Re-use Dockerfile when building on Travis

.travis.yml

@@ -1,12 +1,10 @@
-language: go
+language: minimal
 
-go:
-  - stable
+services:
+  - docker
 
-# Go module behaviour is disabled by default for packages inside GOPATH.
-# Turn module support on explicitly:
-env:
-  - GO111MODULE=on
+script:
+  - make docker-build
 
 deploy:
   - provider: script

Dockerfile

@@ -2,8 +2,8 @@
 FROM golang:1.12-stretch AS build
 WORKDIR /go/src/github.com/mpolden/echoip
 COPY . .
-ENV GO111MODULE=on CGO_ENABLED=0
-RUN go install ./...
+ENV GO111MODULE=on
+RUN make
 
 # Run
 FROM scratch

Makefile

@@ -39,5 +39,5 @@ docker-build:
 docker-login:
 	@echo "$(DOCKER_PASSWORD)" | docker login -u "$(DOCKER_USERNAME)" --password-stdin
 
-docker-push: docker-build docker-login
+docker-push: docker-login
 	docker push $(DOCKER_IMAGE)