Site behind a reverse proxy - subfolder We are using a public apache web server as a reverse proxy for to show a drupal instance (to the client). The website should come up in http://publicSite/path
The Reverse proxy contains basic apache configuration pointing a "subfolder" to the internal webserver. Something like: 

ProxyPass /path http://internaldomain/
ProxyPassReverse /path http://internaldomain/


The problem is that Drupal 8 has no longer a $base_url and the site is broke (CSS, JS). Adding publicSite in the $settings['file_public_base_url'] does not help. CSS/JS and links to themes are still broken.

There is a settings section on a Reverse Proxy in the settings.php, but it does not address the issue on accessing the website from a /subfolder url. 
Any hints to solve this issue!?
You just need to reverse proxy all the asset directories like here (this proxies site preosasde via real site proreos):

ServerName preosasde

ProxyPass /themes/ http://proreos/themes/
ProxyPassReverse /themes/ http://proreos/themes/

ProxyPass /core/ http://proreos/core/
ProxyPassReverse /core/ http://proreos/core/

ProxyPass /vendor/ http://proreos/vendor/
ProxyPassReverse /vendor/ http://proreos/vendor/

ProxyPass /sites/ http://proreos/sites/
ProxyPassReverse /sites/ http://proreos/sites/

ProxyPass / http://proreos/asde/
ProxyPassReverse / http://proreos/asde/


Take care about the order of that entries and be aware that you will loose your users credentials (cause of the different domain).