Fix save_hyperparameters() for top-level CLI (Lightning-AI#1103)

litgpt/utils.py

@@ -403,6 +403,21 @@ def save_hyperparameters(function: callable, checkpoint_dir: Path) -> None:
     """Captures the CLI parameters passed to `function` without running `function` and saves them to the checkpoint."""
     from jsonargparse import capture_parser
 
+    # TODO: Make this more robust
+    # This hack strips away the subcommands from the top-level CLI
+    # to parse the file as if it was called as a script
+    known_commands = [
+        ("finetune", "full"),
+        ("finetune", "lora"),
+        ("finetune", "adapter"),
+        ("finetune", "adapter_v2"),
+        ("pretrain",),
+    ]
+    for known_command in known_commands:
+        unwanted = slice(1, 1 + len(known_command))
+        if tuple(sys.argv[unwanted]) == known_command:
+            sys.argv[unwanted] = []
+
     parser = capture_parser(lambda: CLI(function))
     config = parser.parse_args()
     parser.save(config, checkpoint_dir / "hyperparameters.yaml", overwrite=True)

tests/test_utils.py

@@ -251,6 +251,32 @@ def test_save_hyperparameters(tmp_path):
     assert hparams["bar"] == 1
 
 
+def _test_function2(out_dir: Path, foo: bool = False, bar: int = 1):
+    assert False, "I only exist as a signature, but I should not run."
+
+
+@pytest.mark.parametrize("command", [
+    "any.py",
+    "litgpt finetune full",
+    "litgpt finetune lora",
+    "litgpt finetune adapter",
+    "litgpt finetune adapter_v2",
+    "litgpt pretrain",
+])
+def test_save_hyperparameters_known_commands(command, tmp_path):
+    from litgpt.utils import save_hyperparameters
+
+    with mock.patch("sys.argv", [*command.split(" "), "--out_dir", str(tmp_path), "--foo", "True"]):
+        save_hyperparameters(_test_function2, tmp_path)
+
+    with open(tmp_path / "hyperparameters.yaml", "r") as file:
+        hparams = yaml.full_load(file)
+
+    assert hparams["out_dir"] == str(tmp_path)
+    assert hparams["foo"] is True
+    assert hparams["bar"] == 1
+
+
 def test_choose_logger(tmp_path):
     from litgpt.utils import choose_logger