UC20 does not auto-import assertions until the third boot

[Alfonso Sanchez-Beato]

I have created a UC20 image with latest snaps in stable. Then, I create a small disk image to hold a system-user assertion:

dd if=/dev/zero of=import.img bs=1024 count=100
mkfs.vfat import.img
mkdir mnt
mount import.img mnt/
cp auto-import.assert mnt/
umount mnt

I run qemu with both UC20 and import images attached as disks:

qemu-system-x86_64 -enable-kvm \
                   -bios /usr/share/OVMF/OVMF_CODE.fd \
                   -m 4096 -net nic \
                   -net user,hostfwd=tcp:127.0.0.1:8022-:22 \
                   -drive if=ide,format=raw,file=uc20.img \
                   -drive if=ide,format=raw,file=import.img

But, I cannot ssh into the device after waiting for a few minutes. If I stop qemu (by hard kill), then re-start it and wait again, I still cannot ssh into the VM. However, the *third time* I start qemu, I can finally ssh in the device with the user and password specified in the system-user assertion. I assume this should have been possible on first boot.

See attached tarball for the assertions.

FTR, if I simulate insertion of import.img using QEMU console 2-3 minutes after the system has started on first boot, the assertion is imported. So this is a race condition.

[Alfonso Sanchez-Beato (alfonsosanchezbeato)]

Looking at first boot log, auto-import is failing:

Nov 12 13:33:38 ubuntu systemd-udevd[575]: sdb: Process '/usr/bin/unshare -m /usr/bin/snap auto-import --mount=/dev/sdb' failed with exit code 127.

Maybe there is a race condition, as snapd starts some time later:

Nov 12 13:33:59 ubuntu systemd[1]: Started Snap Daemon.

[Ian Johnson (anonymouse67)]

I don't think this is a race condition, snap auto-import was recently updated to only consider removable devices, so in order for snap auto-import to recognize your block device as a valid auto-import target, it must have the removable bit set in sysfs, see https://github.com/snapcore/snapd/blob/master/cmd/snap/cmd_auto_import.go#L293

TBH, it seems a bug that it worked for you on the third boot...

What I do to test auto-import of assertions with QEMU is to add the following options:

     -drive "if=none,id=stick,format=raw,file=assertions.disk,cache=none" \
     -device nec-usb-xhci,id=xhci \
     -device usb-storage,bus=xhci.0,removable=true,drive=stick \
     -usb \

where assertions.disk is the disk image that you create with auto-import.assert

[Alfonso Sanchez-Beato (alfonsosanchezbeato)]

@Ian I see, but even if you consider removable devices I have seen a race condition. I start qemu (this is the first UC20 boot after having created an image) with:

-device piix3-usb-uhci

Then I connect to the monitor and run:

drive_add 0 id=usb_disk,if=none,format=raw,file=$import_img
device_add usb-storage,id=usb_disk,drive=usb_disk

If I do it too early (~60 sec) the assertion is not imported. I have to wait around 3 minutes.

[roland wisdom (captaingreen55)]

It’s perfect