[Docker] Allow to define port via HTTP_PORT (#2285)

docker-entrypoint.sh

@@ -25,5 +25,13 @@ while IFS= read -r -d '' file; do
     esac
 done
 
+# This feature can set the internal port that apache uses to something else.
+# If docker is run on network:service mode, no two containers can use port 80
+# To use this, start the container with the additional environment variable "HTTP_PORT"
+if [ ! -z ${HTTP_PORT} ]; then
+	sed -i "s/80/$HTTP_PORT/g" /etc/apache2/sites-available/000-default.conf /etc/apache2/ports.conf
+fi
+
+
 # Start apache
 apache2-foreground