[bug#35305] [PATCH] LightDM service

[L p R n d n <guix@lprndn.info>]

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Hello,

New patch for adding the lightDM service replacing the previous one.
Added some doc, simplified lightdm-configuration to look a little bit
more like other display manager's services and use xorg-configuration.
We can always add more options later if needed.
I also made an attempt at factoring out the lightdm-gtk-greeter
configuration. It should be easier to add configuration of other greeter
but there might be better ways.
I'm open to suggestions but otherwise it should be mergeable.
Thanks,

Have a nice day,

L  p R n  d n


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From 90d8f29625eedfce9acf62ad2589498eddf1679e Mon Sep 17 00:00:00 2001
From: L  p R n  d n <guix@lprndn.info>
Date: Thu, 18 Apr 2019 17:58:56 +0200
Subject: [PATCH 10/10] services: Add lightdm-service-type.

* gnu/services/lightdm.scm: Add file.
* doc/guix.texi (@deftp, @deffn): Add documentation.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add it.
---
 doc/guix.texi            |  81 ++++++++++++
 gnu/local.mk             |   1 +
 gnu/services/lightdm.scm | 272 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 354 insertions(+)
 create mode 100644 gnu/services/lightdm.scm

diff --git a/doc/guix.texi b/doc/guix.texi
index 3f50bf77fe..03f50718d9 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -13680,6 +13680,87 @@ type @code{<sddm-configuration>}.
 @end example
 @end deffn
 
