scripts: system: Add support for image-type.

* guix/scripts/system.scm (list-image-types): New procedure,
(%options): add "image-type" and "list-image-types" options, remove
"file-system-type" option,
(show-help): adapt accordingly,
(%default-options): also adapt, and set the default "image-type" to "raw",
(perform-action): add image-type argument and remove file-system-type argument,
(process-action):  adapt perform-action call,
(system-derivation-for-action): remove base-image
argument, add image-type argument, and use it to create the image passed to
"system-image".
* tests/guix-system.sh: Adapt accordingly and add a test for
"--list-image-types" command.
* doc/guix.texi (Building the Installation Image,
Invoking guix system): Adapt accordingly.

Signed-off-by: Mathieu Othacehe <othacehe@gnu.org>

4 files changed, 75 insertions, 52 deletions

diff --git a/Makefile.am b/Makefile.am
index 8e91e1e558..9c3ff4420f 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -833,9 +833,8 @@ release: dist-with-updated-version
 	      -v1 --no-grafts --fallback
 	for system in $(GUIX_SYSTEM_SUPPORTED_SYSTEMS) ; do				\
 	  image=`$(top_builddir)/pre-inst-env						\
-	    guix system disk-image							\
-	    --file-system-type=iso9660							\
-	    --label="GUIX_$${system}_$(VERSION)"						\
+	    guix system disk-image -t iso9660                                           \
+	    --label="GUIX_$${system}_$(VERSION)"					\
             --system=$$system --fallback						\
 	    gnu/system/install.scm` ;							\
 	  if [ ! -f "$$image" ] ; then							\
diff --git a/doc/guix.texi b/doc/guix.texi
index ff2e582347..e8458ad8d8 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -40,7 +40,7 @@ Copyright @copyright{} 2016, 2017, 2018, 2019, 2020 Julien Lepiller@*
 Copyright @copyright{} 2016 Alex ter Weele@*
 Copyright @copyright{} 2016, 2017, 2018, 2019 Christopher Baines@*
 Copyright @copyright{} 2017, 2018, 2019 Clément Lassieur@*
-Copyright @copyright{} 2017, 2018 Mathieu Othacehe@*
+Copyright @copyright{} 2017, 2018, 2020 Mathieu Othacehe@*
 Copyright @copyright{} 2017 Federico Beffa@*
 Copyright @copyright{} 2017, 2018 Carlo Zancanaro@*
 Copyright @copyright{} 2017 Thomas Danckaert@*
@@ -2568,8 +2568,7 @@ The installation image described above was built using the @command{guix
 system} command, specifically:
 
 @example
-guix system disk-image --file-system-type=iso9660 \
-  gnu/system/install.scm
+guix system disk-image -t iso9660 gnu/system/install.scm
 @end example
 
 Have a look at @file{gnu/system/install.scm} in the source tree,
@@ -29375,24 +29374,28 @@ a value.  Docker images are built to contain exactly what they need, so
 the @option{--image-size} option is ignored in the case of
 @code{docker-image}.
 
-You can specify the root file system type by using the
-@option{--file-system-type} option.  It defaults to @code{ext4}.  When its
-value is @code{iso9660}, the @option{--label} option can be used to specify
-a volume ID with @code{disk-image}.
+The @code{disk-image} command can produce various image types.  The
+image type can be selected using the @command{--image-type} option.  It
+defaults to @code{raw}. When its value is @code{iso9660}, the
+@option{--label} option can be used to specify a volume ID with
+@code{disk-image}.
 
-When using @code{vm-image}, the returned image is in qcow2 format, which
-the QEMU emulator can efficiently use. @xref{Running Guix in a VM},
-for more information on how to run the image in a virtual machine.
-
-When using @code{disk-image}, a raw disk image is produced; it can be
-copied as is to a USB stick, for instance.  Assuming @code{/dev/sdc} is
-the device corresponding to a USB stick, one can copy the image to it
-using the following command:
+When using the @code{raw} image type, a raw disk image is produced; it
+can be copied as is to a USB stick, for instance.  Assuming
+@code{/dev/sdc} is the device corresponding to a USB stick, one can copy
+the image to it using the following command:
 
 @example
 # dd if=$(guix system disk-image my-os.scm) of=/dev/sdc status=progress
 @end example
 
+The @code{--list-image-types} command lists all the available image
+types.
+
+When using @code{vm-image}, the returned image is in qcow2 format, which
+the QEMU emulator can efficiently use. @xref{Running Guix in a VM},
+for more information on how to run the image in a virtual machine.
+
 When using @code{docker-image}, a Docker image is produced.  Guix builds
 the image from scratch, not from a pre-existing Docker base image.  As a
 result, it contains @emph{exactly} what you define in the operating
@@ -29494,17 +29497,17 @@ information, one can rebuild the image to make sure it really contains
 what it pretends to contain; or they could use that to derive a variant
 of the image.
 
