add buildarg

Makefile

 # a helper shell script
-MAKE_VERSION=1.2.3
+MAKE_VERSION=1.2.5
 
 define MAKEFUNCTIONCODE
 	function hasChanges() {
@@ -128,6 +128,7 @@ VERSION=$(shell . $(RELEASE_SUPPORT) ; getVersion)
 VERSIONHASH=$(shell . $(RELEASE_SUPPORT) ; getVersionWithHash)
 TAG=$(shell . $(RELEASE_SUPPORT); getTag)
 PROJECTPATH?=.
+BUILDARG?= 
 
 RELEASE_SUPPORT := $(shell dirname $(abspath $(lastword $(MAKEFILE_LIST))))/.make-function
 export MAKEFUNCTIONCODE
@@ -196,7 +197,7 @@ post-init:
 	@rm .make-function
 
 docker-build:
-	docker build -t $(IMAGE):$(VERSIONHASH) $(PROJECTPATH)
+	docker build $(BUILDARG) -t $(IMAGE):$(VERSIONHASH) $(PROJECTPATH)
 	@DOCKER_MAJOR=$(shell docker -v | sed -e 's/.*version //' -e 's/,.*//' | cut -d\. -f1) ; \
 	DOCKER_MINOR=$(shell docker -v | sed -e 's/.*version //' -e 's/,.*//' | cut -d\. -f2) ; \
 	if [ $$DOCKER_MAJOR -eq 1 ] && [ $$DOCKER_MINOR -lt 10 ] ; then \