docker 在 ubuntu-server 16.04 上无法启动

Question

系统版本：ubuntu-server 16.04
docker 版本：Docker version 17.03.0-ce, build 60ccb22

尝试执行docker info，报错说没启动：

Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

然后执行service docker start，报错：

Job for docker.service failed because the control process exited with error code. See "systemctl status docker.service" and "journalctl -xe" for details.

执行systemctl status docker.service查看日志显示如下：

● docker.service - Docker Application Container Engine
   Loaded: loaded (/lib/systemd/system/docker.service; enabled; vendor preset: enabled)
   Active: failed (Result: exit-code) since Fri 2017-03-31 09:58:52 CST; 1min 31s ago
     Docs: https://docs.docker.com
  Process: 21336 ExecStart=/usr/bin/dockerd -H fd:// (code=exited, status=1/FAILURE)
 Main PID: 21336 (code=exited, status=1/FAILURE)

Mar 31 09:58:52 ip-101-37-28-246 systemd[1]: Starting Docker Application Container Engine...
Mar 31 09:58:52 ip-101-37-28-246 dockerd[21336]: unable to configure the Docker daemon with file /etc/docker/daemon.json: EOF
Mar 31 09:58:52 ip-101-37-28-246 systemd[1]: docker.service: Main process exited, code=exited, status=1/FAILURE
Mar 31 09:58:52 ip-101-37-28-246 systemd[1]: Failed to start Docker Application Container Engine.
Mar 31 09:58:52 ip-101-37-28-246 systemd[1]: docker.service: Unit entered failed state.
Mar 31 09:58:52 ip-101-37-28-246 systemd[1]: docker.service: Failed with result 'exit-code'.

大概 3 天前用着都是好的，昨天登录上去莫名就用不了了。