system: image: Add image-type support.

* gnu/system/image.scm (image-with-os): New macro. Rename the old
"image-with-os" procedure to ...
(image-with-os*): ... this new procedure,
(system-image): adapt according,
(raw-image-type, iso-image-type, uncompressed-iso-image-type
%image-types): new variables,
(lookup-image-type-by-name): new procedure.
(find-image): remove it.
* gnu/system/images/hurd.scm (hurd-image-type): New variable,
use it to define ...
(hurd-disk-image): ... this variable, using "os->image" procedure.
* gnu/tests/install.scm (run-install): Rename
installation-disk-image-file-system-type parameter to installation-image-type,
use os->config instead of find-image to compute the image passed to system-image,
(%test-iso-image-installer) adapt accordingly,
(guided-installation-test): ditto.

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

gnu/system/image.scm

@@ -18,6 +18,8 @@
 ;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
 
 (define-module (gnu system image)
+  #:use-module (guix diagnostics)
+  #:use-module (guix discovery)
   #:use-module (guix gexp)
   #:use-module (guix modules)
   #:use-module (guix monads)
@@ -64,9 +66,16 @@ (define-module (gnu system image)
             efi-disk-image
             iso9660-image
 
-            find-image
+            image-with-os
+            raw-image-type
+            iso-image-type
+            uncompressed-iso-image-type
+
+            image-with-label
             system-image
-            image-with-label))
+
+            %image-types
+            lookup-image-type-by-name))
 
 
 ;;;
@@ -113,6 +122,37 @@ (define iso9660-image
            (label "GUIX_IMAGE")
            (flags '(boot)))))))
 
+
+;;;
+;;; Images types.
+;;;
+
+(define-syntax-rule (image-with-os base-image os)
+  "Return an image inheriting from BASE-IMAGE, with the operating-system field
+set to the given OS."
+  (image
+   (inherit base-image)
+   (operating-system os)))
+
+(define raw-image-type
+  (image-type
+   (name 'raw)
+   (constructor (cut image-with-os efi-disk-image <>))))
+
+(define iso-image-type
+  (image-type
+   (name 'iso9660)
+   (constructor (cut image-with-os iso9660-image <>))))
+
+(define uncompressed-iso-image-type
+  (image-type
+   (name 'uncompressed-iso9660)
+   (constructor (cut image-with-os
+                 (image
+                  (inherit iso9660-image)
+                  (compression? #f))
+                 <>))))
+
 
 ;;
 ;; Helpers.
@@ -442,7 +482,7 @@ (define (root-size image)
       image-size)
      (else root-size))))
 
-(define* (image-with-os base-image os)
+(define* (image-with-os* base-image os)
   "Return an image based on BASE-IMAGE but with the operating-system field set
 to OS.  Also set the UUID and the size of the root partition."
   (define root-file-system
@@ -523,7 +563,7 @@ (define target (image-target image))
 
   (with-parameters ((%current-target-system target))
     (let* ((os (operating-system-for-image image))
-           (image* (image-with-os image os))
+           (image* (image-with-os* image os))
            (image-format (image-format image))
            (register-closures? (has-guix-service-type? os))
            (bootcfg (operating-system-bootcfg os))
@@ -556,18 +596,34 @@ (define target (image-target image))
           #:grub-mkrescue-environment
           '(("MKRESCUE_SED_MODE" . "mbr_only"))))))))
 
-(define (find-image file-system-type target)
-  "Find and return an image built that could match the given FILE-SYSTEM-TYPE,
-built for TARGET.  This is useful to adapt to interfaces written before the
-addition of the <image> record."
-  (match file-system-type
-    ("iso9660" iso9660-image)
-    (_ (cond
-        ((and target
-              (hurd-triplet? target))
-         (module-ref (resolve-interface '(gnu system images hurd))
-                     'hurd-disk-image))
-        (else
-         efi-disk-image)))))
+
+;;
+;; Image detection.
+;;
+
+(define (image-modules)
+  "Return the list of image modules."
+  (cons (resolve-interface '(gnu system image))
+        (all-modules (map (lambda (entry)
+                            `(,entry . "gnu/system/images/"))
+                          %load-path)
+                     #:warn warn-about-load-error)))
+
+(define %image-types
+  ;; The list of publically-known image types.
+  (delay (fold-module-public-variables (lambda (obj result)
+                                         (if (image-type? obj)
+                                             (cons obj result)
+                                             result))
+                                       '()
+                                       (image-modules))))
+
+(define (lookup-image-type-by-name name)
+  "Return the image type called NAME."
+  (or (srfi-1:find (lambda (image-type)
+                     (eq? name (image-type-name image-type)))
+                   (force %image-types))
+      (raise
+       (formatted-message (G_ "~a: no such image type~%") name))))
 
 ;;; image.scm ends here

gnu/system/images/hurd.scm

@@ -29,8 +29,11 @@ (define-module (gnu system images hurd)
   #:use-module (gnu system file-systems)
   #:use-module (gnu system hurd)
   #:use-module (gnu system image)
+  #:use-module (srfi srfi-26)
   #:export (hurd-barebones-os
             hurd-disk-image
+            hurd-image-type
+            hurd-qcow2-image-type
             hurd-barebones-disk-image
             hurd-barebones-qcow2-image))
 
