[bug#60521] [v3] home: Add home-dotfiles-service.

[Giacomo Leidi via Guix-patches via <guix-patches@gnu.org>]

* gnu/home/services.scm (dotfiles-for-app): New variable;
(home-dotfiles-configuration): new variable;
(home-dotfiles-service-type): new variable.
* doc/guix.texi: Document it.
---
 doc/guix.texi         | 85 ++++++++++++++++++++++++++++++++++++++++++-
 gnu/home/services.scm | 54 +++++++++++++++++++++++++++
 2 files changed, 138 insertions(+), 1 deletion(-)

diff --git a/doc/guix.texi b/doc/guix.texi
index acb6f0c2e1..b95053039f 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -111,9 +111,9 @@ Copyright @copyright{} 2022 (@*
 Copyright @copyright{} 2022 John Kehayias@*
 Copyright @copyright{} 2022⁠–⁠2023 Bruno Victal@*
 Copyright @copyright{} 2022 Ivan Vilata-i-Balaguer@*
-Copyright @copyright{} 2023 Giacomo Leidi@*
 Copyright @copyright{} 2022 Antero Mejr@*
 Copyright @copyright{} 2023 Karl Hallsby
+Copyright @copyright{} 2023 Giacomo Leidi@*
 
 Permission is granted to copy, distribute and/or modify this document
 under the terms of the GNU Free Documentation License, Version 1.3 or
@@ -42029,6 +42029,89 @@ to use alternative services to implement more advanced use cases like
 read-only home.  Feel free to experiment and share your results.
 @end defvar
 
+It is often the case that Guix Home users already have a setup for versioning
+their user configuration files (also known as @emph{dotfiles}) in a single
+directory, and some way of automatically deploy changes to their user home.
+
+The @code{home-dotfiles-service-type} is designed to ease the way into using
+Guix Home for this kind of users, allowing them to point the service to their
+dotfiles directory (which must follow
+@uref{https://www.gnu.org/software/stow/, GNU Stow}'s layout) and have their
+dotfiles automatically deployed to their user home, without migrating them to
+Guix native configurations.
+
+The dotfiles directory layout is expected to be structured as follows:
+
+@example
+~$ tree -a .dotfiles/
+.dotfiles/
+├── git
+│   └── .gitconfig
+├── gpg
+│   └── .gnupg
+│       ├── gpg-agent.conf
+│       └── gpg.conf
+├── guile
+│   └── .guile
+├── guix
+│   └── .config
+│       └── guix
+│           └── channels.scm
+├── nix
+│   ├── .config
+│   │   └── nixpkgs
+│   │       └── config.nix
+│   └── .nix-channels
+├── tmux
+│   └── .tmux.conf
+└── vim
+    └── .vimrc
+
+13 directories, 10 files
+@end example
+
+For a more formal specification please refer to the
+@pxref{Top,,, stow, GNU Stow Manual}. It is advisable to keep your dotfiles
+directories under version control, for example in the same repository where
+you'd track your Guix Home configuration. A suitable configuration would then
+be:
+
+@lisp
+  (simple-service 'home-dotfiles
+                  home-dotfiles-service-type
+                  (list (string-append (getcwd)
+                                       "/.dotfiles")))
+@end lisp
+
+The expected home directory state would be:
+
+@example
+.
+├── .config
+│   ├── guix
+│   │   └── channels.scm
+│   └── nixpkgs
+│       └── config.nix
+├── .gitconfig
+├── .gnupg
+│   ├── gpg-agent.conf
+│   └── gpg.conf
+├── .guile
+├── .nix-channels
+├── .tmux.conf
+└── .vimrc
+@end example
+
+@defvar home-dotfiles-service-type
+Return a service which is very similiar to @code{home-files-service-type}
+(and actually extends it), but designed to ease the way into using Guix
+Home for users that already track their dotfiles under some kind of version
+control.  This service allows users to point Guix Home to their dotfiles
+directory and have their file automatically deployed to their home directory
+just like Stow would, without migrating all of their dotfiles to Guix native
+configurations.
+@end defvar
+
 @defvar home-xdg-configuration-files-service-type
 The service is very similiar to @code{home-files-service-type} (and
 actually extends it), but used for defining files, which will go to
diff --git a/gnu/home/services.scm b/gnu/home/services.scm
index b17a34d19d..c45b8cbe24 100644
--- a/gnu/home/services.scm
+++ b/gnu/home/services.scm
@@ -2,6 +2,7 @@
 ;;; Copyright © 2021-2023 Andrew Tropin <andrew@trop.in>
 ;;; Copyright © 2021 Xinglu Chen <public@yoctocell.xyz>
 ;;; Copyright © 2022-2023 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2023 Giacomo Leidi <goodoldpaul@autistici.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -22,6 +23,7 @@ (define-module (gnu home services)
   #:use-module (gnu services)
   #:use-module ((gnu packages package-management) #:select (guix))
   #:use-module ((gnu packages base) #:select (coreutils))
+  #:use-module (guix build utils)
   #:use-module (guix channels)
   #:use-module (guix monads)
   #:use-module (guix store)
@@ -35,13 +37,17 @@ (define-module (gnu home services)
   #:use-module (guix modules)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-9)
+  #:use-module (ice-9 ftw)
   #:use-module (ice-9 match)
+  #:use-module (ice-9 string-fun)
   #:use-module (ice-9 vlist)
 
