image: custom guest rootfs image file size alignment

The Guest rootfs image file size is aligned up to 128M boundary,
since commmit 2b0d5b2. This change allows users to use a custom
alignment value - e.g., to align up to 2M, users will be able to
specify IMAGE_SIZE_ALIGNMENT_MB=2 for image_builder.sh.

Signed-off-by: Dan Mihai <dmihai@microsoft.com>

tools/osbuilder/image-builder/image_builder.sh

@@ -12,6 +12,7 @@ set -o pipefail
 
 DOCKER_RUNTIME=${DOCKER_RUNTIME:-runc}
 MEASURED_ROOTFS=${MEASURED_ROOTFS:-no}
+IMAGE_SIZE_ALIGNMENT_MB=${IMAGE_SIZE_ALIGNMENT_MB:-128}
 
 #For cross build
 CROSS_BUILD=${CROSS_BUILD:-false}
@@ -54,9 +55,6 @@ AGENT_INIT=${AGENT_INIT:-no}
 SELINUX=${SELINUX:-no}
 SELINUXFS="/sys/fs/selinux"
 
-# Align image to 128M
-readonly mem_boundary_mb=128
-
 # shellcheck source=../scripts/lib.sh
 source "${lib_file}"
 
@@ -178,6 +176,7 @@ build_with_container() {
 		   --env TARGET_ARCH="${TARGET_ARCH}" \
 		   --env USER="$(id -u)" \
 		   --env GROUP="$(id -g)" \
+		   --env IMAGE_SIZE_ALIGNMENT_MB="${IMAGE_SIZE_ALIGNMENT_MB}" \
 		   -v /dev:/dev \
 		   -v "${script_dir}":"/osbuilder" \
 		   -v "${script_dir}/../scripts":"/scripts" \
@@ -308,9 +307,9 @@ calculate_img_size() {
 		img_size="$((img_size + root_free_space_mb))"
 	fi
 
-	remaining="$((img_size % mem_boundary_mb))"
+	remaining="$((img_size % ${IMAGE_SIZE_ALIGNMENT_MB}))"
 	if [ "${remaining}" != "0" ]; then
-		img_size=$((img_size + mem_boundary_mb - remaining))
+		img_size=$((img_size + ${IMAGE_SIZE_ALIGNMENT_MB} - remaining))
 	fi
 
 	echo "${img_size}"

tools/packaging/kata-deploy/local-build/kata-deploy-binaries-in-docker.sh

@@ -112,6 +112,7 @@ REPO_URL_X86_64="${REPO_URL_X86_64:-}"
 REPO_COMPONENTS="${REPO_COMPONENTS:-}"
 AGENT_POLICY="${AGENT_POLICY:-yes}"
 RUNTIME_CHOICE="${RUNTIME_CHOICE:-both}"
+IMAGE_SIZE_ALIGNMENT_MB=${IMAGE_SIZE_ALIGNMENT_MB:-}
 
 docker run \
 	-v $HOME/.docker:/root/.docker \