installer: Recommend 'ntp-service-type' for non-graphical systems.

We had several bug reports with a root cause of "the clock was
incorrect" from users who used the installer to install a non-graphical
Guix System.

* gnu/installer/services.scm (%system-services): Add the ntp-service-type.
* gnu/installer/newt/services.scm (run-system-administration-cbt-page): New
variable.
(run-services-page): Use run-system-administration-cbt-page when not
installing a desktop.
* gnu/installer/tests.scm (choose-services): Add and use a
choose-misc-service?  procedure.
* gnu/tests/install.scm (installation-target-os-for-gui-tests)<services>: Add
ntp-service-type.

gnu/installer/newt/services.scm

@@ -3,6 +3,7 @@
 ;;; Copyright © 2019, 2020 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2020 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
 ;;; Copyright © 2021 Tobias Geerinckx-Rice <me@tobias.gr>
+;;; Copyright © 2021 Leo Famulari <leo@famulari.name>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -88,6 +89,27 @@ system.")
         (condition
          (&installer-step-abort)))))))
 
+(define (run-console-services-cbt-page)
+  "Run a page to select various system adminstration services for non-graphical
+systems."
+  (let ((items (filter (lambda (service)
+                         (eq? 'administration
+                              (system-service-type service)))
+                       %system-services)))
+    (run-checkbox-tree-page
+      #:title (G_ "Console services")
+      #:info-text (G_ "Select miscellaneous services to run on your \
+non-graphical system.")
+      #:items items
+      #:selection (map system-service-recommended? items)
+      #:item->text (compose G_ system-service-name)
+      #:checkbox-tree-height 5
+      #:exit-button-callback-procedure
+      (lambda ()
+        (raise
+          (condition
+            (&installer-step-abort)))))))
+
 (define (run-network-management-page)
   "Run a page to select among several network management methods."
   (let ((title (G_ "Network management")))
@@ -119,6 +141,7 @@ client may be enough for a server.")
     (append desktop
             (run-networking-cbt-page)
             (if (null? desktop)
-                (list (run-network-management-page))
+                (cons (run-network-management-page)
+                      (run-console-services-cbt-page))
                 '())
             (run-printing-services-cbt-page))))

gnu/installer/services.scm

@@ -3,6 +3,7 @@
 ;;; Copyright © 2019 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2020 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
 ;;; Copyright © 2021 Tobias Geerinckx-Rice <me@tobias.gr>
+;;; Copyright © 2021 Leo Famulari <leo@famulari.name>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -104,6 +105,13 @@
       (packages '((specification->package "nss-certs")))
       (recommended? #t))
 
+     ;; Miscellaneous system administration services.
+     (system-service
+       (name (G_ "Network time service (NTP), to set the clock automatically"))
+       (type 'administration)
+       (recommended? #t)
+       (snippet '((service ntp-service-type))))
+
      ;; Network connectivity management.
      (system-service
       (name (G_ "NetworkManager network connection manager"))

gnu/installer/tests.scm

@@ -221,7 +221,11 @@ ROOT-PASSWORD, and USERS."
                           (choose-network-management-tool?
                            (lambda (service)
                              (string-contains service "DHCP")))
+                          (choose-misc-service?
+                           (lambda (service)
+                             (string-contains service "NTP")))
                           (choose-other-service? (const #f)))
+
   "Converse over PORT to choose services."
   (define desktop-environments '())
 
@@ -243,6 +247,11 @@ ROOT-PASSWORD, and USERS."
      (null? desktop-environments)
      (find choose-network-management-tool? services))
 
+    ((checkbox-list (title "Console services") (text _)
+                    (items ,services))
+     (null? desktop-environments)
+     (filter choose-misc-service? services))
+
     ((checkbox-list (title "Printing and document services") (text _)
                     (items ,services))
      (filter choose-other-service? services))))

gnu/tests/install.scm

@@ -1685,7 +1685,8 @@ build (current-guix) and then store a couple of full system images.")
          (list
           (swap-space
            (target (uuid "11111111-2222-3333-4444-123456789abc"))))))
-    (services (cons (service dhcp-client-service-type)
+    (services (cons* (service dhcp-client-service-type)
+                     (service ntp-service-type)
                      (operating-system-user-services %minimal-os-on-vda)))))
 
 (define* (installation-target-desktop-os-for-gui-tests