   #:export (home-service-type
             home-profile-service-type
             home-environment-variables-service-type
             home-files-service-type
+            home-dotfiles-service-type
+            home-dotfiles-configuration
             home-xdg-configuration-files-service-type
             home-xdg-data-files-service-type
             home-run-on-first-login-service-type
@@ -341,6 +347,54 @@ (define home-files-service-type
                 (description "Files that will be put in
 @file{~/.guix-home/files}, and further processed during activation.")))
 
+(define (dotfiles-for-app directory)
+  "Return a list of objects compatible with @code{home-files-service-type}'s
+value.  Each object is a pair where the first element is the relative path
+of a file and the second is a gexp representing the file content.  Objects are
+generated by recursively visiting DIRECTORY and mapping its contents to the
+user's home directory."
+  (map (lambda (file)
+         (let ((file-relative-path
+                (string-drop file (1+ (string-length directory)))))
+           (list file-relative-path
+                 (local-file file
+                             (string-append "home-dotfiles-"
+                                            (string-replace-substring
+                                             file-relative-path
+                                             "/" "-"))))))
+       (find-files directory)))
+
+(define-public (home-dotfiles-configuration dotfiles-directories)
+  "Return a list of objects compatible with @code{home-files-service-type}'s
+value, generated following GNU Stow's algorithm for each of the
+DOTFILES-DIRECTORIES."
+  (define (directory-contents directories)
+    (append-map
+     (lambda (directory)
+       (map
+        (lambda (content)
+          (with-directory-excursion directory
+              (canonicalize-path content)))
+        (scandir directory
+          (lambda (name)
+            (not (member name '("." "..")))))))
+     directories))
+  (append-map
+   dotfiles-for-app
+   (directory-contents dotfiles-directories)))
+
+(define-public home-dotfiles-service-type
+  (service-type (name 'home-dotfiles)
+                (extensions
+                 (list (service-extension home-files-service-type
+                                          home-dotfiles-configuration)))
+                (default-value '())
+                (extend append)
+                (compose concatenate)
+                (description "Files contained is these directories will be put
+in the user's home directory according to GNU Stow's algorithm, and further
+processed during activation.")))
+
 (define xdg-configuration-files-directory ".config")
 
 (define (xdg-configuration-files files)

base-commit: dd3e5e71104a2bcbad80e52e062a144ea96b8c6a
-- 
2.39.2