Add Default Path (#12)

### Description
<!---Why are we making this change? What does it do?--->
title
### Testing
<!---How was this tested?--->

![image](https://github.com/user-attachments/assets/3403dbfc-b8da-4ba0-af15-70c9a08e435d)

### Impact
<!---What components does this impact? How can it affect prod?--->

### Other
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when reviewing the PR?--->

Author: echavemann

.gitignore

@@ -6,3 +6,4 @@ __pycache__
 .ruff_cache
 .mypy_cache
 *.so
+dist

lens/core.py

@@ -7,13 +7,18 @@
 from lens.util.hostname import check_valid_lens_hostname, get_hostname
 from lens.util.paths import check_file_structure_correct, check_metadata_exists, check_metadata_version_match
 
+DEFAULT_PATH = Path("/pool/lens")
+
 
 class Lens:
     def __init__(self) -> None:
         self.started = False
         self.descriptor: DataDescriptor
 
-    def startup(self, data_root: Path) -> None:
+    def startup(self, data_root: Path | None) -> None:
+        if data_root is None:
+            logger.info("No path specified - falling back to default path.")
+            data_root = DEFAULT_PATH
         self._startup_check_hostname()
         self._startup_check_metadata(data_root)
         self._startup_check_files(data_root)

lens/main.py

@@ -9,20 +9,22 @@
 
 def parse_arguments() -> Any:
     parser = argparse.ArgumentParser()
-    parser.add_argument("-d", "--directory", type=str, required=True)
+    parser.add_argument("-d", "--directory", type=str, required=False)
 
     args = parser.parse_args()
     return args
 
 
 @logger.catch
-def main(data_root: Path) -> None:
+def main(data_root: Path | None) -> None:
     ln = Lens()
     logger.info("Starting lens initialization check.")
     ln.startup(data_root)
 
 
 if __name__ == "__main__":
     args = parse_arguments()
-    data_root = Path(args.directory)
-    main(data_root)
+    specified_root = args.directory
+    if specified_root is not None:
+        specified_root = Path(specified_root)
+    main(specified_root)