fix(volumecache): treat a scalar dirs path as a single directory

Passing dirs as a bare string/Path (e.g. dirs="/root/.cache") iterated it
character by character, putting entries like "/" into _dirs and making
sync/hydrate walk far broader paths than intended. Normalize scalar
str/bytes/PathLike input to a one-element list. Addresses capy-ai review
on PR #531.

Author: deanq

runpod/serverless/utils/rp_volume_cache.py

@@ -57,6 +57,10 @@ class VolumeCache:
     _EXCLUDE_SUBSTRINGS = (os.sep + "refs" + os.sep, os.sep + ".no_exist" + os.sep)
 
     def __init__(self, dirs, *, namespace=None, volume_path="/runpod-volume", best_effort=True):
+        if isinstance(dirs, (str, bytes, os.PathLike)):
+            # A bare path is one directory, not an iterable of path characters:
+            # `dirs="/root/.cache"` must not be split into "/", "r", "o", ...
+            dirs = [dirs]
         self._dirs = [os.path.realpath(os.fspath(d)) for d in dirs]
         self._namespace = namespace or os.environ.get("RUNPOD_ENDPOINT_ID") or ""
         if self._namespace and (

tests/test_serverless/test_utils/test_rp_volume_cache.py

@@ -78,6 +78,24 @@ def test_namespace_accepts_normal_value(tmp_path):
     assert vc._namespace == "ep1"
 
 
+def test_scalar_dirs_path_is_treated_as_single_dir(tmp_path):
+    # A bare string/Path must be one directory, not iterated character-by-character
+    # (which would put "/" and other roots into _dirs).
+    vol = tmp_path / "volume"
+    vol.mkdir()
+    cache = tmp_path / "cache"
+    expected = [os.path.realpath(str(cache))]
+
+    vc_str = VolumeCache(str(cache), namespace="ep1", volume_path=str(vol))
+    assert vc_str._dirs == expected
+
+    vc_path = VolumeCache(cache, namespace="ep1", volume_path=str(vol))  # os.PathLike
+    assert vc_path._dirs == expected
+
+    vc_list = VolumeCache([str(cache)], namespace="ep1", volume_path=str(vol))
+    assert vc_list._dirs == expected  # list input still works
+
+
 # --------------------------------------------------------------------------- #
 # sync -> hydrate round trip
 # --------------------------------------------------------------------------- #