I use an integration server that runs x86 and that does the build. But you could also buy a $4 x86 VM, rsync your project tree to it, and do a “mix release” - I also do that sometimes.

Building on an other server, gitlab or GitHub are definitely options, but what they’re probably doing is building on docker. That’s what I would suggest. Docker seems like a good option.

A $4 VM would increase my monthly costs by 20%. I guess I’ll look into doing it in GitLab CI. Thanks!

I thought Docker is just a virtualization environment, and thus I couldn’t run amd64 containers on ARM unless I went through something like QEMU which would be deadly slow, right?

I think it use QEMU in the back yes, if it’s dealy slow I have no idea. I think that’s something you need to test for yourself.
Anyway if it’s just for building the release, I can’t imagine that even a 2-5x times slowdown is a deal breaker?

We use Hetzner too. With their CLI tool, you can deploy a new VM, install OTP, rsync your program, release, download, shutdown and you’d incur in 15 minutes of usage total… so just a few € cents.

Check out https://getutm.app (which builds on qemu) for running OSs with different architectures on Silicon. But really the easiest is using CI for that, especially if building x86 which those services tend to run on (I use CI for x86 builds but actually also build releases on my Mac to deploy to ARM servers since that takes minutes instead of 1+ hour on CI which uses qemu for it, tbf a lot of the slowness may be due to Rust NIFs rather than the elixir build though)…

From the tags of this post, I guess you are using Apple M1.

I’m using Apple M1, too. And I has the same requirement of deploying to x86_64 machines.

My solution:

1. use GitHub - utmapp/UTM: Virtual machines for iOS and macOS · GitHub
2. create an x86_64 emulator. (not a virtualizor)

One con:
Because it’s an emulator, the building process is very slow. Before building, prepare some drinks and drink slowly.

EDIT: After I wrote this, I found @mayel had already wrote something about it.

Use docker multi arch containers. Setup amd64 and build app inside it

@c4710n I’m curious how slow? I’ve seen how slow emulating ARM on x86 is (using github actions specifically) but haven’t actually tested building a release for x86 emulated on ARM.

In my case, I’m using:

1. an x86_64 linux emulator
2. a docker service running on above emulator

When building x86_64 docker image, I use above docker service.

On my MBP 2015, the build can be done in 4 min. But in the emulator on MBP 2021, the building process can slow 4 times, I think. (I didn’t measure it precisely. All I know is that my tea will be cold after the build. )