Use standard crossbuild for docker build instead of spinning up a doc…

…ker build container.

Dockerfile

@@ -1,20 +1,5 @@
-FROM golang:alpine as builder
-
-# Install git because gin/yaml needs it
-# Install make for building
-RUN apk update && apk upgrade && apk add git make
-
-# Copy the code from the host and compile it
-WORKDIR $GOPATH/src/github.com/tellytv/telly
-COPY . ./
-
-# Build the executable using promu since that builds in the version info
-# copy the resulting executable to the root under the name "app"
-RUN make promu && make build && mv ./telly /app
-
 FROM scratch
-# Original: copy from the builder image above:
-COPY --from=builder /app ./
+COPY .build/linux-amd64/telly ./app
 EXPOSE 6077
 ENTRYPOINT ["./app"]
 

Makefile

@@ -42,7 +42,7 @@ tarball: promu
 	@echo ">> building release tarball"
 	@$(PROMU) tarball $(BIN_DIR)
 
-docker:
+docker: cross
 	@echo ">> building docker image"
 	@docker build -t "$(DOCKER_IMAGE_NAME):$(DOCKER_IMAGE_TAG)" .