Multistep Docker build with Golang

Dockerfile

# builder
FROM golang:1.16-buster AS builder

ARG DEBIAN_FRONTEND="noninteractive"

RUN set -ex && \
    apt-get -qq update && apt-get -y -qq install \
      gcc

WORKDIR /go/src/app
COPY go.* ./
RUN go mod download

COPY . .
RUN go get -d -v
RUN GOOS=linux GOARCH=amd64 go build -a -v


# main
FROM debian:buster-slim

ARG DEBIAN_FRONTEND="noninteractive"

EXPOSE 8080

ENTRYPOINT ["my-app"]

RUN set -ex &&\
    apt-get -qq update && apt-get -y -qq install \
      bash \
      ca-certificates && \
    useradd -md /app -s /bin/bash app

USER app
WORKDIR /app

COPY --from=builder --chown=app:app /go/src/app/my-app /usr/local/bin/