#!/bin/bash
set -e

image='tianon/speedtest'
layer='b31651d7665036bcf58a0b6b0d7aca173daff87b003ec50621cb0fde8d68864f'
# docker inspect b31651d7665036bcf58a0b6b0d7aca173daff87b003ec50621cb0fde8d68864f | grep '"Size"'
#     "Size": 580580561,
# ("Content-Length: 228991341" though...)

token="$(curl -sSL -o /dev/null -D- -H 'X-Docker-Token: true' "https://index.docker.io/v1/repositories/$image/images" | awk -F ':[[:space:]]*|\r' '$1 == "X-Docker-Token" { print $2 }')"

time curl -sSL -o /dev/null -D- -H "Authorization: Token $token" "https://registry-1.docker.io/v1/images/$layer/layer"