Shell script to inspect a Docker image on a remote registry

inspect.sh

#!/bin/bash
# Canonical version: https://gist.github.com/lionello/8fb32ee065774b934ab9af62fd269e39
# Inspired by https://stackoverflow.com/a/69300514/2017049

REGISTRY="registry-1.docker.io"
ref="${1:-library/ubuntu:latest}"
repo="${ref%:*}"
tag="${ref##*:}"

token=$(curl -sSLf "https://auth.docker.io/token?service=registry.docker.io&scope=repository:${repo}:pull" \
        | jq -r '.token')

digest=$(curl -H "Accept: application/vnd.docker.distribution.manifest.list.v2+json" \
              -H "Authorization: Bearer $token" \
              -sSLf "https://$REGISTRY/v2/${repo}/manifests/${tag}" \
        | jq -re '.manifests[] | select(.platform.architecture == "amd64" and .platform.os == "linux") | .digest')

config=$(curl -H "Accept: application/vnd.docker.distribution.manifest.v2+json" \
              -H "Authorization: Bearer $token" \
              -sSLf "https://$REGISTRY/v2/${repo}/manifests/${digest:-$tag}" \
        | jq -r .config.digest)

curl -H "Accept: application/vnd.docker.container.image.v1+json" \
     -H "Authorization: Bearer $token" \
     -sSLf "https://$REGISTRY/v2/${repo}/blobs/${config}" | jq .