UX: changing GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub has no effect in cloud images

[Robie Basak]

I need to modify the kernel command line, such as to work around bug 1573095. I edit GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub and rerun update-grub but this has no effect.

The reason is that this is redefined in /etc/default/grub.d/50-cloudimg-settings.cfg and that one overrides /etc/default/grub. I was misled by the comment in /etc/default/grub and information widely available on the Internet that editing /etc/default/grub is sufficient, and looked no further.

I understand the reason for not modifying /etc/default/grub in cloud image builds (to avoid future conffile prompts) and I'm not suggesting that it should be modified. To fix this UX issue properly I think the grub package needs to provide a mechanism that allows cloud image builds to override the default without dropping in an overriding file (or for that override file to be the sole place that users need to look).

This affects grub2 2.02-2ubuntu8.9 from Bionic cloud image build 20190114 for example.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.