Unexpected change in "df /"output

[TravellingGuy]

An unexpected change in the output of "df /" has happened in either coreutils 8.21-1ubuntu5.3 or 8.21-1ubuntu5.2.

After doing updates on a number of servers today, the output of "df /" has changed. It now shows the full device path, including uuid of the device, instead of just the "generic" device.

For example, on an updated server with coreutils 8.21-1ubuntu5.3:
# df /
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/disk/by-uuid/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx 8115168 3542936 4136956 47% /

On a server with coreutils 8.21-1ubuntu5.1:
# df /
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/xvda1 8115168 4260144 3419748 56% /

This makes scripts or other processes (monitoring scripts to report available disk space, for example) that rely on a standard filesystem name across numerous servers break, as each server will have a different disk UUID.

Oddly, attached volumes (non-root volumes) don't exhibit the behaviour, and continue to show the "generic" device:
# df /media/ebs1
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/xvdf 104806400 43260 104763140 1% /media/ebs1

# lsb_release -rd
Description: Ubuntu 14.04.3 LTS
Release: 14.04

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Marc Tamsky (tamsky)]

Probably caused by the thoughtless changes that have been upstreamed in
https://bugs.launchpad.net/ubuntu/+source/coreutils/+bug/1432871

How could the difference between:

vagrant@vagrant-ubuntu-trusty-64:~$ df /
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/disk/by-uuid/3af531bb-7c15-4e60-b23f-4853c47ccc91 41251136 1356000 38159224 4% /

and

vagrant@vagrant-ubuntu-trusty-64:~$ df | grep /$
/dev/sda1 41251136 1356000 38159224 4% /

not be a bug?

[Marc Tamsky (tamsky)]

I'd like to take back my earlier comment.

It all starts in https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=653073

In 14.04.3, the final straw for me is the transition from coreutils 8.21-1ubuntu5.2 to coreutils 8.21-1ubuntu5.3.

In my case, there is an enabling requirement: grub must pass root=UUID=<uuid-string> to the kernel at boot time.

I can restore the "correct" output from `df /` if I first uncomment GRUB_DISABLE_LINUX_UUID=true in `/etc/default/grub`, followed by running `update-grub`, and reboot. This type of change may not work for everyone, as some folks may be relying on UUIDs for consistent volume identification. Ymmv.

It would be nice if `df /` could run `readlink -f` on the filesystem in column one, perhaps as a flag or ENV variable, but that's a separate story.