+@defvr {Scheme Variable} lightdm-service-type
+Service type for the LightDM graphical login manager.
+It uses the @code{lightdm-gtk-greeter} as default greeter.
+See @code{lightdm-configuration} below for configuration of both lightdm
+and lightdm-gtk-greeter or even using a different greeter.
+@end defvr
+
+@deftp {Data Type} lightdm-configuration
+Data type representing the lightDM service configuration.
+
+@table @asis
+@item @code{session-directory} (default:"/run/current-system/profile/share/xsessions:/run/current-system/profile/share/wayland-sessions")
+Directories where LightDM will search for sessions' @code{.desktop} files.
+
+@item @code{allow-empty-passwords?} (default: @code{#f})
+Whether to allow logins with empty passwords.
+
+@item @code{greeter-name} (default: "lightdm-gtk-greeter")
+The name of the default greeter to be used by LightDM.
+
+@item @code{greeter-package} (default: @code{lightdm-gtk-greeter})
+The package containing the greeter described by @code{greeter-name}
+and that will be included in the system's profile.
+
+@item @code{greeter-assets} (default: @code{(list adwaita-icon-theme gnome-themes-standard)})
+A list of packages needed by the greeter: icons, themes, fonts etc.
+
+@item @code{greeter-configuration-file} (default: (lightdm-gtk-greeter-configuration-file (lightdm-gtk-greeter-configuration)))
+The file that will be place in @code{/etc/xdg/lightdm/} directory.
+A @code{computed-file} is expected.
+
+@item @code{xorg-configuration} (default: @code{(xorg-configuration)})
+Configuration of the Xorg graphical server.
+
+@item @code{session-wrapper} (default: @code{(xinitrc)})
+The command to run for a session. It is run as the user and needs
+to exec the command passed in the arguments to complete running the session.
+
+@item @code{default-session-name} (default: @code{#f})
+The name of the default @code{.desktop} file describing as session.
+If @code {autologin-user} and @code{autologin-timeout} are defined,
+LightDM logs in directly using the session described by @code{default-session-name}.
+
+@item @code{autologin-user} (default: @code{#f})
+If @code {default-session-name} and @code{autologin-timeout} are defined,
+LightDM logs in directly as @code{autologin-user}.
+
+@item @code{autologin-timeout} (default: @code{#f})
+If @code {default-session-name} and @code{autologin-user} are defined,
+LightDM logs in automatically after @code{autologin-timeout} seconds.
+Any user activity during that time will cancel autologin
+and allow usual login through authentification.
+
+@item @code{lightdm} (default: @code{lightdm})
+The LightDM package to use.
+
+@end table
+@end deftp
+
+@deftp {Data Type} lightdm-gtk-greeter-configuration
+This data type represents the configuration for ligtdm-gtk-greeter.
+
+@table @asis
+@item @code{theme-name} (default: "Adwaita")
+The name of the GTK+ theme to be used.
+
+@item @code{icon-theme-name} (default: "Adwaita")
+The name of the icon theme to be used for displaying icons.
+
+@item @code{cursor-theme-name} (default: "Adwaita")
+The name of the theme to be used for the cursor.
+
+@item @code{cursor-size} (default: @code{16})
+The size of the cursor.
+
+@item @code{background} (default: "")
+Path to the background image to be used.
+
+@end table
+@end ftp
+
 @cindex Xorg, configuration
 @deftp {Data Type} xorg-configuration
 This data type represents the configuration of the Xorg graphical display
diff --git a/gnu/local.mk b/gnu/local.mk
index 133293aad3..782e71f0df 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -514,6 +514,7 @@ GNU_SYSTEM_MODULES =				\
   %D%/services/authentication.scm		\
   %D%/services/games.scm			\
   %D%/services/kerberos.scm			\
+  %D%/services/lightdm.scm      		\
   %D%/services/lirc.scm				\
   %D%/services/virtualization.scm		\
   %D%/services/mail.scm				\
diff --git a/gnu/services/lightdm.scm b/gnu/services/lightdm.scm
new file mode 100644
index 0000000000..d0d6c20c2f
--- /dev/null
+++ b/gnu/services/lightdm.scm
@@ -0,0 +1,272 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2019 L  p R n  d n   <guix@lprndn.info>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+
+(define-module (gnu services lightdm)
+  #:use-module (guix gexp)
+  #:use-module (guix records)
+
+  #:use-module (gnu system pam)
+  #:use-module (gnu system shadow)
+
+  #:use-module (gnu services)
+  #:use-module (gnu services dbus)
+  #:use-module (gnu services desktop)
+  #:use-module (gnu services shepherd)
+  #:use-module (gnu services xorg)
+
+  #:use-module (gnu packages admin)
+  #:use-module (gnu packages display-managers)
+  #:use-module (gnu packages freedesktop)
+  #:use-module (gnu packages gnome)
+  #:use-module (gnu packages xorg)
+
+  #:export (lightdm-configuration
+            lightdm-configuration?
+            lightdm-service-type
