[CentOS] 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

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