allow to override VNC port (#1296)

* allow to override VNC port

fixes #457

* Update README.md

Co-authored-by: Diego Molina <[email protected]>

Author: michalskrivanek

NodeBase/start-vnc.sh

@@ -31,7 +31,7 @@ if [ "${START_XVFB}" = true ] ; then
     echo "Waiting for Xvfb..."
   done
 
-  x11vnc ${X11VNC_OPTS} -forever -shared -rfbport 5900 -rfbportv6 5900 -display ${DISPLAY}
+  x11vnc ${X11VNC_OPTS} -forever -shared -rfbport ${VNC_PORT:-5900} -rfbportv6 ${VNC_PORT:-5900} -display ${DISPLAY}
 else
   echo "Vnc won't start because Xvfb is configured to not start."
 fi

README.md

@@ -576,7 +576,8 @@ inside the container. Users can connect to this server in two ways:
 The VNC server is listening to port 5900, you can use a VNC client and connect to it. Feel free to map port 5900 to 
 any free external port that you wish.
 
-The internal 5900 port remains the same because that is the configured port for the VNC server running inside the container.
+The internal 5900 port remains the same because that is the configured port for the VNC server running inside the container. 
+You can override it with the `VNC_PORT` environment variable in case you want to use `--net=host`.
 
 Here is an example with the standalone images, the same concept applies to the node images.
 ``` bash