fix image build not using cache

This commit fixes issue #528 by adding a default value to
parameters layers and outputformat. This change aligns the
behavior with podman-remote.

Signed-off-by: Federico Rizzo <[email protected]>

Author: fulminemizzega

podman/domain/images_build.py

@@ -204,8 +204,16 @@ def _render_params(kwargs) -> dict[str, list[Any]]:
         if "labels" in kwargs:
             params["labels"] = json.dumps(kwargs.get("labels"))
 
-        if params["dockerfile"] is None:
-            params["dockerfile"] = f".containerfile.{random.getrandbits(160):x}"
+        def default(value, def_value):
+            return def_value if value is None else value
+
+        params["outputformat"] = default(
+            params["outputformat"], "application/vnd.oci.image.manifest.v1+json"
+        )
+        params["layers"] = default(params["layers"], True)
+        params["dockerfile"] = default(
+            params["dockerfile"], f".containerfile.{random.getrandbits(160):x}"
+        )
 
         # Remove any unset parameters
         return dict(filter(lambda i: i[1] is not None, params.items()))

podman/tests/integration/test_images.py

@@ -15,6 +15,7 @@
 """Images integration tests."""
 
 import io
+import json
 import platform
 import tarfile
 import types
@@ -144,6 +145,19 @@ def test_build(self):
         self.assertIsNotNone(image)
         self.assertIsNotNone(image.id)
 
+    def test_build_cache(self):
+        """Check that building twice the same image uses caching"""
+        buffer = io.StringIO("""FROM quay.io/libpod/alpine_labels:latest\nLABEL test=value""")
+        image, _ = self.client.images.build(fileobj=buffer)
+        buffer.seek(0)
+        _, stream = self.client.images.build(fileobj=buffer)
+        for line in stream:
+            # Search for a line with contents "-> Using cache <image id>"
+            parsed = json.loads(line)['stream']
+            if "Using cache" in parsed:
+                break
+        self.assertEqual(parsed.split()[3], image.id)
+
     def test_build_with_context(self):
         context = io.BytesIO()
         with tarfile.open(fileobj=context, mode="w") as tar: