From d6215a055e393ceb44a3cf83062849fb4cd8a41c Mon Sep 17 00:00:00 2001
From: "Quentin McGaw (desktop)" <quentin.mcgaw@gmail.com>
Date: Mon, 2 Aug 2021 18:26:17 -0400
Subject: [PATCH] Change Dockerfile for cross building - Download and build
 vendor dependencies once on native platform - Build final image N times for N
 platforms with Docker emulation

---
 Dockerfile | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/Dockerfile b/Dockerfile
index d9c1aad8..e790113f 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,13 +1,16 @@
+ARG BUILDPLATFORM=linux/amd64
+ARG TARGETPLATFORM
 ARG DEBIAN_VERSION=buster-slim
 ARG COMPOSER_VERSION=2.1
 ARG SUPERVISORD_VERSION=v0.7.3
 
+FROM --platform=${BUILDPLATFORM} composer:${COMPOSER_VERSION} AS build-composer
 FROM composer:${COMPOSER_VERSION} AS composer
 FROM qmcgaw/binpot:supervisord-${SUPERVISORD_VERSION} AS supervisord
 
-FROM debian:${DEBIAN_VERSION} AS vendor
+FROM --platform=${BUILDPLATFORM} debian:${DEBIAN_VERSION} AS vendor
 ENV DEBIAN_FRONTEND=noninteractive
-COPY --from=composer --chown=www-data /usr/bin/composer /usr/bin/composer
+COPY --from=build-composer --chown=www-data /usr/bin/composer /usr/bin/composer
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
     # PHP