build_image: Deduplicate --extract_update and --generate_update options

The --extract_update option used to do exactly that, just extract the
USR-A partition for updates and no more. Now it does the same thing as
--generate_update, except it names the file flatcar_test_update.gz
rather than flatcar_production_update.gz. --generate_update is never
actually used because official update payloads are manually generated
with the generate_payload script later on.

Resolve this confusion by deduplicating the common code between them.
Any update payload produced during this stage of the build is only
useful for testing, so change --generate_update to always create
flatcar_test_update.gz. --generate_update now implies --extract_update
and both are enabled by default.

Signed-off-by: James Le Cuirot <jlecuirot@microsoft.com>

build_image

@@ -41,10 +41,10 @@ DEFINE_string disk_layout "" \
   "The disk layout type to use for this image."
 DEFINE_string group "${DEFAULT_GROUP}" \
   "The update group."
-DEFINE_boolean generate_update "${FLAGS_FALSE}" \
-  "Generate update payload. (prod only)"
 DEFINE_boolean extract_update "${FLAGS_TRUE}" \
-  "Extract the /usr partition for generating updates."
+  "Extract the /usr partition for generating updates. Only valid for the prod image."
+DEFINE_boolean generate_update "${FLAGS_TRUE}" \
+  "Generate update payload for testing. The update is signed with a dev key. The kernel is signed with a dev key (unofficial builds) or not at all (official builds). Only valid for the prod image. Implies --extract_update."
 DEFINE_string developer_data "" \
   "Insert a custom cloudinit file into the image."
 DEFINE_string devcontainer_binhost "${DEFAULT_DEVCONTAINER_BINHOST}" \
@@ -139,6 +139,11 @@ fi
 # Create the output directory and temporary mount points.
 mkdir -p "${BUILD_DIR}"
 
+# --generate_update implies --extract_update.
+if [[ ${FLAGS_generate_update} -eq ${FLAGS_TRUE} ]]; then
+  FLAGS_extract_update=${FLAGS_TRUE}
+fi
+
 DISK_LAYOUT="${FLAGS_disk_layout:-base}"
 CONTAINER_LAYOUT="${FLAGS_disk_layout:-container}"
 
@@ -169,11 +174,12 @@ fi
 if [[ "${PROD_IMAGE}" -eq 1 ]]; then
   IMAGE_BUILD_TYPE="prod"
   create_prod_image ${FLATCAR_PRODUCTION_IMAGE_NAME} ${DISK_LAYOUT} ${FLAGS_group} ${FLAGS_base_pkg} ${FLAGS_base_sysexts}
-  if [[ ${FLAGS_generate_update} -eq ${FLAGS_TRUE} ]]; then
-    generate_update "${FLATCAR_PRODUCTION_IMAGE_NAME}" ${DISK_LAYOUT}
-  elif [[ ${FLAGS_extract_update} -eq ${FLAGS_TRUE} ]]; then
+  if [[ ${FLAGS_extract_update} -eq ${FLAGS_TRUE} ]]; then
     extract_update "${FLATCAR_PRODUCTION_IMAGE_NAME}" "${DISK_LAYOUT}"
   fi
+  if [[ ${FLAGS_generate_update} -eq ${FLAGS_TRUE} ]]; then
+    generate_update "${FLATCAR_PRODUCTION_IMAGE_NAME}" "${DISK_LAYOUT}"
+  fi
   if [[ "${PROD_TAR}" -eq 1 ]]; then
     create_prod_tar ${FLATCAR_PRODUCTION_IMAGE_NAME}
   fi
@@ -182,9 +188,7 @@ if [[ "${SYSEXT}" -eq 1 ]]; then
   create_prod_sysexts "${FLATCAR_PRODUCTION_IMAGE_NAME}"
 fi
 
