Example defaults to amd64 architecture

[jmgilman]

Running the example in the README:

> nix run github:nlewo/nix2container#examples.bash.copyToDockerDaemon  
> docker run -it bash:2bq5nc0g665z2ixfv1lzypxki5cqjf42 
WARNING: The requested image's platform (linux/amd64) does not match the detected host platform (linux/arm64/v8) and no specific platform was requested
standard_init_linux.go:228: exec user process caused: exec format error

This is running on a Macbook M1 Pro. I've tried parsing through some of the logic and I'm not familiar enough with the backend to understand why it's defaulting to this architecture. Any ideas?

[nlewo]

Currently, nix2container.buildImage doesn't expose an attribute to specify the architecture.

To support this feature, we would need to do two things:

• expose an attribute in nix2container functions. The architecture would be then written in the produced image JSON file. This should be quite easy to implemented
• use this attribute in the Nix Skopeo transport: i don't know (yet) how to specify it but this should not be a big deal.

Regarding the default architecture value, i think it's Skopeo that decides it (but i don't know how).

I think it would be nice to support different architectures but i only have a x86-linux machine, so i won't be able to test this feature (expecting via the CI but that's time consuming...).

[jmgilman]

This issue shouldn't be closed. I'm still getting the wrong architecture being generated on the M1 platform.

❯ docker run -it bash:2bq5nc0g665z2ixfv1lzypxki5cqjf42 
WARNING: The requested image's platform (linux/amd64) does not match the detected host platform (linux/arm64/v8) and no specific platform was requested
standard_init_linux.go:228: exec user process caused: exec format error

[jmgilman]

I apologize for my oversight, the issue is fixed, I just didn't account for the fact that the image being built was targeting darwin.

[nlewo]

@jmgilman No problem. I always like to see an issue being closed ;)

[hrajchert]

I'm building a docker image from an and Linux machine and a M1 user is having the error that @jmgilman posted. Is there an option to build to both architectures? does this need to be build on a M1 CI?

[jmgilman]

If Nix is running on an M1, it's going to attempt to build the binaries for the native M1 architecture/OS. If you then copy this to the Docker daemon running on an M1, you'll run into a host of exec errors because it's expecting a completely different format (ELF, to be exact). You need to run Nix in an ARM Linux machine to get the correct results.

[blaggacao]

You need to run Nix in an ARM Linux machine to get the correct results.

I'm recognizing some GH handles here and presuming some more context I have, I can also suggest to try std|paisano --for x86_64-linux ... It was precisely made to build a x86_64-linux image more ergonomically on another machine. Due to lack of an M1 in my hands, it hasn't been thoroughly tested, but it was designed to locally (e.g. on a M1) use native toolchain to execute all actions (such as copyToDockerDaemon) while at the same time still building an x86_64-linux image.