nixos/x11/display-managers: don't touch graphical-session.target in xsession-wrapper by K900 · Pull Request #233981 · NixOS/nixpkgs

K900 · 2023-05-25T11:59:52Z

This is not correct and will in fact break things because they try to run before the target is reached.

WMs users may need some sort of a manual workaround for this...

Description of changes

Things done

apfelkuchen6 · 2023-05-25T12:19:11Z

Looks like this should fix #225605.

K900 · 2023-05-25T16:01:36Z

Yes, it should.

K900 · 2023-07-07T05:23:27Z

Pinging everyone who touched all the other DE/WM modules recently for testing:

@FedericoSchonborn for Budgie
@bobby285271 for Cinnamon
@wineee for Deepin
@romildo for a bunch of stuff
@jtojnar for GNOME
@edwtjo for Kodi
@worldofpeace for MATE
@tomfitzhenry for Phosh
@j0hax for RetroArch
@etu for Surf
@sternenseemann for 2bwm and xmonad
@AndersonTorres for a bunch of stuff
@necauqua and @teto for Awesome
@3JlOy-PYCCKUi for dk
@bobvanderlinden for dwm
@reedrw and @Ma27 for i3
@marcusramberg for nimdow
@arjan-s for qtile
@Uthar for StumpWM

If anyone else knows anyone who's actively using the more obscure sessions, please ping them so they can test too.

wineee · 2023-07-07T06:59:47Z

DDE (deepin) works fine

test by:

# nix run -v -L
{
  inputs.nixpkgs.url = "github:K900/nixpkgs/dont-touch-graphical-session-target";
  #inputs.nixpkgs.url = "path:/home/rewine/nur/nixpkgs";

  outputs = inputs@{ self, nixpkgs }: let 
    system = "x86_64-linux";
    pkgs = import nixpkgs { inherit system; };
  in {
    nixosConfigurations.vm = nixpkgs.lib.nixosSystem {
      inherit system;
      modules = [
        {
        imports = [ "${nixpkgs}/nixos/modules/virtualisation/qemu-vm.nix" ];
        services.xserver = {
          enable = true;
          displayManager = {
            lightdm.enable = true;
            autoLogin = {
              enable = false;
              user = "test";
            };
          };
          desktopManager.deepin.enable = true;
        };
        
        users.users.test = {
          isNormalUser = true;
          uid = 1000;
          extraGroups = [ "wheel" "networkmanager" ];
          password = "test";
          createHome = true;
        };
        virtualisation = {
          qemu.options = [ "-device intel-hda -device hda-duplex" ];
          cores = 8;
          memorySize = 8192;
          diskSize = 16384;
          resolution = { x = 1024; y = 768; };
        };
        system.stateVersion = "23.05";
      }];
    };
    packages.${system}.default = self.nixosConfigurations.vm.config.system.build.vm;
    apps.${system}.default = {
      type = "app";
      program = "${self.packages.${system}.default}/bin/run-nixos-vm";
    };
  };
}

wineee · 2023-07-07T07:13:30Z

@OPNA2608 You can test whether this modification affects lomiri

bobvanderlinden · 2023-07-07T07:33:24Z

I'm not maintaining/using dwm. @viric and @neonfuz are 👍

K900 · 2023-07-07T07:34:52Z

FWIW I can personally vouch for this working fine on Plasma, but Plasma is the odd one out here, as it actually uses systemd correctly.

OPNA2608 · 2023-07-07T15:18:12Z

You can test whether this modification affects lomiri

Lomiri seems to still work fine after this.

3JlOy-PYCCKUi · 2023-07-07T18:48:03Z

well, i tested bspwm and dk (via sddm), both started fine, but auto start via systemd user services is broken, cuz graphical-session.target is not started/reached

i don't get purpose of this pr, from my point of view it just breaks things

(i just applied this pr as patch to f292b49 commit)

K900 · 2023-07-07T18:50:32Z

The purpose of this PR is to stop breaking things that actually rely on a graphical session being fully started. Right now every autostart application is basically racing the session setup to determine whether it gets the right environment set up.

AndersonTorres · 2023-07-07T23:47:35Z

We will figure the correct workaround in the future.

AndersonTorres

Reword the commit as:

Modifying the state of graphical-session.target breaks things that try to run before the target is fully reached. This is wrong behavior and should not happen.

This change affect users of window managers, that will need some sort of a manual workaround.

