How to download or tag an untagged image on ECR?

Question

The UI on ECR does not let you apply tags to images. When you push images to ECR that have a tag that exists, the existing image becomes untagged, as expected. However, there does not appear to be a way to download untagged images. For example, I can't simply download the image hash

docker pull myarn.amazonaws.com/sandbox:e226e9aaa12beb32bfe65c571cb60605b2de13338866bc832bba0e39f6819365
Error response from daemon: manifest for myarn.amazonaws.com/sandbox:e226e9aaa12beb32bfe65c571cb60605b2de13338866bc832bba0e39f6819365 not found

Answer 1

So I discovered a user-unfriendly way of doing this. You first tag an untagged image, then you can download it. Here I tag an untagged image to backup

MANIFEST=$(aws ecr batch-get-image --repository-name sandbox --image-ids imageDigest=sha256:e226e9aaa12beb32bfe65c571cb60605b2de13338866bc832bba0e39f6819365 --query 'images[].imageManifest' --output text)
aws ecr put-image --repository-name sandbox --image-tag backup --image-manifest "$MANIFEST"

Then I can download it as normal

docker pull myarn.amazonaws.com/sandbox:backup