[Bug 2003250] Re: networkctl reload with bond devices causes slaves to go DOWN and UP, causing couple of seconds of network loss

[Sergey Borodavkin]

Seems its not "low importance" bug. 🤕
Updating systemd package can trigger such bug, and if you have a unattended-upgrade it's gonna cause a network flap on that host.
Easy to reproduce it with:
# apt install --reinstall systemd

----------------------------------
Distributor ID:	Ubuntu
Description:	Ubuntu 22.04.2 LTS
Release:	22.04
Codename:	jammy

systemd 249 (249.11-0ubuntu3.9)

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Title:
  networkctl reload with bond devices causes slaves to go DOWN and UP,
  causing couple of seconds of network loss

Status in systemd package in Ubuntu:
  Triaged
Status in systemd source package in Jammy:
  Triaged
Status in systemd source package in Kinetic:
  Triaged

Bug description:
  We currently use Ubuntu 22.04.1 LTS including updates for our production cloud (switched from legacy Centos 7).
  Although we like the distribution we recently hit serious systemd buggy behavior described in [1] bugreport using packages [2].

  Unfortunatelly the clouds we are running consist of openstack on top
  of kubernetes and we need to have complex network configuration
  including linux bond devices.

  Our observation is that every time we apply our configuration via
  CI/CD infrastructure using ansible and netplan (regardless whether
  there is actual network configuration change) we see approximatelly
  8-16 seconds network interruptions and see bond interfaces going DOWN
  and then UP.

  We expect bond interfaces stay UP when there is no network
  configuration change.

  We went though couple of options how to solve the issue and the first
  one is to add such existing patch [3] into current
  systemd-249.11-0ubuntu3.6.

  Could you comment whether this kind of non-security patch is likely to land in 22.04.1 LTS soon.
  We are able to help to bring patch into systemd package community way if you suggest the steps.

  
  [1] https://github.com/systemd/systemd/issues/25067
  [2] Packages
  root at controlplane-001:/etc/apt0# apt list | grep -E '^(systemd/|netplan.io)'
  netplan.io/jammy-updates,now 0.105-0ubuntu2~22.04.1 amd64 [installed,automatic]
  systemd/jammy-updates,now 249.11-0ubuntu3.6 amd64 [installed,automatic]
  [3] https://github.com/systemd/systemd/pull/25162
  [4] # lsb_release -rd
  Description:    Ubuntu 22.04.1 LTS
  Release:        22.04

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