fixed reverse proxy for websockets

frontend/Dockerfile

     ln -s /dev/stdout /var/log/apache2/access.log &&\
     ln -s /dev/stdout /var/log/apache2/other_vhosts_access.log
 
-RUN a2enmod proxy_http
+RUN a2enmod proxy_http proxy_wstunnel
 
 COPY apache2.conf /etc/apache2/apache2.conf
 

frontend/apache2.conf

 </Directory>
 
 <Location "/api/">
-  ProxyPass http://BACKEND_HOST:BACKEND_PORT/
+  ProxyPass http://BACKEND_HOST:BACKEND_PORT/ retry=0
   ProxyPassReverse http://BACKEND_HOST:BACKEND_PORT/
 </Location>
+<Location "/signalr/">
+  ProxyPass http://BACKEND_HOST:BACKEND_PORT/signalr/ retry=0
+  ProxyPassReverse http://BACKEND_HOST:BACKEND_PORT/signalr/
+</Location>
+<Location "/signalr/connect">
+  ProxyPass ws://BACKEND_HOST:BACKEND_PORT/signalr/connect retry=0
+</Location>
+<Location "/signalr/reconnect">
+  ProxyPass ws://BACKEND_HOST:BACKEND_PORT/signalr/reconnect retry=0
+</Location>
 
 
 LogFormat "%v:%p %h %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\"" vhost_combined