allow websockets to containers (#1340)

* allow websockets to containers

* fix format string

backend/src/net/nginx.conf.template

@@ -11,5 +11,8 @@ server {{
         client_max_body_size 0;
         proxy_request_buffering off;
         proxy_buffering off;
+        proxy_http_version 1.1;
+        proxy_set_header Upgrade $http_upgrade;
+        proxy_set_header Connection $connection_upgrade;
     }}
 }}

backend/src/nginx/main-ui.conf.template

@@ -1,4 +1,8 @@
 
+map $http_upgrade $connection_upgrade {{
+        default upgrade;
+        '' $http_connection;
+}}
 
 server {{
         listen 443 ssl default_server;