记录在实际操作中碰到的docker问题
环境信息：
安装完kolla ocata版本，并且编译成功各openstack 组件的容器镜像
[root@localhost ~]# docker --version
Docker version 17.09.1-ce, build 19e2cf6
[root@localhost ~]# uname -a
Linux localhost.localdomain 3.10.0-514.el7.x86_64 #1 SMP Tue Nov 22 16:42:41 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
[root@localhost ~]#
问题上下文：
执行systemctl restart docker命令，提示如下错误信息
[root@localhost ~]# systemctl start docker
Job for docker.service failed because the control process exited with error code. See "systemctl status docker.service" and "journalctl -xe" for details.
查看journalctl -xe|grep docker信息，报如下错误
Sep 06 23:27:13 localhost.localdomain dockerd[16753]: time="2018-09-06T23:27:13.704150779-04:00" level=info msg="libcontainerd: new containerd process, pid: 16756" Sep 06 23:27:14 localhost.localdomain dockerd[16753]: time="2018-09-06T23:27:14.723917687-04:00" level=info msg="[graphdriver] using prior storage driver: overlay" Sep 06 23:27:14 localhost.localdomain dockerd[16753]: Error starting daemon: layer does not exist Sep 06 23:27:14 localhost.localdomain systemd[1]: docker.service: main process exited, code=exited, status=1/FAILURE -- Subject: Unit docker.service has failed -- Unit docker.service has failed. Sep 06 23:27:14 localhost.localdomain systemd[1]: Unit docker.service entered failed state. Sep 06 23:27:14 localhost.localdomain systemd[1]: docker.service failed. Sep 06 23:27:15 localhost.localdomain systemd[1]: docker.service holdoff time over, scheduling restart.
问题解决方式：
1)卸载Docker安装包
yum remove docker*
2)清空/var/lib/docker/目录的内容(这一步必须做)
rm -rf /var/lib/docker/
3)重新安装docker
yum -y install docker-ce-17.09.1.ce
4)启动docker并查看安装的docker版本
systemctl enable docker
systemctl daemon-reload #这步是必须的，重新加载docker.service文件的配置，否则重启也是启动之前的配置。
systemctl start docker