Describe the bug

I am using buildkit to build my image and then using crane to authenticate to a registry and push the image.

Here are some docs about the buildctl build command, specifically, the output option.

The command I am running to build the image is:

buildctl build \
--frontend dockerfile.v0 \
--local context=. \
--local dockerfile=. \
--output type=oci,dest=my-image.tar

This creates a my-image.tar OCI tarball file in the current working directory.

I am then authenticating to a private AWS ECR using aws ecr get-login-password --region ${region} | crane auth login --username AWS --password-stdin ${ecrRegistryUrl}") and attempting to run crane push my-image.tar ${ecrRegistryUrl}/my-repo/my-image:latest, but I get an error: Error: loading my-image.tar as tarball: file manifest.json not found in tar

To Reproduce

1. Install buildkit/buildctl for whatever OS you run.
2. Install crane
3. Build an image using buildctl build ... and make sure to save it as an OCI tarball using the flags --output type=oci,dest=my-image-tarball.tar
4. Attempt to push the image using crane push

Expected behavior

I would expect the crane push to work is all.

Anything else

❯ crane version
0.20.5