Refresh token request to auth.docker.io returning 404

I am trying to use the api documented here: https://docker.github.io/registry/spec/auth/oauth/

When I POST to the service as described in the docs, it always returns a 404.

I’ve tried this using my own account and also using the exact query in the documentation.

Here is an example:
[prompt]$ curl -v \

-H ‘Content-Type: application/x-www-form-urlencoded’
-X POST -d ‘grant_type=password&username=johndoe&password=A3ddj3w&service=hub.docker.io&client_id=dockerengine&access_type=offline’
https://auth.docker.io/token

  • Trying 52.5.234.85…
  • Connected to auth.docker.io (52.5.234.85) port 443 (#0)
  • TLS 1.2 connection using TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256
  • Server certificate: *.docker.io
  • Server certificate: RapidSSL SHA256 CA - G3
  • Server certificate: GeoTrust Global CA

POST /token HTTP/1.1
Host: auth.docker.io
User-Agent: curl/7.43.0
Accept: /
Content-Type: application/x-www-form-urlencoded
Content-Length: 118

  • upload completely sent off: 118 out of 118 bytes
    < HTTP/1.1 404 Not Found
    < Content-Type: text/plain; charset=utf-8
    < X-Content-Type-Options: nosniff
    < Date: Fri, 04 Nov 2016 01:10:14 GMT
    < Content-Length: 19
    < Strict-Transport-Security: max-age=31536000
    <
    404 page not found
  • Connection #0 to host auth.docker.io left intact

The same response is returned using credentials for an active account.
It seems that I should at least receive a 401 if the account not authenticated.

Is this service no longer supported?

There is a GET api that I can use to acquire a short-lived bearer token, but I need a refresh token.
That GET api is documented here: [docs.docker.com]/registry/spec/auth/jwt/