osbuild: accept only a single image type in the configuration

Modify the osbuild configuration schema to accept only an array with a
single value as the `image_types`, in addition to a single string. The
single string was supported by the schema also before, but this fact was
not mentioned in the documentation, nor it was supported by the
`koji-osbuild` plugin of version lower than `9`.

Update the documentation accordingly.

Add unit test for invalid configuration containing more than one image
type.

Signed-off-by: Tomas Hozza <thozza@redhat.com>

doc/configuration.rst

@@ -1594,7 +1594,9 @@ OSBuild Composer for building images
 
     * ``name`` -- name of the Koji package
     * ``distro`` -- image for which distribution should be build TODO examples
-    * ``image_types`` -- a list of image types to build (e.g. ``qcow2``)
+    * ``image_types`` -- a list with a single image type string or just a
+      string representing the image type to build (e.g. ``qcow2``). In any
+      case, only a single image type can be provided as an argument.
 
     Optional keys:
 

pungi/checks.py

@@ -1171,7 +1171,21 @@ def make_schema():
                                 "version": {"type": "string"},
                                 "distro": {"type": "string"},
                                 "target": {"type": "string"},
-                                "image_types": {"$ref": "#/definitions/strings"},
+                                # Only a single image_type can be specified
+                                # https://github.com/osbuild/koji-osbuild/commit/c7252650814f82281ee57b598cb2ad970b580451
+                                # https://github.com/osbuild/koji-osbuild/commit/f21a2de39b145eb94f3d49cb4d8775a33ba56752
+                                "image_types": {
+                                    "oneOf": [
+                                        {
+                                            "type": "array",
+                                            "items": {"type": "string"},
+                                            "description": "Deprecated variant",
+                                            "minItems": 1,
+                                            "maxItems": 1,
+                                        },
+                                        {"type": "string"},
+                                    ]
+                                },
                                 "arches": {"$ref": "#/definitions/list_of_strings"},
                                 "release": {"type": "string"},
                                 "repo": {"$ref": "#/definitions/list_of_strings"},

tests/test_osbuild_phase.py

@@ -8,6 +8,7 @@ import koji as orig_koji
 
 from tests import helpers
 from pungi.phases import osbuild
+from pungi.checks import validate
 
 
 class OSBuildPhaseTest(helpers.PungiTestCase):
@@ -105,6 +106,24 @@ class OSBuildPhaseTest(helpers.PungiTestCase):
         phase = osbuild.OSBuildPhase(compose)
         self.assertTrue(phase.skip())
 
+    def test_fail_multiple_image_types(self):
+        cfg = {
+            "name": "test-image",
+            "distro": "rhel-8",
+            # more than one image type is not allowed
+            "image_types": ["qcow2", "rhel-ec2"],
+        }
+        compose = helpers.DummyCompose(
+            self.topdir,
+            {
+                "osbuild": {"^Everything$": [cfg]},
+                "osbuild_target": "image-target",
+                "osbuild_version": "1",
+                "osbuild_release": "2",
+            },
+        )
+        self.assertNotEqual(validate(compose.conf), ([], []))
+
 
 class RunOSBuildThreadTest(helpers.PungiTestCase):
     def setUp(self):