Use forward in docker-remote.

#!/bin/sh

set -eu

[ -n "$1" ] || { echo "You must specify host." >> /dev/stderr; exit 1; }

host="$1"

localsocket="$HOME/.ssh/docker_$host.sock"

ssh="ssh -fnNTS ~/.ssh/%C.sock"

# Check for exiting forward

if ! $ssh -O check -L "$localsocket:/var/run/docker.sock" "$host" 2> /dev/null

then

    # Delete socket if it exists

    [ ! -S "$localsocket" ] || rm "$localsocket"

    # Open SSH ControlMaster

    $ssh -o ExitOnForwardFailure=no -o ControlMaster=auto -o ControlPersist=0 "$host"

    # Forward socket

    $ssh -O forward -L "$localsocket:/var/run/docker.sock" "$host"

fi

lsof -t "$localsocket" > /dev/null || rm "$localsocket"

forward "$host" "$localsocket:/var/run/docker.sock"

# Echo the DOCKER_HOST export command, for eval'ing.

echo "export DOCKER_HOST=unix://$localsocket"