Make logging.yml read by default

docs/source/logging/index.md

@@ -42,6 +42,17 @@
 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, including the logging configuration file. However, changing `CONF_SOURCE` does not automatically update the path to `logging.yml`. To use a custom location or filename for the logging configuration, you must explicitly set the `KEDRO_LOGGING_CONFIG` environment variable.
+
+By default, Kedro looks for a file named `logging.yml` in the `conf` directory. If you move or rename your logging configuration file after changing `CONF_SOURCE`, specify the new path using the `KEDRO_LOGGING_CONFIG` environment variable:
+```bash
+export KEDRO_LOGGING_CONFIG=<project_root>/custom_config_folder/custom_logging_name.yml
+```
+
+Please note that adjusting `CONF_SOURCE` or renaming `logging.yml` without updating the logging configuration accordingly can lead to Kedro not locating the 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

@@ -216,13 +216,34 @@ 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))
 
+        # Log info about the logging configuration
+        if not user_logging_path and default_logging_path == Path("conf/logging.yml"):
+            logger = logging.getLogger(__name__)
+            logger.info(
+                f"Using `{path}` as logging configuration. "
+                f"You can change this by setting the KEDRO_LOGGING_CONFIG environment variable accordingly."
+            )
+
     def configure(self, logging_config: dict[str, Any]) -> None:
         """Configure project logging using ``logging_config`` (e.g. from project
         logging.yml). We store this in the UserDict data so that it can be reconfigured

tests/framework/project/test_logging.py

@@ -144,3 +144,33 @@ def test_rich_traceback_disabled_on_databricks(
 
     rich_traceback_install.assert_not_called()
     rich_pretty_install.assert_called()
+
+
+def test_default_logging_info_emission(monkeypatch, capsys):
+    # Expected path and logging configuration
+    expected_path = Path("conf/logging.yml")
+    dummy_logging_config = yaml.dump(
+        {"version": 1, "loggers": {"kedro": {"level": "INFO"}}}
+    )
+
+    # Setup environment and path mocks
+    monkeypatch.delenv("KEDRO_LOGGING_CONFIG", raising=False)
+    monkeypatch.setattr(Path, "exists", lambda x: x == expected_path)
+    monkeypatch.setattr(
+        Path,
+        "read_text",
+        lambda x, encoding="utf-8": dummy_logging_config
+        if x == expected_path
+        else FileNotFoundError("File not found"),
+    )
+
+    from kedro.framework.project import _ProjectLogging
+
+    _ProjectLogging()
+
+    captured = capsys.readouterr()
+
+    expected_message = f"Using `{expected_path}`"
+    assert (
+        expected_message in captured.out
+    ), f"Expected message not found in logs: {captured.out}"