support copying image referrers from index predecessor via oras copy

[qweeah]

Suppose we have an index directly pointing to several images with different platforms. Each image have an artifact attached as below:

graph TD
Z>v1] -..-> index
A["artifact(linux/s390x)"] -- subject --> B["image"]
C["artifact(linux/amd64)"] -- subject --> D["image"]
E["artifact(linux/arm64)"] -- subject --> F["image"]

index -- linux/s390x --> B
index -- linux/arm64 --> D
index -- linux/amd64 --> F

Loading

Using below command, oras user can copy all the images and artifacts into a new target (registry or image layout) and tag the index in the destination as v2:

oras cp $FROM:v1 $TO:v2 --recursive

[qweeah]

Moving this to future mile stone since the state-of-the-art practice is not clear in CSSC industry. E.g. can a certain arch image being distributed and verified without the multi-arch bundle? If not, the sbom and signature can be attach directly to the multi-arch bundle as below, and this feature is not needed.

graph TD
Z>v1] -..-> index
A["artifact(sbom, signature...)"] -- subject --> index

index -- linux/s390x --> B[image]
index -- linux/arm64 --> D[image]
index -- linux/amd64 --> F[image]

Loading

[github-actions]

This issue is stale because it has been open 60 days with no activity. Remove stale label or comment or this will be closed in 30 days.

[sajayantony]

if --recursive doesn't copy all the refereers for a related index then that is extra burden on the user.
Recommen supporting.