lightdm-mini-greeter: init at 0.3.2

[mnacamura]

Motivation for this change

lightdm-mini-greeter is a neat, minimalistic LightDM greeter. It could be alternative to SLiM.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option build-use-sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.

[emmanuelrosa]

Nice 😁

In the lightdm-mini-greeter documentation it says:

If you have multiple Desktop Environments or Window Mangers installed, you can specify the one to start by changing the user-session option as well(look in /usr/share/xsession for possible values).

In my case, although I only have i3 installed as the window manager lightdm-mini-greeter doesn't know to use it and instead simply runs xterm. How can/will the desktop environment or window manager be configured with this greeter on NixOS?

Other than that, I'm liking this! Here it is running in a VM built with nixos-rebuild build-vm:

[dotlambda]

@emmanuelrosa For turning off xterm you might want to set the respective option to false: https://nixos.org/nixos/options.html#xterm.

[mnacamura]

@emmanuelrosa You can choose your session in ~/.dmrc. Otherwise you can configure the default desktop session in /etc/nixos/configuration.nix by for example

services.xserver.desktopManager.default = "none";
services.xserver.windowManager.default = "bspwm";

in my case using bspwm.

[emmanuelrosa]

This is what it took to make it work with i3:

services.xserver.windowManager.default = "i3";
services.xserver.desktopManager.xterm.enable = false;

When I set the Desktop Manager to "none" i3 started but so did xterm, and killing xterm also killed i3.

Given this, the only recommendation I have is to document what is needed to set the window/desktop manager (since this greeter doesn't provide a way to do so via the GUI). Better yet, an option which simply takes care of it. Something like this:

services.xserver.displayManager.lightdm.greeters.mini.userSession = "i3";

[mnacamura]

Ahh I was wrong. ~/.dmrc is ignored. Mini greeter seems to start only the default session.

Given this, the only recommendation I have is to document what is needed to set the window/desktop manager (since this greeter doesn't provide a way to do so via the GUI). Better yet, an option which simply takes care of it. Something like this:

services.xserver.displayManager.lightdm.greeters.mini.userSession = "i3";

To document something like ``For using this greeter, you need to set the default session by ...'' would be sufficiently helpful IMHO.

This is what it took to make it work with i3:

services.xserver.windowManager.default = "i3";
services.xserver.desktopManager.xterm.enable = false;

I tested

services.xserver.desktopManager.default = "none";
services.xserver.windowManager.default = "i3";

and it worked fine. I did not need to set services.xserver.desktopManager.xterm.enable = false.

[mnacamura]

All set, maybe. I'm waiting for review.

[matthewbauer]

This add a few too many options. Can add an "extraConfig" like the lightdm-gtk-greeter has? Any options in common with lightdm-gtk-greeter are probably worth keeping.

[mnacamura]

I agree. However, mini-greeter requires that in the config file, all the options are explicitly specified; it does not provide default options when they are omitted in the config file. So, unlike GTK greeter, it could be unsafe to introduce extraConfig, with which users might forget to specify some options, causing failure, and after nixos-rebuild switch they cannot login.

EDIT: I noticed that glib's keyfile can have the same keys multiple times and the last entry wins. So it can be done by putting default options first and then overwriting them in extraConfig.

[mnacamura]

I added extraConfig and most options can be set there.

[mnacamura]

@matthewbauer Could you review this again?

[matthewbauer]

If you could add yourself as maintainer, this becomes a little easier to merge.

[mnacamura]

I'll be glad to.