Update get and set functions to use digests.
Update push code to use the digest type instead of string
Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)
Move graph related functions in image to graph package.
Consolidating graph functionality is the first step in refactoring graph into an image store model.
Subsequent refactors will involve breaking up graph into multiple types with a strongly defined interface.
Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)
Manifest is now generated during a v2 push, not relying on previously generated hashes. When pushing a layer, the hash is directly calculated from the tar contents which will be pushed. Computing the hash on push ensures that the hash contents always match what is seen by the registry. This also mitigates issues with tarsum differences and permits using pure SHA digests.
Additionally the new manifest function is moved to the unit tests since it is no longer called outside the tests.
Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)
