Unable to create a http-file provider, 404 ensues

I'm running a very simple file provider

[http]
    [http.routers]
        [http.routers.prometheus]
            rule = "Path(`/`)"
            service = "prometheus"

    [http.services]
        [http.services.prometheus.loadBalancer]
            [[http.services.prometheus.loadBalancer.servers]]
                url = "https://google.com"

With traefik:

traefik:
    image: "traefik:v2.2.0"
    container_name: "traefik-external"
    ports:
      - "80:80"
      - "8080:8080"
    volumes:
      - "${PWD}/dynamic_traefik.toml:/dynamic_traefik.toml:ro"
    command:
      - --global.sendAnonymousUsage=false
      - --log.level=DEBUG
      - --api.insecure=true
      - --api.dashboard=true
      - --entrypoints.web.address=:80
      - --providers.file.filename=/dynamic_traefik.toml

However, curling this server now generates a 404 from google?

lilja in ~ λ curl -v localhost:80
* Rebuilt URL to: localhost:80/
*   Trying ::1...
* TCP_NODELAY set
* Connected to localhost (::1) port 80 (#0)
> GET / HTTP/1.1
> Host: localhost
> User-Agent: curl/7.54.0
> Accept: */*
>
< HTTP/1.1 404 Not Found
< Alt-Svc: quic=":443"; ma=2592000; v="46,43",h3-Q050=":443"; ma=2592000,h3-Q049=":443"; ma=2592000,h3-Q048=":443"; ma=2592000,h3-Q046=":443"; ma=2592000,h3-Q043=":443"; ma=2592000,h3-T050=":443"; ma=2592000
< Content-Length: 1561
< Content-Type: text/html; charset=UTF-8
< Date: Thu, 16 Apr 2020 21:43:20 GMT
< Referrer-Policy: no-referrer
<
<!DOCTYPE html>
<html lang=en>
  <meta charset=utf-8>
  <meta name=viewport content="initial-scale=1, minimum-scale=1, width=device-width">
  <title>Error 404 (Not Found)!!1</title>
  <style>
    *{margin:0;padding:0}html,code{font:15px/22px arial,sans-serif}html{background:#fff;color:#222;padding:15px}body{margin:7% auto 0;max-width:390px;min-height:180px;padding:30px 0 15px}* > body{background:url(//www.google.com/images/errors/robot.png) 100% 5px no-repeat;padding-right:205px}p{margin:11px 0 22px;overflow:hidden}ins{color:#777;text-decoration:none}a img{border:0}@media screen and (max-width:772px){body{background:none;margin-top:0;max-width:none;padding-right:0}}#logo{background:url(//www.google.com/images/branding/googlelogo/1x/googlelogo_color_150x54dp.png) no-repeat;margin-left:-5px}@media only screen and (min-resolution:192dpi){#logo{background:url(//www.google.com/images/branding/googlelogo/2x/googlelogo_color_150x54dp.png) no-repeat 0% 0%/100% 100%;-moz-border-image:url(//www.google.com/images/branding/googlelogo/2x/googlelogo_color_150x54dp.png) 0}}@media only screen and (-webkit-min-device-pixel-ratio:2){#logo{background:url(//www.google.com/images/branding/googlelogo/2x/googlelogo_color_150x54dp.png) no-repeat;-webkit-background-size:100% 100%}}#logo{display:inline-block;height:54px;width:150px}
  </style>
  <a href=//www.google.com/><span id=logo aria-label=Google></span></a>
  <p><b>404.</b> <ins>That’s an error.</ins>
  <p>The requested URL <code>/</code> was not found on this server.  <ins>That’s all we know.</ins>
* Connection #0 to host localhost left intact

What's going on here? Why am I not being redirected to google.com?

solved. https://github.com/containous/traefik/issues/6735