docker安装前检查你对应centos版本，一般要高与3.8版本才支持
root@bogon ~]# uname -a
Linux bogon 3.10.0-693.21.1.el7.x86_64 #1 SMP Wed Mar 7 19:03:37 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
在安装docker时出现如下错误信息，
[root@bogon ~]# yum -y install docker
Loaded plugins: fastestmirror, langpacks
Existing lock /var/run/yum.pid: another copy is running as pid 2310.
Another app is currently holding the yum lock; waiting for it to exit...
The other application is: PackageKit
Memory : 292 M RSS (1.6 GB VSZ)
Started: Tue May 22 16:37:43 2018 - 02:11 ago
State : Sleeping, pid: 2310
排查问题方式
已经有一个yum进程在运行了，使用kill干掉它：
[root@bogon ~]# kill -s -9 2310 -----------------发现kill 无法起效果
bash: kill: -9: invalid signal specification
暴力方式，可以通过强制关掉yum进程
[root@bogon ~]# rm -f /var/run/yum.pid
然后重新运行命令安装，
[root@bogon ~]# yum -y install docker
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
- base: mirrors.163.com
- epel: mirrors.tongji.edu.cn
- extras: mirrors.aliyun.com
- updates: mirrors.163.com
Resolving Dependencies
--> Running transaction check
---> Package docker.x86_64 2:1.13.1-53.git774336d.el7.centos will be updated
---> Package docker.x86_64 2:1.13.1-63.git94f4240.el7.centos will be an update
--> Processing Dependency: docker-common = 2:1.13.1-63.git94f4240.el7.centos for package: 2:docker-1.13.1-63.git94f4240.el7.centos.x86_64
--> Processing Dependency: docker-client = 2:1.13.1-63.git94f4240.el7.centos for package: 2:docker-1.13.1-63.git94f4240.el7.centos.x86_64
--> Running transaction check
---> Package docker-client.x86_64 2:1.13.1-53.git774336d.el7.centos will be updated
---> Package docker-client.x86_64 2:1.13.1-63.git94f4240.el7.centos will be an update
---> Package docker-common.x86_64 2:1.13.1-53.git774336d.el7.centos will be updated
---> Package docker-common.x86_64 2:1.13.1-63.git94f4240.el7.centos will be an update
--> Processing Dependency: container-storage-setup >= 0.9.0-1 for package: 2:docker-common-1.13.1-63.git94f4240.el7.centos.x86_64