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Show HN: Unregistry – “docker push” directly to servers without a registry

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726 points psviderski | 2 comments | 18 Jun 25 23:17 UTC | HN request time: 0.508s | source

I got tired of the push-to-registry/pull-from-registry dance every time I needed to deploy a Docker image.

In certain cases, using a full-fledged external (or even local) registry is annoying overhead. And if you think about it, there's already a form of registry present on any of your Docker-enabled hosts — the Docker's own image storage.

So I built Unregistry [1] that exposes Docker's (containerd) image storage through a standard registry API. It adds a `docker pussh` command that pushes images directly to remote Docker daemons over SSH. It transfers only the missing layers, making it fast and efficient.

  docker pussh myapp:latest user@server
Under the hood, it starts a temporary unregistry container on the remote host, pushes to it through an SSH tunnel, and cleans up when done.

I've built it as a byproduct while working on Uncloud [2], a tool for deploying containers across a network of Docker hosts, and figured it'd be useful as a standalone project.

Would love to hear your thoughts and use cases!

[1]: https://github.com/psviderski/unregistry

[2]: https://github.com/psviderski/uncloud

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richardc323 ◴[19 Jun 25 20:10 UTC] No.44322119[source]▶
I naively sent the Docker developers a PR[1] to add this functionality into mainline Docker back in 2015. I was rapidly redirected into helping out in other areas - not having to use a registry undermined their business model too much I guess.

[1]: https://github.com/richardcrichardc/docker2docker

replies(1): >>44324775 #
1. psviderski ◴[20 Jun 25 04:32 UTC] No.44324775[source]▶
You're the OG! Hats off, mate.

It's a bummer docker still doesn't have an API to explore image layers. I guess their plans to eventually transition to containerd image store as the default. Once we have containerd image store both locally and remotely we will finally be able to do what you've done without the registry wrapper.

replies(1): >>44326453 #
2. cik ◴[20 Jun 25 10:41 UTC] No.44326453[source]▶
You're bang on, but you can do things with dive (https://github.com/wagoodman/dive) and use chunks of the code in other projects... That's what I've been doing. The license is MIT so it's permissive.

But yes, an API would be ideal. I've wasted far too much time on this.