Can you download a docker image from a repository to a docker container without a running docker daemon?

Question

I have a docker container with Trivy installed.
I have a remote registry with docker images.

and

I would like to download the docker images to the container for scanning

Challenges

It is hard to run docker within a docker container for pulling the images. Trivy requires that you have the images locally before it can scan the images, either in a local registry or as a file.

Answer 1

I found two solutions:

1. Download the images with Skopeo
2. Download the images with the HTTP API V2
   • For the API I had a hard time making the authentication work, as it is repository specific, and Scaleways' authentication had unexpected behaviour.