Add kola tests for unique bootfs work

[jlebon]

We've added new services in coreos/fedora-coreos-config#1269 and coreos/fedora-coreos-config#1540 which verify that there is only one boot filesystem. We currently don't have CI that exercises them.

Add tests for these. I see at least one for each:

1. we attach a block device which has a pre-existing boot filesystem on it, and verify that coreos-unique-boot.service fails as expected.
2. we boot with an Ignition config which creates a second boot filesystem and verify that coreos-ignition-unique-boot.service fails as expected.

We have at least one test already which verifies Ignition failure in the initrd (see qemufailure.go). Using that code as a base for the new tests would be a good starting point.

[jlebon]

For 1., note that you can make a dummy e.g. ext4 filesystem ahead of time using e.g.:

$ truncate -s 1G fakeboot
$ mkfs.ext4 -L boot fakeboot

(But called from golang.)

For 2., it'd be interesting to enhance the external test harness to handle expected initrd failures. E.g. we could have a new directive like initrd-failure: "Error: System has 2 devices with a filesystem labeled 'boot'" that tells kola to verify that the initrd did fail and that the journal has that error string and if so, mark the test as passed.

That would also allow us to convert coreos.ignition.failure to an external test.

[c4rt0]

Thanks, this clarifies some of my questions indeed!

[c4rt0]

The above isn't functional, I uploaded it just to set a starting point and discuss my concerns.
1.

verify that coreos-unique-boot.service fails

Is it enough for me to create an additional fakeboot partition? I saw the module-setup.sh just not sure if I understand it correctly?

[c4rt0]

cc @jlebon

[c4rt0]

Fixed by: #3647