From 6350e3cb721634182e7f6f424cfc450dbf6aa01d Mon Sep 17 00:00:00 2001
From: Sebastian Hugentobler <sebastian@vanwa.ch>
Date: Wed, 19 Aug 2020 12:22:01 +0200
Subject: [PATCH] support aarch64

---
 Dockerfile            | 25 +++++++++++++++++++++----
 fetch-platform-rootfs | 17 +++++++++++++++++
 2 files changed, 38 insertions(+), 4 deletions(-)
 create mode 100755 fetch-platform-rootfs

diff --git a/Dockerfile b/Dockerfile
index c922eed..e4ca18f 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,11 +1,28 @@
-FROM alpine:3.12
+FROM alpine:3.12 AS builder
 LABEL maintainer="Sebastian Hugentobler <sebastian@vanwa.ch>"
 
+ARG TARGETPLATFORM
+
 ENV S6_OVERLAY_VERSION=v2.0.0.1
+ENV SHA256_amd64=df235428444be7737caf363e5dcfb58e3022fa611f5a27fe309ecd6fc1755cda
+ENV SHA256_aarch64=5bc75be125409f0a22ba5a5b60f9150fa236bf858200809c91f72956326f8812
+
+RUN apk --no-cache add \
+    bash
+
+ADD fetch-platform-rootfs /
+RUN ./fetch-platform-rootfs
+RUN mkdir /overlay
+RUN tar -xvf s6-overlay.tar.gz -C /overlay
+
+FROM alpine:3.12
+
 ENV LANG=en_US.UTF-8
-    
-RUN apk --no-cache add syslog-ng
-RUN wget -qO- https://github.com/just-containers/s6-overlay/releases/download/$S6_OVERLAY_VERSION/s6-overlay-amd64.tar.gz | tar -xz -C /
+
+COPY --from=builder /overlay /
+
+RUN apk --no-cache add \
+    syslog-ng
 
 RUN apk --no-cache upgrade
 
diff --git a/fetch-platform-rootfs b/fetch-platform-rootfs
new file mode 100755
index 0000000..c276465
--- /dev/null
+++ b/fetch-platform-rootfs
@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+set -ex
+
+case $TARGETPLATFORM in
+	linux-arm64)
+		ARCH=aarch64
+		;;
+	*)
+		ARCH=amd64
+		;;
+  esac
+
+DOWNLOAD="https://github.com/just-containers/s6-overlay/releases/download/$S6_OVERLAY_VERSION/s6-overlay-$ARCH.tar.gz"
+wget "$DOWNLOAD"
+
+sha256_name=SHA256_$ARCH && echo "${!sha256_name}  /s6-overlay-$ARCH.tar.gz" | sha256sum -c - || exit 1
+mv /s6-overlay-$ARCH.tar.gz /s6-overlay.tar.gz