@@ -83,14 +86,28 @@ (define hurd-disk-image
            (flags '(boot))
            (initializer hurd-initialize-root-partition))))))
 
+(define hurd-image-type
+  (image-type
+   (name 'hurd-raw)
+   (constructor (cut image-with-os hurd-disk-image <>))))
+
+(define hurd-qcow2-image-type
+  (image-type
+   (name 'hurd-qcow2)
+   (constructor (lambda (os)
+                  (image
+                   (inherit hurd-disk-image)
+                   (format 'compressed-qcow2)
+                   (operating-system os))))))
+
 (define hurd-barebones-disk-image
   (image
-   (inherit hurd-disk-image)
-   (name 'hurd-barebones-disk-image)
-   (operating-system hurd-barebones-os)))
+   (inherit
+    (os->image hurd-barebones-os #:type hurd-image-type))
+   (name 'hurd-barebones-disk-image)))
 
 (define hurd-barebones-qcow2-image
   (image
-   (inherit hurd-barebones-disk-image)
-   (name 'hurd-barebones.qcow2)
-   (format 'compressed-qcow2)))
+   (inherit
+    (os->image hurd-barebones-os #:type hurd-qcow2-image-type))
+   (name 'hurd-barebones.qcow2)))

gnu/tests/install.scm

@@ -218,7 +218,7 @@ (define* (run-install target-os target-os-source
                            #:imported-modules '((gnu services herd)
                                                 (gnu installer tests)
                                                 (guix combinators))))
-                      (installation-disk-image-file-system-type "ext4")
+                      (installation-image-type 'raw)
                       (install-size 'guess)
                       (target-size (* 2200 MiB)))
   "Run SCRIPT (a shell script following the system installation procedure) in
@@ -228,10 +228,6 @@ (define* (run-install target-os target-os-source
 
   (mlet* %store-monad ((_      (set-grafting #f))
                        (system (current-system))
-                       (target (current-target-system))
-                       (base-image -> (find-image
-                                       installation-disk-image-file-system-type
-                                       target))
 
                        ;; Since the installation system has no network access,
                        ;; we cheat a little bit by adding TARGET to its GC
@@ -239,18 +235,20 @@ (define* (run-install target-os target-os-source
                        ;; succeed.  Also add guile-final, which is pulled in
                        ;; through provenance.drv and may not always be present.
                        (target (operating-system-derivation target-os))
+                       (base-image ->
+                                   (os->image
+                                    (operating-system-with-gc-roots
+                                     os (list target guile-final))
+                                    #:type (lookup-image-type-by-name
+                                            installation-image-type)))
                        (image ->
-                        (system-image
-                         (image
-                          (inherit base-image)
-                          (size install-size)
-                          (operating-system
-                            (operating-system-with-gc-roots
-                             os (list target guile-final)))
-                          ;; Do not compress to speed-up the tests.
-                          (compression? #f)
-                          ;; Don't provide substitutes; too big.
-                          (substitutable? #f)))))
+                              (system-image
+                               (image
+                                (inherit base-image)
+                                (size install-size)
+
+                                ;; Don't provide substitutes; too big.
+                                (substitutable? #f)))))
     (define install
       (with-imported-modules '((guix build utils)
                                (gnu build marionette))
@@ -270,16 +268,16 @@ (define marionette
                  "-no-reboot"
                  "-m" "1200"
                  #$@(cond
-                     ((string=? "ext4" installation-disk-image-file-system-type)
+                     ((eq? 'raw installation-image-type)
                       #~("-drive"
                          ,(string-append "file=" #$image
                                          ",if=virtio,readonly")))
-                     ((string=? "iso9660" installation-disk-image-file-system-type)
+                     ((eq? 'uncompressed-iso9660 installation-image-type)
                       #~("-cdrom" #$image))
                      (else
                       (error
-                       "unsupported installation-disk-image-file-system-type:"
-                       installation-disk-image-file-system-type)))
+                       "unsupported installation-image-type:"
+                       installation-image-type)))
                  "-drive"
                  ,(string-append "file=" #$output ",if=virtio")
                  ,@(if (file-exists? "/dev/kvm")
@@ -443,8 +441,8 @@ (define %test-iso-image-installer
                                    %minimal-os-on-vda-source
                                    #:script
                                    %simple-installation-script-for-/dev/vda
-                                   #:installation-disk-image-file-system-type
-                                   "iso9660"))
+                                   #:installation-image-type
+                                   'uncompressed-iso9660))
                          (command (qemu-command/writable-image image)))
       (run-basic-test %minimal-os-on-vda command name)))))
 
@@ -1309,8 +1307,8 @@ (define* (guided-installation-test name
                                #:os installation-os-for-gui-tests
                                #:install-size install-size
                                #:target-size target-size
-                               #:installation-disk-image-file-system-type
-                               "iso9660"
+                               #:installation-image-type
+                               'uncompressed-iso9660
                                #:gui-test
                                (lambda (marionette)
                                  (gui-test-program