services: dhcp-client: Implement and use a configuration record.

* gnu/services/networking.scm (dhcp-client-configuration): New record
configuration.
(dhcp-client-shepherd-service): Implement a shepher service. Provide a
deprication message for legacy configurations.
(dhcp-client-service-type): Use dhcp-client-shepherd-service.
* doc/guix.texi (Networking Setup): Update.
* po/guix/POTFILES.in: Add 'gnu/services/networking.scm'.

Co-authored-by: Ludovic Courtès <ludo@gnu.org>

1 files changed, 18 insertions, 2 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index eeec4dec2c..6691ae5844 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -19230,10 +19230,26 @@ the user mode network stack,,, QEMU, QEMU Documentation}).
 @cindex DHCP, networking service
 @defvr {Scheme Variable} dhcp-client-service-type
 This is the type of services that run @var{dhcp}, a Dynamic Host Configuration
-Protocol (DHCP) client, on all the non-loopback network interfaces.  Its value
-is the DHCP client package to use, @code{isc-dhcp} by default.
+Protocol (DHCP) client.
 @end defvr
 
+@deftp {Data Type} dhcp-client-configuration
+Data type representing the configuration of the DHCP client service.
+
+@table @asis
+@item @code{package} (default: @code{isc-dhcp})
+DHCP client package to use.
+
+@item @code{interfaces} (default: @code{'all})
+Either @code{'all} or the list of interface names that the DHCP client
+should listen on---e.g., @code{'("eno1")}.
+
+When set to @code{'all}, the DHCP client listens on all the available
+non-loopback interfaces that can be activated.  Otherwise the DHCP
+client listens only on the specified interfaces.
+@end table
+@end deftp
+
 @cindex NetworkManager
 
 @defvr {Scheme Variable} network-manager-service-type