Enable anonymous S3 access by default

src/hats/io/file_io/__init__.py

@@ -22,5 +22,6 @@
     find_files_matching_path,
     get_directory_contents,
     get_upath,
+    get_upath_for_protocol,
     is_regular_file,
 )

src/hats/io/file_io/file_pointer.py

@@ -11,7 +11,19 @@ def get_upath(path: str | Path | UPath) -> UPath:
         return None
     if isinstance(path, UPath):
         return path
-    return UPath(path)
+    return get_upath_for_protocol(path)
+
+
+def get_upath_for_protocol(path: str | Path) -> UPath:
+    """Create UPath with protocol-specific configurations.
+
+    If we access pointers on S3 and credentials are not found we assume
+    an anonymous access, i.e., that the bucket is public.
+    """
+    upath = UPath(path)
+    if upath.protocol == "s3":
+        upath = UPath(path, anon=True)
+    return upath
 
 
 def append_paths_to_pointer(pointer: str | Path | UPath, *paths: str) -> UPath:

tests/hats/catalog/loaders/test_read_hats.py

@@ -1,3 +1,4 @@
+from hats.io.file_io import get_upath_for_protocol
 from hats.loaders import read_hats
 
 
@@ -17,3 +18,17 @@ def test_read_hats_branches(
     read_hats(margin_catalog_path)
     read_hats(small_sky_source_dir)
     read_hats(test_data_dir / "square_map")
+
+
+def test_read_hats_initializes_upath_once(small_sky_dir, mocker):
+    mock_method = "hats.io.file_io.file_pointer.get_upath_for_protocol"
+    # Setting the side effect allows us to run the mocked function's code
+    mocked_upath_call = mocker.patch(mock_method, side_effect=get_upath_for_protocol)
+    read_hats(small_sky_dir)
+    # The construction of the UPath is called once, at the start of `read_hats`
+    mocked_upath_call.assert_called_once_with(small_sky_dir)
+
+
+def test_read_hats_with_s3_anonymous_access():
+    upath = get_upath_for_protocol("s3://bucket/catalog")
+    assert upath.storage_options.get("anon")