Allow to import tar.zst archives when using ADD operation

[Miguel-Rodrigues]

Hello.

I use buildah to create LXC rootfs images to be used by Proxmox VE.

I don't use Docker or OCI prebuilt images as I had some incompatibilities to containers networking and init systems, so I create images from scratch based on their rootfs template archives.

I created an automation shell script that pulls these archives into Buildah images and tags them appropriately, like it would be importing from Dockerhub. Unfortunately some of the images use ZSTD compression so when using ADD $url / it just downloads the tar.zst archive into root folder instead of extracting into it.

As a workaround I have to create a temporary folder to download, extract, and copy the contents instead of doing all this in a single command.

More a nice to have than a bug I suppose.

Best regards.
Miguel

[Miguel-Rodrigues]

My bad... I did some tests and what is happening is that when downloading directly from an URL it doesn't automatically extract into the container. Regardless of the archive compression or format I allways need to download the archive first and then add it to the container. Could we have instead some sort of flag that would allow to download and extract or allow FROM to pull and extract from rootfs archives?