update config, should fix issue #4

hooks/.config

@@ -1,17 +1,54 @@
+#!/usr/bin/env bash
+
+set +u
+echo "variables (see https://docs.docker.com/docker-hub/builds/advanced/):"
+echo "SOURCE_BRANCH:   $SOURCE_BRANCH"
+echo "SOURCE_COMMIT:   $SOURCE_COMMIT"
+echo "COMMIT_MSG:      $COMMIT_MSG"
+echo "DOCKER_REPO:     $DOCKER_REPO"
+echo "DOCKERFILE_PATH: $DOCKERFILE_PATH"
+echo "CACHE_TAG:       $CACHE_TAG"
+echo "IMAGE_NAME:      $IMAGE_NAME"
+echo
+
+: "${DOCKERFILE_PATH:=./Dockerfile}"
+: "${IMAGE_NAME:=rmoriz/openra}"
+
+echo "variables after applying defaults:"
+echo "DOCKERFILE_PATH: $DOCKERFILE_PATH"
+echo "IMAGE_NAME:      $IMAGE_NAME"
+echo
+
 export PATH="$PWD/docker:$PATH"
 
 # =>
 # https://hub.docker.com/u/arm64v8/
 # https://hub.docker.com/u/arm32v7/
 # https://hub.docker.com/u/arm32v6/
-declare -A base_image_prefix_map=( ["aarch64"]="arm64v8/" ["arm"]="arm32v6/" ["amd64"]="")
+# https://hub.docker.com/u/arm32v5/
+declare -A base_image_prefix_map=( ["aarch64"]="arm64v8/" ["arm"]="arm32v5/" ["amd64"]="")
 
 # => dpkg -L qemu-user-static | grep /usr/bin/
 declare -A docker_qemu_arch_map=( ["aarch64"]="aarch64" ["arm"]="arm" ["amd64"]="x86_64")
 
 # => https://github.com/docker/docker-ce/blob/76ac3a4952a9c03f04f26fc88d3160acd51d1702/components/cli/cli/command/manifest/util.go#L22
 declare -A docker_to_manifest_map=( ["aarch64"]="arm64" ["arm"]="arm" ["amd64"]="amd64")
 
+# what we want to build
 build_architectures=(amd64 aarch64 arm)
+verified_build_architectures=()
+verified_build_architectures+=("$(docker version -f '{{.Server.Arch}}')")
+
+# what we can build
+for arch in ${build_architectures[@]}; do
+  if [ -f "qemu-${docker_qemu_arch_map[${arch}]}-static" ]; then
+    echo "qemu binary for $arch found";
+    verified_build_architectures+=($arch)
+  fi
+done
+
+echo $verified_build_architectures
+set -u
 
 docker -v
+echo