How to use systemd-firstboot.service?

Question

I'm making an image of Debian Jessie. On boot the system has no /etc/machine-id file. This causes some problems with the journald that doesn't start.

I've found that in the systemd repo:

#  This file is part of systemd.
#
#  systemd is free software; you can redistribute it and/or modify it
#  under the terms of the GNU Lesser General Public License as published by
#  the Free Software Foundation; either version 2.1 of the License, or
#  (at your option) any later version.

[Unit]
Description=First Boot Wizard
Documentation=man:systemd-firstboot(1)
DefaultDependencies=no
Conflicts=shutdown.target
After=systemd-remount-fs.service
Before=systemd-sysusers.service sysinit.target shutdown.target
ConditionPathIsReadWrite=/etc
ConditionFirstBoot=yes

[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=@rootbindir@/systemd-firstboot --prompt-locale --prompt-timezone --prompt-root-password
StandardOutput=tty
StandardInput=tty
StandardError=tty

Where it should be placed so it'll run?

In systemd 215 the ConditionFirstBoot is not available. How to deal with that?

Solution

I am a bit surprised you didn't have this script in place from simply installing systemd, but (in general) I think the answer is that you should put it into /etc/systemd/system.

In this situation (since you are doing all this to try and get a machine-id, in order to make journald work), I guess I might replace the ConditionFirstBoot with a check for the file you care about,/etc/machine-id.

So I would probably re-write the Unit section as:

[Unit]
Description=First Boot Wizard
Documentation=man:systemd-firstboot(1)
DefaultDependencies=no
Conflicts=shutdown.target
After=systemd-remount-fs.service
Before=systemd-sysusers.service sysinit.target shutdown.target
ConditionPathIsReadWrite=/etc
ConditionPathExists=!/etc/machine-id

That being said, if it was possible to ship a more recent systemd with your image (I am not good on Debian, so I couldn't find anywhere to check what the latest supported version was), that might be worth looking into - systemd 215 has a few issues that have since been fixed (https://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=systemd).

Comments

[kkm]

Just a note to verify twice that the proposed solution would work. When I started imaging systemd-controlled OS (based on Debian 10, IIRC, when he still was Sid) a couple years ago, my first impulse was delete the /etc/machine-id right before imaging, among other personality erasure tasks. The effect was quite dramatic: the system flatly refused to boot and went into recovery mode (a brick if you are deploying a cloud vm). The fix was truncate but keep the file (: > /etc/machine-id). Maybe this is not even true anymore, but I learnt to treat this file with a great respect and awe ever since.