1-1.el7.centos.noarch.rpm
$ sudo yum -y localinstall docker-engine-1.13.1-1.el7.centos.x86_64.rpm如果出現某個倉庫不能連接的情況，可使用如下命令禁用掉，例（查看具體的錯誤信息可獲知倉庫名稱，這裏是dockerrepo）：
sudo yum-config-manager --disable dockerrepo重新輸入命令，安裝成功
附錄1：安裝中的問題
Loaded plugins: fastestmirror
Repository cloudera-manager is listed more than once in the configuration
Examining docker-engine-selinux-1.13.1-1.el7.centos.noarch.rpm: docker-engine-selinux-1.13.1-1.el7.centos.noarch
Marking docker-engine-selinux-1.13.1-1.el7.centos.noarch.rpm to be installed
Resolving Dependencies
--> Running transaction check
---> Package docker-engine-selinux.noarch 0:1.13.1-1.el7.centos will be installed
--> Processing Dependency: selinux-policy-base >= 3.13.1-102 for package: docker-engine-selinux-1.13.1-1.el7.centos.noarch
http://s7repo01/centos/7.2.1511/os/x86_64/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found
Trying other mirror.
To address this issue please refer to the below knowledge base article
https://access.redhat.com/articles/1320623
If above article doesn't help to resolve this issue please create a bug on https://bugs.centos.org/
http://s7repo01/centos/7.2.1511/extras/x86_64/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found
Trying other mirror.
http://s7repo01/centos/7.2.1511/updates/x86_64/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found
Trying other mirror.
Loading mirror speeds from cached hostfile
... 省略
Error: Package: docker-engine-selinux-1.13.1-1.el7.centos.noarch (/docker-engine-selinux-1.13.1-1.el7.centos.noarch)
Requires: selinux-policy-base >= 3.13.1-102
Installed: selinux-policy-targeted-3.13.1-60.el7.noarch (@anaconda)
selinux-policy-base = 3.13.1-60.el7
Available: selinux-policy-minimum-3.13.1-60.el7.noarch (base)
selinux-policy-base = 3.13.1-60.el7
Available: selinux-policy-minimum-3.13.1-60.el7_2.3.noarch (updates)
selinux-policy-base = 3.13.1-60.el7_2.3
Available: selinux-policy-minimum-3.13.1-60.el7_2.7.noarch (updates)
selinux-policy-base = 3.13.1-60.el7_2.7
Available: selinux-policy-minimum-3.13.1-60.el7_2.9.noarch (updates)
selinux-policy-base = 3.13.1-60.el7_2.9
Available: selinux-policy-mls-3.13.1-60.el7.noarch (base)
selinux-policy-base = 3.13.1-60.el7
Available: selinux-policy-mls-3.13.1-60.el7_2.3.noarch (updates)
selinux-policy-base = 3.13.1-60.el7_2.3
Available: selinux-policy-mls-3.13.1-60.el7_2.7.noarch (updates)
selinux-policy-base = 3.13.1-60.el7_2.7
Available: selinux-policy-mls-3.13.1-60.el7_2.9.noarch (updates)
selinux-policy-base = 3.13.1-60.el7_2.9
Available: selinux-policy-targeted-3.13.1-60.el7_2.3.noarch (updates)
selinux-policy-base = 3.13.1-60.el7_2.3
Available: selinux-policy-targeted-3.13.1-60.el7_2.7.noarch (updates)
selinux-policy-base = 3.13.1-60.el7_2.7
Available: selinux-policy-targeted-3.13.1-60.el7_2.9.noarch (updates)
selinux-policy-base = 3.13.1-60.el7_2.9
Error: Package: docker-engine-selinux-1.13.1-1.el7.centos.noarch (/docker-engine-selinux-1.13.1-1.el7.centos.noarch)
Requires: selinux-policy-targeted >= 3.13.1-102
Installed: selinux-policy-targeted-3.13.1-60.el7.noarch (@anaconda)
selinux-policy-targeted = 3.13.1-60.el7
Available: selinux-policy-targeted-3.13.1-60.el7_2.3.noarch (updates)
selinux-policy-targeted = 3.13.1-60.el7_2.3
Available: selinux-policy-targeted-3.13.1-60.el7_2.7.noarch (updates)
selinux-policy-targeted = 3.13.1-60.el7_2.7
Available: selinux-policy-targeted-3.13.1-60.el7_2.9.noarch (updates)
selinux-policy-targeted = 3.13.1-60.el7_2.9
You could try using --skip-broken to work around the problem
You could try running: rpm -Va --nofiles --nodigest使用rpm命令安裝，可看見需要的依賴包
sudo rpm -ivh docker-engine-selinux-1.13.1-1.el7.centos.noarch.rpm
warning: docker-engine-selinux-1.13.1-1.el7.centos.noarch.rpm: Header V4 RSA/SHA512 Signature, key ID 2c52609d: NOKEY
error: Failed dependencies:
policycoreutils-python is needed by docker-engine-selinux-1.13.1-1.el7.centos.noarch
selinux-policy-base >= 3.13.1-102 is needed by docker-engine-selinux-1.13.1-1.el7.centos.noarch
selinux-policy-targeted >= 3.13.1-102 is needed by docker-engine-selinux-1.13.1-1.el7.centos.noarch附錄2：參考鏈接
http://www.cnblogs.com/mchina/archive/2013/01/04/2842275.html \
http://www.178linux.com/11404 \
http://www.jianshu.com/p/1fc580b71ea4 \
https://my.oschina.net/hanhanztj/blog/504915