Add option to serve http via proxy to use apt-cacher (on host)

build/Makefile

@@ -1,7 +1,8 @@
 TMP = /build/tmp
 FROM = debian:jessie
-MODE = normal
+MODE = minimal
 ARGS = --rm=false --no-cache=false
+PROXY = $(shell ifconfig eth0 | grep 'inet addr:' | cut -d: -f2 | cut -d' ' -f1)
 include $(wildcard $(DOCKER_HOME)/build/make/*.mk)
 
 define add
@@ -36,6 +37,9 @@ build: prepare base
 	$(call script,cleanup)
 	@echo 'RUN chmod +x -R /opt/init.d' >> ${FILE}
 	@echo 'CMD ["/opt/init"]' >> ${FILE}
+ifneq ($(PROXY),)
+	@$(eval ARGS += --build-arg HTTP_PROXY=http://$(PROXY):3142)
+endif
 	@docker build -t $(NAME):$(VERSION) $(ARGS) -f $(FILE) $(DOCKER_HOME)/build
 	@rm ${FILE}
 
@@ -47,6 +51,7 @@ prepare:
 	$(call add,init,/opt/init)
 	@echo 'RUN chmod +x /opt/init' >> ${FILE}
 	$(call script,prepare)
+
 clean:
 	@rm -f ${FILE}
 	@rm -rf build