Make logging.yml read by default

docs/source/logging/index.md

@@ -42,6 +42,19 @@ After setting the environment variable, any subsequent Kedro commands use the lo
 If the `KEDRO_LOGGING_CONFIG` environment variable is not set, Kedro will use the [default logging configuration](https://github.com/kedro-org/kedro/blob/main/kedro/framework/project/default_logging.yml).
 ```
 
+## Custom `CONF_SOURCE` with logging
+
+When you customise the [`CONF_SOURCE`](../configuration/configuration_basics.md#how-to-change-the-configuration-source-folder-at-runtime) setting in your Kedro project, it determines where Kedro looks for configuration files, it does not automatically affect where the `logging.yml` is searched for.
+
+By default, Kedro expects the logging configuration file to be located in the `conf` directory. If you change `CONF_SOURCE` and want to use a different location for your `logging.yml`, you must update the `KEDRO_LOGGING_CONFIG` environment variable to point to the new location of your logging configuration.
+
+For example:
+```bash
+export KEDRO_LOGGING_CONFIG=<project_root>/custom_config_folder/logging.yml
+```
+
+Please note that adjusting `CONF_SOURCE` without updating the logging configuration accordingly can lead to Kedro not locating the `logging.yml` file, which will result in the default logging settings being used instead.
+
 ### How to show DEBUG level messages
 To see `DEBUG` level messages, change the level of logging in your project-specific logging configuration file (`logging.yml`). We provide a `logging.yml` template:
 

kedro/framework/project/__init__.py

@@ -216,10 +216,23 @@ def configure(self, pipelines_module: str | None = None) -> None:
 class _ProjectLogging(UserDict):
     def __init__(self) -> None:
         """Initialise project logging. The path to logging configuration is given in
-        environment variable KEDRO_LOGGING_CONFIG (defaults to default_logging.yml)."""
-        path = os.environ.get(
-            "KEDRO_LOGGING_CONFIG", Path(__file__).parent / "default_logging.yml"
-        )
+        environment variable KEDRO_LOGGING_CONFIG (defaults to conf/logging.yml)."""
+
+        # Check if a user path is set in the environment variable
+        user_logging_path = os.environ.get("KEDRO_LOGGING_CONFIG")
+
+        # Check if the default logging configuration exists
+        default_logging_path = Path("conf/logging.yml")
+        if not default_logging_path.exists():
+            default_logging_path = Path(__file__).parent / "default_logging.yml"
+
+        # Use the user path if available, otherwise, use the default path
+        if user_logging_path and Path(user_logging_path).exists():
+            path = Path(user_logging_path)
+        else:
+            path = default_logging_path
+
+        # Load and apply the logging configuration
         logging_config = Path(path).read_text(encoding="utf-8")
         self.configure(yaml.safe_load(logging_config))