better container access regex; buffering can lead to problems

lib/confs/nginx/ipynbsrv.conf

@@ -56,7 +56,7 @@ server {
     }
 
     # proxy/workspace location
-    location ~* /ct/([^\/]+)/(.*) {
+    location ~* /ct/([^\/]+)(\/.*)?$ {
         # authorization
         # ensure only container's owner can access it
         satisfy  all;
@@ -79,6 +79,7 @@ server {
         proxy_read_timeout  86400s;
         proxy_send_timeout  86400s;
 
+        # headers for the upstream server
         proxy_set_header  Host                  $host;
         proxy_set_header  X-Forwarded-Host      $host;
         proxy_set_header  X-Forwarded-For       $proxy_add_x_forwarded_for;
@@ -88,6 +89,7 @@ server {
         proxy_set_header  X-Scheme              $scheme;
         proxy_set_header  X-Script-Name         /ct/$1;
 
+        proxy_buffering  off;
         proxy_pass  http://$decoded_backend;
     }
 }