Missing `strings` command results in non-bootable ISOs

[jloeser]

Problem description

I am using a Fedora 40 image in Hetzner Cloud in a pipeline to build ISO live systems in an automated way.

Builds runs through smoothly.

Resulting ISOs didn't boot up correctly because of missing (cd0)/EFI/ubuntu (here for Ubuntu OS) path for GRUB2. Only the default path (cd0)/EFI/BOOT is available. Boot stops at GRUB2 rescue shell.

Root cause is missing strings command on the build host which extracts the path from GRUB2 binary: https://github.com/OSInside/kiwi/blob/98608861e4b612b19f533ad4ac0a38cbb1e16f54/kiwi/bootloader/config/grub2.py#L576

Fedora image might be stripped down by Hetzner, however I would expect at least a warning if a command invocation fails in case of "command not found" errors (or any error) and/or a dependency to strings command - which is in the most cases part of binutils.

According to the logs, there is no issue with missing strings command at all:

...
[ INFO    ]: 07:09:23 | --> Using standard boot template
[ DEBUG   ]: 07:09:23 | EXEC: [bash -c strings /root/image/build/image-root/usr/lib/grub/x86_64-efi-signed/grubx64.efi.signed | grep EFI\/]
[ DEBUG   ]: 07:09:23 | EXEC: [mkdir -p /root/image/live-media.ypc4hwrk/EFI/ubuntu]
[ INFO    ]: 07:09:23 | Copying /root/image/live-media.ypc4hwrk/EFI/BOOT/grub.cfg -> /root/image/live-media.ypc4hwrk/EFI/ubuntu/grub.cfg to be found by EFI
[ INFO    ]: 07:09:23 | Writing KIWI template grub.cfg file
...

Installing binutils fixed the issue for me.

Expected behaviour

Bootable ISO after successful built.

Steps to reproduce the behaviour

• absent strings command on build host
• build a live ISO (dmsquash)
• boot the ISO and end up in GRUB2 rescue shell
• check for existing paths with grub> ls (cd0)/EFI/

OS and Software information

• KIWI version: 10.0.11
• Operating system host version: Fedora Linux 40 (Hetzner Cloud image)
• Operating system target version: Ubuntu 20.04
• Open Build Service version (N/A if not using OBS):
• Koji version (N/A if not using Koji):

[schaefi]

Hi, yes this is a bad one. The strings call is intentionally done with raise_on_error=False which then leads to the default efi boot path EFI/BOOT. However the case when there is not even a strings tool available and the distro requires a vendor path to boot will then also fall into "not so bad" category.

Adding binutils as a requirement on the packaging level is too expensive. I'll add a check for the command such that it will end with a proper error message.