Support private repositories

[cthtrifork]

sudo podman run --rm \
...
    -e PREV_REF="${{ inputs.prev-ref }}" \
...
    ${{ inputs.rechunk }} \
...

Will partially fail if the prev-ref is for a private image.
It will still rechunk the new image, but skopeo wont succed when trying to get the previous manifest:
https://github.com/hhd-dev/rechunk/blob/master/3_chunk.sh#L32

I propose syncing the auth.json file to podman in your action:

sudo podman run --rm \
    -v "${HOME}/.config/containers/auth.json:/run/containers/0/auth.json:ro" \
...
    -e PREV_REF="${{ inputs.prev-ref }}" \
...
    ${{ inputs.rechunk }} \
...

alternatively use skopeo --creds with env vars:

if [ -n "$REGISTRY_AUTH_USERNAME" ] && [ -n "$REGISTRY_AUTH_PASSWORD" ]; then
    skopeo inspect \
      --creds "${REGISTRY_AUTH_USERNAME}:${REGISTRY_AUTH_PASSWORD}" \
      docker://${PREV_REF}
else
    skopeo inspect docker://${PREV_REF}
fi

I can make a PR for this. Let me know what you think

[antheas]

PRsbare welcome! If you PR it I will merge it

[cthtrifork]

Cool let me test it on some e2e and get back to you later today.