3 stage is work

Dockerfile

@@ -4,7 +4,11 @@ ARG NET_NAME=kek
 ARG CONTAINER_NAME=lol
 ARG STATIC_FILE=/usr/share/nginx/html/index.html
 
+COPY ./scripts/knocking_setup.sh /root/scripts/knocking_setup.sh
 
 RUN sed -i '13,21d' $STATIC_FILE && \
-    sed -i "13i <h2>$NET_NAME<br>$CONTAINER_NAME</h2>" $STATIC_FILE
+    sed -i "13i <table>\
+    <tr><th>NETWORK</th><th>CONTAINER</th></tr>\
+    <tr><td>$NET_NAME</td><td>$CONTAINER_NAME</td></tr>\
+    </table>" $STATIC_FILE