Docker-Compose Auto-Scale with Nginx Upstreams

docker-compose.yml

nginx:
  image: myclient/nginx
  environment:
    - HOSTHOST=UBUNTU
    - PROXY_PORT=8069
  links:
    - myservice:myservice
  ports:
    - "80:80"
    - "443:443"

nginx.conf

daemon off;
worker_processes 4;
events{
  worker_connections 4096;
}

http{
upstream myservice {
  ## This is the important part, and the following line will be replaced with all of the ip:port ##
  ## combinations from the instances of docker-compose scaling                                   ##
  --PROXY_UPSTREAM_REPLACEMENTS--
}

server {
  listen      443 default;
  server_name myservice.io www.myservice.io;
  root        /usr/share/nginx/html;
  index       index.html index.htm;
  
  location / {
    proxy_pass  http://myservice;
    # force timeouts if the backend dies
    proxy_next_upstream error timeout invalid_header http_500 http_502 http_503 http_504;
    proxy_redirect off;

    # set headers
    proxy_set_header    Host            $host;
    proxy_set_header    X-Real-IP       $remote_addr;
    proxy_set_header    X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header    X-Forwarded-Proto https;

    # This adds the docker internal IP to the response
    add_header X-Backend-Server $upstream_addr;
  }
}  
}

run.sh

#!/bin/bash

NEWLINE=$'\n'
ALLSERVERS=''

# This line extracts all of the environment vars that contain the port being proxied and the host's host name
SERVERS=$( env | grep "${HOSTHOST}_.*${PROXY_PORT}_TCP_ADDR" | sed 's/_PORT.*/ /g' - )

# We'll loop through all the deteced servers that match the pattern, and insert thier values: IP and Port number
for server in $SERVERS
do
	servervar="${server}_PORT_${PROXY_PORT}_TCP_ADDR"
	serverport="${server}_PORT_${PROXY_PORT}_TCP_PORT"

	ALLSERVERS="$ALLSERVERS \n   server ${!servervar}:${!serverport};"
done

# Echo out the results to the Docker log
echo "Adding Linked Contianers to NGINX conf:$NEWLINE $ALLSERVERS"

# and replace the actual entry in the nginx.conf file
sed "s/--PROXY_UPSTREAM_REPLACEMENTS--/$ALLSERVERS/g" /etc/nginx/nginx.conf.vars > /etc/nginx/nginx.conf

# Finally, start nginx
nginx

environment vars will obsolete soon in docker, is there any other solutions?
https://gist.github.com/cmoore4/4659db35ec9432a70bca#file-run-sh-L7