CentOS - Dec 2018 - Can't configure GDM after update to CentOS 7.6

Hi,

It looks like the upgrade to CentOS 7.6 has been unusually disruptive
with the GNOME desktop version bump and a series of moving targets under
the hood. The result is some wreckage at my client's desktop
installations, which I've been busy to repair since yesterday. First
things first.

I have a custom configuration of GDM, which consists mainly of two things.

  1. Display my company's logo instead of the CentOS logo.

  2. Disable the user list (since I have about 100 users here).

Until CentOS 7.5, here's what I did.

  1. Create a file /etc/dconf/profile/gdm :

  user-db:user
  system-db:gdm
  file-db:/usr/share/gdm/greeter-dconf-defaults

  2. Create a file /etc/dconf/db/gdm.d/01-logo :

  [org/gnome/login-screen]
  logo='/usr/share/pixmaps/microlinux-logo.png'

  3. Create a file /etc/dconf/db/gdm.d/00-login-screen :

  [org/gnome/login-screen]
  disable-user-list=true

  4. Update dconf :

  # dconf update

Now with CentOS 7.6 this doesn't work anymore. The /etc/dconf/db/gdm.d
directory is nowhere to be found, and I'm currently mildly cursing the
GNOME developers' (and Red Hat's) policy of releasing moving targets.
Until now, the whole purpose of Enterprise Linux seemed to be low-risk
updates. </rant>

I've documented the whole GDM customization process until CentOS 7.5 in
a short article on my french blog :

  * https://blog.microlinux.fr/gdm-centos/

Any idea how I can configure GDM with the new version ?

Cheers,

Niki

-- 
Microlinux - Solutions informatiques durables
7, place de l'?glise - 30730 Montpezat
Site : https://www.microlinux.fr
Blog : https://blog.microlinux.fr
Mail : info at microlinux.fr
T?l. : 04 66 63 10 32

On Thu, Dec 06, 2018 at 10:01:25AM +0100, Nicolas Kovacs
wrote:
> Now with CentOS 7.6 this doesn't work anymore. The /etc/dconf/db/gdm.d
> directory is nowhere to be found, and I'm currently mildly cursing the
> GNOME developers' (and Red Hat's) policy of releasing moving
targets.
> Until now, the whole purpose of Enterprise Linux seemed to be low-risk
> updates. </rant>
While the /etc/dconf/db/gdm.d/ directory doesn't exist, I've got many
RHEL7.6 and CentOS 7.6 systems where GDM behaves the same way as
before, as long as you create /etc/dconf/db/gdm.d/ and put the files
in there, and as soon as you run 'dconf update', you see it change.

I'm not sure why the /etc/dconf/db/gdm.d/ and
/etc/dconf/db/gdm.d/locks/ directory aren't owned by a package
anymore, that seems like a bug, but as far as I can tell, GDM
continues to get its information from there.

-- 
Jonathan Billings <billings at negate.org>

Jonathan Billings wrote:
> 
> On Thu, Dec 06, 2018 at 10:01:25AM +0100, Nicolas Kovacs wrote:
>> Now with CentOS 7.6 this doesn't work anymore. The
/etc/dconf/db/gdm.d
>> directory is nowhere to be found, and I'm currently mildly cursing
the
>> GNOME developers' (and Red Hat's) policy of releasing moving
targets.
>> Until now, the whole purpose of Enterprise Linux seemed to be low-risk
>> updates. </rant>
> 
> While the /etc/dconf/db/gdm.d/ directory doesn't exist, I've got
many
> RHEL7.6 and CentOS 7.6 systems where GDM behaves the same way as
> before, as long as you create /etc/dconf/db/gdm.d/ and put the files
> in there, and as soon as you run 'dconf update', you see it change.
> 
> I'm not sure why the /etc/dconf/db/gdm.d/ and
> /etc/dconf/db/gdm.d/locks/ directory aren't owned by a package
> anymore, that seems like a bug, but as far as I can tell, GDM
> continues to get its information from there.
I suspect it might be something that has been left out in the rebase to 
GDM 3.28.1 - an earlier change log for GDM has:

* Thu Jun 25 2015 Ray Strode <rstrode at redhat.com> 3.14.2-4
- Make sure user customizations to gdm via /etc/dconf/db/gdm.d
   continue to work following rebase.
   Related: #1174564

So, I'm guessing that something similar was left out with this change 
from 3.26 to 3.28 ?

Maybe a bug report to https://bugzilla.redhat.com is needed ?

James Pearson