issues: 543197350

I am currently trying to read netCDF files directly from a THREADS server or from Azure blob storage using xarray.open_dataset using a url. I have tested NetCDFs from several sources and the files themselves appear to be fine. xarray_open_dataset works if I download them to my local environment using either wget.download or just moving the files manually.

MCVE Code Sample

```python import xarray as xr url = 'https://ooiopendata.blob.core.windows.net/botpt/NOAA_NCDC_ERSST_v3b_SST.nc' ds = xr.open_dataset(url)

```

I have also tested it with these additional urls: python url = 'https://opendap.oceanobservatories.org/async_results/dax.soule@qc.cuny.edu/20191227T065318736Z-RS03ECAL-MJ03E-06-BOTPTA302-streamed-botpt_nano_sample/deployment0001_RS03ECAL-MJ03E-06-BOTPTA302-streamed-botpt_nano_sample_20141005T000000-20141005T235959.nc' python url = 'https://opendap.oceanobservatories.org/thredds/fileServer/ooi/dax.soule@qc.cuny.edu/20191228T052214778Z-RS03ECAL-MJ03E-06-BOTPTA302-streamed-botpt_nano_sample/deployment0001_RS03ECAL-MJ03E-06-BOTPTA302-streamed-botpt_nano_sample_20191005T000000-20191005T235959.950000.nc'

Expected Output - In all cases, the expected output is the xarray dataset:

python <xarray.Dataset> Dimensions: (time: 1727934) Coordinates: obs (time) int32 0 1 2 3 4 ... 1727930 1727931 1727932 1727933 * time (time) datetime64[ns] 2019-10-05 ... 2019-10-05T23:59:59.949999616 Data variables: bottom_pressure (time) float32 ... press_trans_temp (time) float64 ... sensor_id (time) object ... Attributes:

Problem Description

As far as I can tell, permissions are not the issue and neither are the files because the url's will download the files and xarray will open the files that I download. The only thing I am not able to do is open the files with xarray directly from the server. Any help or suggestions are greatly appreciated.

Output of xr.open_dataset(url)

```python

KeyError Traceback (most recent call last) /srv/conda/envs/notebook/lib/python3.7/site-packages/xarray/backends/file_manager.py in _acquire_with_cache_info(self, needs_lock) 197 try: --> 198 file = self._cache[self._key] 199 except KeyError:

/srv/conda/envs/notebook/lib/python3.7/site-packages/xarray/backends/lru_cache.py in getitem(self, key) 52 with self._lock: ---> 53 value = self._cache[key] 54 self._cache.move_to_end(key)

KeyError: [<class 'netCDF4._netCDF4.Dataset'>, ('https://ooiopendata.blob.core.windows.net/botpt/NOAA_NCDC_ERSST_v3b_SST.nc',), 'r', (('clobber', True), ('diskless', False), ('format', 'NETCDF4'), ('persist', False))]

During handling of the above exception, another exception occurred:

OSError Traceback (most recent call last) <ipython-input-25-2eaba4f9d881> in <module> ----> 1 ds1 = xr.open_dataset('https://ooiopendata.blob.core.windows.net/botpt/NOAA_NCDC_ERSST_v3b_SST.nc') 2 ds1

/srv/conda/envs/notebook/lib/python3.7/site-packages/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, use_cftime) 497 if engine == "netcdf4": 498 store = backends.NetCDF4DataStore.open( --> 499 filename_or_obj, group=group, lock=lock, **backend_kwargs 500 ) 501 elif engine == "scipy":

/srv/conda/envs/notebook/lib/python3.7/site-packages/xarray/backends/netCDF4_.py in open(cls, filename, mode, format, group, clobber, diskless, persist, lock, lock_maker, autoclose) 355 netCDF4.Dataset, filename, mode=mode, kwargs=kwargs 356 ) --> 357 return cls(manager, group=group, mode=mode, lock=lock, autoclose=autoclose) 358 359 def _acquire(self, needs_lock=True):

/srv/conda/envs/notebook/lib/python3.7/site-packages/xarray/backends/netCDF4_.py in init(self, manager, group, mode, lock, autoclose) 311 self._group = group 312 self._mode = mode --> 313 self.format = self.ds.data_model 314 self._filename = self.ds.filepath() 315 self.is_remote = is_remote_uri(self._filename)

/srv/conda/envs/notebook/lib/python3.7/site-packages/xarray/backends/netCDF4_.py in ds(self) 364 @property 365 def ds(self): --> 366 return self._acquire() 367 368 def open_store_variable(self, name, var):

/srv/conda/envs/notebook/lib/python3.7/site-packages/xarray/backends/netCDF4_.py in _acquire(self, needs_lock) 358 359 def _acquire(self, needs_lock=True): --> 360 with self._manager.acquire_context(needs_lock) as root: 361 ds = _nc4_require_group(root, self._group, self._mode) 362 return ds

/srv/conda/envs/notebook/lib/python3.7/contextlib.py in enter(self) 110 del self.args, self.kwds, self.func 111 try: --> 112 return next(self.gen) 113 except StopIteration: 114 raise RuntimeError("generator didn't yield") from None

/srv/conda/envs/notebook/lib/python3.7/site-packages/xarray/backends/file_manager.py in acquire_context(self, needs_lock) 184 def acquire_context(self, needs_lock=True): 185 """Context manager for acquiring a file.""" --> 186 file, cached = self._acquire_with_cache_info(needs_lock) 187 try: 188 yield file

/srv/conda/envs/notebook/lib/python3.7/site-packages/xarray/backends/file_manager.py in _acquire_with_cache_info(self, needs_lock) 202 kwargs = kwargs.copy() 203 kwargs["mode"] = self._mode --> 204 file = self._opener(self._args, *kwargs) 205 if self._mode == "w": 206 # ensure file doesn't get overriden when opened again

netCDF4/_netCDF4.pyx in netCDF4._netCDF4.Dataset.init()

netCDF4/_netCDF4.pyx in netCDF4._netCDF4._ensure_nc_success()

OSError: [Errno -90] NetCDF: file not found: b'https://ooiopendata.blob.core.windows.net/botpt/NOAA_NCDC_ERSST_v3b_SST.nc' ``` cc @tjcrone