services: Add nwg-hello greeter for greetd.

* gnu/services/base.scm (nwg-hello-configuration): New configuration.
(nwg-hello-configuration-file): New variable.
(nwg-hello-style): New configuration.
(nwg-hello-stylesheet): New variable.
(greetd-nwg-hello-sway-session): New configuration.
(make-greetd-nwg-hello-sway-session-sway-config): New variable.
(greetd-nwg-hello-sway-session-compiler): New gexp compiler.
* doc/guix.texi (Base Services): Document the new greeter.

Merges: guix/guix!7644
Reviewed-by: Maxim Cournoyer <maxim@guixotic.coop>
Signed-off-by: Sharlatan Hellseher <sharlatanus@gmail.com>

1 files changed, 126 insertions, 0 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index 127c87f7f48..c349ffc6d33 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -154,6 +154,7 @@ Copyright @copyright{} 2026 Yarl Baudig@*
 Copyright @copyright{} 2026 Joan Vilardaga Castro@*
 Copyright @copyright{} 2026 Nemin@*
 Copyright @copyright{} 2026 Fredrik Salomonsson@*
+Copyright @copyright{} 2026 Sughosha@*
 
 Permission is granted to copy, distribute and/or modify this document
 under the terms of the GNU Free Documentation License, Version 1.3 or
@@ -22126,6 +22127,131 @@ instance of @code{greetd-user-session}.
 @end table
 @end deftp
 
+@c %start of fragment
+
+@deftp {Data Type} greetd-nwg-hello-sway-session
+Configuration record for the nwg-hello greetd greeter.  It can be used as
+follows:
+
+@lisp
+  (greetd-configuration
+   ;; The graphical greeter requires additional groups membership.
+   (greeter-supplementary-groups (list "input" "video"))
+   (terminals
+    (list (greetd-terminal-configuration
+           ;; Sway requires either seatd or elogind service, but elogind
+           ;; is preferred for nwg-hello to reboot, shutdown or halt as
+           ;; user by using the loginctl command.
+           (extra-shepherd-requirement '(elogind))
+           (terminal-vt "1")
+           (terminal-switch #t)
+           (default-session-command
+            (greetd-nwg-hello-sway-session))))))
+@end lisp
+
+Available @code{greetd-nwg-hello-sway-session} fields are:
+
+@table @asis
+@item @code{sway} (default: @code{sway}) (type: package)
+Package providing the @command{sway} and @command{swaymsg} commands.
+
+@item @code{sway-configuration} (type: maybe-file-like)
+Extra configuration for @command{sway} to be included before executing
+the greeter.
+
+@item @code{nwg-hello} (default: @code{nwg-hello}) (type: package)
+Package providing the @command{nwg-hello} command.
+
+@item @code{nwg-hello-config} (type: nwg-hello-configuration)
+Configuration of @command{nwg-hello}.
+
+@item @code{nwg-hello-style} (type: nwg-hello-style)
+CSS style rules for @command{nwg-hello}.
+
+@end table
+
+@end deftp
+
+
+@c %end of fragment
+
+@c %start of fragment
+
+@deftp {Data Type} nwg-hello-configuration
+Available @code{nwg-hello-configuration} fields are:
+
+@table @asis
+@item @code{session-dirs} (default: @code{("/run/current-system/profile/share/wayland-sessions" "/run/current-system/profile/share/xsessions")}) (type: list-of-strings)
+List of directories containing Wayland or X session desktop files.
+
+@item @code{custom-sessions} (type: alist-of-strings-to-greetd-user-sessions)
+Session names and the commands.
+
+@item @code{environment-variables} (default: @code{()}) (type: alist-of-strings-to-strings)
+Environment variables associated to their values to pass to user
+sessions.
+
+@item @code{halt-command} (default: @code{"loginctl suspend"}) (type: string)
+Command to run when halting the device.
+
+@item @code{reboot-command} (default: @code{"loginctl reboot"}) (type: string)
+Command to run when rebooting the device.
+
+@item @code{shutdown-command} (default: @code{"loginctl poweroff"}) (type: string)
+Command to run when shutting down the device.
+
+@item @code{gtk-theme} (default: @code{"Advaita"}) (type: string)
+GTK theme to use.
+
+@item @code{icon-theme} (default: @code{"Advaita"}) (type: string)
+Icon theme to use.
+
+@item @code{cursor-theme} (default: @code{"Adwaita"}) (type: string)
+Cursor theme to use.
+
+@item @code{prefer-dark-theme?} (default: @code{#t}) (type: boolean)
+Flag to prefer dark mode for the theme.
+
+@item @code{extra-config} (type: maybe-alist-of-strings-to-strings)
+Extra configuration of keys and values.
+
+@end table
+
+@end deftp
+
+
+@c %end of fragment
+
+@c %start of fragment
+
+@deftp {Data Type} nwg-hello-style
+Available @code{nwg-hello-style} fields are:
+
+@table @asis
+@item @code{background-image} (type: file-like-or-#f)
+Image file to be set as the background.  Setting this to @code{#f}
+respects the background color.
+
+@item @code{background-size} (default: @code{"auto 100%"}) (type: string)
+Size of the background image.  It can be @code{"auto"} (for preserving
+the original size), @code{"cover"} (for resizing to fill while allowing
+to cut or to stretch), @code{"contain"} (for resizing to fit assuring
+the full visibility of the image), or a string of a number suffixed with
+with @code{px} (to represent in pixels) or @code{%} (to represent in
+percentage).  It can also be a string of two such values separated by a
+whitespace, representing width and height respectively.
+
+@item @code{extra-style} (type: maybe-alist-of-strings-to-alists-of-strings-to-strings)
+List of CSS selectors associated to their lists of CSS properties
+associated to their values.
+
+@end table
+
+@end deftp
+
+
+@c %end of fragment
+
 @node Scheduled Job Execution
 @subsection Scheduled Job Execution