Put docker release in Makefile.release (#562)

Make the docker release part of the normal CoreDNS release

Makefile

@@ -2,9 +2,6 @@ BUILD_VERBOSE := -v
 
 TEST_VERBOSE := -v
 
-DOCKER_IMAGE_NAME ?= $$USER/coredns
-DOCKER_VERSION ?= $(shell grep 'coreVersion' coremain/version.go | awk '{ print $$3 }' | tr -d '"')
-
 all: coredns
 
 # Phony this to ensure we always build the binary.
@@ -13,12 +10,6 @@ all: coredns
 coredns: deps core/zmiddleware.go core/dnsserver/zdirectives.go
 	go build $(BUILD_VERBOSE) -ldflags="-s -w"
 
-.PHONY: docker
-docker: deps
-	CGO_ENABLED=0 GOOS=linux go build -ldflags="-s -w"
-	docker build -t $(DOCKER_IMAGE_NAME) .
-	docker tag $(DOCKER_IMAGE_NAME):latest $(DOCKER_IMAGE_NAME):$(DOCKER_VERSION)
-
 .PHONY: deps
 deps: fmt
 	go get ${BUILD_VERBOSE}

Makefile.release

@@ -24,14 +24,24 @@
 #   * will commit your change with 'Release $VERSION'
 #   * push to github
 #   * build the release and do all that fluff.
+#
+# Steps for docker
+# * Login into docker: docker login (should have push creds for coredns registry)
+# * Run: make -f Makefile.release docker
+# 
+# Docker push should happen after you make the new release and uploaded it to Github.
 
 NAME:=coredns
 VERSION:=$(shell grep 'coreVersion' coremain/version.go | awk '{ print $$3 }' | tr -d '"')
 ARCH:=$(shell uname -m)
 GITHUB:=coredns
+DOCKER:=coredns
+DOCKER_IMAGE_NAME:=$(DOCKER)/$(NAME)
 
 all:	commit push build tar release
 
+docker: docker-build docker-release
+
 .PHONY: push
 push:
 	@echo Pushing release to master
@@ -62,6 +72,17 @@ release:
 	@echo Releasing: $(VERSION)
 	gh-release create $(GITHUB)/$(NAME) $(VERSION)
 
+.PHONY: docker-build
+docker:
+	CGO_ENABLED=0 GOOS=linux go build -ldflags="-s -w"
+	docker build -t $(DOCKER_IMAGE_NAME) .
+	docker tag $(DOCKER_IMAGE_NAME):latest $(DOCKER_IMAGE_NAME):$(VERSION)
+
+.PHONY: docker-release
+docker-release:
+	@echo Pushing: $(VERSION)
+	docker tag $(DOCKER_IMAGE_NAME):latest $(DOCKER_IMAGE_NAME):$(VERSION)
+
 .PHONY: clean
 clean:
 	rm -rf release