title: Traefik: Cannot login to service with digest authentication
body: <p>I am trying to use Traefik to reverse proxy to a service that uses digest authentication.</p>
  
  <p>When I access the service directly by its port after exposing it in the docker-compose it works fine but when I access it through Traefik the login pop up keeps appearing because a 401 is returned.</p>
  
  <p>I also had a look at the Traefik middleware but I think it is only to add digest authentication and not to be used with services that already have it.</p>
  
  <p>How do I have to configure Traefik to resolve this?</p>
  
  <p>Working docker-compose:</p>
  
  <pre><code>version: "3"
  
  services:
    service:
      image: service:tag
      cap_add:
        - NET_ADMIN
      ports:
        - "8082:8082/tcp"
  </code></pre>
  
  <p>docker-compose to be used with traefik:</p>
  
  <pre><code>version: "3"
  
  networks:
    web:
      external: true
    internal:
      external: false
  
  services:
    service:
      image: service:tag
      cap_add:
        - NET_ADMIN
      labels:
        - traefik.api.frontend.rule=Host:domain.com
        - traefik.docker.network=web
        - traefik.port=8082
      networks:
        - internal
        - web
      ports:
        - "1194:1194/udp"
  
  </code></pre>
  
  <p>and the traefik.toml:</p>
  
  <pre><code>logLevel = "DEBUG"
  
  defaultEntryPoints = ["http"]
  
  [entryPoints]
    [entryPoints.dashboard]
      address = ":8080"
      [entryPoints.dashboard.auth]
        [entryPoints.dashboard.auth.basic]
          users = ["user:hash"]
  
    [entryPoints.http]
      address = ":80"
  
  [api]
  entrypoint="dashboard"
  
  [docker]
  domain = "domain.com"
  watch = true
  network = "web"
  </code></pre>
  
  <p>I start traefik like this:</p>
  
  <pre><code>docker run -d -v /var/run/docker.sock:/var/run/docker.sock -v $PWD/traefik.toml:/traefik.toml -p 80:80 -l traefik.frontend.rule=Host:monitor.domain.com -l traefik.port=8080 --network web --name traefik traefik:1.7.2-alpine
  </code></pre>
  
  <p>and then the service with:</p>
  
  <pre><code>docker-compose up
  </code></pre>
  
  <p>Everything works fine except the authentication.</p>