Add emulation for i386 in the vm images

[triptec]

Description

When we're cross-compiling on mac m1 computers we're running amd64 docker-images and some of the binaries are i386 binaries which I guess runs just find on actual amd64 processors but won't run on emulated amd64. Our current solution is to run docker run --privileged --rm tonistiigi/binfmt --install 386 which will install i386 emulation in the host vm but we need to re-run that after colima stop; colima start and often it's not realized until pretty far into the build process.

Link to the triaging on slack:
https://cloud-native.slack.com/archives/C05SPLRAS7J/p1703844990323929

[v-chernyshev]

I've stumbled upon the same issue. My workaround for the latest colima version is the provisioning step in the config:

provision:
  - mode: system
    script: QEMU_PRESERVE_ARGV0=1 /usr/bin/binfmt --install 386

Not sure if the env variable is actually required, I've just copied the command from another place in the colima codebase:

colima/core/core.go

Line 31 in 89895bb

if err := guest.Run("sh", "-c", "sudo QEMU_PRESERVE_ARGV0=1 /usr/bin/binfmt --install 386,"+qemuArch.GoArch()); err != nil {

This way I no longer have to remember to add the i386 emulation support after every VM restart.

[abiosoft]

@v-chernyshev what version are you? This should be resolved already.

[v-chernyshev]

I'm on the latest version.

> colima version
colima version 0.8.4
git commit: e2ddc15483af66e9b8a525d779a0cc926f15dbcb

runtime: docker
arch: aarch64
client: v28.3.3
server: v28.3.3

> colima status
INFO[0000] colima is running using macOS Virtualization.Framework
INFO[0000] arch: aarch64
INFO[0000] runtime: docker
INFO[0000] mountType: virtiofs
INFO[0000] docker socket: unix:///Users/vchernyshev/.colima/default/docker.sock
INFO[0000] containerd socket: unix:///Users/vchernyshev/.colima/default/containerd.sock

If I remove the provisioning script that I've mentioned above then i386 binaries don't work any longer. i386 is not present in the supported architectures:

> docker run --privileged --rm tonistiigi/binfmt
{
  "supported": [
    "linux/arm64"
  ],
  "emulators": [
    "python3.12",
    "rosetta"
  ]
}

Any attempt to run such binaries fails with cannot execute binary file: Exec format error.

[v-chernyshev]

For comparison, here's the output with the provisioning script in place:

> docker run --privileged --rm tonistiigi/binfmt
{
  "supported": [
    "linux/arm64",
    "linux/386"
  ],
  "emulators": [
    "python3.12",
    "qemu-i386",
    "rosetta"
  ]
}

[abiosoft]

Oh, I see the issue. It doesn't enable 386 when Rosetta is enabled.
Will fix that soon.

[abiosoft]

You can try with the development version brew install --head colima, it should be resolved now.