id,node_id,number,title,user,state,locked,assignee,milestone,comments,created_at,updated_at,closed_at,author_association,active_lock_reason,draft,pull_request,body,reactions,performed_via_github_app,state_reason,repo,type
394423623,MDU6SXNzdWUzOTQ0MjM2MjM=,2634,Opening a file with open_mfdataset fails if dask is not installed: ModuleNotFoundError: No module named 'dask.base',226037,closed,0,,,3,2018-12-27T15:33:27Z,2023-12-05T21:43:15Z,2023-12-05T21:43:15Z,MEMBER,,,,"#### Problem description

Opening a file with `open_mfdataset` fails if *dask* is not installed:
```
>>> xr.open_mfdataset('tests/sample-data/era5-levels-members.nc')
---------------------------------------------------------------------------
ModuleNotFoundError                       Traceback (most recent call last)
~/devel/MPY/xarray/xarray/backends/api.py in open_mfdataset(paths, chunks, concat_dim, compat, preprocess, engine, lock, data_vars, coords, autoclose, parallel, **kwargs)
    626 
--> 627     datasets = [open_(p, **open_kwargs) for p in paths]
    628     file_objs = [getattr_(ds, '_file_obj') for ds in datasets]
    629     if preprocess is not None:

~/devel/MPY/xarray/xarray/backends/api.py in open_dataset(filename_or_obj, group, decode_cf, mask_and_scale, decode_times, autoclose, concat_characters, decode_coords, engine, chunks, lock, cache, drop_variables, backend_kwargs)
    340 
    341         with close_on_error(store):
--> 342             return maybe_decode_store(store)
    343     else:
    344         if engine is not None and engine != 'scipy':

~/devel/MPY/xarray/xarray/backends/api.py in maybe_decode_store(store, lock)
    276 
    277         if chunks is not None:
--> 278             from dask.base import tokenize
    279             # if passed an actual file path, augment the token with
    280             # the file modification time

ModuleNotFoundError: No module named 'dask.base'
```

#### Reason

The reason is that the test in `maybe_decode_store` is for `None` but `open_mfdataset` in line 614 sets `chunks` to `{}` if it evaluates to `False`.

In fact setting line https://github.com/pydata/xarray/blob/master/xarray/backends/api.py#L614 as follows solves the problem:
```
    open_kwargs = dict(engine=engine, chunks=chunks, lock=lock,
                       autoclose=autoclose, **kwargs)
```
I could not run the tests to see what breaks with this change as running `pytest` without *dask* fails with:
```
../cpython3/lib/python3.7/site-packages/py/_path/local.py:668: in pyimport
    __import__(modname)
xarray/tests/__init__.py:105: in <module>
    if LooseVersion(dask.__version__) < '0.18':
E   AttributeError: module 'dask' has no attribute '__version__'
```","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/2634/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,not_planned,13221727,issue
1215082284,I_kwDOAMm_X85IbK8s,6514,plugins.py:98: DeprecationWarning: SelectableGroups dict interface is deprecated. Use select.,226037,closed,0,,,4,2022-04-25T21:49:20Z,2022-04-27T01:07:50Z,2022-04-27T01:07:50Z,MEMBER,,,,"### What happened?

The plugin interface warns with `DeprecationWarning` in python 3.10.

### What did you expect to happen?

No warning to be issued.

### Minimal Complete Verifiable Example

```Python
Running `pytest` on any *Xarray* importing test.
```


### Relevant log output

```Python
   .../python3.10/site-packages/xarray/backends/plugins.py:98: DeprecationWarning: SelectableGroups dict interface is deprecated. Use select.
    entrypoints = entry_points().get(""xarray.backends"", ())
```

### Anything else we need to know?

According to the *Compatibity note* in:

https://docs.python.org/3/library/importlib.metadata.html#entry-points

the new API is `entry_points(group='xarray.backends')`

### Environment

<details>
INSTALLED VERSIONS
------------------
commit: None
python: 3.10.4 | packaged by conda-forge | (main, Mar 24 2022, 17:42:03) [Clang 12.0.1 ]
python-bits: 64
OS: Darwin
OS-release: 21.3.0
machine: arm64
processor: arm
byteorder: little
LC_ALL: None
LANG: None
LOCALE: (None, 'UTF-8')
libhdf5: None
libnetcdf: None

