[PATCH v3] fix on-first-boot for systemd >= 247

[Felix Moessbauer <felix.moessbauer@siemens.com>]

This patch fixes the bug that /etc/machine-id is never
generated when running from within an initrd with an ro rootfs.

In this case, the magic value "uninitialized" has to be used
instead of deleting the file.

For older systemd versions, we set it to the empty string
which is non-documented, but works as identified
in various tests on debian buster (systemd version 241).

Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
---
 meta/classes/image-postproc-extension.bbclass | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/meta/classes/image-postproc-extension.bbclass b/meta/classes/image-postproc-extension.bbclass
index 0c412c0d..4a901cbf 100644
--- a/meta/classes/image-postproc-extension.bbclass
+++ b/meta/classes/image-postproc-extension.bbclass
@@ -56,8 +56,15 @@ image_postprocess_mark() {
 ROOTFS_POSTPROCESS_COMMAND =+ "image_postprocess_machine_id"
 image_postprocess_machine_id() {
     # systemd(1) takes care of recreating the machine-id on first boot
+    # for systemd < v247, set to empty string, else set to uninitialized
+    # (required if initramfs with ro root is used)
+    SYSTEMD_VERSION=$( sudo chroot ${IMAGE_ROOTFS} dpkg-query --showformat='${source:Upstream-Version}' --show systemd || echo "0" )
+    MACHINE_ID="uninitialized"
+    if dpkg --compare-versions "$SYSTEMD_VERSION" "lt" "247"; then
+        MACHINE_ID=""
+    fi
+    echo "$MACHINE_ID" | sudo tee '${IMAGE_ROOTFS}/etc/machine-id'
     sudo rm -f '${IMAGE_ROOTFS}/var/lib/dbus/machine-id'
-    sudo rm -f '${IMAGE_ROOTFS}/etc/machine-id'
 }
 
 ROOTFS_POSTPROCESS_COMMAND =+ "image_postprocess_sshd_key_regen"
-- 
2.30.2