[uc20] auto-import service failed

In 66-snapd-autoimport.rules, auto-import been applied to each drive to find auto-import.assertion.

There are two cases will cause the service failed:

1. If the last block device which checked by the service is an invalid file-system, then the service will be marked as failed due to mount failed.

2. If the partitions already been mounted, so it returns error: cannot create user: device already managed.

below is the log from "sudo journalctl -u snapd.autoimport.service"

-- Logs begin at Tue 2020-09-01 07:19:42 UTC, end at Tue 2020-09-01 07:23:31 UTC. --
systemd[1]: Starting Auto import assertions from block devices...
snap[1358]: cmd_auto_import.go:183: imported /run/mnt/ubuntu-boot/auto-import.assert
snap[1358]: cmd_auto_import.go:183: imported /run/mnt/ubuntu-seed/auto-import.assert
snap[1358]: cmd_auto_import.go:183: imported /var/lib/snapd/seed/auto-import.assert
snap[1358]: cmd_auto_import.go:183: imported /writable/system-data/var/lib/snapd/seed/auto-import.assert
snap[1358]: error: cannot create user: device already managed
systemd[1]: snapd.autoimport.service: Main process exited, code=exited, status=1/FAILURE
systemd[1]: snapd.autoimport.service: Failed with result 'exit-code'.
systemd[1]: Failed to start Auto import assertions from block devices.

although MVO already has a fix[1] on case-2 in of #1,
but still in the case-1 of #1 will cause a failed case.

[1] https://github.com/snapcore/snapd/pull/9293

Thanks @Hugh - I will look into fixing the error from an invalid file-system.

@Hugh I looked at the auto-import code and it looks like we do ignore errors from devices with incorrect filesystems. Could you please provide the output of:

    $ sudo journal -u snapd.auto-import

for the scenario (1) that the filesystem is invalid? That should help me understand more about this particular issue.

@Michael,

I can't reproduce this issue anymore, I think it's because the user import has been taken care by cloud-init, which meant the failed caused by unmovable device/partition can't be reproduce in our current environment.

So I will try to create another usb sticker which has several partition and file systems, or maybe a non-mountable one to reproduce it, just not sure this is a valid case or not....

I tried to create a usb sticker which with 7 partitions,
and the format them as different fs type,
still can't reproduce this issue, I think we can close this one.