How to set up traefik on docker to listen to multiple ip addresses

How to have Traefik Docker listening on two ip addresses (or more)s

Why
====================

For example, so that your firewall can apply different rules to different services 
based on ip

What is the problem: 
====================
docker allows you to have one ip address per network interface. 

Solution
====================
1. change the downstream network of the traefik container to a macvlan network. 
 docker network create --drive=macvlan --subnet=X.X.X.0/24   YOUR_NET_NAME

2. download and modify <entrypoint.sh> from https://github.com/traefik/traefik/
note the change to the shebang to !#/bin/ash 
add the following at the top:

  #!/bin/ash

  if [ -n "$ADD_ADDRESSES" ]; then
    for ipaddr in $ADD_ADDRESSES ; do
      ip address add $ipaddr  dev eth0
    done
  fi

3. create in the same directory a local dockerfile with at least these commands

  FROM traefik:v2.5
  RUN apk update && apk add iproute2
  COPY ./entrypoint.sh /

and build local image of traefik

4. make changes to your docker-compose file

  a. change the image to the local image built in step 3. above
  b. add the following to the traefik service: 

    cap_add:
      - NET_ADMIN
    environment:
      - ADD_ADDRESSES=X.X.X.Y/24 X.X.X.Z/24
    
  c. make sure to specify the correct network (step 1) in the docker-compose file