build_sysext: Remove any opaque directory markers

The Flatcar extension images built with build_sysext created directories
in the overlay in a way that masked contents from other layers.
Instead of fixing the way we create directories, make use of
postprocessing to avoid any similar problems show up again in the
future.

build_sysext

@@ -275,6 +275,10 @@ all_fields=(
   "ARCHITECTURE=${ARCH}"
 )
 printf '%s\n' "${all_fields[@]}" >"${BUILD_DIR}/install-root/usr/lib/extension-release.d/extension-release.${SYSEXTNAME}"
+
+info "Removing opaque directory markers to always merge all contents"
+find "${BUILD_DIR}/install-root" -xdev -type d -exec sh -c 'if [ "$(attr -R -q -g overlay.opaque {} 2>/dev/null)" = y ]; then attr -R -r overlay.opaque {}; fi' \;
+
 mksquashfs "${BUILD_DIR}/install-root" "${BUILD_DIR}/${SYSEXTNAME}.raw" \
                -noappend -comp "${FLAGS_compression}" ${FLAGS_mksquashfs_opts}
 rm -rf "${BUILD_DIR}"/{fs-root,install-root,workdir}

changelog/bugfixes/2024-03-05-ensure-sysext-contents-merge.md

@@ -0,0 +1 @@
+- Fixed that systemd-sysext images can extend directories where Flatcar extensions are also shipping files, e.g., that the sysext-bakery Kubernetes extension works when OEM extensions are present ([sysext-bakery#50](https://github.com/flatcar/sysext-bakery/issues/50))