Testcase for DNS caching bug

testcase-dns-lookup.sh

#!/bin/bash
## @author gdm85
## tests DNS caching in Docker
##
#

if pgrep dnsmasq >/dev/null; then
        echo "You are running dnsmasq, this test would not be consistent" 1>&2
        exit 1
fi

echo "Stopping running docker..."
service docker stop >/dev/null 2>/dev/null

echo "Adding index.docker.io override"
echo "127.0.0.1         index.docker.io" >> /etc/hosts
service docker start >/dev/null || exit $?

echo "Waiting for docker to be online..."
## wait for service to be responsive
while ! docker ps >/dev/null 2>/dev/null; do
        sleep 1
done

echo "Pulling (expected failure)"
docker pull ubuntu
echo "Pull result is: $? (expected 1)"

## remove the override from /etc/hosts
echo "Now removing index.docker.io override"
sed -i '$ d' /etc/hosts

## expected success
docker pull ubuntu
RV=$?
echo "Pull result is: $RV (expected 0)"

exit $RV