CentOS7安装docker 启动不了，在工作当中遇到这个问题，当时急的不清，网上资料又不多，不过经过自己的捣鼓终于解决了
这个问题！
[root@test ~]# yum update[root@test ~]# yum install docker[root@test ~]# service docker startRedirecting to /bin/systemctl start docker.service
Job for docker.service failed because the control process exited with error code. See "systemctl status docker.service" and "journalctl -xe" for details.
[root@test ~]# systemctl status docker.service● docker.service - Docker Application Container Engine
Loaded: loaded (/usr/lib/systemd/system/docker.service; disabled; vendor preset: disabled)
Active: inactive (dead) (Result: exit-code) since 四 2016-03-10 13:01:21 CST; 7s ago
Docs: http://docs.docker.com
Process: 29939 ExecStart=/usr/bin/docker daemon $OPTIONS $DOCKER_STORAGE_OPTIONS $DOCKER_NETWORK_OPTIONS $ADD_REGISTRY $BLOCK_REGISTRY $INSECURE_REGISTRY (code=exited, status=2)
Main PID: 29939 (code=exited, status=2)
CGroup: /system.slice/docker.service
└─29970 mkfs.ext4 -E nodiscard,lazy_itable_init=0,lazy_journal_ini...
3月 10 13:01:20 test.mayocase.com systemd[1]: Failed to start Docker Applic….
3月 10 13:01:20 test.mayocase.com systemd[1]: Unit docker.service entered f….
3月 10 13:01:20 test.mayocase.com systemd[1]: docker.service failed.
3月 10 13:01:21 test.mayocase.com systemd[1]: docker.service holdoff time o….
Hint: Some lines were ellipsized, use -l to show in full.
[root@test ~]#使用yum install docker安装完后启动不了
[root@apptest ~]# service docker start
Redirecting to /bin/systemctl start docker.service一直停留在以上步骤
可以使用以下命令来安装，即可成功。
一个问题让我折腾了两天，试过关闭防火墙，关闭selinux，重装系统，等等网上能查到的方法都解决不了。
如果大家解决了，回复感谢下我吧。
[root@apptest ~]# yum remove docker
[root@apptest ~]# yum remove docker-selinux[root@test yum.repos.d]# vi /etc/yum.repos.d/docker.repo[dockerrepo]name=Docker Repository
baseurl=https://yum.dockerproject.org/repo/main/centos/$releasever/
enabled=1
gpgcheck=1
gpgkey=https://yum.dockerproject.org/gpg[root@test yum.repos.d]# yum install docker-engine已安装:
docker-engine.x86_64 0:1.10.2-1.el7.centos
作为依赖被安装:
docker-engine-selinux.noarch 0:1.10.2-1.el7.centos
