wip: add build script using buildx

Repo type remains unchanged even though CI will trigger the
build-in-container task for the engine now.
We need the balena-engine type here to ensure versioning works with the
engine specific quirks.

Change-type: patch
Signed-off-by: Robert Günzler <robertg@balena.io>

build-docker.sh

@@ -0,0 +1,65 @@
+#!/bin/sh
+set -e
+
+[ -z "$HERE" ] && HERE="$(dirname "$(readlink -f -- "$0")")"
+
+#     __            __ 
+#    / /____  _____/ /_
+#   / __/ _ \/ ___/ __/
+#  / /_/  __(__  ) /_  
+#  \__/\___/____/\__/  
+#                      
+
+[ -z "$SKIP_TEST" ] && DOCKER_BUILDKIT=1 make test-unit # test-integration
+
+# install buildx
+BUILDX_VERSION="0.4.1"
+BUILDX_BIN="${HOME}/.docker/cli-plugins/docker-buildx"
+if [ ! -e "${BUILDX_BIN}" ]; then
+    curl -LO "https://github.com/docker/buildx/releases/download/v${BUILDX_VERSION}/buildx-v${BUILDX_VERSION}.linux-amd64"
+    mkdir -vp "$(dirname "${BUILDX_BIN}")"
+    mv -vf "buildx-v${BUILDX_VERSION}.linux-amd64" "${BUILDX_BIN}"
+    chmod a+x "${BUILDX_BIN}"
+fi
+
+# create builder instance for this build
+# BUILDX_BUILDER="builder-$(date +%s)"
+# docker buildx create --name="${BUILDX_BUILDER}" \
+#     --driver=docker-container \
+#     --node="${BUILDX_BUILDER}-0" \
+#     --use
+
+VERSION=$(cat VERSION)
+export VERSION
+
+mkdir -p "${HERE}/deploy"
+pack() {
+    echo "* packing $1"
+    [ -n "$2" ] && postfix="-${2}"
+    cd "${BUNDLE_DIR}/cross/$1" || exit 1
+    md5sum "balena-engine-${VERSION}.md5"
+    tar cvzf "${HERE}/deploy/balena-engine-v${VERSION}${postfix}-$(echo "$1" | sed 's/\//-/g').tar.gz" .
+    cd "${HERE}" || exit 1
+}
+
+#      __          _ __    __
+#     / /_  __  __(_) /___/ /
+#    / __ \/ / / / / / __  /
+#   / /_/ / /_/ / / / /_/ /
+#  /_.___/\__,_/_/_/\__,_/
+#
+
+BUNDLE_DIR="${HERE}/bundles"
+if [ ! -e "${BUNDLE_DIR}" ]; then
+    mkdir -p "${BUNDLE_DIR}"
+fi
+
+rm -rf "${BUNDLE_DIR:?}/*"
+BUILDTAGS="no_btrfs no_cri no_devmapper no_zfs exclude_disk_quota exclude_graphdriver_btrfs exclude_graphdriver_devicemapper exclude_graphdriver_zfs no_buildkit"
+export BUILDTAGS
+docker buildx bake --progress=plain \
+    --set=*.output=type=local,dest="${BUNDLE_DIR}"
+
+pack linux/amd64
+pack linux/arm64
+pack linux/arm/v7

docker-compose.yml

@@ -0,0 +1,34 @@
+# needed because buildx only supports >=3
+# 3.4 is needed for the 'target' field
+version: '3.4'
+
+services:
+  binary-amd64:
+    image: balena/balena-engine:${VERSION:?err}-amd64
+    build:
+      target: cross
+      args:
+      - "CROSS=false"
+      - "VERSION=${VERSION}"
+      - "DOCKER_CROSSPLATFORMS=linux/amd64"
+      - "DOCKER_BUILDTAGS=${BUILDTAGS:?err}"
+
+  binary-aarch64:
+    image: balena/balena-engine:${VERSION:?err}-aarch64
+    build:
+      target: cross
+      args:
+      - "CROSS=true"
+      - "VERSION=${VERSION}"
+      - "DOCKER_CROSSPLATFORMS=linux/arm64"
+      - "DOCKER_BUILDTAGS=${BUILDTAGS:?err}"
+
+  binary-rpi:
+    image: balena/balena-engine:${VERSION:?err}-rpi
+    build:
+      target: cross
+      args:
+      - "CROSS=rpi"
+      - "VERSION=${VERSION}"
+      - "DOCKER_CROSSPLATFORMS=linux/arm/v7"
+      - "DOCKER_BUILDTAGS=${BUILDTAGS:?err}"