core: keep machine-id transient until first boot completes

Currently, a loss of power after the machine-id was written but before
all units with ConditionFirstBoot=yes ran would lead to the next boot
finding a valid machine-id, thus not being marked first boot and not
re-running these units.

To make the first boot mechanism more robust, instead of writing
/etc/machine-id very early, fill it with a marker value "uninitialized"
and overmount it with a transiently provisioned machine-id.  Then, after
the first boots completes (when systemd-machine-id-commit.service runs),
write the real machine-id to disk.

This mechanism is of course only invoked on first boot.  If a first boot
is not detected, the machine-id is handled as previously.

Fixes: #4511

1 files changed, 1 insertions, 1 deletions

diff --git a/src/machine-id-setup/machine-id-setup-main.c b/src/machine-id-setup/machine-id-setup-main.c
index 872b00c158..2bcd99109e 100644
--- a/src/machine-id-setup/machine-id-setup-main.c
+++ b/src/machine-id-setup/machine-id-setup-main.c
@@ -128,7 +128,7 @@ static int run(int argc, char *argv[]) {
                 if (r < 0)
                         return log_error_errno(r, "Failed to read machine ID back: %m");
         } else {
-                r = machine_id_setup(arg_root, SD_ID128_NULL, &id);
+                r = machine_id_setup(arg_root, false, SD_ID128_NULL, &id);
                 if (r < 0)
                         return r;
         }