Enable multiarch container builds

[inknos]

No description provided.

[praiskup]

LGTM, needed for: rpm-software-management/mock#1347

[inknos]

@praiskup one thing that I am not sure about is if the tags for containers are the same archs references that fedora uses. like, is it aarch64 or arm64? 🤔

[praiskup]

Mock uses just podman pull <image_id>, and Podman by default selects the appropriate architecture, if exists in the registry. See this PR for more info. I think we should be fine.

[inknos]

Mock uses just podman pull <image_id>, and Podman by default selects the appropriate architecture, if exists in the registry. See this PR for more info. I think we should be fine.

not sure, I'll reopen the PR against an upstream branch to test the action.
I think the arch should actually be selected by buildah-build and I am not sure about the aliases

       --arch="ARCH"

       Set  the  ARCH  of the image to be built, and that of the base image to be pulled, if the build uses one, to the provided value instead of
       using the architecture of the host. (Examples: arm, arm64, 386, amd64, ppc64le, s390x)

[praiskup]

Yeah, actually, I don't know how the "build time" architecture selection is implemented. I rather meant that we (Mock) - at runtime - can use those images just fine (multiarch metadata/manifests). Hm.

[inknos]

now it should be good to go.

I tested it on aarch64 images on quay.io and it works. Some images will fail if the nightlies are not ready but all the fedora-dnf5 images should be fine

[praiskup]

This installation is emulated though, at least it seems (with the emulated runtime for rpm, but also installation scriptlets, etc.). This could make quite some difference compared to the official Fedora images..?

[inknos]

not sure, this is how it is documented in the buildah docs, see here and most importantly the multi-platform example

The reasons are that first, I believe github does not offer multi arch hosts (need to verify that).
Secondly, this should emulate the architecture of the host only, then the invoked command should be.

Here, the action was run on the test branch.

From what I see in Build Image:29 the command invoked seems right and it specifies the right platform --platform linux/amd64. I tried on my laptop (it's arm) and works.

What difference should it do if we use emulated runtimes? I am not sure if we have other options in GH.

[praiskup]

What difference should it do if we use emulated runtimes?

I don't have anything specific in mind. It's just a bad feeling :-) because it's quite common for Mock builds with forcearch to fail for various reasons.

For example, the entire DNF in the build container is emulated (including RPM) for additional package installation. DNF/RPM interacts with the underlying databases, and these databases are supposed to be utilized by native executors later on.

I don't know; I wouldn't love it if my overexcitement caused issues with our production Copr builders :-) nb, we should have a "natively built" DNF5-based default Fedora 41 image soon.

[inknos]

I don't know; I wouldn't love it if my overexcitement caused issues with our production Copr builders :-) nb, we should have a "natively built" DNF5-based default Fedora 41 image soon.

Agree, I'll dig some more I guess