Container Support

Each repository and distribution should have a Foreign Key to a Namespace. A Namespace should just have a 'name'.

From https://docs.docker.com/registry/spec/api/#overview :

Classically, repository names have always been two path components where each path component is less than 30 characters. The V2 registry API does not enforce this. The rules for a repository name are as follows:

A repository name is broken up into path components. A component of a repository name must be at least one lowercase, alpha-numeric characters, optionally separated by periods, dashes or underscores. More strictly, it must match the regular expression [a-z0-9]+(?:[._-][a-z0-9]+)*. If a repository name has two or more path components, they must be separated by a forward slash (“/”). The total length of a repository name, including slashes, must be less than 256 characters.

These name requirements only apply to the registry API and should accept a superset of what is supported by other docker ecosystem components.

It looks like we try to support having arbitrary path's for container repositories. I am quite unsure, how this will work with a namespace concept. Can we assume a two component model for this? Should we have nested namespaces?

I heard/read about the 2+ path components however I have never witnessed that so far. We do have though a user story that would require 2+ path components https://pulp.plan.io/issues/5545 I also digged out some old pulp2 RFE https://pulp.plan.io/issues/3136 https://pulp.plan.io/issues/3128 related to having more path components