testcase for port-in-use Docker recognition issue

port-testcase-7158.sh

#!/bin/bash
## @author gdm85
## testcase for inconsistent Docker port-in-use recognition
#

TMPD=$(mktemp -d) || exit $?

function cleanup() {
	local CONTAINER="$1"
	docker kill "$CONTAINER" >/dev/null && docker rm "$CONTAINER" >/dev/null
}

IMG=port-testcase-7158

docker rmi "$IMG" 2>/dev/null

cd $TMPD && \
cat <<EOF > $TMPD/Dockerfile || exit $?
FROM ubuntu:latest
CMD sleep 600000
EXPOSE 23
EOF

cd $TMPD && \
docker build --tag="$IMG" . > /dev/null && \
cd && rm -rf $TMPF && \
docker run -d -p 23:23 --name=test1 $IMG || exit $?

## here the evil happens
IP=$(docker inspect --format '{{ .NetworkSettings.IPAddress }}' test1) && \
iptables -D FORWARD -d $IP/32 ! -i docker0 -o docker0 -p tcp -m tcp --dport 23 -j ACCEPT && \
cleanup test1

## finally, docker ports state is corrupted and can only be restored by restarting the daemon
docker run -d -p 23:23 --name=test1 $IMG
RV=$?

cleanup test1 || exit $?

if [ $RV -eq 0 ]; then
	echo "$IMG: all OK"
else
	echo "$IMG: docker port in use state is corrupted" 1>&2
	exit $RV
fi