osbuilder:rootfs: support to unpack pause image to rootfs

This env ver will serve us to pass the pause image tarball to the rootfs builder, which will then just
unpack the content into the rootfs.

Signed-off-by: ChengyuZhu6 <chengyu.zhu@intel.com>
Co-authored-by: Fabiano Fidêncio <fabiano.fidencio@intel.com>
Co-authored-by: Wang, Arron <arron.wang@intel.com>
Co-authored-by: stevenhorsman <steven@uk.ibm.com>
Co-authored-by: Jakob Naucke <jakob.naucke@ibm.com>

tools/osbuilder/rootfs-builder/rootfs.sh

@@ -32,6 +32,7 @@ AGENT_SOURCE_BIN=${AGENT_SOURCE_BIN:-""}
 AGENT_TARBALL=${AGENT_TARBALL:-""}
 COCO_GUEST_COMPONENTS_TARBALL=${COCO_GUEST_COMPONENTS_TARBALL:-""}
 CONFIDENTIAL_GUEST="${CONFIDENTIAL_GUEST:-no}"
+PAUSE_IMAGE_TARBALL=${PAUSE_IMAGE_TARBALL:-""}
 
 lib_file="${script_dir}/../scripts/lib.sh"
 source "$lib_file"
@@ -176,6 +177,12 @@ KERNEL_MODULES_DIR  Path to a directory containing kernel modules to include in
 LIBC                libc the agent is built against (gnu or musl).
                     Default value: ${LIBC} (varies with architecture)
 
+PAUSE_IMAGE_TARBALL Path to the kata-static-pause-image.tar.xz tarball to be unpacked inside the
+                    rootfs.
+                    If set, the tarball will be unpacked onto the rootfs.
+                    Default value: <not set>
+
+
 ROOTFS_DIR          Path to the directory that is populated with the rootfs.
                     Default value: <${script_name} path>/rootfs-<DISTRO-name>
 
@@ -796,6 +803,11 @@ EOF
 	[ -x "${init}" ] || [ -L "${init}" ] || die "/sbin/init is not installed in ${ROOTFS_DIR}"
 	OK "init is installed"
 
+	if [ -n "${PAUSE_IMAGE_TARBALL}" ] ; then
+		info "Installing the pause image tarball"
+		tar xvJpf ${PAUSE_IMAGE_TARBALL} -C ${ROOTFS_DIR}
+	fi
+
 	if [ -n "${COCO_GUEST_COMPONENTS_TARBALL}" ] ; then
 		info "Installing the Confidential Containers guest components tarball"
 		tar xvJpf ${COCO_GUEST_COMPONENTS_TARBALL} -C ${ROOTFS_DIR}

tools/packaging/guest-image/build_image.sh

@@ -45,7 +45,8 @@ build_initrd() {
 		AGENT_TARBALL="${AGENT_TARBALL}" \
 		AGENT_INIT="yes" \
 		AGENT_POLICY="${AGENT_POLICY:-}" \
-		COCO_GUEST_COMPONENTS_TARBALL="${COCO_GUEST_COMPONENTS_TARBALL:-}"
+		COCO_GUEST_COMPONENTS_TARBALL="${COCO_GUEST_COMPONENTS_TARBALL:-}" \
+		PAUSE_IMAGE_TARBALL="${PAUSE_IMAGE_TARBALL:-}"
 	mv "kata-containers-initrd.img" "${install_dir}/${artifact_name}"
 	(
 		cd "${install_dir}"
@@ -65,7 +66,8 @@ build_image() {
 		ROOTFS_BUILD_DEST="${builddir}/rootfs-image" \
 		AGENT_TARBALL="${AGENT_TARBALL}" \
 		AGENT_POLICY="${AGENT_POLICY:-}" \
-		COCO_GUEST_COMPONENTS_TARBALL="${COCO_GUEST_COMPONENTS_TARBALL:-}"
+		COCO_GUEST_COMPONENTS_TARBALL="${COCO_GUEST_COMPONENTS_TARBALL:-}" \
+		PAUSE_IMAGE_TARBALL="${PAUSE_IMAGE_TARBALL:-}"
 	mv -f "kata-containers.img" "${install_dir}/${artifact_name}"
 	if [ -e "root_hash.txt" ]; then
 	    cp root_hash.txt "${install_dir}/"