Add fail-safe to test the image architecture

Verify that the target image architecture matches what is expected
according to the balena app architecture.

Change-type: patch

Dockerfile.template

@@ -133,6 +133,10 @@ COPY typings ./typings
 COPY src ./src
 COPY test ./test
 
+# Fail-safe, check the architecture used by apk against the expected architecture
+# from the device type
+RUN APK_ARCH=$(./build-utils/apk-print-arch.sh); [ "$APK_ARCH" = "$ARCH" ] || (echo "Image architecture ($APK_ARCH) does not match the target architecture ($ARCH)" && exit 1)
+
 # Run type checking and unit tests here
 # to prevent setting up a test environment that will
 # most likely fail.

build-utils/apk-print-arch.sh

@@ -0,0 +1,24 @@
+#!/bin/sh
+# detect-arch.sh
+
+apk_arch=$(apk --print-arch)
+case $apk_arch in
+x86_64)
+	printf "amd64"
+	;;
+aarch64)
+	printf "aarch64"
+	;;
+armv7)
+	printf "armv7hf"
+	;;
+armhf)
+	printf "rpi"
+	;;
+x86)
+	printf "i386"
+	;;
+*)
+	printf "%s" "$apk_arch"
+	;;
+esac