After install D8, I found some issues. (Please let me know whether there's a better place to post these issues.)
1. Block "new forum topics" can NOT be refreshed automatically. Once you pin the block to front page, the content of this block is fixed, even you have many new posts in the forum, it will not be refreshed.
2. Image function can't process those pictures with non-English file names. These images can be uploaded, but can't be shown. It will show a red cross and said: the image has been removed and only the image from local site is allowed.
Just installed Drupal 8 alpha 3, everything is fine.
But all the forums and topics are public.
If I set the block "new forum topics" to "Show block for specific roles: Authenticated user", yes, this block is hidden to public, but the topics in forum are still visible.
So, how to setup Private forums and member-only sites on Drupal 8.x?
Left to its own devices, drupal_bootstrap() will only load the "master" Drupal site. If you want to bootstrap a subsite, you can use drupal_override_server_variables():