Tiles are missing when applying zappend to zarr files stored in s3

[konstntokas]

Describe the bug
Zappend has been applied to append multiple zarr files along the time axis. The resulting cube shows random blocks being filled with nan values. Running it multiple times, the missing blocks are changing.

To Reproduce
A data ID looks like cubes/aux/era5_small/2016_11.zarr.

The following zappend config was used.

config = {
    "target_dir": f"s3://{os.environ['S3_USER_STORAGE_BUCKET']}/{data_id_era5}",
    "target_storage_options": {
        "key": os.environ["S3_USER_STORAGE_KEY"],
        "secret": os.environ["S3_USER_STORAGE_SECRET"],
    },
    "slice_storage_options": {
        "key": os.environ["S3_USER_STORAGE_KEY"],
        "secret": os.environ["S3_USER_STORAGE_SECRET"],
    },
    "force_new": True,
    "disable_rollback": True,
    "logging": "DEBUG",
}



zappend(
    (
        open_zarr(f"s3://{os.environ['S3_USER_STORAGE_BUCKET']}/{data_id}")
        for data_id in data_ids[3]
    ),
    config=config,
)

Expected behavior
Zappend should just append the data cubes along a specific dimension without errors.

Python Environment

• operating system: DeepESDL (user environment built with conda store in DeepESDL)
• zappend version, output of zappend --version: 0.8.0

[forman]

I don't think that this is actually a bug in zappend code, as it does not deal with individual chunks on its own, this is left to the preprocessing chain and the potential use of zarr / dask.