FileProvider: httpService and httprouter: How to specify url route for external file based routes with stripprefix

Traefik Traefik v2
,
1

if I am running apache service in the server behind the proxy as www.bar.com and want to server its content as www.foo.com/bar/
will the following will rewrite the route if I add stripPrefix OR should I have to do with a sidecar in this case. This works if the service is running in the same docker server as traefik is running. However, it does not work for external servers. I receive 404 error from traefik.
www.foo.com/bar/product/abc should proxy www.bar.com/product/abc

[http.middlewares]
  [http.middlewares.admin-stripprefix.stripPrefix]
  prefixes = ["/bar"]

[http.routers]
  [http.routers.Router-1]
    rule = "Host(`www.foo.com`) && Path(`/bar`)"
    service = "my-service"
    # will terminate the TLS request
    [http.routers.Router-1.tls]

[http.services]
  [http.services.my-service.loadBalancer]

    [[http.services.my-service.loadBalancer.servers]]
      url = "https://www.bar.com/"

traefik labels:

    labels:
      - traefik.serversTransport.insecureSkipVerify=true
      - traefik.http.routers.http-catchall.rule=hostregexp(`{host:.+}`)
      - traefik.http.routers.http-catchall.entrypoints=web
      - traefik.http.routers.http-catchall.middlewares=redirecttohttps@docker
      - traefik.http.middlewares.redirecttohttps.redirectscheme.scheme=https
      - traefik.http.middlewares.redirecttohttps.redirectscheme.port=443
      - traefik.http.middlewares.redirecttohttps.redirectscheme.permanent=true
      - traefik.http.routers.traefikapi.rule=Host(`www.mytraffic.com`)
      - traefik.http.routers.traefikapi.service=api@internal
      - traefik.http.routers.traefikapi.tls=true
      - traefik.http.routers.traefikapi.middlewares=redirecttohttps

a working service as a docker container:

    labels:
      - traefik.http.middlewares.testnodejsappapiprefix.stripprefix.prefixes=/testnode
      - traefik.http.middlewares.testnodejsappapiprefix.stripprefix.forceslash=false
      - traefik.enable=true
      - traefik.http.routers.testnodejsappapi.entrypoints=websecure
      - traefik.http.routers.testnodejsappapi.tls=true
      - traefik.http.routers.testnodejsappapi.rule=Host(`www.foo.com`) && PathPrefix(`/testnode`)
      - traefik.http.routers.testnodejsappapi.middlewares=redirecttohttps,testnodejsappapiprefix
      - traefik.http.routers.testnodejsappapi.middlewares=testnodejsappapiprefix