+            lightdm-gtk-greeter-configuration
+            lightdm-gtk-greeter-configuration-file))
+
+
+(define-record-type* <lightdm-gtk-greeter-configuration>
+  lightdm-gtk-greeter-configuration make-lightdm-gtk-greeter-configuration
+  lightdm-gtk-greeter-configuration?
+  (theme-name lightdm-gtk-greeter-configuration-theme-name
+              (default "Adwaita"))
+  (icon-theme-name
+   lightdm-gtk-greeter-configuration-icon-theme-name
+   (default "Adwaita"))
+  (cursor-theme-name
+   lightdm-gtk-greeter-configuration-cursor-theme-name
+   (default "Adwaita"))
+  (cursor-size lightdm-gtk-greeter-configuration-cursor-size
+               (default 16))
+  (background lightdm-gtk-greeter-configuration-background
+              (default "")))
+
+(define (lightdm-gtk-greeter-configuration-file config)
+  (mixed-text-file "lightdm-gtk-greeter.conf" "
+[greeter]
+theme-name = "        (lightdm-gtk-greeter-configuration-theme-name config) "
+icon-theme-name = "   (lightdm-gtk-greeter-configuration-icon-theme-name config) "
+cursor-theme-name = " (lightdm-gtk-greeter-configuration-cursor-theme-name config) "
+cursor-theme-size = " (number->string
+                       (lightdm-gtk-greeter-configuration-cursor-size config)) "
+background = "        (lightdm-gtk-greeter-configuration-background config)))
+
+(define-record-type* <lightdm-configuration>
+  lightdm-configuration make-lightdm-configuration
+  lightdm-configuration?
+
+  (lightdm lightdm-configuration-lightdm
+           (default lightdm))
+  (sessions-directory lightdm-configuration-sessions-directory
+                      (default (string-append
+                                "/run/current-system/profile/share/xsessions"
+                                ":/run/current-system/profile/share/wayland-sessions")))
+  (allow-empty-passwords? lightdm-configuration-allow-empty-passwords?
+                          (default #f))
+  ;; [Seat]
+  (xorg-configuration lightdm-configuration-xorg
+                      (default (xorg-configuration)))
+  (session-wrapper lightdm-configuration-session-wrapper
+                   (default (xinitrc)))
+  (default-session-name lightdm-configuration-default-session
+    (default ""))
+
+  ;; [Autologin]
+  (autologin-user lightdm-configuration-autologin-user
+                  (default #f))
+  (autologin-timeout lightdm-configuration-autologin-timeout
+                     (default #f))
+  ;; [Greeter]
+  (greeter-name lightdm-configuration-greeter-name
+                (default "lightdm-gtk-greeter"))
+  (greeter-package lightdm-configuration-greeter-package
+                   (default lightdm-gtk-greeter))
+  (greeter-assets lightdm-configuration-greeter-assets
+                  (default (list adwaita-icon-theme
+                                 gnome-themes-standard)))
+  (greeter-configuration-file lightdm-configuration-greeter-configuration
+                              (default (lightdm-gtk-greeter-configuration-file
+                                        (lightdm-gtk-greeter-configuration)))))
+
+(define %lightdm-accounts
+  (list (user-group (name "lightdm") (system? #t))
+        (user-account
+         (name "lightdm")
+         (group "lightdm")
+         (system? #t)
+         (comment "LighDM user")
+         (home-directory "/var/lib/lightdm")
+         (shell (file-append shadow "/sbin/nologin")))))
+
+
+(define (lightdm-configuration-file config)
+  (mixed-text-file "lightdm.conf" "
+[LightDM]
+greeter-user = lightdm
+greeters-directory = /run/current-system/profile/share/xgreeters
+sessions-directory = "  (lightdm-configuration-sessions-directory config) "
+
+
+[Seat:*]
+xserver-command = "  (xorg-start-command (lightdm-configuration-xorg config)) "
+greeter-session = "       (lightdm-configuration-greeter-name config) "
+user-session = "          (lightdm-configuration-default-session config)
+(if (lightdm-configuration-autologin-user config) (string-append "
+autologin-user = " (lightdm-configuration-autologin-user config)) "")
+(if (string-null? (lightdm-configuration-default-session config)) ""
+    (string-append "
+autologin-session = " (lightdm-configuration-default-session config)))
+(if (lightdm-configuration-autologin-timeout config) (string-append "
+autologin-user-timeout = " (lightdm-configuration-autologin-timeout config)) "") "
+session-wrapper = " (lightdm-configuration-session-wrapper config)))
+
+
+(define (lightdm-pam-service config)
+  "Return a PAM service for @command{lightdm}."
+  (unix-pam-service
+   "lightdm"
+   #:allow-empty-passwords?
+   (lightdm-configuration-allow-empty-passwords? config)))
+
+
+(define (lightdm-greeter-pam-service)
+  "Return a PAM service for @command{lightdm-greeter}}."
+  (pam-service
+   (name "lightdm-greeter")
+   (auth
+    (list
