use multistage build Dockerfile (#142)

* use multistage build dockerfile
* add .git to dockeringore
* simplify makefile

.dockerignore

@@ -0,0 +1,5 @@
+.git
+bin
+docs
+ci
+deploy

.drone.yml

@@ -16,11 +16,6 @@ pipeline:
     commands:
       - make bench
 
-  build:
-    image: golang:1.10
-    commands:
-      - make build-linux
-
   docker:
     when:
       event: push

Dockerfile

@@ -1,7 +1,10 @@
-FROM alpine:3.8
+FROM golang:1.10-alpine3.8 as build
+RUN apk add --no-cache make
+WORKDIR /go/src/github.com/uswitch/kiam
+ADD . .
+RUN make
 
+FROM alpine:3.8
 RUN apk --no-cache add iptables
-
-COPY bin/kiam-linux-amd64 /kiam
-
+COPY --from=build /go/src/github.com/uswitch/kiam/bin/kiam-linux-amd64 /kiam
 CMD []

Makefile

@@ -1,13 +1,17 @@
+NAME?=kiam
 ARCH=amd64
 BIN = bin/kiam
 BIN_LINUX = $(BIN)-linux-$(ARCH)
 BIN_DARWIN = $(BIN)-darwin-$(ARCH)
-
+GIT_BRANCH?=$(shell git rev-parse --abbrev-ref HEAD)
+IMG_NAMESPACE?=quay.io/uswitch
+IMG_TAG?=$(GIT_BRANCH)
+REGISTRY?=$(IMG_NAMESPACE)/$(NAME)
 SOURCES := $(shell find . -iname '*.go') proto/service.pb.go
 
 .PHONY: test clean all coverage
 
-all: proto/service.pb.go build-darwin build-linux
+all: build-linux
 
 build-darwin: $(SOURCES)
 	GOARCH=$(ARCH) GOOS=darwin go build -o $(BIN_DARWIN) cmd/kiam/*.go
@@ -31,8 +35,8 @@ coverage: $(SOURCES) coverage.txt
 bench: $(SOURCES)
 	go test -run=XX -bench=. github.com/uswitch/kiam/pkg/...
 
-docker: Dockerfile $(BIN_LINUX)
-	docker image build -t quay.io/uswitch/kiam:devel .
+docker: Dockerfile
+	docker image build -t "$(REGISTRY):$(IMG_TAG)" .
 
 clean:
 	rm -rf bin/