dind required to work on debian

docker-entrypoint

@@ -1,6 +1,10 @@
 #!/usr/bin/env bash
 set -e
 
+if [ -z "$DOCKER_HOST" -a "$DOCKER_PORT_2375_TCP" ]; then
+	export DOCKER_HOST='tcp://docker:2375'
+fi
+
 # for local testing only
 #HOME_DIR=.