[Nix-dev] Problem setting a systemd service using dbus

[Eric Sagnes]

Hi,

I am having trouble setting a systemd service for a program that requires dbus.
At first it complained that it couldn't find `dbus-launch`, but adding `pkgs.dbus_daemon` to the service `path` fixed that.
But now it is complaining that DBUS_SESSION_BUS_ADDRESS is not set and that X11 is not initialized (the last line).

```
1月 30 16:34:54 alpha fcitx[14131]: (WARN-14131 /tmp/nix-build-fcitx-4.2.9.drv-0/fcitx-4.2.9/src/module/dbus/dbusstuff.c:188) Without DISPLAY or DBUS_SESSION_BUS_ADDRESS session bus will not work
1月 30 16:34:54 alpha fcitx[14131]: (ERROR-14131 /tmp/nix-build-fcitx-4.2.9.drv-0/fcitx-4.2.9/src/module/notificationitem/notificationitem.c:187) DBus Not initialized
1月 30 16:44:15 alpha fcitx[14131]: (ERROR-14131 /tmp/nix-build-fcitx-4.2.9.drv-0/fcitx-4.2.9/src/ui/kimpanel/kimpanel.c:317) DBus Not initialized
1月 30 16:44:15 alpha fcitx[14131]: (ERROR-14131 /tmp/nix-build-fcitx-4.2.9.drv-0/fcitx-4.2.9/src/lib/fcitx/ui.c:165) no usable user interface.
1月 30 16:44:15 alpha fcitx[14131]: (FATAL-14131 /tmp/nix-build-fcitx-4.2.9.drv-0/fcitx-4.2.9/src/frontend/xim/xim.c:134) X11が初期化されていません
```

Here the unit relevant settings:

```
  path        = [ pkgs.dbus_daemon ];
  after       = [ "display-manager.service" ];
  wantedBy    = [ "graphical.target" ];
```

The unit is loaded and active but the program is not appearing in the systray as it should, probably because it cannot find X11 and dbus.

Does someone knows how to address this problem?

-- 
Eric Sagnes
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