Login to hub.docker.com to get user specific pull rate. (#73)

Author: falkzoll

tools/travis/build.sh

@@ -11,6 +11,12 @@ export OPENWHISK_HOME=$WHISKDIR
 
 IMAGE_PREFIX="testing"
 
+# Login to hub.docker.com to get user specific pull rate.
+if [ ! -z "${DOCKER_USER}" ] && [ ! -z "${DOCKER_PASSWORD}" ]; then
+  echo "Run docker login..."
+  echo ${DOCKER_PASSWORD} | docker login -u "${DOCKER_USER}" --password-stdin
+fi
+
 # Build OpenWhisk
 cd $WHISKDIR