When integrating several web apps together, it's a very good idea to
put an nginx server in front of them and use it's
routing and it's location / proxy_pass combinations make them work
together like one web app. That also lets you handle all HTTPS via the
nginx instance.
Unfortunately, it's a bit difficult to configure nginx, especially if you are new to it. This Python WSGI app exists to make it easier to experiment with an nginx server by having an extremely simple URL echoing app that simply echoes the request full URL to the calling client (I'd recommend curl for this).
Using this you can experiment with your nginx configuration, send requests to the nginx instance and see directly on your command line what the requesting URL was interpreted as by the application server.
E.g as configured from the start, your URL echo server runs on port 12345, and your nginx server on port 5000. A request to the nginx instance with an experimental URI will return:
$ curl "http://localhost:5000/foo/bar?foo=bar"
http://localhost/foo/bar?foo=bar
Here you can see that the URL echo server think's it's name is simply
'localhost', and that the entire URI have been transmitted
correctly. The purpose of the tool is that you should experiment with
this nginx configuration and see what different rules are transforming
your requests to in the proxy.