-@item --file-system-type=@var{type}
+@item --image-type=@var{type}
 @itemx -t @var{type}
-For the @code{disk-image} action, create a file system of the given
-@var{type} on the image.
+For the @code{disk-image} action, create an image with given @var{type}.
 
-When this option is omitted, @command{guix system} uses @code{ext4}.
+When this option is omitted, @command{guix system} uses the @code{raw}
+image type.
 
 @cindex ISO-9660 format
 @cindex CD image format
 @cindex DVD image format
-@option{--file-system-type=iso9660} produces an ISO-9660 image, suitable
+@option{--image-type=iso9660} produces an ISO-9660 image, suitable
 for burning on CDs and DVDs.
 
 @item --image-size=@var{size}
diff --git a/guix/scripts/system.scm b/guix/scripts/system.scm
index bd5f84fc5b..7b3eacf2e1 100644
--- a/guix/scripts/system.scm
+++ b/guix/scripts/system.scm
@@ -666,8 +666,8 @@ checking this by themselves in their 'check' procedure."
 ;;; Action.
 ;;;
 
-(define* (system-derivation-for-action os base-image action
-                                       #:key image-size file-system-type
+(define* (system-derivation-for-action os action
+                                       #:key image-size image-type
                                        full-boot? container-shared-network?
                                        mappings label)
   "Return as a monadic value the derivation for OS according to ACTION."
@@ -690,12 +690,15 @@ checking this by themselves in their 'check' procedure."
                                                 (* 70 (expt 2 20)))
                                             #:mappings mappings))
     ((disk-image)
-     (lower-object
-      (system-image
-       (image
-        (inherit (if label (image-with-label base-image label) base-image))
-        (size image-size)
-        (operating-system os)))))
+     (let ((base-image (os->image os #:type image-type)))
+       (lower-object
+        (system-image
+         (image
+          (inherit (if label
+                       (image-with-label base-image label)
+                       base-image))
+          (size image-size)
+          (operating-system os))))))
     ((docker-image)
      (system-docker-image os #:shared-network? container-shared-network?))))
 
@@ -748,18 +751,19 @@ and TARGET arguments."
                          install-bootloader?
                          dry-run? derivations-only?
                          use-substitutes? bootloader-target target
-                         image-size file-system-type full-boot? label
-                         container-shared-network?
+                         image-size image-type
+                         full-boot? label container-shared-network?
                          (mappings '())
                          (gc-root #f))
   "Perform ACTION for OS.  INSTALL-BOOTLOADER? specifies whether to install
 bootloader; BOOTLOADER-TAGET is the target for the bootloader; TARGET is the
 target root directory; IMAGE-SIZE is the size of the image to be built, for
-the 'vm-image' and 'disk-image' actions.  The root file system is created as a
-FILE-SYSTEM-TYPE file system.  FULL-BOOT? is used for the 'vm' action; it
-determines whether to boot directly to the kernel or to the bootloader.
-CONTAINER-SHARED-NETWORK? determines if the container will use a separate
-network namespace.
+the 'vm-image' and 'disk-image' actions.  IMAGE-TYPE is the type of image to
+be built.
+
+FULL-BOOT? is used for the 'vm' action; it determines whether to
+boot directly to the kernel or to the bootloader.  CONTAINER-SHARED-NETWORK?
+determines if the container will use a separate network namespace.
 
