WordPress behind Microsoft Web App Proxy with TLS/HTTPS

When a reverse proxy is used, it typically also handles the encryption/decryption of HTTPS-HTTP. This means that WordPress, in my case the Docker image, is accessed via HTTP and consequently returns all links via HTTP.

At least in the current Docker image, this is already taken into account; normally, reverse proxies set the HTTP header X-FORWARDED-PROTO to "https", and thus WP is made to output the links (also to CSS and images, etc.) as "https://" through the following code snippet from wp-config.php.

if (!empty($_SERVER['HTTP_X_FORWARDED_PROTO']) && $_SERVER['HTTP_X_FORWARDED_PROTO'] === 'https') {
	$_SERVER['HTTPS'] = 'on';
}

BUT...

Microsoft likes to do everything differently. In their defense, it must be said that X-FORWARDED_PROTO and similar headers are not really standardized. However, Microsoft sets the header "Front-End-Https" to "on" in WebAppProxy. So let's use that. Following is a bit of code that I inserted into wp-config.php just before the "Stop edit here" line:

if (!empty($_SERVER['HTTP_FRONT_END_HTTPS']) && $_SERVER['HTTP_FRONT_END_HTTPS'] === 'on') {
	$_SERVER['HTTPS'] = 'on';
}