Bug#986046: gdm3: dependencies do not include an X11 server and a window manager

[Simon McVittie]

Control: severity -1 normal

(Re-sending to the correct bug number, not the archived bug from which
it was cloned)

On Sun, 28 Mar 2021 at 16:45:23 +0100, Simon McVittie wrote:
> The underlying issue here is that if you want things "already done
> for you", then installing a complete desktop environment like GNOME,
> KDE Plasma or XFCE is going to be a better route than building your own
> desktop environment from individual pieces; and if you want to build your
> own desktop environment from individual pieces, this is going to require
> some understanding of how the pieces fit together and which ones you want.
> 
> If we added enough dependencies to make apt prevent you from accidentally
> setting up an incomplete environment that is not actually practically
> usable, then we would also prevent advanced users from building their own
> desktop environments (or non-desktop-environment graphical environments)
> that are more minimal.

I don't think this is necessarily even a bug, and certainly not a
release-critical bug, so I'm lowering its severity to take it off the radar
for people preparing release notes. Release team cc'd for information (it's
already tagged bullseye-ignore).

As far as we know, gdm3 has all the dependencies that are necessary to
present a display manager (login prompt). It won't provide a useful login
session on its own; to get one of those, it's necessary to install a
desktop environment, session manager or window manager separately.

> - gnome-shell could have a Recommends on gnome-session, as a heavier hint
>   that gnome-session is how you get the intended GNOME session user
>   experience. However, this would be circular
>   (gnome-shell Depends: gnome-session Recommends: gnome-shell), which is
>   probably undesirable.

I think we probably don't want to do this, because Depends/Recommends
cycles make it hard to remove unneeded packages.

> - gdm3 could have a Recommends on "gnome-session | x-session-manager",
>   with no x-window-manager or x-terminal-emulator alternative, as a
>   heavier hint that an x-session-manager is a really good idea. Xsession
>   runs an x-session-manager in preference to a plain x-window-manager
>   or an x-terminal-emulator, so installing an x-session-manager (such
>   as gnome-session or xfce4-session) would result in that session being
>   run in preference to mutter.

If nobody objects, I intend to do this post-bullseye and close
bug #986046 with that change. I don't think this is urgent to do in
bullseye.

    smcv