To bring the implementation inline with the specification, the names and
structure of the API routes have been updated.
The overloaded term "image" has been replaced with the term "manifest", which
may also be known as "image manifest". The desire for the layer storage to be
more of a general blob storage is reflected in moving from "layer" api prefixes
to "blob". The "tarsum" path parameter has been replaced by a more general
"digest" parameter and is no longer required to start uploads. Another set of
changes will come along to support this change at the storage service layer.
To be able to support multi-level repository names, the API has been adjusted
to disabiguate routes tagged image manifest routes and tag list routes. With
this effort, the regular expressions have been defined in a single place to
reduce repitition and ensure that validation is consistent across the registry.
The router was also refactored to remove the use of subrouters, simplifying the
route definition code. This also reduces the number of regular expression match
checks during the routing process.
This commit includes the initial API router, based on gorilla mux and a test
suite ensuring the expected variables are extracted. Currently unexported, the
structure here will likely change as this definition will be shared with the
API client.
