Since Fedora 30 grub2 has support to populate its menu entries from the
BootLoaderSpec fragments in /boot/loader/entries, so there's no need to
generate menu entries anymore using the /etc/grub.d/15_ostree script.
But since ostree doesn't update the bootloader, it may be that the grub2
installed is an old one that doesn't have BLS support.
For new installs, GRUB_ENABLE_BLSCFG=true is set in /etc/default/grub to
tell the /etc/grub.d/10_linux script if a blscfg command has to be added
to the generated grub2 config file.
So check if BLS is enabled in /etc/default/grub and only add the entries
if that's not the case. Otherwise the menu entries will be duplicated.
The approach has the drawback that if a user sets GRUB_ENABLE_BLSCFG=true
in /etc/default/grub without updating grub2, they will get an empty menu.
Since there won't be any entries created by the 30_ostree script and the
blscfg command won't work on the older grub2.
Unfortunately there is no way to know if the installed grub2 already has
BLS support or not.
Related: https://bugzilla.redhat.com/show_bug.cgi?id=1751272#c27Closes: #1929
Approved by: jlebon
Apparently there testing systems that literally install *all*
packages. Having `ostree-grub2` currently causes grub2 to fail
on a non-ostree managed system. Let's just gracefully exit
if there's no system repository.
https://bugzilla.redhat.com/show_bug.cgi?id=1532668Closes: #1399
Approved by: jlebon
ostree-grub-generator can be used to customize
the generated grub.cfg file. Compile time
decision ostree-grub-generator vs grub2-mkconfig
can be overwritten with the OSTREE_GRUB2_EXEC
envvar - useful for auto tests and OS installers.
Why this alternative approach:
1) The current approach is less flexible than using a
custom 'ostree-grub-generator' script. Each system can
adjust this script for its needs, instead of using the
hardcoded values from ostree-bootloader-grub2.c.
2) Too much overhead on embedded to generate grub.cfg
via /etc/grub.d/ configuration files. It is still
possible to do so, even with this patch applied.
No need to install grub2 package on a target device.
3) The grub2-mkconfig code path has other issues:
https://bugzilla.gnome.org/show_bug.cgi?id=761180
Task: https://bugzilla.gnome.org/show_bug.cgi?id=762220Closes: #228
Approved by: cgwalters
Javier Martinez Canillas
Colin Walters
Gatis Paeglis