[systemd-devel] systemd enables custom service units on firstboot

[Paul Menzel]

Dear Martin,


Am 29.04.23 um 16:12 schrieb Martin Petzold:

> we are building our OS with debootstrap (Debian bullseye). Our image 
> shall be flashed on embedded devices. In order to get a unique 
> machine-id we removed '/etc/machine-id' as instructed in [1] and also 
> removed '/var/lib/dbus/machine-id' as instructed in [2]) from the golden 
> image.
> 
> After we flash the image and boot it, new machine-ids are created and 
> identical.
> 
> However, now we realized that some of our systemd service units added to 
> '/lib/systemd/system' are enabled and starting on boot. We did not 
> enable them, we just copied them to that location at the end of our 
> rootfs build. They are just there to be used in some special test cases.
> 
> We already checked '/lib/systemd/system-preset/*'. But there is only a 
> single file '90-systemd.preset' and there is no rule which matches our 
> service units.
> 
> 1. Why are our service units placed in '/lib/systemd/system' enabled?
> 2. What actually happens during firstboot?

Sorry, you provide not enough information.

Please provide an example `systemctl status X` and `systemctl cat X` for 
service X, that is started but does not. Does that happen with all 
services you add?

Please enable debug logs by for example adding `debug` to the Linux 
command line.

> Related 3. If we do A/B rootfs updates could there be any problems if a 
> new machine-id is created on each (sys)update?

I recommend to start a separate thread for this question.


Kind regards,

Paul


> Platform:
> 
> systemd 252.5-2~bpo11+1 (from bullseye-backports)
> systemd-resolved and systemd-networkd with iwd (all from 
> bullseye-backports)
> Custom Debian bullseye (with some packages from bullseye-backports)
> Custom Kernel 5.10
> U-Boot
> 
> [1] https://systemd.io/BUILDING_IMAGES/
> [2] https://wiki.debian.org/MachineId