Configure remote access for Docker daemon

By default, the Docker daemon listens for connections on a Unix socket to accept requests from local clients. It's possible to allow Docker to accept requests from remote hosts by configuring it to listen on an IP address and port as well as the Unix socket. For more detailed information on this configuration option, refer to the dockerd CLI reference.

Warning

Before configuring Docker to accept connections from remote hosts it's critically important that you understand the security implications of opening Docker to the network. If steps aren't taken to secure the connection, it's possible for remote non-root users to gain root access on the host. For more information on how to use TLS certificates to secure this connection, check Protect the Docker daemon socket.

You can configure Docker to accept remote connections. This can be done using the docker.service systemd unit file for Linux distributions using systemd. Or you can use the daemon.json file, if your distribution doesn't use systemd.

systemd vs daemon.json

Configuring Docker to listen for connections using both the systemd unit file and the daemon.json file causes a conflict that prevents Docker from starting.

Configuring remote access with systemd unit file

  1. Use the command sudo systemctl edit docker.service to open an override file for docker.service in a text editor.

  2. Add or modify the following lines, substituting your own values.

    [Service]
ExecStart=
ExecStart=/usr/bin/dockerd -H fd:// -H tcp://127.0.0.1:2375

  3. Save the file.

  4. Reload the systemctl configuration.

    $ sudo systemctl daemon-reload

  5. Restart Docker.

    $ sudo systemctl restart docker.service

  6. Verify that the change has gone through.

    $ sudo netstat -lntp | grep dockerd
tcp        0      0 127.0.0.1:2375          0.0.0.0:*               LISTEN      3758/dockerd

Configuring remote access with daemon.json

  1. Set the hosts array in the /etc/docker/daemon.json to connect to the Unix socket and an IP address, as follows:

    {
  "hosts": ["unix:///var/run/docker.sock", "tcp://127.0.0.1:2375"]
}

  2. Restart Docker.

  3. Verify that the change has gone through.

    $ sudo netstat -lntp | grep dockerd
tcp        0      0 127.0.0.1:2375          0.0.0.0:*               LISTEN      3758/dockerd