[Unit]
Description=Docker Application Container Engine
Documentation=https://docs.docker.com
After=network.target docker.socket
Requires=docker.socket

[Service]
Type=notify
EnvironmentFile=-/etc/default/docker
# the default is not to use systemd for cgroups because the delegate issues still
# exists and systemd currently does not support the cgroup feature set required
# for containers run by docker
ExecStartPre=/bin/sh -x -c "if [ ! -s /var/lib/docker/repositories-overlay ]; then rm -f /var/lib/docker/repositories-overlay; fi"
ExecStart=/usr/bin/dockerd -s overlay --registry-mirror=https://mirror.gcr.io --host=fd:// $DOCKER_OPTS
ExecReload=/bin/kill -s HUP $MAINPID
ExecStopPost=/bin/echo "docker daemon exited"
LimitNOFILE=1048576
# Having non-zero Limit*s causes performance problems due to accounting overhead
# in the kernel. We recommend using cgroups to do container-local accounting.
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

[Install]
WantedBy=multi-user.target