Is is possible to build amd64 image only on arm platform?

[k0va1]

Hi, I'm using Apple Silicon, and I want to build locally and push only amd64 image because I'm using linux/amd64 as a target server. I've tried different approaches, but I couldn't figure out how to achieve it. I don't feel like using a remote build because my laptop is much more performant than the application server with 1 CPU and 2 GB of RAM. Is there any way to make it work out?

[nickhammond]

I think this might work but I haven't tried it:

builder:
  local:
    arch: amd64 
    multiarch: false

[k0va1]

Thanks for fast reply, but unfortunately no. It still generates build command like this docker buildx build --push --platform linux/amd64,linux/arm64 --builder kamal-blog-multiarch -t ....

[nickhammond]

The other thought I had was you could setup a simple local VM via Vagrant and point the builder to that as a remote using the local IP which you can hardcode in Vagrant.

[bibstha]

I solved this by switching to colima. You can start an amd64 vm with docker using rosetta (should be faster than qemu).
Make sure your docker desktop is not running. colima is a drop in replacement for docker desktop.

brew install colima
colima start --arch amd64 --vm-type=vz --vz-rosetta
colima ssh
uname -a
# Linux colima 6.1.55-0-virt #1-Alpine SMP PREEMPT_DYNAMIC Sun, 24 Sep 2023 23:14:02 +0000 x86_64 Linux

As you can see, the colima VM is a x86_64 Linux machine. kamal uses docker that runs through colima and the default arch is amd64. Here is my config/deploy.yml.

builder:
  multiarch: false

That's all I needed in the builder section.

[buncis]

curious isn't --arch am64 forcing colima to use qemu instead vz, and therefore it can't use rosetta?

[anderssvendal]

Had the same issue and found this thread. Adding the solution that worked for me if others end up here.

builder:
  remote:
    arch: amd64

The "remote" will be a buildx instance running locally on both amd64 and arm64.

[gregjotau]

This seems to work (Thanks Anders!):

The first container is before adding:

builder:
  remote:
    arch: amd64

Seems to save 10 seconds in my case (about 60-70 seconds for second deploy before, now 50-60)

[Talha345]

This works however I had to remove the existing builders from my docker engine to make it work.

[kaka-ruto]

I have tried the suggestions above, most notably the last one

builder:
  remote:
    arch: amd64

But I keep getting this error

Running docker image rm --force ghcr.io/name/name_staging:45eea3075e64ec33e842afb99e600f30810bdbb2 on 135.181.251.34
  INFO [6623a9a4] Finished in 0.316 seconds with exit status 0 (successful).
  INFO [930dea80] Running docker pull ghcr.io/name/name_staging:45eea3075e64ec33e842afb99e600f30810bdbb2 on 135.181.251.34
  Finished all in 23.3 seconds
  ERROR (SSHKit::Command::Failed): Exception while executing on host 135.181.251.34: docker exit status: 1
docker stdout: 45eea3075e64ec33e842afb99e600f30810bdbb2: Pulling from name/name_staging
docker stderr: no matching manifest for linux/amd64 in the manifest list entries

Anyone have an idea how to fix?