xarray: 2022.3.0
pandas: 1.4.2
numpy: 1.22.3
scipy: 1.8.0
netCDF4: None
pydap: None
h5netcdf: None
h5py: None
Nio: None
zarr: 2.11.3
cftime: None
nc_time_axis: None
PseudoNetCDF: None
rasterio: 1.2.10
cfgrib: None
iris: None
bottleneck: None
dask: 2022.04.1
distributed: 2022.4.1
matplotlib: 3.5.1
cartopy: None
seaborn: None
numbagg: None
fsspec: 2022.3.0
cupy: None
pint: None
sparse: None
setuptools: 62.1.0
pip: 22.0.4
conda: 4.12.0
pytest: 7.1.2
IPython: 8.2.0
sphinx: None
</details>
","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/6514/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,completed,13221727,issue
852256995,MDU6SXNzdWU4NTIyNTY5OTU=,5125,Add `BackendEntrypoint` to an easier to find location,226037,closed,0,,,3,2021-04-07T10:21:16Z,2021-04-11T18:53:03Z,2021-04-11T18:53:03Z,MEMBER,,,,"**Is your feature request related to a problem? Please describe.**

I started implementing a few backend plugins following the documentation so I noticed a few easily fixable quirks:

http://xarray.pydata.org/en/latest/internals/how-to-add-new-backend.html

The main one is the `BackendEntrypoint` is found deep into `xarray.backends.common`.

**Describe the solution you'd like**

I suggest to add an easier to find reference:
* `xarray.backends.BackendEntrypoint` would do
* but maybe even `xarray.BackendEntrypoint`. 

**Additional context**

For the simplest plugins `BackendEntrypoint` would be the only import to connect to *xarray*.

See this dummy GDAL plugin: https://github.com/bopen/xarray-gdal/blob/main/xarray_gdal/xarray_plugin.py
But also the *rioxarray* plugin in this PR: corteva/rioxarray/pull/281","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/5125/reactions"", ""total_count"": 1, ""+1"": 1, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,completed,13221727,issue
850231277,MDU6SXNzdWU4NTAyMzEyNzc=,5111,Rename of LazilyOuterIndexedArray to LazilyIndexedArray breaks rioxarray,226037,closed,0,,,0,2021-04-05T09:25:16Z,2021-04-06T09:18:49Z,2021-04-06T09:18:49Z,MEMBER,,,,"**What happened**:

With current xarray `master` the `rioxarray.open_rasterio` crashes.

**What you expected to happen**:

With the released version 0.17.0 of xarray the open works as expected.

**Minimal Complete Verifiable Example**:

```python
>>> import rioxarray
>>> rioxarray.open_rasterio(""myfile.tif"")
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-7-fedc16472305> in <module>
----> 1 da = rioxarray.open_rasterio(""../../../FLAIR-PROC/rome-lockdown-2020/georeferenced/20200309+0130+417_VV-20200109-20200115-EPSG:32632-5.human-activity.tif"")
      2 da

/usr/local/Caskroom/miniconda/base/envs/BOP/lib/python3.8/site-packages/rioxarray/_io.py in open_rasterio(filename, parse_coordinates, chunks, cache, lock, masked, mask_and_scale, variable, group, default_name, **open_kwargs)
    820 
    821     da_name = attrs.pop(""NETCDF_VARNAME"", default_name)
--> 822     data = indexing.LazilyOuterIndexedArray(
    823         RasterioArrayWrapper(
    824             manager,

AttributeError: module 'xarray.core.indexing' has no attribute 'LazilyOuterIndexedArray'
```

**Anything else we need to know?**:

`LazilyOuterIndexedArray` was recently renamed to `LazilyIndexedArray` by @aurghs in https://github.com/pydata/xarray/pull/4810 after a suggestion from @shoyer https://github.com/pydata/xarray/pull/4810#discussion_r586754165

Adding an alias would make the transition easier.","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/5111/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,completed,13221727,issue
708459047,MDU6SXNzdWU3MDg0NTkwNDc=,4457,Silently ignoring user passed `engine` key in some cases when opening file objects,226037,closed,0,,,0,2020-09-24T20:37:37Z,2020-09-28T15:42:01Z,2020-09-28T15:42:01Z,MEMBER,,,,"**What happened**:

When I `open()` a netCDF4 file and pass the file object to `xr.open_dataset` with `engine='scipy'` xarray silently ignores the value of the `engine` keyword and opens the file with `h5netcdf`. When opening an netCDF3 file with `engine='h5netcdf'` the `scipy` engine is used instead without warning.

