Using consolidate_metadata with FSStore result in a read-only store

[jhamman]

Minimal, reproducible code sample, a copy-pastable example if possible

import xarray as xr
from zarr.convenience import consolidate_metadata


ds = xr.tutorial.open_dataset('air_temperature')
ds.to_zarr('file://foo.zarr', mode='w', consolidated=False)
consolidate_metadata('file://foo.zarr')

raises:

---------------------------------------------------------------------------
ReadOnlyError                             Traceback (most recent call last)
/tmp/ipykernel_63/1636373769.py in <module>
----> 1 consolidate_metadata('file://foo.zarr')

/srv/conda/envs/notebook/lib/python3.9/site-packages/zarr/convenience.py in consolidate_metadata(store, metadata_key)
   1126         }
   1127     }
-> 1128     store[metadata_key] = json_dumps(out)
   1129     return open_consolidated(store, metadata_key=metadata_key)
   1130 

/srv/conda/envs/notebook/lib/python3.9/site-packages/zarr/storage.py in __setitem__(self, key, value)
   1134     def __setitem__(self, key, value):
   1135         if self.mode == 'r':
-> 1136             raise ReadOnlyError()
   1137         key = self._normalize_key(key)
   1138         path = self.dir_path(key)

ReadOnlyError: object is read-only

Problem description

When using a fsspec compatible string as the store argument, zarr's consolidate_metadata function returns a read-only store, resulting in the error shown above. I believe the expected behavior is to have generate an FSStore object with write privileges (so the consolidated meatadata key can be written).

Version and installation information

Please provide the following:

• Value of zarr.__version__: 2.10.3
• Value of numcodecs.__version__: 0.9.1
• Version of Python interpreter: 3.9
• Operating system (Linux/Windows/Mac): Linux and OSX
• How Zarr was installed: conda