Build and push image to other registry

Command: `make push DOCKER_REGISTRY=index.docker.io PROJECT=(your account)`

expandybird/Makefile

-# Makefile for the Docker image gcr.io/$(PROJECT)/expandybird
+# Makefile for the Docker image $(DOCKER_REGISTRY)/$(PROJECT)/expandybird
 # MAINTAINER: Jack Greenfield <jackgr@google.com>
 # If you update this image please check the tag value before pushing.
 
 .PHONY : all build test push container clean
 
-PREFIX := gcr.io/$(PROJECT)
+DOCKER_REGISTRY := gcr.io
+PREFIX := $(DOCKER_REGISTRY)/$(PROJECT)
 IMAGE := expandybird
 TAG := latest
 
 DIR := .
 
 push: container
+ifeq ($(DOCKER_REGISTRY),gcr.io)
 	gcloud docker push $(PREFIX)/$(IMAGE):$(TAG)
+else
+	docker push $(PREFIX)/$(IMAGE):$(TAG)
+endif
 
 container: expandybird
 	cp $(shell which expandybird) .
@@ -25,4 +30,4 @@ expandybird:
 clean:
 	-docker rmi $(PREFIX)/$(IMAGE):$(TAG)
 	rm -f expandybird
-	
+

manager/Makefile

-# Makefile for the Docker image gcr.io/$(PROJECT)/manager
+# Makefile for the Docker image $(DOCKER_REGISTRY)/$(PROJECT)/manager
 # MAINTAINER: Jack Greenfield <jackgr@google.com>
 # If you update this image please check the tag value before pushing.
 
 .PHONY : all build test push container clean .project
 
-PREFIX := gcr.io/$(PROJECT)
+DOCKER_REGISTRY := gcr.io
+PREFIX := $(DOCKER_REGISTRY)/$(PROJECT)
 IMAGE := manager
 TAG := latest
 
@@ -12,11 +13,15 @@ ROOT_DIR := $(abspath ./..)
 DIR = $(ROOT_DIR)
 
 push: container
+ifeq ($(DOCKER_REGISTRY),gcr.io)
 	gcloud docker push $(PREFIX)/$(IMAGE):$(TAG)
+else
+	docker push $(PREFIX)/$(IMAGE):$(TAG)
+endif
 
-container: 
+container:
 	docker build -t $(PREFIX)/$(IMAGE):$(TAG) -f Dockerfile $(DIR)
 
 clean:
 	-docker rmi $(PREFIX)/$(IMAGE):$(TAG)
-	
\ No newline at end of file
+

resourcifier/Makefile

-# Makefile for the Docker image gcr.io/$(PROJECT)/resourcifier
+# Makefile for the Docker image $(DOCKER_REGISTRY)/$(PROJECT)/resourcifier
 # MAINTAINER: Jack Greenfield <jackgr@google.com>
 # If you update this image please check the tag value before pushing.
 
 .PHONY : all build test push container clean
 
-PREFIX := gcr.io/$(PROJECT)
+DOCKER_REGISTRY := gcr.io
+PREFIX := $(DOCKER_REGISTRY)/$(PROJECT)
 IMAGE := resourcifier
 TAG := latest
 
@@ -12,7 +13,11 @@ ROOT_DIR := $(abspath ./..)
 DIR = $(ROOT_DIR)
 
 push: container
+ifeq ($(DOCKER_REGISTRY),gcr.io)
 	gcloud docker push $(PREFIX)/$(IMAGE):$(TAG)
+else
+	docker push $(PREFIX)/$(IMAGE):$(TAG)
+endif
 
 container:
 	docker build -t $(PREFIX)/$(IMAGE):$(TAG) -f Dockerfile $(DIR)