Add support for docker volume

Added an environment variable which can be used to pass in the docker volume for the container. This allows caching the pulled images between runs, preventing unnecessary image pulls.

Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)

contrib/docker-integration/README.md

@@ -14,7 +14,7 @@ locally.
 
 *Building locally*
 ```
-docker build -t distribution/docker-integration .
+$ docker build -t distribution/docker-integration .
 ```
 
 ### Run script
@@ -22,7 +22,14 @@ docker build -t distribution/docker-integration .
 Invoke the tests within Docker through the `run.sh` script.
 
 ```
-./run.sh
+$ ./run.sh
+```
+
+Run with aufs driver and tmp volume
+**NOTE: Using a volume will prevent multiple runs from needing to
+re-pull images**
+```
+$ STORAGE_DRIVER=aufs DOCKER_VOLUME=/tmp/volume ./run.sh
 ```
 
 ## Running manually outside of Docker

contrib/docker-integration/run.sh

@@ -6,6 +6,11 @@ cd "$(dirname "$(readlink -f "$BASH_SOURCE")")"
 # Root directory of Distribution
 DISTRIBUTION_ROOT=$(cd ../..; pwd -P)
 
+volumeMount=""
+if [ "$DOCKER_VOLUME" != "" ]; then
+	volumeMount="-v ${DOCKER_VOLUME}:/var/lib/docker"
+fi
+
 # Image containing the integration tests environment.
 INTEGRATION_IMAGE=${INTEGRATION_IMAGE:-distribution/docker-integration}
 
@@ -14,9 +19,8 @@ INTEGRATION_IMAGE=${INTEGRATION_IMAGE:-distribution/docker-integration}
 #docker pull $INTEGRATION_IMAGE
 
 # Start the integration tests in a Docker container.
-ID=$(docker run -d -t --privileged \
+ID=$(docker run -d -t --privileged $volumeMount \
 	-v ${DISTRIBUTION_ROOT}:/go/src/github.com/docker/distribution \
-	-e "DOCKER_IMAGE=$DOCKER_IMAGE" \
 	-e "DOCKER_VERSION=$DOCKER_VERSION" \
 	-e "STORAGE_DRIVER=$STORAGE_DRIVER" \
 	-e "EXEC_DRIVER=$EXEC_DRIVER" \