Improve http url glob error

xarray/backends/common.py

@@ -22,6 +22,7 @@
     NdimSizeLenMixin,
     attempt_import,
     emit_user_level_warning,
+    is_http_url,
     is_remote_uri,
 )
 from xarray.namedarray.parallelcompat import get_chunked_array_type
@@ -143,28 +144,31 @@ def _find_absolute_paths(
     ['common.py']
     """
     if isinstance(paths, str):
-        if is_remote_uri(paths) and kwargs.get("engine") == "zarr":
-            if TYPE_CHECKING:
-                import fsspec
+        if is_remote_uri(paths):
+            if not is_http_url(paths):
+                # remote uris that are not http are likely s3 or similar, which support globbing with fsspec
+
+                if TYPE_CHECKING:
+                    import fsspec
+                else:
+                    fsspec = attempt_import("fsspec")
+
+                fs, _, _ = fsspec.core.get_fs_token_paths(
+                    paths,
+                    mode="rb",
+                    storage_options=kwargs.get("backend_kwargs", {}).get(
+                        "storage_options", {}
+                    ),
+                    expand=False,
+                )
+                tmp_paths = fs.glob(fs._strip_protocol(paths))  # finds directories
+                return [fs.get_mapper(path) for path in tmp_paths]
             else:
-                fsspec = attempt_import("fsspec")
-
-            fs, _, _ = fsspec.core.get_fs_token_paths(
-                paths,
-                mode="rb",
-                storage_options=kwargs.get("backend_kwargs", {}).get(
-                    "storage_options", {}
-                ),
-                expand=False,
-            )
-            tmp_paths = fs.glob(fs._strip_protocol(paths))  # finds directories
-            return [fs.get_mapper(path) for path in tmp_paths]
-        elif is_remote_uri(paths):
-            raise ValueError(
-                "cannot do wild-card matching for paths that are remote URLs "
-                f"unless engine='zarr' is specified. Got paths: {paths}. "
-                "Instead, supply paths as an explicit list of strings."
-            )
+                raise ValueError(
+                    "cannot do wild-card matching for paths that are remote http URLs. "
+                    f"Got paths: {paths}. "
+                    "Instead, supply paths as an explicit list of strings."
+                )
         else:
             return sorted(glob(_normalize_path(paths)))
     elif isinstance(paths, os.PathLike):

xarray/core/utils.py

@@ -617,14 +617,22 @@ def close_on_error(f):
 
 
 def is_remote_uri(path: str) -> bool:
-    """Finds URLs of the form protocol:// or protocol::
+    """Matches URLs of the form protocol:// or protocol::
 
     This also matches for http[s]://, which were the only remote URLs
     supported in <=v0.16.2.
     """
     return bool(re.search(r"^[a-z][a-z0-9]*(\://|\:\:)", path))
 
 
+def is_http_url(path: str) -> bool:
+    """Matches URLs of the form http[s]://
+
+    Does not match for
+    """
+    return bool(re.search(r"^https?\://", path))
+
+
 def read_magic_number_from_file(filename_or_obj, count=8) -> bytes:
     # check byte header to determine file type
     if isinstance(filename_or_obj, bytes):

xarray/tests/test_backends.py

@@ -4741,11 +4741,11 @@ def test_open_mfdataset(self) -> None:
 
     @requires_fsspec
     def test_open_mfdataset_no_files(self) -> None:
-        pytest.importorskip("aiobotocore")
-
-        # glob is attempted as of #4823, but finds no files
-        with pytest.raises(OSError, match=r"no files"):
-            open_mfdataset("http://some/remote/uri", engine="zarr")
+        with pytest.raises(
+            ValueError,
+            match=r"cannot do wild-card matching for paths that are remote http URLs",
+        ):
+            open_mfdataset("http://some/remote/uri")
 
     def test_open_mfdataset_2d(self) -> None:
         original = Dataset({"foo": (["x", "y"], np.random.randn(10, 8))})

xarray/tests/test_utils.py

@@ -176,6 +176,15 @@ def test_is_remote_uri():
     assert utils.is_remote_uri("https://example.com")
     assert not utils.is_remote_uri(" http://example.com")
     assert not utils.is_remote_uri("example.nc")
+    assert utils.is_remote_uri("s3://bucket/example.nc")
+
+
+def test_is_http_url():
+    assert utils.is_http_url("http://example.com")
+    assert utils.is_http_url("https://example.com")
+    assert not utils.is_http_url(" http://example.com")
+    assert not utils.is_http_url("example.nc")
+    assert not utils.is_http_url("s3://bucket/example.nc")
 
 
 class Test_is_uniform_and_sorted: