Inspect file changes by every step in `docker build`

docker-build-and-log-changeset.sh

#!/bin/bash

mkdir -p build.diffs;
i=0;

# put your docker build at enxt line. required `--no-cache --rm=false`
docker build --no-cache --rm=false -t docker101tutorial . |
	grep -Pzo 'Step(.*)\n ---> Running .*\n' |
		while read -r line && read -r line2;
			do
				echo $i;
				step_command=$(echo $line | sed -n --expression "s/Step [[:digit:]]\+\/[[:digit:]]\+ : \(.\+\)/\1/p");
				container_id=$(echo $line2 | sed -n --expression "s/---> Running in \(.\+\)/\1/p");
				echo $step_command > build.diffs/${i}.diff;
				docker container diff $container_id >> build.diffs/${i}.diff;
				# TODO use `docker export $container_id | tar -tv` to more information about file sizes
				(( i++ ));
			done;