Fix config structure enforcing and typechecking. Add full Tuner suppo…

…rt. (#133)

* Fix config structure enforcing and typechecking. Add full Tuner support.

* Fix config loading when in parse_config()

* Improve error message when CLI command is incorrect

* Reduce system's learning_rate property docs

lighter/system.py

@@ -361,6 +361,20 @@ def setup(self, stage: str) -> None:
             self.predict_dataloader = partial(self._base_dataloader, mode="predict")
             self.predict_step = partial(self._base_step, mode="predict")
 
+    @property
+    def learning_rate(self) -> float:
+        """Get the learning rate of the optimizer. Ensures compatibility with the Tuner's 'lr_find()' method."""
+        if len(self.optimizer.param_groups) > 1:
+            raise ValueError("The learning rate is not available when there are multiple optimizer parameter groups.")
+        return self.optimizer.param_groups[0]["lr"]
+
+    @learning_rate.setter
+    def learning_rate(self, value) -> None:
+        """Set the learning rate of the optimizer. Ensures compatibility with the Tuner's 'lr_find()' method."""
+        if len(self.optimizer.param_groups) > 1:
+            raise ValueError("The learning rate is not available when there are multiple optimizer parameter groups.")
+        self.optimizer.param_groups[0]["lr"] = value
+
     def _init_placeholders_for_dataloader_and_step_methods(self) -> None:
         """
         Initializes placeholders for dataloader and step methods.

lighter/utils/misc.py

@@ -119,13 +119,23 @@ def apply_fns(data: Any, fns: Union[Callable, List[Callable]]) -> Any:
 
 def get_optimizer_stats(optimizer: Optimizer) -> Dict[str, float]:
     """
-    Extract learning rates and momentum values from each parameter group of the optimizer.
+    Extract learning rates and momentum values from an optimizer into a dictionary.
+
+    This function iterates over the parameter groups of the given optimizer and collects
+    the learning rate and momentum (or beta values) for each group. The collected values
+    are stored in a dictionary with keys formatted to indicate the optimizer type and
+    parameter group index (if multiple groups are present).
 
     Args:
-        optimizer (Optimizer): A PyTorch optimizer.
+        optimizer (Optimizer): A PyTorch optimizer instance.
 
     Returns:
-        Dictionary with formatted keys and values for learning rates and momentum.
+        Dict[str, float]: A dictionary containing the learning rates and momentum values
+        for each parameter group in the optimizer. The keys are formatted as:
+        - "optimizer/{optimizer_class_name}/lr" for learning rates
+        - "optimizer/{optimizer_class_name}/momentum" for momentum values
+        If there are multiple parameter groups, the keys will include the group index, e.g.,
+        "optimizer/{optimizer_class_name}/lr/group1".
     """
     stats_dict = {}
     for group_idx, group in enumerate(optimizer.param_groups):

lighter/utils/runner.py

@@ -1,22 +1,45 @@
 from typing import Any
 
+import copy
 from functools import partial
 
 import fire
 from monai.bundle.config_parser import ConfigParser
-from pytorch_lightning import seed_everything
+from pytorch_lightning import Trainer, seed_everything
+from pytorch_lightning.tuner import Tuner
 
 from lighter.system import LighterSystem
 from lighter.utils.dynamic_imports import import_module_from_path
 
-CONFIG_STRUCTURE = {"project": None, "system": {}, "trainer": {}, "args": {}, "vars": {}}
-TRAINER_METHOD_NAMES = ["fit", "validate", "test", "predict", "lr_find", "scale_batch_size"]
+CONFIG_STRUCTURE = {
+    "project": None,
+    "vars": {},
+    "args": {
+        # Keys - names of the methods; values - arguments passed to them.
+        "fit": {},
+        "validate": {},
+        "test": {},
+        "predict": {},
+        "lr_find": {},
+        "scale_batch_size": {},
+    },
+    "system": {},
+    "trainer": {},
+}
 
 
 def cli() -> None:
     """Defines the command line interface for running lightning trainer's methods."""
-    commands = {method: partial(run, method) for method in TRAINER_METHOD_NAMES}
-    fire.Fire(commands)
+    commands = {method: partial(run, method) for method in CONFIG_STRUCTURE["args"]}
+    try:
+        fire.Fire(commands)
+    except TypeError as e:
+        if "run() takes 1 positional argument but" in str(e):
+            raise ValueError(
+                "Ensure that only one command is run at a time (e.g., 'lighter fit') and that "
+                "other command line arguments start with '--' (e.g., '--config', '--system#batch_size=1')."
+            ) from e
+        raise
 
 
 def parse_config(**kwargs) -> ConfigParser:
@@ -29,25 +52,24 @@ def parse_config(**kwargs) -> ConfigParser:
     Returns:
         An instance of ConfigParser with configuration and overrides merged and parsed.
     """
-    # Ensure a config file is specified.
     config = kwargs.pop("config", None)
     if config is None:
         raise ValueError("'--config' not specified. Please provide a valid configuration file.")
 
