This is a simple set of lua scripts to enable basic OAuth against GitHub, allowing access to users in a specific organization and not on a blocklist.
Create a new GitHub OAuth 2 application at GitHub, then, with the client id and client secret, run CLIENT_ID=<your client id> CLIENT_SECRET=<your client secret> vagrant up. This will set up a vagrant instance exposing Nginx configured to Authenticate against your app at 192.168.29.42.
The example nginx configuration requires either nginx-extras from ubuntu xenial (or maybe openresty), but will work with default nginx-extras from ubuntu trusty if the init_by_lua_block and content_by_lua_block are replaced with Nginx variables and a regular webpage.