Local docker cli, remote docker engine

Local docker cli, remote docker engine.md

Local docker cli, remote docker engine

Local ssh config

Host docker2
  HostName admin-docker-2.example.com
  User ubuntu
  IdentitiesOnly yes
  IdentityFile ~/.ssh/example.pem
  KnownHostsCommand /Users/jacob/bin/prune-docker-socket "%k"
  LocalForward /tmp/docker.docker2.sock /var/run/docker.sock

The LocalForward directive creates the local socket file, but doesn't remove it. If the local socket file already exists, then the LocalForward fails. There's no way to run a command when ssh disconnects. Which is why we abuse KnownHostsCommand to run a command before ssh connects.

The prune-docker-socket script is a few lines of shell that constructs the expected socket file path and then deletes the socket file IF it exists and IF it's a socket file. Don't accidentally delete something if any of these expectations are wrong!

#!/bin/sh
[ -z "$1" ] && exit 1
socket="/tmp/docker.$1.sock"
[ -S "$socket" ] && rm "$socket"
printf "%s: %s\n" "🥑" "$@" >&2

Use docker the annoying way

In one shell, connect via ssh:

ssh -nNT docker2

List containers on the remote docker engine:

docker --host unix:///tmp/docker.docker2.sock ps

Use docker the easy way with a docker context

A docker context tells the docker cli what docker engine to connect to. You can have as many as you want!

docker context create docker2 --description 'first run: ssh -nNT docker2' --docker 'host=unix:///tmp/docker.docker2.sock'

Switch contexts:

docker context use docker2

Connect to the remote:

ssh -nNT docker2

Use docker!

❯ docker ps
STATE     NAMES                 PORTS
running   typesense-dashboard   443/tcp, 2019/tcp, 443/udp, 0.0.0.0:3007->80/tcp, :::3007->80/tcp
running   nexus                 0.0.0.0:3002->8081/tcp, :::3002->8081/tcp
running   mail                  1110/tcp, 0.0.0.0:25->1025/tcp, :::25->1025/tcp, 0.0.0.0:3003->8025/tcp, :::3003->8025/tcp
running   uptime-kuma           0.0.0.0:3001->3001/tcp, :::3001->3001/tcp

❯ docker context ls
NAME            DESCRIPTION                               DOCKER ENDPOINT                                 ERROR
default         Current DOCKER_HOST based configuration   unix:///var/run/docker.sock
desktop-linux   Docker Desktop                            unix:///Users/jacob/.docker/run/docker.sock
docker2 *       first run: ssh -nNT docker2               unix:///tmp/docker.docker2.sock
orbstack        OrbStack                                  unix:///Users/jacob/.orbstack/run/docker.sock