Add outputfile option to inspect (mlcommons#340)

New CLI argument (`--output-file`, `--output_file`) for the mlcube's `inspect` command can be used to specify the file to save inspect results.

mlcube/mlcube/__main__.py

@@ -1,6 +1,7 @@
 """This requires the MLCube 2.0 that's located somewhere in one of dev branches."""
 import logging
 import os
+from pathlib import Path
 import shutil
 import sys
 import typing as t
@@ -666,28 +667,49 @@ def create() -> None:
     default="json",
     help="Format for reporting results.",
 )
+@click.option(
+    "--output-file",
+    "--output_file",
+    required=False,
+    type=str,
+    default=None,
+    help="File path to store the MLCube information. Defaults to print to STDOUT",
+)
 @Options.help
 def inspect(
-    mlcube: t.Optional[str], platform: str, force: bool = False, format_: str = "json"
+    mlcube: t.Optional[str],
+    platform: str,
+    force: bool = False,
+    format_: str = "json",
+    output_file: t.Optional[str] = None,
 ) -> None:
     """Return low-level information on MLCube objects."""
     runner_cls, mlcube_config = parse_cli_args(
         parsed_args={"mlcube": mlcube, "platform": platform},
         unparsed_args=[],
         resolve=True,
     )
+    if output_file is None:
+        output_stream = sys.stdout
+    else:
+        dir_path = Path(output_file).resolve().parent
+        dir_path.mkdir(parents=True, exist_ok=True)
+        output_stream = open(output_file, "w")
+
     try:
         runner = runner_cls(mlcube_config, task=None)
         info: t.Dict = runner.inspect(force=force)
         logger.debug("inspect info=%s", info)
         if format_ == "json":
             import json
 
-            print(json.dumps(info))
+            json.dump(info, output_stream)
+            if output_stream == sys.stdout:
+                print()  # json doesn't print a newline
         else:
             import yaml
 
-            yaml.dump(info, sys.stdout)
+            yaml.dump(info, output_stream)
     except MLCubeError as err:
         print("MLCube inspect failed")
         logger.exception(err)