services: network-manager: Add extra-configuration-files field.

Allow users to specify additional configuration files for NetworkManager.
These files will be added to /etc/NetworkManager/conf.d (NetworkManager's
default configuration directory location).

* gnu/services/networking.scm (<network-manager-configuration>)
[extra-configuration-files]: New field.
(network-manager-activation): Honor the new field.
* doc/guix.texi (Networking Setup): Document the new field.

Change-Id: I07479958e4d0aa318328c666a9630b779230b300
Modified-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>
Signed-off-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>

doc/guix.texi

@@ -21636,6 +21636,28 @@ This is the list of available plugins for virtual private networks
 (VPNs).  An example of this is the @code{network-manager-openvpn}
 package, which allows NetworkManager to manage VPNs @i{via} OpenVPN.
 
+@item @code{extra-configuration-files} (default: @code{'()})
+A list of two-element lists; the first element of each list is a file
+name (as a string), and the second is a file-like object.  Used to
+specify configuration files which will be added to the
+@file{/etc/NetworkManager/conf.d}.  NetworkManager will read additional
+configuration from this directory.  For details on configuration file
+precedence and the configuration file format, see @samp{man 5
+NetworkManager.conf}.
+
+For example, to add two files named @file{001-basic.conf} and
+@file{002-unmanaged.conf}:
+
+@lisp
+(service network-manager-service-type
+         (network-manager-configuration
+          (extra-configuration-files
+           `(("existing-file" ,(local-file "001-basic.conf"))
+             ("constructed-file" ,(plain-file "002-unmanaged.conf"
+                                              "[keyfile]
+unmanaged-devices=interface-name:wlo1_ap\n"))))))
+@end lisp
+
 @end table
 @end deftp
 

gnu/services/networking.scm

@@ -23,6 +23,7 @@
 ;;; Copyright © 2023 Bruno Victal <mirai@makinata.eu>
 ;;; Copyright © 2023 muradm <mail@muradm.net>
 ;;; Copyright © 2024 Nigko Yerden <nigko.yerden@gmail.com>
+;;; Copyright © 2025 45mg <45mg.writes@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -1253,18 +1254,27 @@ project's documentation} for more information."
                (default '()))
   (iwd? network-manager-configuration-iwd?  ; TODO: deprecated field, remove.
         (default #f)
-        (sanitize warn-iwd?-field-deprecation)))
+        (sanitize warn-iwd?-field-deprecation))
+  (extra-configuration-files
+   network-manager-configuration-extra-configuration-files
+   (default '())))                 ;'((file-name-string file-like-object) ...)
 
 (define (network-manager-activation config)
   ;; Activation gexp for NetworkManager
   (match-record config <network-manager-configuration>
-    (network-manager dns vpn-plugins)
+                (network-manager dns vpn-plugins extra-configuration-files)
     #~(begin
         (use-modules (guix build utils))
         (mkdir-p "/etc/NetworkManager/system-connections")
         #$@(if (equal? dns "dnsmasq")
                ;; create directory to store dnsmasq lease file
                '((mkdir-p "/var/lib/misc"))
+               '())
+        #$@(if (pair? extra-configuration-files)  ;if non-empty
+               `((symlink
+                  ,(file-union "network-manager-configuration-directory"
+                               extra-configuration-files)
+                  "/etc/NetworkManager/conf.d"))
                '()))))
 
 (define (vpn-plugin-directory plugins)