问题现象描述

重启服务器后，执行restart docker命令报错，报错提示Failed to start Docker Application Container Engine。

原因分析

docker.service的启动配置错误，导致Docker服务启动失败。

解决措施

1. 执行以下命令，打开docker.service文件。

   vi /usr/lib/systemd/system/docker.service

2. 使用以下ExecStart配置，替换原来的ExecStart配置。

   [Unit]
   Description=Docker Application Container Engine
   Documentation=http://docs.docker.com
   After=network.target docker.socket
   [Service]
   Type=notify
   EnvironmentFile=-/run/flannel/docker
   WorkingDirectory=/usr/local/bin
   ExecStart=/usr/bin/dockerd \
   --graph /devcloud/docker\
   -H tcp://0.0.0.0:2375 \
   -H unix:///var/run/docker.sock \
   --selinux-enabled=false \
   --log-opt max-size=1g \
   --iptables=false
   ExecReload=/bin/kill -s HUP $MAINPID
   # Having non-zero Limit*s causes performance problems due to accounting overhead
   # in the kernel. We recommend using cgroups to do container-local accounting.
   LimitNOFILE=infinity
   LimitNPROC=infinity
   LimitCORE=infinity
   # Uncomment TasksMax if your systemd version supports it.
   # Only systemd 226 and above support this version.
   #TasksMax=infinity
   TimeoutStartSec=0
   # set delegate yes so that systemd does not reset the cgroups of docker containers
   Delegate=yes
   # kill only the docker process, not all processes in the cgroup
   KillMode=process
   Restart=on-failure
   [Install]
   WantedBy=multi-user.target

3. 依次执行以下命令，重启Docker服务。

   systemctl daemon-reload
   systemctl restart docker