Docker-mailserver: Publish multi architecture image

[dragoneena12]

Is your feature request related to a problem?

It seems to be published only amd64 image. I want to run docker-mailserver in arm64 environment like raspberrypi4.

Describe the solution you'd like

Add multi-architecture image build workflow.
I think we can use docker buildx.

Alternatives you've considered

Who will that feature be useful to?

Those who want to install docker-mailserver in various architectures.

What have you done already?

What are you going to contribute?

Additional context

[aendeavor]

Literally the second entry on Docker Hiub:

https://hub.docker.com/r/radicand/docker-mailserver

Have you even searched before opening this, or is there something wrong with it?

[dragoneena12]

@aendeavor I didn't know this. Thank you!

[guysoft]

That container upldates slower than tvial/docker-mailserver. Its 3 days behind for some reason.
It seems like its not automatically built like the repo here with a hook.
Its also less secure because they could be pushing anything

[aendeavor]

That container upldates slower than tvial/docker-mailserver. Its 3 days behind for some reason.
It seems like its not automatically built like the repo here with a hook.

You're right @guysoft. This image is not built on a regular basis. There was an issue related to multi-arch builds, #1092. The owner, @radicand is the creator of the ARM version.

Its also less secure because they could be pushing anything

This could be true, but most likely isn't.

---

If you like, you could investigate this issue and provide a PR so we can build other architectures as well.

[casperklein]

btw: Using buildx, building an arm image on an amd64 plattform is no problem: docker buildx build --platform linux/arm64 -t test .

Its also less secure because they could be pushing anything

@guysoft That's also the case for this repo. But you can always verify each commit yourself and then build the image locally.

[radicand]

Chiming in here as the arm64 maintainer - two things to note:

1. The arm64 image I maintain is automatic CI using Github actions - you can validate here: https://github.com/radicand/docker-mailserver/ if there are any questions around build transparency. My image lags because I have not found a way to automatically sync upstream changes without requiring me to pull/push manually. This is a hobby, so I don't do this more than a week at most.
2. I would support a long-term enhancement to move the docker build image to this repo using the same Github action I use to build arm64, which leverages buildx - but this requires upstream (here) to switch from building on Dockerhub to building on Github (using actions). It's a very simple process to adjust, but needs coordination.

[aendeavor]

@radicand Thanks for joining in. This sounds like a reasonable idea.

Please, someone here open a new tracking issue for what @radicand said. I would like to hear other opinions on this too. Moreover, a tracking issue would allow us to _coordinate_ this major change.