Add an ability to tag a remote manifest in the registry

[ipanova]

Feature request description

podman tag can tag only locally stored images. Add an ability to tag a manifest that already exists on the registry.

Suggest potential solution

For regular manifests it would be enough to perform 'podman pull and then tag/push' but it will unnecessarily pull besides the manifest also the layers.

For manifests that contain artifacts it is not possible to podman pull, neither push a standalone manifest artifact that can be tagged.

Have you considered any alternatives?

Current workaround is to use skopeo copy docker://$foo@$digest docker://$foo:$tag

Additional context

Add any other context or screenshots about the feature request here.

[rhatdan]

@mtrmac PTAL

[github-actions[bot]]

A friendly reminder that this issue had no activity for 30 days.

[rhatdan]

@baude PTAL

[gbraad]

I do the following

$ podman manifest create --all fedora-manifest docker://ghcr.io/gbraad-actions/fedora:latest
$ podman login ghcr.io -u ${{ github.actor }} -p ${{ secrets.GITHUB_TOKEN }}
$ podman manifest push --all fedora-manifest docker://ghcr.io/gbraad-actions/fedora:stable

as part of a GitHub workflow. It correctly tags all the images in the manifest from latest to stable. While this LOOKS OK from the Web UI, I did experience issues from time to time, such as "manifest unknown"