-    # Read the config file and update it with overrides.
-    parser = ConfigParser(CONFIG_STRUCTURE, globals=False)
-    parser.read_config(config)
+    # Create a deep copy to ensure the original structure remains unaltered by ConfigParser.
+    structure = copy.deepcopy(CONFIG_STRUCTURE)
+    # Initialize the parser with the predefined structure.
+    parser = ConfigParser(structure, globals=False)
+    # Update the parser with the configuration file.
+    parser.update(parser.load_config_files(config))
+    # Update the parser with the provided cli arguments.
     parser.update(kwargs)
     return parser
 
 
 def validate_config(parser: ConfigParser) -> None:
     """
-    Validates the configuration parser against predefined structures and allowed method names.
-
-    This function checks if the keys in the top-level of the configuration parser are valid according to the
-    CONFIG_STRUCTURE. It also verifies that the 'args' section of the configuration only contains keys that
-    correspond to valid trainer method names as defined in TRAINER_METHOD_NAMES.
+    Validates the configuration parser against predefined structure.
 
     Args:
         parser (ConfigParser): The configuration parser instance to validate.
@@ -56,20 +78,28 @@ def validate_config(parser: ConfigParser) -> None:
         ValueError: If there are invalid keys in the top-level configuration.
         ValueError: If there are invalid method names specified in the 'args' section.
     """
-    # Validate parser keys against structure
-    root_keys = parser.get().keys()
-    invalid_root_keys = set(root_keys) - set(CONFIG_STRUCTURE.keys()) - {"_meta_", "_requires_"}
+    invalid_root_keys = set(parser.get()) - set(CONFIG_STRUCTURE)
     if invalid_root_keys:
-        raise ValueError(f"Invalid top-level config keys: {invalid_root_keys}. Allowed keys: {CONFIG_STRUCTURE.keys()}")
+        raise ValueError(f"Invalid top-level config keys: {invalid_root_keys}. Allowed keys: {list(CONFIG_STRUCTURE)}.")
 
-    # Validate that 'args' contains only valid trainer method names.
-    args_keys = parser.get("args", {}).keys()
-    invalid_args_keys = set(args_keys) - set(TRAINER_METHOD_NAMES)
+    invalid_args_keys = set(parser.get("args")) - set(CONFIG_STRUCTURE["args"])
     if invalid_args_keys:
-        raise ValueError(f"Invalid trainer method in 'args': {invalid_args_keys}. Allowed methods are: {TRAINER_METHOD_NAMES}")
-
-
-def run(method: str, **kwargs: Any):
+        raise ValueError(f"Invalid key in 'args': {invalid_args_keys}. Allowed keys: {list(CONFIG_STRUCTURE['args'])}.")
+
+    typechecks = {
+        "project": (str, type(None)),
+        "vars": dict,
+        "system": dict,
+        "trainer": dict,
+        "args": dict,
+        **{f"args#{k}": dict for k in CONFIG_STRUCTURE["args"]},
+    }
+    for key, dtype in typechecks.items():
+        if not isinstance(parser.get(key), dtype):
+            raise ValueError(f"Invalid value for key '{key}'. Expected a {dtype}.")
+
+
+def run(method: str, **kwargs: Any) -> None:
     """Run the trainer method.
 
     Args:
@@ -82,30 +112,36 @@ def run(method: str, **kwargs: Any):
     parser = parse_config(**kwargs)
     validate_config(parser)
 
-    # Import the project folder as a module, if specified.
+    # Project. If specified, the give path is imported as a module.
     project = parser.get_parsed_content("project")
     if project is not None:
         import_module_from_path("project", project)
 
-    # Get the main components from the parsed config.
+    # System
     system = parser.get_parsed_content("system")
+    if not isinstance(system, LighterSystem):
+        raise ValueError("Expected 'system' to be an instance of 'LighterSystem'")
+
+    # Trainer
     trainer = parser.get_parsed_content("trainer")
-    trainer_method_args = parser.get_parsed_content(f"args#{method}", default={})
+    if not isinstance(trainer, Trainer):
+        raise ValueError("Expected 'trainer' to be an instance of PyTorch Lightning 'Trainer'")
 
-    # Checks
-    if not isinstance(system, LighterSystem):
-        raise ValueError(f"Expected 'system' to be an instance of LighterSystem, got {system.__class__.__name__}.")
-    if not hasattr(trainer, method):
-        raise ValueError(f"{trainer.__class__.__name__} has no method named '{method}'.")
-    if any("dataloaders" in key or "datamodule" in key for key in trainer_method_args):
-        raise ValueError("All dataloaders should be defined as part of the LighterSystem, not passed as method arguments.")
-
-    # Save the config to checkpoints under "hyper_parameters" and log it if a logger is defined.
-    config = parser.get()
-    config.pop("_meta_")  # MONAI Bundle adds this automatically, remove it.
-    system.save_hyperparameters(config)
-    if trainer.logger is not None:
-        trainer.logger.log_hyperparams(config)
+    # Trainer/Tuner method arguments.
+    method_args = parser.get_parsed_content(f"args#{method}")
+    if any("dataloaders" in key or "datamodule" in key for key in method_args):
+        raise ValueError("Datasets are defined within the 'system', not passed in `args`.")
 
-    # Run the trainer method.
-    getattr(trainer, method)(system, **trainer_method_args)
+    # Save the config to checkpoints under "hyper_parameters". Log it if a logger is defined.
+    system.save_hyperparameters(parser.get())
+    if trainer.logger is not None:
+        trainer.logger.log_hyperparams(parser.get())
+
+    # Run the trainer/tuner method.
+    if hasattr(trainer, method):
+        getattr(trainer, method)(system, **method_args)
+    elif hasattr(Tuner, method):
+        tuner = Tuner(trainer)
+        getattr(tuner, method)(system, **method_args)
+    else:
+        raise ValueError(f"Method '{method}' is not a valid Trainer or Tuner method [{list(CONFIG_STRUCTURE['args'])}].")