Hosts

Hosts lists the Docker engines Docker Manager looks after. One Docker Manager can look after several servers; switch between them at the bottom of the sidebar.

Each host shows how it’s connected (local, SSH, TLS or TCP), whether it’s Connected or Not reachable, its Docker version and operating system, how many containers are running, and its public address if it has one.

The local host

When the Docker socket is mounted into Docker Manager’s container (/var/run/docker.sock, as in the install example), the server it runs on is added automatically on first start.

Add a remote host

1. On Hosts, choose Add host.
2. Give it a Name (optional), like Home server.
3. Under Connect with, choose SSH, TCP with TLS, TCP or This server, and fill in the details below.
4. Choose Connect.

SSH

Docker Manager signs in over SSH and opens a tunnel to the remote Docker socket.

• User: a user in the docker group on the server, like deploy.
• Server and Port (22 by default).
• Private key: an OpenSSH key without a passphrase, whose public key is in that user’s ~/.ssh/authorized_keys. It’s stored encrypted.

The server’s identity is remembered on the first connection and checked every time after.

Note

The server needs AllowTcpForwarding yes in its SSH configuration (/etc/ssh/sshd_config), because the connection to Docker goes through an SSH tunnel.

TCP with TLS

This is Docker’s own way of protecting a remote daemon (tcp://host:2376). Paste the three files you made when you set up TLS on the daemon:

• CA certificate (ca.pem)
• Client certificate (cert.pem)
• Client key (key.pem)

TCP

Plain TCP (tcp://host:2375) works, but Docker’s plain TCP port gives full control of the server to anyone who can reach it, with no password. Only use it on a private network or VPN, or choose SSH or TLS.

Public address

A host’s Public IPv4 and Public IPv6 are the addresses that DNS records for its ingress routes point at. Fill them in when you add or edit a host, or choose Detect: Docker Manager asks a public service from the host, which can take up to 20 seconds. Detection only runs when you choose it.

Edit or remove a host

Administrators can use a host’s menu to Edit its name and public address, or Remove it.

Removing a host only means Docker Manager stops managing it: its containers keep running. Stacks, routes and repositories set up for it stop working in Docker Manager.

Hosts can also be described in the configuration file. Hosts managed that way are marked Config file and can only be changed through the file.