[Bug 1718966] Re: Cannot install snaps on Ubuntu 14.04 with /var on its own partition
Rafael David Tinoco
rafael.tinoco at canonical.com
Thu Sep 28 21:09:52 UTC 2017
Ok so in systemd-204, in TRUSTY, you will find the following logic to
create the mount units:
- manager_loop
- process-event (WATCH_MOUNT)
- mount_fd_event
- mount_load_proc_self_mountinfo
- mount_add_one (if load_extras == true)
- mount_add_extras
- mount_add_device_links
The last function will add: device/mount/socket/swap/path/requires/...
dependencies in the mount unit to be created. The first one "device" is
handled by "mount_add_device_links" and, according to logic:
if (p->passno > 0 &&
UNIT(m)->manager->running_as == SYSTEMD_SYSTEM) {
char *name;
Unit *fsck;
/* Let's add in the fsck service */
/* aka SPECIAL_FSCK_SERVICE */
name = unit_name_from_path_instance("systemd-fsck", p->what, ".service");
if (!name)
return -ENOMEM;
If filesystem option passno is 0, it won't have the systemd-fsck unit as
a requirement, meaning that no error will be given, allowing the mount
unit, created by snappy, to work.
----
Check it out:
1)
## /etc/fstab
LABEL=LVROOT / ext4 errors=remount-ro 0 1
LABEL=LVVAR /var ext4 defaults 0 1
LABEL=TESTE /teste ext4 defaults 0 1
$ sudo snap install hello-world
error: cannot perform the following tasks:
- Mount snap "core" (2898) ([start snap-core-2898.mount] failed with exit status 6: Failed to issue method call: Unit systemd-fsck at dev-disk-by\x2dlabel-LVVAR.service failed to load: No such file or directory. See system logs and 'systemctl status systemd-fsck at dev-disk-by\x2dlabel-LVVAR.service' for details.
2)
## /etc/fstab
LABEL=LVROOT / ext4 errors=remount-ro 0 1
LABEL=LVVAR /var ext4 defaults 0 0
LABEL=TESTE /teste ext4 defaults 0 0
$ sudo snap install hello-world
hello-world 6.3 from 'canonical' installed
----
Now I'm checking why debian/rules in systemd-204 didn't include
fsck at .service files in the final .deb for "systemd" package. Possibly
this wasn't noticed because at the time systemd was running in Trusty,
it wasn't imagined that mount units would be managed by systemd (like
snappy is doing now). I'll check if adding the units for fsck (plus
having systemd-fsck binary, already there) is enough for the mount logic
to work.
For now, use the workaround above ^.
** Changed in: systemd (Ubuntu Trusty)
Status: Confirmed => In Progress
** Changed in: snapd
Status: Confirmed => In Progress
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https://bugs.launchpad.net/bugs/1718966
Title:
Cannot install snaps on Ubuntu 14.04 with /var on its own partition
Status in snapd:
In Progress
Status in systemd package in Ubuntu:
In Progress
Status in systemd source package in Trusty:
In Progress
Bug description:
Installing snaps is not possible on Ubuntu 14.04 when having /var on
its own partition, whether its LVM or not.
The issue is with the core snap being unable to mount:
The error with /var isolated and using LVM:
root at ubuntu:~# snap install canonical-livepatch
error: cannot perform the following tasks:
- Mount snap "core" (2898) ([start snap-core-2898.mount] failed with exit status 6: Failed to issue method call: Unit systemd-fsck at dev-mapper-vg00\x2dvarvol.service failed to load: No such file or directory. See system logs and 'systemctl status systemd-fsck at dev-mapper-vg00\x2dvarvol.service' for details.
)
The error with /var isolated but without using LVM:
root at ubuntu:~# snap install canonical-livepatch
error: cannot perform the following tasks:
- Mount snap "core" (2898) ([start snap-core-2898.mount] failed with exit status 6: Failed to issue method call: Unit systemd-fsck at dev-disk-by\x2duuid-7383abd2\x2d019c\x2d46c2\x2d8b36\x2d34633cc8f3ca.service failed to load: No such file or directory. See system logs and 'systemctl status systemd-fsck at dev-disk-by\x2duuid-7383abd2\x2d019c\x2d46c2\x2d8b36\x2d34633cc8f3ca.service' for details.
)
The same error happens if I try to install the hello-world snap (with
LVM in this example):
root at ubuntu:~# snap install hello-world
error: cannot perform the following tasks:
- Mount snap "core" (2898) ([start snap-core-2898.mount] failed with exit status 6: Failed to issue method call: Unit systemd-fsck at dev-mapper-vg00\x2dvarvol.service failed to load: No such file or directory. See system logs and 'systemctl status systemd-fsck at dev-mapper-vg00\x2dvarvol.service' for details.
)
I cannot reproduce the issue in Ubuntu 16.04.
I couldn't reproduce this issue by using the Ubuntu 14.04 cloud image
which doesn't isolate /var on its own partition. I tried adding a
secondary disk to that cloud image VM and create a dummy VG and LV,
but couldn't reproduce the issue.
Also could not reproduce using Ubuntu 14.04 (with LVM or not) but with
only a / partition and swap.
Steps to reproduce:
===================
# Install Ubuntu 14.04 in KVM (I used the 14.04.4 server iso) and
configure /, /var and swap on their own partitions (with LVM or not,
the issue happens in both situations).
root at ubuntu:~# lvs
LV VG Attr LSize Pool Origin Data% Move Log Copy% Convert
rootvol vg00 -wi-ao--- 3.72g
swap vg00 -wi-ao--- 3.72g
varvol vg00 -wi-ao--- 3.72g
root at ubuntu:~# df -h
Filesystem Size Used Avail Use% Mounted on
udev 484M 4.0K 484M 1% /dev
tmpfs 100M 988K 99M 1% /run
/dev/dm-0 3.7G 1.7G 1.8G 49% /
none 4.0K 0 4.0K 0% /sys/fs/cgroup
none 5.0M 0 5.0M 0% /run/lock
none 497M 0 497M 0% /run/shm
none 100M 0 100M 0% /run/user
/dev/mapper/vg00-varvol 3.7G 716M 2.8G 21% /var
# Upgrade system, install snapd and reboot
root at ubuntu:~# apt update
root at ubuntu:~# apt upgrade -y
root at ubuntu:~# apt install -y snapd
root at ubuntu:~# reboot
# After reboot, check kernel version and try to install the canonical-livepatch snap:
root at ubuntu:~# uname -a
Linux ubuntu 4.4.0-96-generic #119~14.04.1-Ubuntu SMP Wed Sep 13 08:40:48 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
root at ubuntu:~# snap list
No snaps are installed yet. Try "snap install hello-world".
root at ubuntu:~# snap install canonical-livepatch
error: cannot perform the following tasks:
- Mount snap "core" (2898) ([start snap-core-2898.mount] failed with exit status 6: Failed to issue method call: Unit systemd-fsck at dev-mapper-vg00\x2dvarvol.service failed to load: No such file or directory. See system logs and 'systemctl status systemd-fsck at dev-mapper-vg00\x2dvarvol.service' for details.
)
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