Description of problem:
Secure and expose registry, then push causes "unauthorized: authentication required". If port is on 443, for instance, then running "docker push" should default to trying 443 (if in additional registries in /etc/sysconfig/docker or if specifying https://) or 80 (if in insecure registry or if specifying http://). As it stands this message occurs unless manually specifying the actual port.

Version-Release number of selected component (if applicable):
3.5

How reproducible:
Unconfirmed

Steps to Reproduce:
1. Secure and expose registry
2. docker push registry.cloudapps.example.com/openshift/php:latest

Actual results:
Cannot set persistent booleans, please try as root.
The push refers to a repository [registry.cloudapps.example.com/openshift/php]
95c4fd550d8e: Preparing
b41b282bd373: Preparing
3cb03dc081c0: Preparing
f483edd7a42b: Preparing
f7b626558f10: Preparing
unauthorized: authentication required

Expected results:
Push successful

Additional info:

not sure if this appears only in certain conditions. I documented in a KCS solution https://access.redhat.com/solutions/3090231 -- may be related to upstream issue https://github.com/openshift/origin/issues/12260 and PRs https://github.com/openshift/origin/pull/11391 and https://github.com/openshift/origin/pull/14319

This is a slightly odd user experience, as we should expect that if you specify https, or if it's a known secure registry, that you'd automatically try port 443. Or otherwise it would be good to have a slightly more useful error message.

Or if the above is not able to be modified due to upstream conventions, we can change this to a docs bug to add a quick note in the docs, "On a secured, exposed registry it is required to specify the port"