add configuration to use nginx-golang-postgres sample with Docker Dev Environments feature

Signed-off-by: Guillaume Lours <guillaume.lours@docker.com>

nginx-golang-postgres/backend/Dockerfile

@@ -1,9 +1,29 @@
-FROM golang:1.13-alpine AS build
+# syntax=docker/dockerfile:1.4
+
+FROM --platform=$BUILDPLATFORM golang:1.18 AS build
 WORKDIR /go/src/github.com/org/repo
+COPY go.* .
 COPY . .
 
+ENV CGO_ENABLED=0
 RUN go build -o server .
 
+FROM build as dev-envs
+
+RUN <<EOF
+apt-get update
+apt-get install -y --no-install-recommends git
+EOF
+
+RUN <<EOF
+useradd -s /bin/bash -m vscode
+groupadd docker
+usermod -aG docker vscode
+EOF
+# install Docker tools (cli, buildx, compose)
+COPY --from=gloursdocker/docker / /
+CMD ["go", "run", "main.go"]
+
 FROM alpine:3.12
 EXPOSE 8000
 COPY --from=build /go/src/github.com/org/repo/server /server