 When DERIVATIONS-ONLY? is true, print the derivation file name(s) without
 building anything.
@@ -799,11 +803,9 @@ static checks."
       (check-initrd-modules os)))
 
   (mlet* %store-monad
-      ((target*   (current-target-system))
-       (image ->  (find-image file-system-type target*))
-       (sys       (system-derivation-for-action os image action
+      ((sys       (system-derivation-for-action os action
                                                 #:label label
-                                                #:file-system-type file-system-type
+                                                #:image-type image-type
                                                 #:image-size image-size
                                                 #:full-boot? full-boot?
                                                 #:container-shared-network? container-shared-network?
@@ -888,6 +890,17 @@ Run 'herd status' to view the list of services on your system.\n"))))))
 
 
 ;;;
+;;; Images.
+;;;
+
+(define (list-image-types)
+  "Print the available image types."
+  (display (G_ "The available image types are:\n"))
+  (newline)
+  (format #t "~{   - ~a ~%~}" (map image-type-name (force %image-types))))
+
+
+;;;
 ;;; Options.
 ;;;
 
@@ -945,9 +958,9 @@ Some ACTIONS support additional ARGS.\n"))
                          apply STRATEGY (one of nothing-special, backtrace,
                          or debug) when an error occurs while reading FILE"))
   (display (G_ "
-      --file-system-type=TYPE
-                         for 'disk-image', produce a root file system of TYPE
-                         (one of 'ext4', 'iso9660')"))
+      --list-image-types list available image types"))
+  (display (G_ "
+  -t, --image-type=TYPE  for 'disk-image', produce an image of TYPE"))
   (display (G_ "
       --image-size=SIZE  for 'vm-image', produce an image of SIZE"))
   (display (G_ "
@@ -1008,10 +1021,14 @@ Some ACTIONS support additional ARGS.\n"))
                  (lambda (opt name arg result)
                    (alist-cons 'on-error (string->symbol arg)
                                result)))
-         (option '(#\t "file-system-type") #t #f
+         (option '(#\t "image-type") #t #f
                  (lambda (opt name arg result)
-                   (alist-cons 'file-system-type arg
+                   (alist-cons 'image-type (string->symbol arg)
                                result)))
+         (option '("list-image-types") #f #f
+                 (lambda (opt name arg result)
+                   (list-image-types)
+                   (exit 0)))
          (option '("image-size") #t #f
                  (lambda (opt name arg result)
                    (alist-cons 'image-size (size->number arg)
@@ -1080,7 +1097,7 @@ Some ACTIONS support additional ARGS.\n"))
     (debug . 0)
     (verbosity . #f)                              ;default
     (validate-reconfigure . ,ensure-forward-reconfigure)
-    (file-system-type . "ext4")
+    (image-type . raw)
     (image-size . guess)
     (install-bootloader? . #t)
     (label . #f)))
@@ -1177,7 +1194,8 @@ resulting from command-line parsing."
                                (assoc-ref opts 'skip-safety-checks?)
                                #:validate-reconfigure
                                (assoc-ref opts 'validate-reconfigure)
-                               #:file-system-type (assoc-ref opts 'file-system-type)
+                               #:image-type (lookup-image-type-by-name
+                                             (assoc-ref opts 'image-type))
                                #:image-size (assoc-ref opts 'image-size)
                                #:full-boot? (assoc-ref opts 'full-boot?)
                                #:container-shared-network?
diff --git a/tests/guix-system.sh b/tests/guix-system.sh
index 0e22686a34..667e084fcf 100644
--- a/tests/guix-system.sh
+++ b/tests/guix-system.sh
@@ -261,8 +261,8 @@ guix system vm "$tmpfile" -d | grep '\.drv$'
 drv1="`guix system vm "$tmpfile" -d`"
 drv2="`guix system vm "$tmpfile" -d`"
 test "$drv1" = "$drv2"
-drv1="`guix system disk-image --file-system-type=iso9660 "$tmpfile" -d`"
-drv2="`guix system disk-image --file-system-type=iso9660 "$tmpfile" -d`"
+drv1="`guix system disk-image -t iso9660 "$tmpfile" -d`"
+drv2="`guix system disk-image -t iso9660 "$tmpfile" -d`"
 test "$drv1" = "$drv2"
 
 make_user_config "group-that-does-not-exist" "users"
@@ -320,5 +320,8 @@ guix system -n vm gnu/system/examples/vm-image.tmpl
 guix system -n vm-image gnu/system/examples/vm-image.tmpl
 # This invocation was taken care of in the loop above:
 # guix system -n disk-image gnu/system/examples/bare-bones.tmpl
-guix system -n disk-image --file-system-type=iso9660 gnu/system/examples/bare-bones.tmpl
+guix system -n disk-image -t iso9660 gnu/system/examples/bare-bones.tmpl
 guix system -n docker-image gnu/system/examples/docker-image.tmpl
+
+# Verify that at least the raw image type is available.
+guix system --list-image-types | grep "raw"