nginx proxy with docker compose

docker-compose.yml

version: '2'

services:
  proxy:
    image: jwilder/nginx-proxy
    ports:
      - "80:80"
    volumes:
      - /var/run/docker.sock:/tmp/docker.sock:ro
    environment:
      - DEFAULT_HOST=proxy.example

  webapp:
    image: katacoda/docker-http-server
    ports:
      - "80"
    environment:
      - VIRTUAL_HOST=proxy.example