Properly closes zarr groups in zarr store (#8425)

Co-authored-by: Maximilian Roos <[email protected]>
Co-authored-by: Anderson Banihirwe <[email protected]>

doc/whats-new.rst

@@ -174,6 +174,9 @@ Bug fixes
 - Fix a bug where :py:meth:`DataArray.to_dataset` silently drops a variable
   if a coordinate with the same name already exists (:pull:`8433`, :issue:`7823`).
   By `András Gunyhó <https://github.com/mgunyho>`_.
+- Fix for :py:meth:`DataArray.to_zarr` & :py:meth:`Dataset.to_zarr` to close
+  the created zarr store when passing a path with `.zip` extension (:pull:`8425`).
+  By `Carl Andersson <https://github.com/CarlAndersson>_`.
 
 Documentation
 ~~~~~~~~~~~~~

xarray/backends/zarr.py

@@ -381,6 +381,7 @@ class ZarrStore(AbstractWritableDataStore):
         "_write_region",
         "_safe_chunks",
         "_write_empty",
+        "_close_store_on_close",
     )
 
     @classmethod
@@ -464,6 +465,7 @@ def open_group(
             zarr_group = zarr.open_consolidated(store, **open_kwargs)
         else:
             zarr_group = zarr.open_group(store, **open_kwargs)
+        close_store_on_close = zarr_group.store is not store
         return cls(
             zarr_group,
             mode,
@@ -472,6 +474,7 @@ def open_group(
             write_region,
             safe_chunks,
             write_empty,
+            close_store_on_close,
         )
 
     def __init__(
@@ -483,6 +486,7 @@ def __init__(
         write_region=None,
         safe_chunks=True,
         write_empty: bool | None = None,
+        close_store_on_close: bool = False,
     ):
         self.zarr_group = zarr_group
         self._read_only = self.zarr_group.read_only
@@ -494,6 +498,7 @@ def __init__(
         self._write_region = write_region
         self._safe_chunks = safe_chunks
         self._write_empty = write_empty
+        self._close_store_on_close = close_store_on_close
 
     @property
     def ds(self):
@@ -762,7 +767,8 @@ def set_variables(self, variables, check_encoding_set, writer, unlimited_dims=No
             writer.add(v.data, zarr_array, region)
 
     def close(self):
-        pass
+        if self._close_store_on_close:
+            self.zarr_group.store.close()
 
 
 def open_zarr(

xarray/tests/test_backends.py

@@ -5251,6 +5251,16 @@ def test_pickle_open_mfdataset_dataset():
     assert_identical(ds, pickle.loads(pickle.dumps(ds)))
 
 
+@requires_zarr
+def test_zarr_closing_internal_zip_store():
+    store_name = "tmp.zarr.zip"
+    original_da = DataArray(np.arange(12).reshape((3, 4)))
+    original_da.to_zarr(store_name, mode="w")
+
+    with open_dataarray(store_name, engine="zarr") as loaded_da:
+        assert_identical(original_da, loaded_da)
+
+
 @requires_zarr
 class TestZarrRegionAuto:
     def test_zarr_region_auto_all(self, tmp_path):