> On the other hand, the HTTP status code does matter (sometimes a lot) to programs that hit the URL, including status monitoring programs; these will probably consider their checks to fail if the web server returns a 404 and succeed if it returns a 200. If you're pointing status checking programs at the front page of your just set up web server to make sure it's up, probably you want a HTTP 200 code (although not if the real thing you're checking is whether or not the web server and the site have been fully set up).

This is a subtle but important distinction…

There are so many layers now between a user and the application code. What if due to some misconfiguration or new image push or ___ the web server or load balancer or PaaS router or CDN or Cloudflare or whatever starts serving some default placeholder, or error message, or its own content up on my URL?

That’s why I’d argue for a non-200 status code for the default “hello” page.

And in production monitoring I’d use something like https://heiioncall.com/blog/enhanced-api-monitoring-with-exp... to verify the presence of some special header set only by your application, so you know that your desired code is actually being called. (In addition to asserting the HTTP status code.)