-if [[ ${FLAGS_generate_update} -eq ${FLAGS_TRUE} ]] || \
-   [[ ${FLAGS_extract_update} -eq ${FLAGS_TRUE} ]]
-then
+if [[ ${FLAGS_extract_update} -eq ${FLAGS_TRUE} ]]; then
   zip_update_tools
 fi
 

build_library/build_image_util.sh

@@ -61,23 +61,32 @@ delete_prompt() {
 extract_update() {
   local image_name="$1"
   local disk_layout="$2"
-  local update_path="${BUILD_DIR}/${image_name%_image.bin}_update.bin"
+  local update="${BUILD_DIR}/${image_name%_image.bin}_update.bin"
 
   "${BUILD_LIBRARY_DIR}/disk_util" --disk_layout="${disk_layout}" \
-    extract "${BUILD_DIR}/${image_name}" "USR-A" "${update_path}"
+    extract "${BUILD_DIR}/${image_name}" "USR-A" "${update}"
 
   # Compress image
-  files_to_evaluate+=( "${update_path}" )
+  files_to_evaluate+=( "${update}" )
   compress_disk_images files_to_evaluate
+}
 
-  # For production as well as dev builds we generate a dev-key-signed update
-  # payload for running tests (the signature won't be accepted by production systems).
-  local update_test="${BUILD_DIR}/flatcar_test_update.gz"
+generate_update() {
+  local image_name="$1"
+  local disk_layout="$2"
+  local image_kernel="${BUILD_DIR}/${image_name%.bin}.vmlinuz"
+  local update="${BUILD_DIR}/${image_name%_image.bin}_update.bin"
+  local devkey="/usr/share/update_engine/update-payload-key.key.pem"
+
+  # Extract the partition if it isn't extracted already.
+  [[ -s ${update} ]] || extract_update "${image_name}" "${disk_layout}"
+
+  echo "Generating update payload, signed with a dev key"
   delta_generator \
-      -private_key "/usr/share/update_engine/update-payload-key.key.pem" \
-      -new_image "${update_path}" \
-      -new_kernel "${BUILD_DIR}/${image_name%.bin}.vmlinuz" \
-      -out_file "${update_test}"
+      -private_key "${devkey}" \
+      -new_image "${update}" \
+      -new_kernel "${image_kernel}" \
+      -out_file "${BUILD_DIR}/flatcar_test_update.gz"
 }
 
 zip_update_tools() {
@@ -86,34 +95,11 @@ zip_update_tools() {
 
   info "Generating update tools zip"
   # Make sure some vars this script needs are exported
-  export REPO_MANIFESTS_DIR SCRIPTS_DIR
+  local -x REPO_MANIFESTS_DIR SCRIPTS_DIR
   "${BUILD_LIBRARY_DIR}/generate_au_zip.py" \
     --arch "$(get_sdk_arch)" --output-dir "${BUILD_DIR}" --zip-name "${update_zip}"
 }
 
-generate_update() {
-  local image_name="$1"
-  local disk_layout="$2"
-  local image_kernel="${BUILD_DIR}/${image_name%.bin}.vmlinuz"
-  local update_prefix="${image_name%_image.bin}_update"
-  local update="${BUILD_DIR}/${update_prefix}"
-  local devkey="/usr/share/update_engine/update-payload-key.key.pem"
-
-  echo "Generating update payload, signed with a dev key"
-  "${BUILD_LIBRARY_DIR}/disk_util" --disk_layout="${disk_layout}" \
-    extract "${BUILD_DIR}/${image_name}" "USR-A" "${update}.bin"
-  delta_generator \
-      -private_key "${devkey}" \
-      -new_image "${update}.bin" \
-      -new_kernel "${image_kernel}" \
-      -out_file "${update}.gz"
-
-  # Compress image
-  declare -a files_to_evaluate
-  files_to_evaluate+=( "${update}.bin" )
-  compress_disk_images files_to_evaluate
-}
-
 # ldconfig cannot generate caches for non-native arches.
 # Use qemu & the native ldconfig to work around that.
 # http://code.google.com/p/chromium/issues/detail?id=378377