remove pynio from most test envs (#4492)

* remove pynio from py38 tests

* remove pynio from other test envs

* update docs

* Apply suggestions from code review

Author: mathause

ci/requirements/py36.yml

@@ -32,7 +32,7 @@ dependencies:
   - pip
   - pseudonetcdf
   - pydap
-  - pynio
+  # - pynio: not compatible with netCDF4>1.5.3; only tested in py36-bare-minimum
   - pytest
   - pytest-cov
   - pytest-env

ci/requirements/py37.yml

@@ -32,7 +32,7 @@ dependencies:
   - pip
   - pseudonetcdf
   - pydap
-  - pynio
+  # - pynio: not compatible with netCDF4>1.5.3; only tested in py36-bare-minimum
   - pytest
   - pytest-cov
   - pytest-env

ci/requirements/py38-all-but-dask.yml

@@ -29,7 +29,7 @@ dependencies:
   - pip
   - pseudonetcdf
   - pydap
-  - pynio
+  # - pynio: not compatible with netCDF4>1.5.3; only tested in py36-bare-minimum
   - pytest
   - pytest-cov
   - pytest-env

ci/requirements/py38.yml

@@ -32,7 +32,7 @@ dependencies:
   - pip
   - pseudonetcdf
   - pydap
-  - pynio
+  # - pynio: not compatible with netCDF4>1.5.3; only tested in py36-bare-minimum
   - pytest
   - pytest-cov
   - pytest-env

doc/installing.rst

@@ -25,8 +25,9 @@ For netCDF and IO
 - `pydap <http://www.pydap.org/>`__: used as a fallback for accessing OPeNDAP
 - `h5netcdf <https://github.com/shoyer/h5netcdf>`__: an alternative library for
   reading and writing netCDF4 files that does not use the netCDF-C libraries
-- `pynio <https://www.pyngl.ucar.edu/Nio.shtml>`__: for reading GRIB and other
-  geoscience specific file formats. Note that pynio is not available for Windows.
+- `PyNIO <https://www.pyngl.ucar.edu/Nio.shtml>`__: for reading GRIB and other
+  geoscience specific file formats. Note that PyNIO is not available for Windows and
+  that the PyNIO backend may be moved outside of xarray in the future.
 - `zarr <http://zarr.readthedocs.io/>`__: for chunked, compressed, N-dimensional arrays.
 - `cftime <https://unidata.github.io/cftime>`__: recommended if you
   want to encode/decode datetimes for non-standard calendars or dates before

doc/io.rst

@@ -1022,6 +1022,11 @@ We recommend installing PyNIO via conda::
 
     conda install -c conda-forge pynio
 
+    .. note::
+    
+    PyNIO is no longer actively maintained and conflicts with netcdf4 > 1.5.3.
+    The PyNIO backend may be moved outside of xarray in the future.
+
 .. _PyNIO: https://www.pyngl.ucar.edu/Nio.shtml
 
 .. _io.PseudoNetCDF: