Update config.py

settings/config.py

@@ -1,33 +1,79 @@
 from pathlib import Path
+from typing import Type
 
-from pydantic_settings import BaseSettings, PydanticBaseSettingsSource, SettingsConfigDict, YamlConfigSettingsSource
+from pydantic_settings import (
+    BaseSettings,
+    PydanticBaseSettingsSource,
+    SettingsConfigDict,
+    YamlConfigSettingsSource,
+)
 
+# Assuming settings.models is available and contains ChainConfig class.
 import settings.models as DataModels
 
+# Define the base directory of the project, typically two levels up from this file.
 BASE_DIR = Path(__file__).resolve().parent.parent
-settings = DataModels.Settings()
 
 
-def get_chain_settings(chain_config_file: str):
-    config_file = Path(BASE_DIR, "settings", "chains", f"{chain_config_file}")
+def get_chain_settings(chain_config_file: str) -> DataModels.ChainConfig:
+    """
+    Dynamically loads chain-specific configuration from a YAML file.
 
+    This method uses Pydantic's custom settings sources to ensure the YAML file
+    is loaded and prioritized before environment variables or other sources.
+
+    :param chain_config_file: The name of the chain configuration YAML file (e.g., 'ethereum.yaml').
+    :return: An instance of ChainConfig loaded with data from the specified file.
+    :raises FileNotFoundError: If the specified configuration file does not exist.
+    """
+    # 1. Construct the absolute path to the configuration file.
+    config_path = BASE_DIR / "settings" / "chains" / chain_config_file
+
+    # Check if the file exists to provide an early and clearer error message.
+    if not config_path.exists():
+        raise FileNotFoundError(f"Chain configuration file not found at: {config_path}")
+
+    # 2. Define a specialized Pydantic BaseSettings class dynamically.
+    # This nested class inherits the structure (fields) but customizes the source (where data comes from).
     class YamlChainConfig(DataModels.ChainConfig):
-        model_config = SettingsConfigDict(yaml_file=config_file)
-        file_path: str = chain_config_file
-        file_name: str = config_file.stem
+        # Optional: Add metadata fields to the instance, derived from the file path.
+        # These are not Pydantic fields, just class attributes for context.
+        file_path: str = str(config_path)
+        file_name: str = config_path.stem
+
+        # Pydantic configuration dictionary.
+        model_config = SettingsConfigDict(
+            # Ignore extra fields found in the YAML for robustness.
+            extra='ignore'
+        )
 
         @classmethod
         def settings_customise_sources(
-            cls,
-            settings_cls: type[BaseSettings],
+            cls: Type[BaseSettings],
+            settings_cls: Type[BaseSettings],
             init_settings: PydanticBaseSettingsSource,
             env_settings: PydanticBaseSettingsSource,
             dotenv_settings: PydanticBaseSettingsSource,
             file_secret_settings: PydanticBaseSettingsSource,
         ) -> tuple[PydanticBaseSettingsSource, ...]:
-            sources = super().settings_customise_sources(
+            """
+            Overrides the default source loading order.
+
+            It places the YAML configuration source first, guaranteeing that values
+            from the file are loaded and prioritized over all subsequent sources
+            (like environment variables).
+            """
+            # Create the YAML source instance.
+            yaml_source = YamlConfigSettingsSource(settings_cls, yaml_file=config_path)
+
+            # Retrieve default sources from the base class.
+            default_sources = super().settings_customise_sources(
                 settings_cls, init_settings, env_settings, dotenv_settings, file_secret_settings
             )
-            return YamlConfigSettingsSource(settings_cls, yaml_file=config_file), *sources
 
+            # Prepend the YAML source to the tuple of default sources.
+            return (yaml_source, *default_sources)
+
+    # 3. Instantiate the dynamically configured class. Pydantic automatically
+    # loads the data from the customized sources upon instantiation.
     return YamlChainConfig()