Checkpoint new build orchestrator

Test: rm -rf out && multitree_build
Change-Id: Ic274182f0925f30d56227597b65e5b9ef3b19707

orchestrator/core/interrogate.py

@@ -0,0 +1,29 @@
+#
+# Copyright (C) 2022 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import json
+import os
+
+def interrogate_tree(tree_key, inner_tree, cookie):
+    inner_tree.invoke(["describe"])
+
+    info_json_filename = inner_tree.out.tree_info_file()
+
+    # TODO: Error handling
+    with open(info_json_filename) as f:
+        info_json = json.load(f)
+
+    # TODO: Check orchestrator protocol
+