Preseeded btrfs installation fails on zesty amd64

[Max Brustkern]

When I run a preseeded virtual machine install using btrfs on a zesty ubuntu-desktop amd64 image, the system never starts the bootloader after the post-install reboot. i386 works fine, and manual selection of btrfs on amd64 seems to work.

[Max Brustkern (nuclearbob)]

Last successful install was 2016-12-08

[Phillip Susi (psusi)]

Please attach /var/log/syslog and /var/log/partman after the install finishes. They are copied to the hard drive under /var/log/installer/ if you have already left the live environment.

[Max Brustkern (nuclearbob)]

When I mount the disk image leftover after the install, I get a single btrfs partition containing the following files:
.
./@
./@/home
./@/swapfile
./@/etc
./@/etc/fstab
./@/media
./@home

[Phillip Susi (psusi)]

It used to be that you would see /@, which is normally mounted in /, and /@home, which is normally mounted in /home, thus the log files would be under /@/var/log/installer. I am not sure where these other directories came from.

[Max Brustkern (nuclearbob)]

Is there a convenient way to access the installer environment on a preseeded install? I recall being able to ctrl-alt-f1, etc. in the past, but I think that's restricted on more recent builds. I can put a delay in the ubiquity success command to give myself the opportunity to get in and grab the installer logs, but I'm not sure how to get in to do so.

[Phillip Susi (psusi)]

As I have been saying, they are copied to the hard drive at the end of the installation process, so you can just get them off of there.

[Max Brustkern (nuclearbob)]

The list I gave before comprised all of the files on the drive. The log files do not appear to be available after the installations I've seen complete. That was after mounting the only partition on the drive as well.

[Phillip Susi (psusi)]

Did you not understand that /@ is a directory, not a file? Look in /@/var/log/installer.

[Max Brustkern (nuclearbob)]

As I previously attempted to convey, that is an exhaustive list of files on the partition. This is the output of ls -lR:
.:
total 0
drwxr-xr-x 1 root root 40 Mar 9 15:57 @
drwxr-xr-x 1 root root 0 Mar 9 15:56 @home

./@:
total 376520
drwxrwxr-x 1 root root 10 Mar 9 15:56 etc
drwxrwxr-x 1 root root 0 Mar 9 15:56 home
drwxrwxr-x 1 root root 0 Mar 9 15:57 media
-rw------- 1 root root 385556480 Mar 9 15:56 swapfile

./@/etc:
total 4
-rw-rw-r-- 1 root root 693 Mar 9 15:57 fstab

./@/home:
total 0

./@/media:
total 0

./@home:
total 0

/@/var is not present.

[Max Brustkern (nuclearbob)]

I ran the test again. This time, I did get a /var directory under @ on the partition, but it's empty. /usr and /lib are populated; I can get a full file list if necessary, but it's very long, unlike the previous install. The preseed in use is here:
http://bazaar.launchpad.net/~ubuntu-test-case-dev/ubuntu-test-cases/desktop/view/head:/preseeds/default_btrfs.cfg
The only difference between that and the preseed here that works:
http://bazaar.launchpad.net/~ubuntu-test-case-dev/ubuntu-test-cases/desktop/view/head:/preseeds/default.cfg
is this line:
d-i partman/default_filesystem string btrfs

[Phillip Susi (psusi)]

It looks like the installation never finished, but you say it appeared to finish, and prompt to restart? Strange...

[Max Brustkern (nuclearbob)]

I'm running these on a fast VM host. Is there any chance that the filesystem doesn't finish syncing before the qemu/kvm/libvirt VM restarts? That could explain the difference in contents between the different installs.

[Max Brustkern (nuclearbob)]

I watched an installation with today's iso (20170321) and it was indicating that it was creating the btrfs filesystem for / when ubiquity stopped and the system rebooted. We're not getting as far as the success_command, so I don't think I can use that to copy logs out. Is there something I can do in an early_command that would work to help get logs out of the installer environment? The automation system we're using (https://code.launchpad.net/utah) uses rsyslog on the system under test after the install completes, I can look into whether it's possible to get it running during the installation. Any other suggestions would be welcome. I can also send the repacked iso or the initrd (with preseed) that we're using to anyone else who might be able to recreate the issue.