Makefile: add rules for docker image build

Makefile

@@ -1,4 +1,11 @@
-.PHONY: default rest-server install uninstall clean
+# Copyright © 2017 Zlatko Čalušić
+#
+# Use of this source code is governed by an MIT-style license that can be found in the LICENSE file.
+#
+
+DOCKER_IMAGE ?= restic/rest-server
+
+.PHONY: default rest-server install uninstall docker_build docker_push clean
 
 default: rest-server
 
@@ -11,5 +18,18 @@ install: rest-server
 uninstall:
 	sudo rm -f /usr/local/bin/rest-server
 
+docker_build:
+	docker pull golang:1.9.1-alpine
+	docker run --rm -it \
+		-v $(CURDIR):/go/src/github.com/restic/rest-server \
+		-w /go/src/github.com/restic/rest-server \
+		golang:1.9.1-alpine \
+		go run build.go
+	docker pull alpine:3.6
+	docker build -t $(DOCKER_IMAGE) .
+
+docker_push:
+	docker push $(DOCKER_IMAGE):latest
+
 clean:
 	rm -f rest-server