Set default architecture (without passing --platform)?

[flouthoc]

Discussed in #25623

^{Originally posted by jeliker1 March 18, 2025}
I have been happily using podman to create fnproject.io deployments until this week. The issue is that the build is for arm64 (which is my local machine Mac M4) though previously I was building amd64 without doing anything special.

Frankly can't tell what changed except possibly a version upgrade for podman. Is all very perplexing as I don't find any reference to this behavior changing (even if it is version related).

Any recommendations how to set a default build architecture such as you would set with --platform since the fn executable doesn't support passing through parameters like that. It can pass build-args but I've not found anything that will set the build target architecture. Thank you for any advice.

Jon-Eric

[sebastian-philipp]

If I'm not mistaken, the only way to force kind to use a linux/amd64 container is to create the cluster via DOCKER_DEFAULT_PLATFORM=linux/arm64 kind create cluster, as there is no CLI option or [config option](https://github.com/kubernetes-sigs/kind/blob/1e95d05eeccdf615e24d7af11276e2954fe265a2/pkg/apis/config/v1alpha4/types.go)

Edit

Turns out this is not going to work for kind: I managed to circumvent this by using:

$ cat ./golang-go-issues-43724/podman
#!/usr/bin/env python3
import sys
from subprocess import run

e = "/opt/homebrew/bin/podman"
argv = [e] + sys.argv[1:]

if argv[1] in ["create", "pull", "run"]:
  argv = argv[:2] + ["--arch=amd64"] + argv[2:]

with open("/tmp/podman-arch", "a") as f:
    f.write(f"{' '.join(argv)}\n")

out = run(argv)
sys.exit(out.returncode)
$ export PATH=$(pwd)/golang-go-issues-43724:$PATH

BUT, this fails later for me with:

$ journalctl -xeu kubelet | tail -n something
Apr 08 09:27:53 kind-control-plane kubelet[651]: E0408 09:27:53.024450     651 run.go:72] "command failed" err="failed to run Kubelet: could not detect clock speed from output: \"processor	: 0
BogoMIPS	: 48.00
Features	: fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm jscvt fcma lrcpc dcpop sha3 asimddp sha512 asimdfhm dit uscat ilrcpc flagm sb paca pacg dcpodp flagm2 frint afp
CPU implementer	: 0x61
CPU architecture: 8
CPU variant	: 0x0
CPU part	: 0x000
CPU revision	: 0

Which is probably related to qemu user emulation not being enough for kubelet. Bummer.

[pyxelr]

Adding another use case where this feature is critical: VS Code Dev Containers on Apple Silicon.

Currently, when using an upstream base image that is linux/amd64 only (no multi-arch manifest), VS Code fails immediately during the image resolution phase. This happens because the extension defaults to the host architecture (arm64) to inspect the manifest, and there is no way to globally tell Podman to default to linux/amd64 for all operations (pull, build, run, inspect).

Unlike Docker, which respects DOCKER_DEFAULT_PLATFORM, the lack of an equivalent environment variable or containers.conf setting in Podman forces us to rely on manual pre-pull steps or brittle configuration hacks.

I have documented the specific failure mode and the required workaround for VS Code users in this Stack Overflow question: https://stackoverflow.com/questions/79822859/how-to-enforce-linux-amd64-platform-architecture-in-visual-studio-code-dev-con

Native support for a default platform would solve this integration gap immediately.

[TrevorBurnham]

I've submitted an upstream PR (containers/container-libs#669) to add support for setting the platform in containers.conf:

[engine]
platform = "linux/amd64"

Once that's merged, I can submit a PR for Podman to support DOCKER_DEFAULT_PLATFORM, which I think would be very good for Docker compatibility.