takes care of point 3

Only one allowed host is enough in the container environment. All traffic is coming from Nginx.
Do not set the Host header in Nginx it will screw with the ALLOWED_HOSTS in Python.

The TUBESYNC_HOSTS now only affects the CSRF_TRUSTED_ORIGINS.
If there is a *need* the hosts are required in ALLOWED_HOSTS I would like to know in which scenario.

config/root/etc/nginx/nginx.conf

@@ -61,7 +61,6 @@ http {
 
         location / {
             proxy_pass http://127.0.0.1:8080;
-            proxy_set_header Host localhost;
             proxy_set_header X-Forwarded-Proto $real_proto;
             proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
             proxy_set_header X-Real-IP $remote_addr;