systemd commands

Add docker.service and docker.socket files in /usr/lib/system/systemd directory.

# cd /usr/lib/systemd/system
# ls -l docker.*
-rw-r--r--. 1 root root 203 Jan 16 18:12 docker.service
-rw-r--r--. 1 root root 198 Jan 16 18:26 docker.socket

# systemctl daemon-reload
# systemctl enable docker 
# systemctl start docker 

How to use the latest current version of Docker Containers

# cat /usr/lib/systemd/system/mydocker.service
[Unit]
Description=Hemant's Docker daemon
Requires=mydocker.socket
After=network.target

[Service]
Type=simple
WorkingDirectory=/tmp
ExecStart=/usr/local/sbin/dockerd  --config-file=/etc/docker/mydocker.json

[Install]
WantedBy=multi-user.target

$ cat /usr/lib/systemd/system/mydocker.socket 
[Unit]
Description=Docker Socket for the API
PartOf=docker.service

[Socket]
ListenStream=/var/run/docker.sock
SocketMode=0660
SocketUser=root
#SocketGroup=docker ( use this group if required )

[Install]
WantedBy=sockets.target