issue_comments: 598577015

If Nio.open_file supported these options as keyword arguments instead of environment variables, these arguments could get set in open_dataset via backend_kwargs.

I think that would be the ideal resolution, but if I recall PyNIO isn't under active development anymore. So in that case, we could consider adding our own solution in xarray to add a new backend argument, but it should be specific PyNIO, not all xarray backends, i.e., it should live entirely in xarray/backends/pynio_.py

To make this work robustly with all of xarray's file caching machinery (used with dask, etc), the setup of the environment variable needs to happen inside a helper function wrapping Nio.open_file, which could replace Nio.open_file on this line: https://github.com/pydata/xarray/blob/650a981734ce3291f5aaa68648ebde451339f28a/xarray/backends/pynio_.py#L54

I think you could do something similar with overriding environment variables here inside this helper function.

Ideally you could also do clean-up here, deleting these environment variables, but I'm not sure if there's an easy/safe way to do this currently. These methods can get called in multiple threads (e.g., from dask) and I don't think we have a global clean-up mechanism that would work for this.