The codec factory should support two distinct interfaces - negotiating
for a serializer with a client, vs reading or writing data to a storage
form (etcd, disk, etc). Make the EncodeForVersion and DecodeToVersion
methods only take Encoder and Decoder, and slight refactoring elsewhere.
In the storage factory, use a content type to control what serializer to
pick, and use the universal deserializer. This ensures that storage can
read JSON (which might be from older objects) while only writing
protobuf. Add exceptions for those resources that may not be able to
write to protobuf (specifically third party resources, but potentially
others in the future).
The decoder will return a nil gvk in case it errors out and getting
the version out of that gvk naturally will panic. Bail out as soon
as we can check that the error is non-nil. kubectl edit was the primary
victim.
Most of the logic related to type and kind retrieval belongs in the
codec, not in the various classes. Make it explicit that the codec
should handle these details.
Factory now returns a universal Decoder and a JSONEncoder to assist code
in kubectl that needs to specifically deal with JSON serialization
(apply, merge, patch, edit, jsonpath). Add comments to indicate the
serialization is explicit in those places. These methods decode to
internal and encode to the preferred API version as previous, although
in the future they may be changed.
React to removing Codec from version interfaces and RESTMapping by
passing it in to all the places that it is needed.
Create a unified Builder object for working with files, selectors,
types, and items that makes it easier to get multi-object functionality.
Supports all of the behaviors previously in resource.go, but with
additional flexibility to allow multi-type retrieval and access, directories,
URLs, nested objects, and lists.
Kris