Registry fails to serve imported manifest of schema 2 to old client

[miminar]

Manifest V2 schema 2 refers to a special blob by a digest. The blob is a config file which used to be embedded in manifest V2 schema 1. During an image import, the config file is stored in image object. Registry storage is not modified. When such an image is pulled by older client (supporting just manifest V2 schema 1), the registry attempts to convert schema 2 fetched from etcd to schema 1. For this it needs the config file. It attempts to load it from registry's storage and fails.

Version

openshift v1.3.0-alpha.3+3fc2c7c-dirty
kubernetes v1.3.0+507d3a7

docker:

Server:
 Version:         1.9.1
 API version:     1.21
 Package version: docker-common-1.9.1-40.el7.x86_64
 Go version:      go1.4.2
 Git commit:      ab77bde/1.9.1

Steps To Reproduce

1. deploy registry
2. login as a user U and start a new project P
3. tag some remote image of schema 2: oc tag --source docker docker.io/busybox:latest busybox:latest
4. login to docker 1.9 with U's token
5. manually pull the image: docker pull ${REGISTRY_URL}/P/busybox:latest

Current Result

Trying to pull repository 172.30.241.183:5000/pjoe/busybox ... failed
manifest invalid: manifest invalid

Expected Result

Successful pull.

Additional Information

• This case should be handled by pullthroughmiddleware. The middleware needs to override Get() method.
• A case where imagestreamimage is tagged to another repository/namespace needs to be tested as well.