Fake HTTP(S) state for stubborn PHP app that won't operate over HTTP even though you desire it too. Pay attention to in-code comment.

fake-ssl-enabled.php

<?php
/**
 * Fake headers so it looks like request is  coming from SSL
 * In my case, I'm hosting app in the isolated docker container behind nginx-proxy. 
 * For simplicity sake, connection between nginx-proxy and the app is http. 
 * Connection between nginx-proxy and the client is normally SSL-only (HSTS). 
 * Wordpress in particular caused problems in this config. 
 * NOTE: DO NOT USE THIS ON WEBSITE EXPOSED TO THE INTERNET IF SSL SECURITY IS DESIRABLE!
 */
$_SERVER['HTTP_UPGRADE_INSECURE_REQUESTS'] = false;
$_SERVER['HTTP_X_FORWARDED_PORT']          = 443;
$_SERVER['HTTP_X_FORWARDED_SSL']           = 'on';
$_SERVER['HTTPS']                          = 'on';
$_SERVER['SERVER_PORT']                    = 443;
$_SERVER['REQUEST_SCHEME']                 = 'https';

If this is the answer, you're almost certainly asking the wrong question.

HTTPS becomes almost mandatory nowadays, and there should be ALMOST no cases when you'll need this.
Here are A FEW exceptions I can think of:

• Development/local environment (who wants to bother with SSL certs locally??)
• Hidden behind a reverse proxy. Example: Client --HTTPS--> nginx-proxy --HTTP--> webapp