K900 · 2023-07-08T02:30:00Z

I'd rather just not merge this until a workaround is in place.

tomfitzhenry · 2023-07-08T02:34:56Z

Pinging everyone who touched all the other DE/WM modules recently for testing:
@tomfitzhenry for Phosh

Seeing nixosTests.phosh pass would be sufficient for this change.

K900 · 2023-07-08T05:59:52Z

The tests do pass, but this may have unexpected side effects that are not caught by the test.

K900 · 2023-07-08T11:27:23Z

Updated with a hack to retain the old behavior for non-compliant WMs. Thanks to @hrnz on Matrix for coming up with the XDG_CURRENT_DESKTOP idea.

K900 · 2023-07-08T11:29:24Z

Tested locally with Plasma and i3 and things work mostly as expected.

…session-wrapper if the desktop knows how to handle it This is not correct and will in fact break things because they try to run before the target is reached. Ideally we'd get rid of it entirely, but WM users rely on this behavior, so allowlist some desktops to get the sane behavior, and fake the session for the rest until upstreams/NixOS modules catch up.

K900 · 2023-07-08T12:13:25Z

Also added a magic value X-NIXOS-SYSTEMD-AWARE to allow custom sessions to opt into this behavior.

K900 · 2023-07-08T13:30:22Z

@3JlOy-PYCCKUi can you retest if the current workaround works for your setup?

K900 · 2023-07-08T13:43:24Z

So I just went through and checked the session configs for the most common WMs, and I'm pretty sure we're fine here.

jtojnar · 2023-07-08T14:50:41Z

Looks like for GNOME-based DEs, gnome-session.target has BindsTo=graphical-session.target.

Tested GNOME Shell and the graphical-session.target is properly started there:

$ systemctl status --user graphical-session.target
● graphical-session.target - Current graphical user session
     Loaded: loaded (/etc/systemd/user/graphical-session.target; static)
     Active: active since Sat 2023-07-08 14:25:58 UTC; 25s ago
       Docs: man:systemd.special(7)

Jul 08 14:25:58 nixos systemd[1340]: Reached target Current graphical user session.

However, in GNOME Flashback (XDG_CURRENT_DESKTOP=GNOME-Flashback:GNOME), it does not appear to be the case:

$ systemctl status --user graphical-session.target
○ graphical-session.target - Current graphical user session
     Loaded: loaded (/etc/systemd/user/graphical-session.target; static)
     Active: inactive (dead)
       Docs: man:systemd.special(7)

cc @chpatrick

VM configuration

{ pkgs, lib, config, ... }:
{
  environment.systemPackages = with pkgs; [
    gdb
  ];

  environment.enableDebugInfo = true;

  services.xserver = {
    enable = true;

    displayManager.defaultSession = "gnome-flashback-metacity";
    displayManager.gdm = {
      enable = true;
    };
    desktopManager.gnome = {
      flashback.enableMetacity = true;
    };
  };

  services.openssh.enable = true;

  systemd.coredump.extraConfig = ''
    Storage=external
  '';

  users.extraUsers.jtojnar = {
    isNormalUser = true;
    uid = 1000;
    extraGroups = [ "wheel" "networkmanager" ];
    password = "";
    openssh.authorizedKeys.keys = [ "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDYbOlZydfRRCGCT08wdtPcpfSrgxMc6weDx3NcWrnMpVgxnMs3HozzkaS/hbcZUocn7XbCOyaxEd1O8Fuaw4JXpUBcMetpPXkQC+bZHQ3YsZZyzVgCXFPRF88QQj0nR7YVE1AeAifjk3TCODstTxit868V1639/TVIi5y5fC0/VbYG2Lt4AadNH67bRv8YiO3iTsHQoZPKD1nxA7yANHCuw38bGTHRhsxeVD+72ThbsYSZeA9dBrzACpEdnwyXclaoyIOnKdN224tu4+4ytgH/vH/uoUfL8SmzzIDvwZ4Ba2yHhZHs5iwsVjTvLe7jjE6I1u8qY7X8ofnanfNcsmz/ jtojnar@kaiser" ];
  };

  imports = [ <nixpkgs/nixos/modules/virtualisation/qemu-vm.nix> ];
  virtualisation.memorySize = 3 * 2048;
  virtualisation.diskSize = 28048;
  virtualisation.qemu.options = [ "-device intel-hda" "-device hda-duplex" ];
  virtualisation.forwardPorts = [
    # forward local port 2222 -> 22, to ssh into the VM
    { from = "host"; host.port = 2222; guest.port = 22; }
  ];

  systemd.user.services.test-g-s-t = {
    description = "test-g-s-t";
    wantedBy = [ "graphical-session.target" ];
    partOf = [ "graphical-session.target" ];
    serviceConfig.ExecStart = "${pkgs.bash}/bin/sh -c 'while true; do echo running in graphical-session; sleep 5; done'";
  };
}

I would also expect it to work in Pantheon if I add it to the list but it does not appear to.

