Redesign integration testing to copy images to nested containers

Previously, the strategy for avoiding lots of rebuilding and repulling
for each Docker version being tested was to use a mountpoint to persist
/var/lib/docker. This was pretty broken, and may not be a reliable
strategy. This commit changes the scripts to instead build/pull images
outside the innermost container, and copy them to the final test
environment with docker save/docker load.

This requires a fair amount of changes, since run.sh must now
communicate with the Docker engine that was formerly started by
test_runner.sh. The code that starts this engine has been broken out to
run_engine.sh so that starting the engine and running the tests under it
can be done separately (with the images loaded in between these steps).

Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>

contrib/docker-integration/test_runner.sh

@@ -3,48 +3,16 @@ set -e
 
 cd "$(dirname "$(readlink -f "$BASH_SOURCE")")"
 
-# Load the helpers.
-#. helpers.bash
-
 TESTS=${@:-.}
 
-# Drivers to use for Docker engines the tests are going to create.
-STORAGE_DRIVER=${STORAGE_DRIVER:-overlay}
-EXEC_DRIVER=${EXEC_DRIVER:-native}
-
-
 function execute() {
 	>&2 echo "++ $@"
 	eval "$@"
 }
 
-# Set IP address in /etc/hosts for localregistry
-IP=$(ifconfig eth0|grep "inet addr:"| cut -d: -f2 | awk '{ print $1}')
-execute echo "$IP localregistry" >> /etc/hosts
-
-# Setup certificates
-execute sh install_certs.sh localregistry
-
-# Start the docker engine.
-execute docker --daemon --log-level=panic \
-	--storage-driver="$STORAGE_DRIVER" --exec-driver="$EXEC_DRIVER" &
-DOCKER_PID=$!
-
-# Wait for it to become reachable.
-tries=10
-until docker version &> /dev/null; do
-	(( tries-- ))
-	if [ $tries -le 0 ]; then
-		echo >&2 "error: daemon failed to start"
-		exit 1
-	fi
-	sleep 1
-done
-
 execute time docker-compose build
 
 execute docker-compose up -d
 
 # Run the tests.
 execute time bats -p $TESTS
-