127.0.0.1    back.example.com
127.0.0.1    front.example.com

...
front:
  networks:
    test_network:
      ipv4_address: 10.5.0.4
...
networks:
  test_network:
    driver: bridge
    ipam:
      config:
        - subnet: 10.5.0.0/16
          gateway: 10.5.0.1

location / {
  proxy_set_header        Host                    $host;
  proxy_set_header        X-Real-IP               $remote_addr;
  proxy_set_header        X-Forwarded-Proto       https;
  proxy_set_header        X-Forwarded-For         $proxy_add_x_forwarded_for;

  root   /usr/share/nginx/html;
  index  index.html;
  try_files $uri $uri/ /index.html;
}

location / {
  proxy_set_header        Host                    $host;
  proxy_set_header        X-Real-IP               $remote_addr;
  proxy_set_header        X-Forwarded-Proto       https;
  proxy_set_header        X-Forwarded-For         $proxy_add_x_forwarded_for;

  proxy_pass http://front;
}