+     ;; Load environment from /etc/environment and ~/.pam_environment
+     (pam-entry (control "required") (module "pam_env.so"))
+     ;; Always let the greeter start without authentication
+     (pam-entry (control "required") (module "pam_permit.so"))))
+   ;; No action required for account management
+   (account
+    (list
+     (pam-entry (control "required") (module "pam_permit.so"))))
+   ;; Can't change password
+   (password
+    (list
+     (pam-entry (control "required") (module "pam_deny.so"))))
+   ;; Setup session
+   (session
+    (list
+     (pam-entry (control "required") (module "pam_unix.so"))
+     (pam-entry (control "required") (module "pam_env.so"))))))
+
+
+(define (lightdm-autologin-pam-service)
+  "Return a PAM service for @command{lightdm-autologin}}."
+  (pam-service
+   (name "lightdm-autologin")
+   (auth
+    (list
+     ;; Block login if they are globally disabled
+     (pam-entry (control "required") (module "pam_nologin.so"))
+     ;; Load environment from /etc/environment and ~/.pam_environment
+     (pam-entry (control "required") (module "pam_env.so"))
+     ;; Allow access without authentication
+     (pam-entry (control "required") (module "pam_permit.so"))))
+   ;; Stop autologin if account requires action
+   (account
+    (list
+     (pam-entry (control "required") (module "pam_unix.so"))))
+   ;; Can't change password
+   (password
+    (list
+     (pam-entry (control "required") (module "pam_deny.so"))))
+   ;; Setup session
+   (session
+    (list
+     (pam-entry (control "required") (module "pam_unix.so"))))))
+
+
+(define (lightdm-shepherd-service config)
+  "Return a <lightdm-service> for LightDM with CONFIG."
+
+  (define lightdm-command
+    #~(list (string-append #$(lightdm-configuration-lightdm config) "/sbin/lightdm")))
+
+  (list (shepherd-service
+         (documentation "LightDM display manager.")
+         (requirement '(dbus-system user-processes host-name))
+         (provision '(display-manager))
+         (respawn? #f)
+         (start #~(lambda ()
+                    (fork+exec-command
+                     (list #$(file-append
+                              (lightdm-configuration-lightdm config)
+                              "/sbin/lightdm"))
+                     #:environment-variables
+                     (list
+                      (string-append
+                       "PATH=/run/current-system/profile/sbin"
+                       ":/run/current-system/profile/bin")))))
+         (stop #~(make-kill-destructor)))))
+
+(define (lightdm-etc-service config)
+  (list `("xdg/lightdm/lightdm.conf.d/lightdm.conf"
+          ,(lightdm-configuration-file config))
+        `(,(string-append "xdg/lightdm/"
+                          (computed-file-name
+                           (lightdm-configuration-greeter-configuration config)))
+          ,(lightdm-configuration-greeter-configuration config))))
+
+(define (lightdm-pam-services config)
+  (list (lightdm-pam-service config)
+        (lightdm-greeter-pam-service)
+        (lightdm-autologin-pam-service)))
+
+(define (lightdm-profile-service config)
+  (append (list lightdm
+                (lightdm-configuration-greeter-package config))
+          (lightdm-configuration-greeter-assets config)))
+
+(define (lightdm-activation-service config)
+  (with-imported-modules '((guix build utils))
+    #~(begin
+        (use-modules (guix build utils))
+        (define %user
+          (getpw "lightdm"))
+        (let ((directory "/var/lib/lightdm-data"))
+          (mkdir-p directory)
+          (chown directory (passwd:uid %user) (passwd:gid %user))))))
+
+(define lightdm-service-type
+  (service-type (name 'lightdm)
+                (extensions
+                 (list
+                  (service-extension shepherd-root-service-type
+                                     lightdm-shepherd-service)
+                  (service-extension activation-service-type
+                                     lightdm-activation-service)
+                  (service-extension pam-root-service-type
+                                     lightdm-pam-services)
+                  (service-extension etc-service-type
+                                     lightdm-etc-service)
+                  (service-extension dbus-root-service-type
+                                     (compose list lightdm-configuration-lightdm))
+                  (service-extension account-service-type
+                                     (const %lightdm-accounts))
+                  (service-extension profile-service-type
+                                     lightdm-profile-service)))
+                (default-value (lightdm-configuration))
+                (description "Return a service that spawns the LightDM graphical login
+ manager.")))
-- 
2.21.0