Bug#1005282: systemd: Documentation needed for initramfs copies of *.link files

[Kevin P. Fleming]

Package: systemd
Version: 247.3-6
Severity: normal

Dear Maintainer,

Recently I renamed some *.link files on a headless server (changing the names
inside the files to match), but after rebooting the server I was unable to
access it. After much head-scratching I realized that the previous *.link files
had been copied into the initramfs during a kernel package installation some
time in the past, and the new files conflicted with the old ones, so systemd-
networkd could not bring up the network interfaces.

After searching the bug tracker I see that a number of people have been caught
in this 'trap', and the advice given has been to run update-initramfs after
making changes (or adding) *.link files. While that certainly does cure the
problem, I can't find any documentation in the installed system which would
have lead me to know that I needed to do that.

Have I overlooked documentation of this behavior? It doesn't appear in
systemd.link(5), and it doesn't appear in the 'networkd' section of
README.Debian.gz for the systemd package. I can't be certain that this is
Debian-specific behavior (an inquiry about that on the systemd-devel list
hasn't elicited any responses), but it's definitely not 'upstream' behavior.

Please consider documenting this in at least those two places in a very obvious
way. I wish there was a more direct way to notify users that an initramfs
update will be required, but short of having a daemon watch
/etc/systemd/network for changes I can't think of any way to do that.

I'd be happy to provide a patch to add this documentation to those two files if
that would be welcome. Thanks for your time and consideration.


-- Package-specific info:

-- System Information:
Debian Release: 11.2
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable-security'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 5.10.0-11-amd64 (SMP w/8 CPU threads)
Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages systemd depends on:
ii  adduser                          3.118
ii  libacl1                          2.2.53-10
ii  libapparmor1                     2.13.6-10
ii  libaudit1                        1:3.0-2
ii  libblkid1                        2.36.1-8+deb11u1
ii  libc6                            2.31-13+deb11u2
ii  libcap2                          1:2.44-1
ii  libcrypt1                        1:4.4.18-4
ii  libcryptsetup12                  2:2.3.5-1
ii  libgcrypt20                      1.8.7-6
ii  libgnutls30                      3.7.1-5
ii  libgpg-error0                    1.38-2
ii  libip4tc2                        1.8.7-1
ii  libkmod2                         28-1
ii  liblz4-1                         1.9.3-2
ii  liblzma5                         5.2.5-2
ii  libmount1                        2.36.1-8+deb11u1
ii  libpam0g                         1.4.0-9+deb11u1
ii  libseccomp2                      2.5.1-1+deb11u1
ii  libselinux1                      3.1-3
ii  libsystemd0                      247.3-6
ii  libzstd1                         1.4.8+dfsg-2.1
ii  mount                            2.36.1-8+deb11u1
ii  systemd-timesyncd [time-daemon]  247.3-6
ii  util-linux                       2.36.1-8+deb11u1

Versions of packages systemd recommends:
ii  dbus  1.12.20-2

Versions of packages systemd suggests:
ii  policykit-1        0.105-31+deb11u1
ii  systemd-container  247.3-6

Versions of packages systemd is related to:
pn  dracut           <none>
ii  initramfs-tools  0.140
pn  libnss-systemd   <none>
ii  libpam-systemd   247.3-6
ii  udev             247.3-6

-- no debconf information