shellcheck: fix kernel/build.sh

Refactor code to make shellcheck happy

Signed-off-by: Zvonko Kaiser <zkaiser@nvidia.com>

tools/packaging/static-build/kernel/build.sh

@@ -10,8 +10,13 @@ set -o pipefail
 
 script_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 
+# shellcheck disable=SC1091 # import based on variable
 source "${script_dir}/../../scripts/lib.sh"
 
+# repo_root_dir is defined in lib.sh make sure it is set
+repo_root_dir="${repo_root_dir:-}"
+
+[[ -n "${repo_root_dir}" ]] || die "repo_root_dir is not set"
 readonly kernel_builder="${repo_root_dir}/tools/packaging/kernel/build-kernel.sh"
 readonly initramfs_builder="${repo_root_dir}/tools/packaging/static-build/initramfs/build.sh"
 
@@ -23,10 +28,10 @@ PREFIX=${PREFIX:-/opt/kata}
 container_image="${KERNEL_CONTAINER_BUILDER:-$(get_kernel_image_name)}"
 MEASURED_ROOTFS=${MEASURED_ROOTFS:-no}
 KBUILD_SIGN_PIN="${KBUILD_SIGN_PIN:-}"
-kernel_builder_args="-a ${ARCH} $*"
+kernel_builder_args="-a ${ARCH:-} $*"
 KERNEL_DEBUG_ENABLED=${KERNEL_DEBUG_ENABLED:-"no"}
 
-if [ "${MEASURED_ROOTFS}" == "yes" ]; then
+if [[ "${MEASURED_ROOTFS}" == "yes" ]]; then
 	info "build initramfs for cc kernel"
 	"${initramfs_builder}"
 	# Turn on the flag to build the kernel with support to
@@ -34,43 +39,59 @@ if [ "${MEASURED_ROOTFS}" == "yes" ]; then
 	kernel_builder_args+=" -m"
 fi
 
-if [ "${CROSS_BUILD}" == "true" ]; then
+if [[ "${CROSS_BUILD:-}" == "true" ]]; then
-       container_image="${container_image}-${ARCH}-cross-build"
+       container_image="${container_image}-${ARCH:-}-cross-build"
        # Need to build a s390x image due to an issue at
        # https://github.com/kata-containers/kata-containers/pull/6586#issuecomment-1603189242
-       if [ ${ARCH} == "s390x" ]; then
+       if [[ ${ARCH:-} == "s390x" ]]; then
                BUILDX="buildx"
                PLATFORM="--platform=linux/s390x"
        fi
 fi
 
-docker pull ${container_image} || \
+container_engine=${CONTAINER_ENGINE:-"docker"}
-	(docker ${BUILDX} build ${PLATFORM} \
+container_build=${container_engine}
-	--build-arg ARCH=${ARCH} -t "${container_image}" "${script_dir}" && \
-	 # No-op unless PUSH_TO_REGISTRY is exported as "yes"
-	 push_to_registry "${container_image}")
 
-docker run --rm -i -v "${repo_root_dir}:${repo_root_dir}" \
+if [[ -n "${BUILDX}" ]]; then
+	container_build+=" ${BUILDX}"
+fi
+
+container_build+=" build"
+
+if [[ -n "${PLATFORM}" ]]; then
+	container_build+=" ${PLATFORM}"
+fi
+
+container_build+=" --build-arg ARCH=${ARCH:-}"
+
+"${container_engine}" pull "${container_image}" || \
+	{
+		${container_build} -t "${container_image}" "${script_dir}" && \
+		# No-op unless PUSH_TO_REGISTRY is exported as "yes"
+		push_to_registry "${container_image}";
+	}
+
+"${container_engine}" run --rm -i -v "${repo_root_dir}:${repo_root_dir}" \
 	-w "${PWD}" \
 	--env KERNEL_DEBUG_ENABLED="${KERNEL_DEBUG_ENABLED}" \
 	--user "$(id -u)":"$(id -g)" \
 	"${container_image}" \
 	bash -c "${kernel_builder} ${kernel_builder_args} setup"
 
-docker run --rm -i -v "${repo_root_dir}:${repo_root_dir}" \
+"${container_engine}" run --rm -i -v "${repo_root_dir}:${repo_root_dir}" \
 	-w "${PWD}" \
 	--user "$(id -u)":"$(id -g)" \
 	"${container_image}" \
 	bash -c "${kernel_builder} ${kernel_builder_args} build"
 
-docker run --rm -i -v "${repo_root_dir}:${repo_root_dir}" \
+"${container_engine}" run --rm -i -v "${repo_root_dir}:${repo_root_dir}" \
 	-w "${PWD}" \
 	--env DESTDIR="${DESTDIR}" --env PREFIX="${PREFIX}" \
 	--user "$(id -u)":"$(id -g)" \
 	"${container_image}" \
 	bash -c "${kernel_builder} ${kernel_builder_args} install"
 
-docker run --rm -i -v "${repo_root_dir}:${repo_root_dir}" \
+"${container_engine}" run --rm -i -v "${repo_root_dir}:${repo_root_dir}" \
 	-w "${PWD}" \
 	--env DESTDIR="${DESTDIR}" --env PREFIX="${PREFIX}" \
 	--env USER="${USER}" \