Enable remote API for dockerd
Overview
The best way to include the required startup options without editing the systemd unit file in place is to use a systemd drop-in file.
Resolution
After completing these steps, you will have enabled the remote API for dockerd, without editing the systemd unit file in place:
Create a file at /etc/systemd/system/docker.service.d/startup_options.conf with the below contents:
# /etc/systemd/system/docker.service.d/override.conf
[Service]
ExecStart=
ExecStart=/usr/bin/dockerd -H fd:// -H tcp://0.0.0.0:2376
Note: The -H flag binds dockerd to a listening socket, either a Unix socket or a TCP port. You can specify multiple -H flags to bind to multiple sockets/ports. The default -H fd:// uses systemd’s socket activation feature to refer to /lib/systemd/system/docker.socket.
Reload the unit files
sudo systemctl daemon-reload
Restart the docker daemon with new startup options:
sudo systemctl restart docker.service
Ensure that anyone that has access to the TCP listening socket is a trusted user since access to the docker daemon is root-equivalent.
https://docs.docker.com/engine/security/