I think we've talked about doing this a number of times in the past. It seems that we've been running into a number of uncaught build failures (e.g. #1898, #1881). This is one way of testing that the documentation build will pass on read the docs. If someone has a better of idea of how to do this, I'm all ears.

This is really good idea, thanks!

The build is failing with an error message about upgrading ruby?!?

Well isn't that nice. CI is a two edged sword! I'll take a look.

It looks like the doc build fails when it hits a warning:

Warning, treated as error:
/home/travis/build/pydata/xarray/doc/api.rst:1: WARNING: Inline emphasis start-string without end-string.

We should either fix these warnings or stop them from failing the build :)

We should either fix these warnings or stop them from failing the build :)

It's really hard to get rid of all of them - I'd rather try option B ;)

Currently we have 106 warnings at doc build on my system

I had the fail-on-warning option turned on. I agree we should drop that for now. After we merge this, I'll open an issue to track cleaning those up at some point. I don't have time to fix them right now.