Things have diverged a bit from the docs. Just want to document here what I got working:

I had already checked out Keystone and run the unit tests.

I needed uwsgi

sudo apt install uwsgi-core
sudo apt install uwsgi-plugin-python3

Then a modified command line to run the server:

uwsgi --http-socket 127.0.0.1:5000    --plugin /usr/lib/uwsgi/plugins/python3_plugin.so   --wsgi-file $(which keystone-wsgi-public)

This got me the last part

https://stackoverflow.com/questions/31330905/uwsgi-options-wsgi-file-and-module-not-recognized

There are a handful of questions a user will (implicitly) ask when using your API:

1. What actions can I do against this endpoint?
2. How do I find the URLs for those actions?
3. What information do I need to provide in order to perform this action?
4. What permission do I need in order to perform this action.

Answering these questions can be automated. The user, and the tools they use, can discover the answers by working with the system. That is what I mean when I use the word “Discoverability.”

We missed some opportunities to answer these questions when we designed the APIs for Keystone OpenStack. I’d like to talk about how to improve on what we did there.