add API to docs build

[dcherian]

autodoc/autosummary import the package to automatically add the docstrings.

This means cupy-xarray and cupy are imported. importing cupy fails on RTD saying it can't find libcuda.

It'd be nice to find a workaround.

Worst case, I guess we can run autodoc locally and then push the generated html?

(note that installing cuda brings in cudatoolkit which is a 800MB download; it'd be nice to just not do that)

[dcherian]

@keewis, @andersy005 Do either of you have an opinion on how to proceed?

[keewis]

RTD recommends mocking libraries that you can't install easily, maybe that's worth investigating?

Edit: you might also be able to apt-install it, not sure

[keewis]

actually, cupy is using RTD as well, so you might be able to copy their setup?

cc @jacobtomlinson

[jacobtomlinson]

@leofang do you have any quick advice on building sphinx docs for RTD for cupy without having to install everything?

[leofang]

I see. I'd suggest to build a "NO CUDA" CuPy in your RTD env, and then import cupy. They tailored this option specifically for RTD to use it to generate docs. See https://github.com/cupy/cupy/blob/9d439227f1a53bbd9ebb16784e40bcce44bc8042/.github/workflows/pretest.yml#L37-L41