This is a very basic proxy server that adds an X-Request-Start header to
each request, similar to Heroku's router.
The X-Request-Start header is needed to calculate request queue time in Judoscale web adapter libraries, so we use this proxy with sample apps to test the adapters.
Running the proxy server
The proxy server expects to be run via the Heroku CLI, which runs multiple processes via a Procfile and manages the PORT environment variable for us.
Create a Procfile:
proxy: npx judoscale-adapter-proxy-server
web: my-web-application
Run via Heroku CLI:
heroku local