Jupyter notebook server extension to proxy web services. This enables users to reach arbitrary web services running within their spawned Jupyter server and is probably most appropriate for services which can't readily be converted into extensions.
A user starts a web service via New > Terminal:
echo "hello world" > index.html
python -m http.server 8001
The service is proxied off of /proxy/ at https://address.of.notebook.server/user/theuser/proxy/8001.
Install via pip:
pip install nbserverproxy
Or via conda:
conda install -c conda-forge nbserverproxy
Then enable:
jupyter serverextension enable --py nbserverproxy
Based on https://github.com/senko/tornado-proxy.