[Bug]: can't add new kata kernel in zst format even from local archive

[sitano]

I have done the following

• I have searched the existing issues
• If possible, I've reproduced the issue using the 'main' branch of this project

Steps to reproduce

$ container system kernel set --arch amd64 --binary opt/kata/share/kata-containers/vmlinux-6.12.47-166 --recommended --tar ./kata-static-3.21.0-amd64.tar.zst
Installing the recommended kernel from https://github.com/kata-containers/kata-containers/releases/download/3.21.0/kata-static-3.21.0-amd64.tar.zst...
Error: unknown: "Unable to open the archive. Error code -30"

Current behavior

1. it says can't open archive
2. it downloads the kernel instead of using locally downloaded image

Expected behavior

1. successfully complete the request
2. use local file if it is ./file

Environment

- OS: Darwin sc-mac-02301 24.6.0 Darwin Kernel Version 24.6.0: Mon Aug 11 21:16:30 PDT 2025; root:xnu-11417.140.69.701.11~1/RELEASE_ARM64_T8132 arm64
- Xcode: 
- Container: 
container-apiserver version: container-apiserver version 0.5.0 (build: release, commit: 48230f3)
container-apiserver commit: 48230f380499efecd663fdc6749a2cbaf2f8ed76

Relevant log output

N/A

Code of Conduct

• I agree to follow this project's Code of Conduct

[katiewasnothere]

Hi @sitano! It looks like we don't support the zst archive in containerization. See supported compression types here.

Additionally, you're passing in the flag --recommended which from the help output, takes precedence over all other flags, so the --tar flag would be ignored and we would try to download the default kernel.

[jglogan]

Thanks for adding the issue. I knew I'd seen the request before but it was here: #319.

[visuphi]

Are there any plans to add zst support?

[vsarunas]

Since https://github.com/kata-containers/kata-containers/releases/tag/3.21.0 only zst archives are being published (kata-containers/kata-containers#11707).

Unfortunately macOS ships with a very old bsdtar which is built without zstd support, macOS 26 continues to ship with 3.5.3. Feedback: FB15120366 from September 2024.

[EndCredits]

macOS ships with a very old bsdtar which is built without zstd support

I agree that the version is old, but I guess this version of tar supports zstd decompression. It's possible that Apple Container simply doesn't support it yet, but I think that doesn't necessarily mean it doesn't support the new kernel.

If you just wants to upgrade kata-container kernel. You may able to decompression it manually and set the kernel with system command like this

$ cd ~
$ mkdir -p kata-container && cd kata-container
$ curl -OL https://github.com/kata-containers/kata-containers/releases/download/3.24.0/kata-static-3.24.0-arm64.tar.zst
$ tar -xf kata-static-3.24.0-arm64.tar.zst
$ container system kernel set --binary opt/kata/share/kata-containers/vmlinux-6.12.47-173