Honor match directives when installing in a gap using layout.mode: use_gap

[ogayot]

Autoinstall directives allow to specify match directives when using guided use_gap mode:

  storage:
    layout:
      name: direct
      mode: use_gap
      match:
        install-media: true

However, match directives are currently ignored ; unlike when using the reformat_disk mode.
Make sure they are honored.

LP:#2080608

[ogayot]

Testing done using:

storage:
  layout:
    name: direct
    mode: use_gap
    match:
      devpath: "*vdc"

and two empty disks: /dev/vdb (12GiB) and /dev/vdc (8GiB)

• Without the change, the installer picks up /dev/vdb because it is the largest disk, effectively ignoring the match directive.
• With the change, the installer picks up /dev/vdc, honoring the match directive.

The behavior looks correct to me.

On the other hand, I believe, that it will change the behavior when no match directives are specified ; from

• pick the largest gap in the largest disk; to
• pick the largest gap, not necessary in the largest disk

is it acceptable or should we revisit the logic? Revisiting the logic might be a matter of doing:

-            bootable_disks = self.get_bootable_matching_disks(match)
-            gap = gaps.largest_gap(bootable_disks)
+            bootable_disk = self.get_bootable_matching_disk(match)
+            gap = gaps.largest_gap(bootable_disk)

[dbungert]

Looks good but I'd like some test automation to go with. subiquity/server/controllers/tests/test_filesystem.py has some tests that stretch the definition of Unit test but I think are effective at testing this area, and it has some use_gap cases already.

[dbungert]

pick the largest gap, not necessary in the largest disk

That was arguably what I had in mind, so I'd call this a bug fix. Would be worth release noting, to clarify that the use_gap behavior is more intentional and can now be better controlled.

[ogayot]

Looks good but I'd like some test automation to go with. subiquity/server/controllers/tests/test_filesystem.py has some tests that stretch the definition of Unit test but I think are effective at testing this area, and it has some use_gap cases already.

I spent a bit of time doing that. I would like to cover more scenarios but it's a start..

[dbungert]

I see you have more testing in mind, merge when you think it's ready.

[ogayot]

I see you have more testing in mind, merge when you think it's ready.

Thanks! I'm going to hit merge but will revisit this in a follow-up PR.