--- a/nixos/modules/services/x11/display-managers/default.nix
+++ b/nixos/modules/services/x11/display-managers/default.nix
@@ -40,7 +40,7 @@ let
         IFS=:
         for i in $XDG_CURRENT_DESKTOP; do
           case $i in
-            KDE|GNOME|X-NIXOS-SYSTEMD-AWARE) echo "1"; exit; ;;
+            KDE|GNOME|Pantheon|X-NIXOS-SYSTEMD-AWARE) echo "1"; exit; ;;
             *) ;;
           esac
         done

K900 · 2023-07-08T14:52:01Z

I thought Pantheon used gnome-session?

jtojnar · 2023-07-08T15:00:43Z

Oh, we do not actually use systemd code path for Budgie, Pantheon and GNOME Flashback yet, only for GNOME Shell: #228946

SuperSandro2000 · 2023-07-11T19:18:22Z

nixos/modules/services/x11/display-managers/default.nix

+  fakeSession = action: ''
+      session_is_systemd_aware=$(
+        IFS=:
+        for i in $XDG_CURRENT_DESKTOP; do
+          case $i in
+            KDE|GNOME|X-NIXOS-SYSTEMD-AWARE) echo "1"; exit; ;;
+            *) ;;
+          esac
+        done
+      )
+
+      if [ -z "$session_is_systemd_aware" ]; then
+        /run/current-system/systemd/bin/systemctl --user ${action} nixos-fake-graphical-session.target
+      fi
+  '';


Wouldn't it be more nixos like if this was an option and sessions know to support it turn it off?

We can't really do that because the same wrapper is used for all sessions, so we have to resort to runtime dispatch.

bobby285271 · 2023-07-13T05:28:24Z

However, in GNOME Flashback (XDG_CURRENT_DESKTOP=GNOME-Flashback:GNOME), it does not appear to be the case:

It looks like nixosTests.gnome-flashback is now failing 👀

K900 · 2023-07-13T05:29:08Z

I think this might be #228946 ?

bobby285271 · 2023-07-13T05:38:17Z

Ah yeah, I was confused why the Pantheon test passed while not systemd managed but later found it does not have GNOME in XDG_CURRENT_DESKTOP 🤷‍♀️

So I think the budgie test should be failing with same reason, which has Budgie:GNOME as XDG_CURRENT_DESKTOP (cc @FedericoSchonborn)

Edit: #246743

Uthar · 2023-07-14T19:53:06Z

I'm not sure if still needed, but I tested stumpwm like this:

In one terminal:

Xephyr :3

In another terminal:

DISPLAY=:3 /nix/store/...-stumpwm-22.11/bin/stumpwm

And it started.

AndersonTorres · 2023-07-14T21:07:57Z

Cute :3

github-actions bot added 6.topic: nixos Issues or PRs affecting NixOS modules, or package usability issues specific to NixOS 8.has: module (update) This PR changes an existing module in `nixos/` labels May 25, 2023

ofborg bot added 10.rebuild-darwin: 1-10 This PR causes between 1 and 10 packages to rebuild on Darwin. 10.rebuild-darwin: 1 This PR causes 1 package to rebuild on Darwin. 10.rebuild-linux: 1-10 This PR causes between 1 and 10 packages to rebuild on Linux. labels May 25, 2023

AndersonTorres suggested changes Jul 7, 2023

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K900 force-pushed the dont-touch-graphical-session-target branch 2 times, most recently from 99cdb3e to 0bc03c7 Compare July 8, 2023 11:21

K900 force-pushed the dont-touch-graphical-session-target branch from 0bc03c7 to d26393d Compare July 8, 2023 12:09

K900 requested a review from AndersonTorres July 8, 2023 12:20

AndersonTorres approved these changes Jul 8, 2023

View reviewed changes

K900 merged commit 9c98b1a into NixOS:master Jul 8, 2023

bobby285271 mentioned this pull request Jul 9, 2023

pantheon: manage user session with systemd #140429

Merged

2 tasks

SuperSandro2000 reviewed Jul 11, 2023

View reviewed changes

bobby285271 mentioned this pull request Aug 2, 2023

nixos/tests/{budgie,gnome-flashback}: unbreak #246743

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K900 deleted the dont-touch-graphical-session-target branch July 27, 2025 10:50

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