When pushing images to Amazon ECR, if the tag already exists within the repo the old image remains within the registry but goes in an untagged state.
So if i docker
You can delete all images in a single request, without loops:
IMAGES_TO_DELETE=$( aws ecr list-images --region $ECR_REGION --repository-name $ECR_REPO --filter "tagStatus=UNTAGGED" --query 'imageIds[*]' --output json )
aws ecr batch-delete-image --region $ECR_REGION --repository-name $ECR_REPO --image-ids "$IMAGES_TO_DELETE" || true
First it gets a list of images that are untagged, in json format:
[ {"imageDigest": "sha256:..."}, {"imageDigest": "sha256:..."}, ... ]
Then it sends that list to batch-image-delete.
The last || true is required to avoid an error code when there are no untagged images.