ubuntu docker open RESTAPI

systemctl edit docker.service

Add the following:

[Service]
ExecStart=

ExecStart=/usr/bin/dockerd -H fd:// -H tcp://0.0.0.0:2375

Ctrl+X to exit, save the file content, do not modify the file name, press enter 

ps to | grep dockerd  

The following content appears to indicate success.

root      4029  0.1  1.3 516588 41224 ?        Ssl  12:38   0:02 /usr/bin/dockerd -H fd:// -H tcp://0.0.0.0:2375

Access test:

curl 127.0.0.1:2375/info