golang multi stage docker build

Dockerfile

## builder docker
FROM golang:1.9.2 as builder
WORKDIR /go/src/buddytest
copy ./ .

RUN curl https://glide.sh/get | sh
RUN glide install

RUN go test
RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o app .

## final docker
FROM alpine:latest
RUN apk --no-cache add ca-certificates

WORKDIR /app
# notice [--from]: here we get app file from previous docker build stage
COPY --from=builder /go/src/buddytest/app .
CMD ["./app"]

pipe docker builds for less size images