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

[Martin Petzold]

Dear Paul,

Am 29.04.23 um 17:13 schrieb 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?
> 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?
=========================================

tavla at tavla:~$ sudo systemctl status tavla-test

× tavla-test.service - TAVLA Platform OS Tester Service
      Loaded: loaded (/lib/systemd/system/tavla-test.service; enabled; 
preset: enabled)
      Active: failed (Result: signal) since Sat 2023-04-29 15:52:12 
CEST; 17min ago
     Process: 388 ExecStart=/opt/tavla/bin/test (code=killed, signal=HUP)
    Main PID: 388 (code=killed, signal=HUP)
         CPU: 118ms

Apr 29 15:52:12 tavla systemd[1]: Starting tavla-test.service - TAVLA 
Platform OS Tester Service...
Apr 29 15:52:12 tavla systemd[1]: tavla-test.service: Main process 
exited, code=killed, status=1/HUP
Apr 29 15:52:12 tavla systemd[1]: tavla-test.service: Failed with result 
'signal'.
Apr 29 15:52:12 tavla systemd[1]: Failed to start tavla-test.service - 
TAVLA Platform OS Tester Service.

=========================================

tavla-test.service is 'enabled' (and started), but I never enabled it. 
It was enabled after I removed machine-id and did a reboot. Before that, 
it was disabled. The service unit 
('/lib/systemd/system/tavla-test.service') was copied to this location 
during image build after debootstrap and apt installation of systemd.

Here is the only preset ('90-systemd.preset'):

=========================================

enable remote-fs.target
enable remote-cryptsetup.target
enable machines.target

enable getty at .service
enable systemd-timesyncd.service
enable systemd-networkd.service
enable systemd-network-generator.service
enable systemd-resolved.service
enable systemd-homed.service
enable systemd-userdbd.socket
enable systemd-pstore.service
enable systemd-boot-update.service

disable console-getty.service
disable debug-shell.service

disable halt.target
disable kexec.target
disable poweroff.target
enable reboot.target
disable rescue.target
disable exit.target

disable systemd-networkd-wait-online.service
disable systemd-time-wait-sync.service
disable systemd-boot-check-no-failures.service
disable proc-sys-fs-binfmt_misc.mount

disable syslog.socket

disable systemd-journal-gatewayd.*
disable systemd-journal-remote.*
disable systemd-journal-upload.*

=========================================

>
>> 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

Best regards,

Martin