builder: better and unified result value

When returning the result from the task handler function, return
a more complete and structured object in all cases. The name of
the sub-object is named after the service the item belongs to;
specifically composer is used for what belongs to (osbuild)-composer.

plugins/builder/osbuild.py

@@ -313,17 +313,18 @@ class OSBuildImage(BaseTaskHandler):
         self.logger.debug("Waiting for comose to finish")
         status = client.wait_for_compose(cid)
 
-        if not status.is_success:
-            self.logger.error("Compose failed: %s", str(status))
-            return {
-                'koji_builds': []
-            }
 
-        return {
-            'koji_builds': [bid],
-            'composer_id': cid,
-            'build': bid,
+        result = {
+            "status": status.status,
+            "composer": {
+                "server": self.composer_url,
+                "id": cid
+            },
+            "koji": {
+                "build": bid
+            }
         }
+        return result
 
 
 # Stand alone osbuild composer API client executable

test/unit/test_builder.py

@@ -346,7 +346,7 @@ class TestBuilderPlugin(PluginTest):
 
         res = handler.handler(*args)
         assert res, "invalid compose result"
-        compose_id = res["composer_id"]
+        compose_id = res["composer"]["id"]
         compose = composer.composes.get(compose_id)
         self.assertIsNotNone(compose)