Package: guix-patches;
Reported by: Ludovic Courtès <ludo <at> gnu.org>
Date: Wed, 16 Aug 2023 17:45:01 UTC
Severity: normal
Tags: patch
Done: Ludovic Courtès <ludo <at> gnu.org>
Bug is archived. No further changes may be made.
View this message in rfc822 format
From: Ludovic Courtès <ludo <at> gnu.org> To: 65343 <at> debbugs.gnu.org Cc: Ludovic Courtès <ludo <at> gnu.org>, ( <paren <at> disroot.org>, Andrew Tropin <andrew <at> trop.in>, Ludovic Courtès <ludo <at> gnu.org> Subject: [bug#65343] [PATCH] home: services: Add 'x11-display' service. Date: Wed, 16 Aug 2023 19:43:51 +0200
* gnu/home/services/desktop.scm (x11-shepherd-service): New procedure.
(home-x11-service-type): New variable.
(redshift-shepherd-service): Add 'requirement' field.
(home-redshift-service-type): Extend 'home-x11-service-type'.
* doc/guix.texi (Desktop Home Services): Document it.
---
doc/guix.texi | 22 ++++++++++
gnu/home/services/desktop.scm | 82 ++++++++++++++++++++++++++++++++---
2 files changed, 99 insertions(+), 5 deletions(-)
Hello Guix!
This is an attempt to fix a longstanding issue with Home services
that depend on X11: how can we make sure that (1) they are not started
when X is not running, and (2) they get the correct ‘DISPLAY’
variable.
It’s a bit of a hack (the idea came up during a discussion on IRC
a few days ago), but it does the job. I guess it could be
extended to Wayland as well, but I’m not familiar with it.
Thoughts?
Ludo’.
diff --git a/doc/guix.texi b/doc/guix.texi
index 22590b4f9c..a99ef8e5e8 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -44067,6 +44067,28 @@ Desktop Home Services
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
+@code{DISPLAY} environment variable of the @command{shepherd} process;
+otherwise, it fails to start.
+@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
diff --git a/gnu/home/services/desktop.scm b/gnu/home/services/desktop.scm
index 626918fd9e..b293031fd1 100644
--- a/gnu/home/services/desktop.scm
+++ b/gnu/home/services/desktop.scm
@@ -1,5 +1,5 @@
;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2022 Ludovic Courtès <ludo <at> gnu.org>
+;;; Copyright © 2022-2023 Ludovic Courtès <ludo <at> gnu.org>
;;; Copyright © 2022 ( <paren <at> disroot.org>
;;; Copyright © 2023 conses <contact <at> conses.eu>
;;; Copyright © 2023 Janneke Nieuwenhuizen <janneke <at> gnu.org>
@@ -30,7 +30,9 @@ (define-module (gnu home services desktop)
#: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
@@ -43,6 +45,69 @@ (define-module (gnu home services desktop)
home-xmodmap-configuration
home-xmodmap-service-type))
+
+;;;
+;;; 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 ()
+ (define x11-directory
+ "/tmp/.X11-unix")
+
+ ;; Wait for an accessible socket to show up in
+ ;; X11-DIRECTORY, up to DELAY seconds.
+ (let loop ((attempts #$delay))
+ (define socket
+ (find (match-lambda
+ ((or "." "..") #f)
+ (name
+ (let ((name (in-vicinity x11-directory
+ name)))
+ (access? name O_RDWR))))
+ (or (scandir x11-directory) '())))
+
+ (if (and socket (string-prefix? "X" socket))
+ (let ((display (string-append
+ ":" (string-drop socket 1))))
+ (format #t "X11 display server found at ~s.~%"
+ display)
+ (setenv "DISPLAY" display)
+ display)
+ (if (zero? attempts)
+ (begin
+ (display
+ "X11 display server did not show up; \
+giving up.\n"
+ (current-error-port))
+ #f)
+ (begin
+ (sleep 1)
+ (loop (- attempts 1))))))))
+ (stop #~(lambda (_)
+ (unsetenv "DISPLAY")
+ #f))
+ (respawn? #f))))
+
+(define home-x11-service-type
+ (service-type
+ (name 'home-x11-display)
+ (extensions (list (service-extension home-shepherd-service-type
+ x11-shepherd-service)))
+ (default-value 5)
+ (description
+ "Create a @code{x11-display} Shepherd service that waits for the X
+Window (or ``X11'') graphical display server to be up and running, up to a
+configurable delay, and sets the @code{DISPLAY} environment variable of
+@command{shepherd} itself accordingly. If no accessible X11 server shows up
+during that time, the @code{x11-display} service is marked as failing to
+start.")))
+
;;;
;;; Redshift.
@@ -169,8 +234,11 @@ (define (redshift-shepherd-service config)
(list (shepherd-service
(documentation "Redshift program.")
(provision '(redshift))
- ;; FIXME: This fails to start if Home is first activated from a
- ;; non-X11 session.
+
+ ;; Depend on 'x11-display', which sets 'DISPLAY' if an X11 server is
+ ;; available, and fails to start otherwise.
+ (requirement '(x11-display))
+
(start #~(make-forkexec-constructor
(list #$(file-append redshift "/bin/redshift")
"-c" #$config-file)))
@@ -181,7 +249,11 @@ (define home-redshift-service-type
(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
base-commit: 880ada0bdb9e694573ec42200d48658b27744b9b
--
2.41.0
GNU bug tracking system
Copyright (C) 1999 Darren O. Benham,
1997,2003 nCipher Corporation Ltd,
1994-97 Ian Jackson.