Internal. Old instructions used long time ago: Step 1: Generate SSL certificates

On a server with running Docker service, generate SSL certificates using instructions from the Docker documentation.

Important: Use correct and resolvable server hostname and IP addresses when creating certificates.

Save certificate files in /etc/docker/ directory.

Step 2: Configure Docker service to listen on a TCP port

Note: This step depends on your OS

Debian/Ubuntu

1. Execute the following command: 

   # systemctl edit docker.service

   This will create the necessary directory structure under /etc/systemd/system/docker.service.d and open an editor (using the default editor configured for the user) to the override file. Add the section below into the editor:

   [Service]
   ExecStart=
   ExecStart=/usr/bin/dockerd --tlsverify --tlscacert=/etc/docker/ca.pem --tlscert=/etc/docker/server-cert.pem --tlskey=/etc/docker/server-key.pem -H=tcp://0.0.0.0:4243 -H=fd://

   Note: Change TCP port from 4243 to the desired value. The port should not be blocked by a server firewall.

2. Reload systemd and restart Docker service:

   # systemctl daemon-reload

   # systemctl restart docker.service

CentOS/RHEL

1. Create file /lib/systemd/system/docker.socket and put the following configuration inside:

   [Unit]
   Description=Docker Socket for the API
   PartOf=docker.service
   [Socket]
   ListenStream=/var/run/docker.sock
   SocketMode=0660
   SocketUser=root
   SocketGroup=docker
   [Install]
   WantedBy=sockets.target

   Creating socket is necessary only if you plan to manage the Docker service on the server using docker command.

2. Execute the following command: 

   # systemctl edit docker.service

   This will create the necessary directory structure under /etc/systemd/system/docker.service.d and open an editor (using the default editor configured for the user) to the override file. Add the section below into the editor:

   [Service]
   ExecStart=
   ExecStart=/usr/bin/dockerd --tlsverify --tlscacert=/etc/docker/ca.pem --tlscert=/etc/docker/server-cert.pem --tlskey=/etc/docker/server-key.pem -H=tcp://0.0.0.0:4243 -H=fd://

   Note: Change TCP port from 4243 to the desired value. The port should not be blocked by a server firewall.

   Note: If you have not enabled socket, remove -H=fd:// from the parameters.

3. Reload systemd, enable and start the socket, and restart Docker service:

   # systemctl daemon-reload

   # systemctl enable docker.socket

   # systemctl start docker.socket

   # systemctl restart docker.service

Step 3: Connect remote Docker service to Plesk Onyx

1. Download files ca.pem, cert.pem, and key.pem from /etc/docker/ directory.

   On a Plesk Onyx server, install Docker Manager extension from…