**What you expected to happen**:

Silent autodetection of the engine is fine when passing `engine=None`, but it is very surprising when passing a value explicitly. I would have expected an exception or at least a warning.

**Minimal Complete Verifiable Example**:

```python
>>> xr.open_dataset('netCDF4.nc', engine='scipy')
---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
[...]
TypeError: Error: netCDF4.nc is not a valid NetCDF 3 file
            If this is a NetCDF4 file, you may need to install the
            netcdf4 library, e.g.,

            $ pip install netcdf4

>>> fp = open('netCDF4.nc')
>>> xr.open_dataset(fp, engine='scipy')
<xarray.Dataset>
Dimensions:       (line: 41587, pixel: 17751)
Coordinates:
  * line          (line) int64 0 1 2 3 4 5 ... 41582 41583 41584 41585 41586
  * pixel         (pixel) int64 0 1 2 3 4 5 ... 17746 17747 17748 17749 17750
Data variables:
    phase         (line, pixel) float32 ...
Attributes:
    Conventions:             CF-1.7
    [...]
```
","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/4457/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,completed,13221727,issue
368003448,MDU6SXNzdWUzNjgwMDM0NDg=,2475,Please add support for GRIB files via ECMWF cfgrib / ecCodes,226037,closed,0,,,2,2018-10-09T01:04:24Z,2018-10-17T17:17:36Z,2018-10-17T17:14:21Z,MEMBER,,,,"The [*cfgrib* project](https://pypi.org/project/cfgrib/) offers to open a GRIB file as an `xarray.Dataset`:
```
>>> import cfgrib
>>> cfgrib.open_dataset('era5-levels-members.grib')
<xarray.Dataset>
Dimensions:       (air_pressure: 2, latitude: 61, longitude: 120, number: 10, time: 4)
Coordinates:
  * number        (number) int64 0 1 2 3 4 5 6 7 8 9
  * time          (time) datetime64[ns] 2017-01-01 ... 2017-01-02T12:00:00
    step          timedelta64[ns] ...
  * air_pressure  (air_pressure) float64 850.0 500.0
  * latitude      (latitude) float64 90.0 87.0 84.0 81.0 ... -84.0 -87.0 -90.0
  * longitude     (longitude) float64 0.0 3.0 6.0 9.0 ... 351.0 354.0 357.0
    valid_time    (time) datetime64[ns] ...
Data variables:
    z             (number, time, air_pressure, latitude, longitude) float32 ...
    t             (number, time, air_pressure, latitude, longitude) float32 ...
Attributes:
    GRIB_edition:            1
    GRIB_centre:             ecmf
    GRIB_centreDescription:  European Centre for Medium-Range Weather Forecasts
    GRIB_subCentre:          0
    history:                 GRIB to CDM+CF via cfgrib-0.9.../ecCodes-2...
``` 
It would be very helpful to have a backend for it distributed with *xarray* to be selected via the `engine` keyword argument:
```
>>> import xarray as xr
>>> xr.open_dataset('era5-levels-members.grib', engine='cfgrib')
<xarray.Dataset>
Dimensions:       (air_pressure: 2, latitude: 61, longitude: 120, number: 10, time: 4)
Coordinates:
  * number        (number) int64 0 1 2 3 4 5 6 7 8 9
  * time          (time) datetime64[ns] 2017-01-01 ... 2017-01-02T12:00:00
    step          timedelta64[ns] ...
  * air_pressure  (air_pressure) float64 850.0 500.0
  * latitude      (latitude) float64 90.0 87.0 84.0 81.0 ... -84.0 -87.0 -90.0
  * longitude     (longitude) float64 0.0 3.0 6.0 9.0 ... 351.0 354.0 357.0
    valid_time    (time) datetime64[ns] ...
Data variables:
    z             (number, time, air_pressure, latitude, longitude) float32 ...
    t             (number, time, air_pressure, latitude, longitude) float32 ...
Attributes:
    GRIB_edition:            1
    GRIB_centre:             ecmf
    GRIB_centreDescription:  European Centre for Medium-Range Weather Forecasts
    GRIB_subCentre:          0
    history:                 GRIB to CDM+CF via cfgrib-0.9.../ecCodes-2...
```

cc @StephanSiemen @iainrussell","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/2475/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,completed,13221727,issue