Compare contents of two docker images

compare.sh

#!/bin/bash -x
# https://github.com/mozilla/ichnaea/pull/1064
# opendiff is a recursive GUI diff tool on macOS
# This script leaves a lot of files in the /tmp folder

IMG_NAME=python:3.8.1-slim
SHA1=89d719142de465e7c80195dff820a0bbbbba49b148fbd97abf4b58889372b5e3
SHA2=6ff55b7a7dd4db8cd8098ee78e06a4d64384ea0d6bd771c8dd3fc9da74c48c97

function scan_files {
    IMG=$1@sha256:$2
    docker pull $IMG
    docker create --name="tmp_1" $IMG
    mkdir $3
    cd $3
    docker export tmp_1 | tar -xv
    cd -
    docker rm tmp_1
}

OUT1=/tmp/dockerfiles.$SHA1
OUT2=/tmp/dockerfiles.$SHA2
scan_files $IMG_NAME $SHA1 $OUT1
scan_files $IMG_NAME $SHA2 $OUT2
opendiff $OUT1 $OUT2