title: forward url with traefik v2 using docker
body: <p>I want to forward url with traefik(version 2) like If I hit URL <a href="http://localhost/1" rel="nofollow noreferrer">http://localhost/1</a> then it is forwarded to <a href="http://localhost:8081/1" rel="nofollow noreferrer">http://localhost:8081/1</a>.</p>
  
  <p>I have tried with several configuration but no one works. Please find below configuration I have done but it didn't worked.</p>
  
  <pre><code>version: "3.3"
  
  services:
    traefik:
      image: "traefik:v2.0.0-rc3"
      container_name: "traefik"
      command:
        - "--log.level=DEBUG"
        - "--api.insecure=true"
        - "--providers.docker=true"
        - "--providers.docker.exposedbydefault=false"
        - "--entrypoints.web.address=:80"
      ports:
        - "80:80"
        - "8080:8080"
        - "8081:8081"
      volumes:
        - "/var/run/docker.sock:/var/run/docker.sock:ro"
  
    whoami:
      #image: "containous/whoami"
      #container_name: "simple-service"
      #command:
      #  - "--port=8081"
      labels:
        - "traefik.enable=true"
        - "traefik.http.routers.whoami.rule=Host(`localhost`)"
        - "traefik.http.routers.whoami.entrypoints=web"
        - "traefik.http.services.whoami.loadbalancer.server.port=8081" 
  </code></pre>