builder: fix layer leak on multi-stage wildcard copy

[tonistiigi]

fixes #37077

Signed-off-by: Tonis Tiigi tonistiigi@gmail.com

[codecov]

Codecov Report

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The diff coverage is 0%.

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  Lines             ?    45930           
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[thaJeztah]

Looking good now:

Build, and start development container;

make BIND_DIR=. binary shell

Start daemon in the container;

make install
dockerd --debug &> /var/log/dockerd.log &

Create the test-script;

#!/bin/sh
set -e

build_image_ok() {
	docker image build --quiet --no-cache -t my_app:$1 -<<-EOF 1> /dev/null
		FROM busybox AS build
		RUN touch /vraag.html
		FROM scratch
		COPY --from=build /vraag.html ./
	EOF

	docker image prune -af | tail -1

	printf "Directories in /var/lib/docker/overlay2: "
	find /var/lib/docker/overlay2 -maxdepth 1 -type d | wc -l
}

build_image_faulty() {
	docker image build --quiet --no-cache -t my_app:$1 -<<-EOF 1> /dev/null
		FROM busybox AS build
		RUN touch /vraag.html
		FROM scratch
		COPY --from=build /*.html ./
	EOF

	docker image prune -af | tail -1

	printf "Directories in /var/lib/docker/overlay2: "
	find /var/lib/docker/overlay2 -maxdepth 1 -type d | wc -l
}

run_test() {
	echo "Running ok case:"
	i=1
	while [ $i -le 3 ]; do
		build_image_ok $i
		i=$(( i+1 ))
	done

	echo ""
	echo "Running faulty case:"
	i=1
	while [ $i -le 3 ]; do
		build_image_faulty $i
		i=$(( i+1 ))
	done
}

run_test

Run the test;

chmod +x ./repro-37077.sh
./repro-37077.sh 

Running ok case:
Total reclaimed space: 1.146MB
Directories in /var/lib/docker/overlay2: 2
Total reclaimed space: 1.146MB
Directories in /var/lib/docker/overlay2: 2
Total reclaimed space: 1.146MB
Directories in /var/lib/docker/overlay2: 2

Running faulty case:
Total reclaimed space: 1.146MB
Directories in /var/lib/docker/overlay2: 2
Total reclaimed space: 1.146MB
Directories in /var/lib/docker/overlay2: 2
Total reclaimed space: 1.146MB
Directories in /var/lib/docker/overlay2: 2

[thaJeztah]

LGTM

[selansen]

LGTM

[tiborvass]

LGTM