feat: return all schema validation errors

src/karapace/schema_registry.py

@@ -352,12 +352,14 @@ async def write_new_schema_local(
                 result = self.check_schema_compatibility(new_schema, subject)
 
                 if is_incompatible(result):
-                    message = set(result.messages).pop() if result.messages else ""
                     LOG.warning(
                         "Incompatible schema: %s, incompatibilities: %s", result.compatibility, result.incompatibilities
                     )
                     compatibility_mode = self.get_compatibility_mode(subject=subject)
-                    raise IncompatibleSchema(f"Incompatible schema, compatibility_mode={compatibility_mode.value} {message}")
+                    raise IncompatibleSchema(
+                        f"Incompatible schema, compatibility_mode={compatibility_mode.value}. "
+                        f"Incompatibilities: {', '.join(result.messages)[:300]}"
+                    )
 
                 # We didn't find an existing schema and the schema is compatible so go and create one
                 version = self.database.get_next_version(subject=subject)

src/karapace/schema_registry_apis.py

@@ -412,7 +412,8 @@ async def compatibility_check(
             result = SchemaCompatibility.check_compatibility(old_schema, new_schema, compatibility_mode)
 
         if is_incompatible(result):
-            self.r({"is_compatible": False}, content_type)
+            maybe_truncated_error = ", ".join(result.messages)[:300]
+            self.r({"is_compatible": False, "incompatibilities": maybe_truncated_error}, content_type)
         self.r({"is_compatible": True}, content_type)
 
     async def schemas_list(self, content_type: str, *, request: HTTPRequest, user: User | None = None):

tests/integration/test_dependencies_compatibility_protobuf.py

@@ -183,7 +183,7 @@ async def test_protobuf_schema_compatibility_dependencies(registry_async_client:
         json={"schemaType": "PROTOBUF", "schema": evolved_schema, "references": evolved_references},
     )
     assert res.status_code == 200
-    assert res.json() == {"is_compatible": False}
+    assert res.json().get("is_compatible") is False
 
 
 @pytest.mark.parametrize("trail", ["", "/"])
@@ -271,7 +271,7 @@ async def test_protobuf_schema_compatibility_dependencies1(registry_async_client
         json={"schemaType": "PROTOBUF", "schema": evolved_schema, "references": evolved_references},
     )
     assert res.status_code == 200
-    assert res.json() == {"is_compatible": False}
+    assert res.json().get("is_compatible") is False
 
 
 # Do compatibility check when message field is altered from referenced type to google type
@@ -339,7 +339,7 @@ async def test_protobuf_schema_compatibility_dependencies1g(registry_async_clien
         json={"schemaType": "PROTOBUF", "schema": evolved_schema},
     )
     assert res.status_code == 200
-    assert res.json() == {"is_compatible": False}
+    assert res.json().get("is_compatible") is False
 
 
 # Do compatibility check when message field is altered from google type to referenced type
@@ -407,7 +407,7 @@ async def test_protobuf_schema_compatibility_dependencies1g_otherway(registry_as
         json={"schemaType": "PROTOBUF", "schema": evolved_schema, "references": container_references},
     )
     assert res.status_code == 200
-    assert res.json() == {"is_compatible": False}
+    assert res.json().get("is_compatible") is False
 
 
 @pytest.mark.parametrize("trail", ["", "/"])
@@ -491,7 +491,7 @@ async def test_protobuf_schema_compatibility_dependencies2(registry_async_client
         json={"schemaType": "PROTOBUF", "schema": evolved_schema, "references": evolved_references},
     )
     assert res.status_code == 200
-    assert res.json() == {"is_compatible": False}
+    assert res.json().get("is_compatible") is False
 
 
 SIMPLE_SCHEMA = """\

tests/integration/test_schema.py

@@ -332,7 +332,8 @@ async def test_compatibility_endpoint(registry_async_client: Client, trail: str)
         json={"schema": json.dumps(schema)},
     )
     assert res.status_code == 200
-    assert res.json() == {"is_compatible": False}
+    assert res.json().get("is_compatible") is False
+    assert res.json().get("incompatibilities") == "reader type: string not compatible with writer type: int"
 
 
 @pytest.mark.parametrize("trail", ["", "/"])
@@ -536,7 +537,7 @@ def _test_cases():
             json={"schema": json.dumps(schema)},
         )
         assert res.status_code == 200
-        assert res.json() == {"is_compatible": expected}
+        assert res.json().get("is_compatible") == expected
 
 
 @pytest.mark.parametrize("trail", ["", "/"])
@@ -3243,7 +3244,7 @@ async def test_schema_non_compliant_name_in_existing(
         json={"schema": json.dumps(evolved_schema)},
     )
     assert res.status_code == 200
-    assert not res.json().get("is_compatible")
+    assert res.json().get("is_compatible") is False
 
     # Post evolved schema, should not be compatible and rejected.
     res = await registry_async_client.post(
@@ -3253,7 +3254,10 @@ async def test_schema_non_compliant_name_in_existing(
     assert res.status_code == 409
     assert res.json() == {
         "error_code": 409,
-        "message": "Incompatible schema, compatibility_mode=BACKWARD expected: compliant_name_test.test-schema",
+        "message": (
+            "Incompatible schema, compatibility_mode=BACKWARD. "
+            "Incompatibilities: expected: compliant_name_test.test-schema"
+        ),
     }
 
     # Send compatibility configuration for subject that disabled backwards compatibility.

tests/integration/test_schema_protobuf.py

@@ -1123,8 +1123,8 @@ async def test_protobuf_error(registry_async_client: Client) -> None:
         expected=409,
         expected_msg=(
             # ACTUALLY THERE NO MESSAGE_DROP!!!
-            "Incompatible schema, compatibility_mode=BACKWARD "
-            "Incompatible modification Modification.MESSAGE_DROP found"
+            "Incompatible schema, compatibility_mode=BACKWARD. "
+            "Incompatibilities: Incompatible modification Modification.MESSAGE_DROP found"
         ),
     )
     print(f"Adding new schema, subject: '{testdata.subject}'\n{testdata.schema_str}")