Prevent completely empty files

aurora/foundry/common/channel.py

@@ -251,7 +251,9 @@ def _mark(self, name: str) -> None:
         with tempfile.TemporaryDirectory() as td:
             mark_file_path = Path(td) / f"{name}.finished"
             mark_file_path.parent.mkdir(exist_ok=True, parents=True)
-            mark_file_path.touch()
+            # Write a few bytes to the file. Blob storage has behaved weirdly for empty files.
+            with open(mark_file_path, "wb") as f:
+                f.write(b"File is available")
             self._azcopy(["copy", str(mark_file_path), self._blob_path(f"{name}.finished")])
 
     def _is_marked(self, name: str) -> bool:

aurora/foundry/server/score.py

@@ -161,7 +161,7 @@ def run(input_data: AMLRequest) -> dict:
                 logger.info("Initial condition was found. Submitting task.")
                 # Send an acknowledgement back to test that the host can write. The client will
                 # check for this acknowledgement.
-                channel.write(b"", task_id, "input.nc.ack")
+                channel.write(b"Acknowledgement of initial condition", task_id, "input.nc.ack")
 
                 # Queue the task.
                 task.task_info.submitted = True