epel-release-6-8.noarch.rpm包在發行版的介質里面已經自帶了，可以從rpm安裝。

如果出現GPG key retrieval failed: [Errno 14] Could not open/read file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-6問題，請在線安裝epel，下載RPM-GPG-KEY-EPEL-6文件。
這一步執行之后，會在/etc/yum.repos.d/下生成epel.repo、epel-testing.repo兩個文件，用于從Fedora官網下載rpm包。

看到這個最低的內核版本，事實運行起來是沒太大問題的，你也可以升級到3.10.x版本。
另外你也可以運行腳本check-config.sh，來檢查內核模塊符不符合（下面有些missing的，我的docker還是可以正常啟動）：

[root@sean ~]# ./check-config 
warning: /proc/config.gz does not exist, searching other paths for kernel config...
info: reading kernel config from /boot/config-2.6.32-431.el6.x86_64 ...

Generally Necessary:
- cgroup hierarchy: properly mounted [/cgroup]
- CONFIG_NAMESPACES: enabled
- CONFIG_NET_NS: enabled
- CONFIG_PID_NS: enabled
- CONFIG_IPC_NS: enabled
- CONFIG_UTS_NS: enabled
- CONFIG_DEVPTS_MULTIPLE_INSTANCES: enabled
- CONFIG_CGROUPS: enabled
- CONFIG_CGROUP_CPUACCT: enabled
- CONFIG_CGROUP_DEVICE: enabled
- CONFIG_CGROUP_FREEZER: enabled
- CONFIG_CGROUP_SCHED: enabled
- CONFIG_MACVLAN: enabled
- CONFIG_VETH: enabled
- CONFIG_BRIDGE: enabled
- CONFIG_NF_NAT_IPV4: missing
- CONFIG_IP_NF_TARGET_MASQUERADE: enabled
- CONFIG_NETFILTER_XT_MATCH_ADDRTYPE: missing
- CONFIG_NETFILTER_XT_MATCH_CONNTRACK: enabled
- CONFIG_NF_NAT: enabled
- CONFIG_NF_NAT_NEEDED: enabled

Optional Features:
- CONFIG_MEMCG_SWAP: missing
- CONFIG_RESOURCE_COUNTERS: enabled
- CONFIG_CGROUP_PERF: enabled
- Storage Drivers:
  - "aufs":
    - CONFIG_AUFS_FS: missing
    - CONFIG_EXT4_FS_POSIX_ACL: enabled
    - CONFIG_EXT4_FS_SECURITY: enabled
  - "btrfs":
    - CONFIG_BTRFS_FS: enabled
  - "devicemapper":
    - CONFIG_BLK_DEV_DM: enabled
    - CONFIG_DM_THIN_PROVISIONING: enabled
    - CONFIG_EXT4_FS: enabled
    - CONFIG_EXT4_FS_POSIX_ACL: enabled
    - CONFIG_EXT4_FS_SECURITY: enabled

假如你是自己編譯內核，請特別留意幾個絕對不能缺少的：DM_THIN_PROVISIONING、IP_NF_TARGET_MASQUERADE、NF_NAT。（AUFS_FS沒有對應選項，還不清楚怎么回事，但不是必須）

# yum install docker-io
Dependencies Resolved

===========================================================================================
 Package                        Arch               Version          Repository     Size
===========================================================================================
Installing:
 docker-io                      x86_64         1.1.2-1.el6          epel          4.5 M
Installing for dependencies:
 lua-alt-getopt                 noarch         0.7.0-1.el6          epel          6.9 k
 lua-filesystem                 x86_64         1.4.2-1.el6          epel           24 k
 lua-lxc                        x86_64         1.0.6-1.el6          epel           15 k
 lxc                            x86_64         1.0.6-1.el6          epel          120 k
 lxc-libs                       x86_64         1.0.6-1.el6          epel          248 k

Transaction Summary
===========================================================================================
Install       6 Package(s)

許多文檔介紹到這里，下一步為掛載/cgroup文件系統，我的docker版本為1.1.2，沒有修改/etc/fstab的步驟。

在我的一次安裝過程中，很不幸遇到下面的問題：
docker -d啟動，或tail -f /var/log/docker查看日志

[f32e7d9f] +job initserver()
[f32e7d9f.initserver()] Creating server
[f32e7d9f] +job serveapi(unix:///var/run/docker.sock)
2014/10/22 13:02:45 Listening for HTTP on unix (/var/run/docker.sock)
Error running DeviceCreate (createPool) dm_task_run failed
[f32e7d9f] -job initserver() = ERR (1)
2014/10/22 13:02:45 Error running DeviceCreate (createPool) dm_task_run failed

Wed Oct 22 14:35:54 CST 2014

再或者是service docker restart

Stopping docker:                                             [  OK  ]
Starting cgconfig service: Error: cannot mount cpuset to /cgroup/cpuset: Device or resource busy
/sbin/cgconfigparser; error loading /etc/cgconfig.conf: Cgroup mounting failed
Failed to parse /etc/cgconfig.conf                           [FAILED]

Starting docker:                                              [  OK  ]

Unable to enable network bridge NAT: iptables failed: iptables -I POSTROUTING -t nat -s 172.17.42.1/16 ! -d 172.17.42.1/16 -j MASQUERADE: iptables v1.4.7: can"t initialize iptables table `nat": Table does not exist (do you need to insmod?)
Perhaps iptables or your kernel needs to be upgraded.

上面的三個異常都是由于內核模塊的缺失導致的，這也是自己編譯內核來升級帶來的風險，于是就有了sciurus的kernel-ml-aufs的rpm包（見參考的第一個鏈接）。

Installing docker.io on centos 6.4 (64-bit)，在 CentOS 6.4(64位) 安裝 docker.io [中文]

在 CentOS 6.4 上安裝 docker

Official Installing Docker Docs CentOS-6

Troubleshooting:
Error: cannot mount cpuset to /cgroup/cpuset: Device or resource busy
Error running DeviceCreate (createPool) dm_task_run failed

原文鏈接地址：http://seanlook.com/2014/10/26/docker-installed-centos6-successfully/