How can I force my nodejs app running on Google App Engine, to always redirect to HTTPS ?

I have a pretty vanilla app that looks like this:

This thing is running in Google App Engine (GAE), and I’d like to make sure it listens only on HTTPS. There are standards like HSTS that can help. How can I use them?

This question and answer on Stackoverflow showed me the way. Basically, just add in a tiny module called yes-https. The new code looks like this:

Redeploying (no change to app.yaml) gets me the always-HTTPS behavior I want. When a client requests my service via http, it receives a 301 redirect pointing to the secure site.

HTTP/1.1 301 Moved Permanently
Date: Wed, 20 Jun 2018 16:27:56 GMT
Transfer-Encoding: chunked
X-Powered-By: Express
Location: https://foo-bar.appspot.com/
Via: 1.1 google


Nice, easy, clear.
Thanks to Justin for this handy module.