Allow use of obstore in Zarr by setting 'use_obstore' in 'storage_options'

Author: tomwhite

cubed/storage/backends/zarr_python_v3.py

@@ -1,9 +1,13 @@
+from pathlib import Path
 from typing import Optional
 
 import zarr
 
 from cubed.types import T_DType, T_RegularChunks, T_Shape, T_Store
 
+# always write empty chunks to avoid a check for each chunk
+zarr.config.set({"array.write_empty_chunks": True})
+
 
 class ZarrV3ArrayGroup(dict):
     def __init__(
@@ -36,6 +40,22 @@ def open_zarr_v3_array(
     path: Optional[str] = None,
     **kwargs,
 ):
+    # use obstore if requested
+    storage_options = kwargs.get("storage_options", None)
+    if storage_options is not None and storage_options.get("use_obstore", False):
+        import obstore as obs
+        from zarr.storage import ObjectStore
+
+        if isinstance(store, str):
+            if "://" not in store:
+                p = Path(store)
+                store = ObjectStore(obs.store.from_url(p.as_uri(), mkdir=True))
+            else:
+                store = ObjectStore(obs.store.from_url(store))
+        elif isinstance(store, Path):
+            p = store
+            store = ObjectStore(obs.store.from_url(p.as_uri(), mkdir=True))
+
     if isinstance(chunks, int):
         chunks = (chunks,)