Bug#1127834: debhelper: dh_installsystemd does not re-create WantedBy symlinks on upgrade

[Michael Biebl]

Duplicate of https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=797108
and https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=985787


https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=985787#10

It's a tricky problem.


We do kinda have this state in /var/lib/systemd/deb-systemd-*.









Michael

So far, my recommendation has been, that packages handle such upgrades manually. Doing such upgrades automatically within i-s-h, requires that we keep additional state: Once you unpack the package and the new .service file is installed on disk, you no longer have the information what the old .service file contained. As one of the original authors of i-s-h (well, the coding was actually done by Michael Stapelberg): we never really liked the additional bookkeeping we were doing in deb-systemd-helper and wanted to get rid of that at some point and those deb-systemd-* tools would just become very thin wrappers around systemctl. This was one of the reasons why I was reluctant to further pursue this in #985787. Nowadays I'm not really active anymore in systemd/i-s-h but I thought I can give you some context. On Fri, 13 Feb 2026 18:49:41 +0100 Alessandro Astone <alessandro.ast...@canonical.com> wrote:

Package: debhelper
Version: 13.24.2ubuntu1
Severity: normal

Dear Maintainer,







-- System Information:
Debian Release: forky/sid
APT prefers questing-updates

Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 6.17.0-12-generic (SMP w/16 CPU threads; PREEMPT)
Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_WARN, TAINT_OOT_MODULE

Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages debhelper depends on:
ii autotools-dev 20240727.1
ii debugedit 1:5.2-3
ii dh-autoreconf 21
ii dh-strip-nondeterminism 1.14.2-1
ii dpkg 1.22.21ubuntu3.1
ii dpkg-dev 1.22.21ubuntu3.1
ii dwz 0.16-2
ii file 1:5.46-5build1
ii libdebhelper-perl 13.24.2ubuntu1
ii libdpkg-perl 1.22.21ubuntu3.1
ii man-db 2.13.1-1
ii mawk 1.3.4.20250131-1
ii perl 5.40.1-6build1
ii po-debconf 1.0.21+nmu1

debhelper recommends no packages.

Versions of packages debhelper suggests:
ii dh-make 2.202503

-- no debconf information

When enabling a service that specifies [Install] WantedBy=foo.target, a symlink to this service is created at /etc/systemd/system/foo.target.wants/ On package upgrade, if the service file was changed to [Install] WantedBy=bar.target, the symlink at /etc/systemd/system/foo.target.wants/ is not removed and a new symlink at /etc/systemd/system/bar.target.wants/ is not created This may have serious consequences depending on the rest of the contents of the unit file (e.g. it may trigger activation of other dependencies when unwanted), or in the general case users will never see the effects of the update. APT policy: (1001, 'questing-updates'), (1001, 'questing-security'), (1001, 'questing'), (500, 'questing-proposed'), (100, 'questing-proposed'), (100, 'questing-backports') Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US:en

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