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lume/src/notes: docker build over ssh
Signed-off-by: Xe Iaso <me@xeiaso.net>
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lume/src/notes/2024/docker-build-over-ssh.mdx
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lume/src/notes/2024/docker-build-over-ssh.mdx
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---
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title: "Docker builds over SSH"
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desc: "Plan 9 clustering at home"
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date: 2024-10-18
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tags:
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- docker
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- ssh
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- devops
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---
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While on stream today, SlyEcho pointed out that you can set `DOCKER_HOST=ssh://...` to have the Docker client seamlessly do builds and the like over SSH instead of using the local computer's Docker daemon. In the process of playing with this, I found the [`docker context`](https://docs.docker.com/engine/manage-resources/contexts/) command. This is cool as hell, it allows you to manage multiple Docker daemons the same way that you would with Kubernetes clusters.
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For example, here's what it looks like by default on Linux:
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```
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$ docker context ls
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NAME DESCRIPTION DOCKER ENDPOINT ERROR
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default * Current DOCKER_HOST based configuration unix:///var/run/docker.sock
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```
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You can add contexts with the `docker context create` command, and also point those contexts to remote hosts over SSH:
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```
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docker context create \
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--docker host=ssh://cadey@pneuma \
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--description "Iustorum autem semita quasi lux splendens procedit et crescit usque ad perfectam diem" \
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pneuma
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```
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Then whenever you need to deal with the remote host for a command:
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```
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docker --context pneuma pull alpine:edge
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```
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You can set it as the default with `docker context use`:
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```
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docker context use pneuma
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```
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And then whenever you're doing something with Docker, it will seamlessly SSH into the machine `pneuma`, do the operation, and then return the result. This works for building and running containers too:
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```
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$ hostname
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shiroko
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$ docker run -it --rm --network host alpine:edge
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# hostname
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pneuma
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```
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This even works for tools like [Earthly](https://earthly.dev):
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```
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$ earthly +all
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(...)
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$ docker images
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REPOSITORY TAG IMAGE ID CREATED SIZE
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ghcr.io/xe/site/bin earthly 828d989bb3b3 2 minutes ago 263MB
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ghcr.io/xe/site/patreon latest 9d3e945e7d6f 2 minutes ago 23.8MB
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```
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This means that even though I've somehow broken the Docker desktop app on my gaming PC that I stream from, I can still use Docker via one of my homelab machines!
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This is cool as hell!