Performance over SSH

When you manage remote Docker hosts through SSH contexts (host: ssh://user@host), dockform plan and apply shell out to docker many times to read service state, parse compose configs, list volumes, networks, and sync filesets. Each of those calls opens its own SSH connection, and the TCP/SSH handshake on every call can quickly flood.

A single plan against a few hosts can easily make ~200 docker invocations.

Reuse one connection: SSH multiplexing

The workaround is SSH connection multiplexing (ControlMaster / ControlPersist): the first connection to a host becomes a persistent master, and every later call reuses it instead of a new handshaking.

Add this to your ~/.ssh/config:

Host server-one server-two server-three
    ControlMaster auto
    ControlPath ~/.ssh/sockets/%r@%h-%p
    ControlPersist 2m
    ServerAliveInterval 30

Then create the socket directory once:

mkdir -p ~/.ssh/sockets