cc_grub_dpkg: Added UEFI support

[BirknerAlex]

Proposed Commit Message

summary: Fixed cc_grub_dpkg on UEFI systems

On Debian and Ubuntu based systems the cc_grub_dpkg module
handles the needed change of the disk device name / path between
the pre created image and the real hardware system.

Currently it seems only BIOS mode is supported. This adds UEFI support as
well to change the configuration keys for UEFI.

Test Steps

• Unit tests fixed
• Tested on different bare metal UEFI machines
• Tested on a legacy BIOS machine

Checklist:

• My code follows the process laid out in the documentation
• I have updated or added any unit tests accordingly
• I have updated or added any documentation accordingly

[BirknerAlex]

@holmanb Is there any chance to get this inside the upcoming version or too late? This bricks UEFI systems after a new grub-efi-amd64-signed package has been released and apt-get tries to upgrade it.

[BirknerAlex]

Closed for now, found another issue which I need to investigate.

//edit: Should be fine now. 👍🏻

[BirknerAlex]

I just found another issue with NVME disks. While SATA works fine the NVME and UEFI combination seems to fail. Fix is coming.

// edit: I can't reproduce anymore. Will test further but maybe someone can help testing on UEFI too with another hardware type?

Test procedure on Ubuntu:

# Set invalid device, try to reinstall the package, apt-get throws an error, confirm the new disk
echo "set grub-efi/install_devices /dev/notexists1" | debconf-communicate
apt-get update && apt-get reinstall grub-efi-amd64-signed

# Set invalid device again, run cloud-init (with my changes), try reinstall again, no error
echo "set grub-efi/install_devices /dev/notexists1" | debconf-communicate
cloud-init --debug --force single --frequency always --name cc_grub_dpkg
apt-get update && apt-get reinstall grub-efi-amd64-signed

[holmanb]

@holmanb Is there any chance to get this inside the upcoming version or too late?

It is too late, but if something is truly broken we can re-release / SRU.

This bricks UEFI systems after a new grub-efi-amd64-signed package has been released and apt-get tries to upgrade it.

By this do you mean that cloud-init is rendering the hardware unusable? So re-install fails after this occurs?

[BirknerAlex]

@holmanb If it's an EFI machine, the BIOS grub-pc/install_devices keys are definitely wrong here, cloud-init itself does not break the machine configuration (it's already broken before booting the first time). But cloud-init creates unused config entries (which are intended for BIOS mode).

So cc_grub_dpkg should fix the debconf settings but can't since it has no UEFI support and it seems the way how apt-get requires these settings are different between BIOS and UEFI.

But maybe I am completely wrong and I misunderstood the whole thing here, at least with this change the errors disappearing on a fresh install in my case.

Sadly I can't find any documentation on Debian or Ubuntu pages which explains the differences between grub-pc/install_devices and grub-efi/install_devices.

[holmanb]

Thanks for putting this together @BirknerAlex, overall this looks really good.

I reproduced this issue and verified the solution today in a VM with OVMF.

I left a few minor comments inline. Once they're fixed, I'll merge.

[BirknerAlex]

@holmanb Thank you for the review. I am really happy that you were able to reproduce the issue on UEFI.

I did fix all your comments and I'm thankful tor the feedback, let me know if you find anything else.