M doc/guix.texi => doc/guix.texi +34 -0
@@ 44475,6 44475,40 @@ The @code{(gnu home services desktop)} module provides services that you
may find useful on ``desktop'' systems running a graphical user
environment such as Xorg.
+@cindex X Window, for Guix Home services
+@cindex X11, in Guix Home
+@defvar home-x11-service-type
+This is the service type representing the X Window graphical display
+server (also referred to as ``X11'').
+
+X Window is necessarily started by a system service; on Guix System,
+starting it is the responsibility of @code{gdm-service-type} and similar
+services (@pxref{X Window}). At the level of Guix Home, as an
+unprivileged user, we cannot start X Window; all we can do is check
+whether it is running. This is what this service does.
+
+As a user, you probably don't need to worry or explicitly instantiate
+@code{home-x11-service-type}. Services that require an X Window
+graphical display, such as @code{home-redshift-service-type} below,
+instantiate it and depend on its corresponding @code{x11-display}
+Shepherd service (@pxref{Shepherd Home Service}).
+
+When X Window is running, the @code{x11-display} Shepherd service starts
+and sets the @env{DISPLAY} environment variable of the
+@command{shepherd} process, using its original value if it was already
+set; otherwise, it fails to start.
+
+The service can also be forced to use a given value for @env{DISPLAY},
+like so:
+
+@example
+herd start x11-display :3
+@end example
+
+In the example above, @code{x11-display} is instructed to set
+@env{DISPLAY} to @code{:3}.
+@end defvar
+
@defvar home-redshift-service-type
This is the service type for @uref{https://github.com/jonls/redshift,
Redshift}, a program that adjusts the display color temperature
M gnu/home/services/desktop.scm => gnu/home/services/desktop.scm +101 -8
@@ 1,5 1,5 @@
;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2022 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2022-2023 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2022 ( <paren@disroot.org>
;;; Copyright © 2023 conses <contact@conses.eu>
;;; Copyright © 2023 Janneke Nieuwenhuizen <janneke@gnu.org>
@@ 30,7 30,9 @@
#:use-module (guix gexp)
#:use-module (srfi srfi-1)
#:use-module (ice-9 match)
- #:export (home-redshift-configuration
+ #:export (home-x11-service-type
+
+ home-redshift-configuration
home-redshift-configuration?
home-redshift-service-type
@@ 45,6 47,79 @@
;;;
+;;; Waiting for X11.
+;;;
+
+(define (x11-shepherd-service delay)
+ (list (shepherd-service
+ (provision '(x11-display))
+ (modules '((ice-9 ftw)
+ (ice-9 match)
+ (srfi srfi-1)))
+ (start
+ #~(lambda* (#:optional (display (getenv "DISPLAY")))
+ (define x11-directory
+ "/tmp/.X11-unix")
+
+ (define (find-display delay)
+ ;; Wait for an accessible socket to show up in X11-DIRECTORY,
+ ;; up to DELAY seconds.
+ (let loop ((attempts delay))
+ (define socket
+ (find (match-lambda
+ ((or "." "..") #f)
+ (name
+ (let ((name (in-vicinity x11-directory
+ name)))
+ (access? name O_RDWR))))
+ (or (scandir x11-directory) '())))
+
+ (if (and socket (string-prefix? "X" socket))
+ (let ((display (string-append
+ ":" (string-drop socket 1))))
+ (format #t "X11 display server found at ~s.~%"
+ display)
+ display)
+ (if (zero? attempts)
+ (begin
+ (format (current-error-port)
+ "X11 display server did not show up; \
+giving up.\n")
+ #f)
+ (begin
+ (sleep 1)
+ (loop (- attempts 1)))))))
+
+ (let ((display (or display (find-display #$delay))))
+ (when display
+ ;; Note: 'make-forkexec-constructor' calls take their
+ ;; default #:environment-variables value before this service
+ ;; is started and are thus unaffected by the 'setenv' call
+ ;; below. Users of this service have to explicitly query
+ ;; its value.
+ (setenv "DISPLAY" display))
+ display)))
+ (stop #~(lambda (_)
+ (unsetenv "DISPLAY")
+ #f))
+ (respawn? #f))))
+
+(define home-x11-service-type
+ (service-type
+ (name 'home-x11-display)
+ (extensions (list (service-extension home-shepherd-service-type
+ x11-shepherd-service)))
+ (default-value 10)
+ (description
+ "Create a @code{x11-display} Shepherd service that waits for the X
+Window (or ``X11'') graphical display server to be up and running, up to a
+configurable delay, and sets the @code{DISPLAY} environment variable of
+@command{shepherd} itself accordingly. If no accessible X11 server shows up
+during that time, the @code{x11-display} service is marked as failing to
+start.")))
+
+
+;;;
;;; Redshift.
;;;
@@ 169,11 244,25 @@ format."))
(list (shepherd-service
(documentation "Redshift program.")
(provision '(redshift))
- ;; FIXME: This fails to start if Home is first activated from a
- ;; non-X11 session.
- (start #~(make-forkexec-constructor
- (list #$(file-append (home-redshift-configuration-redshift config) "/bin/redshift")
- "-c" #$config-file)))
+
+ ;; Depend on 'x11-display', which sets 'DISPLAY' if an X11 server is
+ ;; available, and fails to start otherwise.
+ (requirement '(x11-display))
+
+ (modules '((srfi srfi-1)
+ (srfi srfi-26)))
+ (start #~(lambda _
+ (fork+exec-command
+ (list #$(file-append
+ (home-redshift-configuration-redshift config)
+ "/bin/redshift")
+ "-c" #$config-file)
+
+ ;; Inherit the 'DISPLAY' variable set by 'x11-display'.
+ #:environment-variables
+ (cons (string-append "DISPLAY=" (getenv "DISPLAY"))
+ (remove (cut string-prefix? "DISPLAY=" <>)
+ (default-environment-variables))))))
(stop #~(make-kill-destructor))
(actions (list (shepherd-configuration-action config-file))))))
@@ 181,7 270,11 @@ format."))
(service-type
(name 'home-redshift)
(extensions (list (service-extension home-shepherd-service-type
- redshift-shepherd-service)))
+ redshift-shepherd-service)
+ ;; Ensure 'home-x11-service-type' is instantiated so we
+ ;; can depend on the Shepherd 'x11-display' service.
+ (service-extension home-x11-service-type
+ (const #t))))
(default-value (home-redshift-configuration))
(description
"Run Redshift, a program that adjusts the color temperature of display