[Bug 2054977] Re: systemd-networkd fails to renew DHCP v4 lease when renew attempt times out

[Nick Rosbrook]

I think this would be better suited as an upstream issue, because AFAICT
this case is still not handled in the latest version. If you do open an
upstream bug (https://github.com/systemd/systemd/issues), they will want
to see this reproduced on at least systemd v254.

Please comment back here if you open a bug upstream.

** Changed in: systemd (Ubuntu)
       Status: Confirmed => Incomplete

** Changed in: systemd (Ubuntu)
   Importance: Undecided => Low

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https://bugs.launchpad.net/bugs/2054977

Title:
  systemd-networkd fails to renew DHCP v4 lease when renew attempt times
  out

Status in systemd package in Ubuntu:
  Incomplete

Bug description:
  I'm seeing exactly what this gist describes:
  https://gist.github.com/raggi/1f8d0b9f45c5b62e7131b03e6e2ffe68

  Summary:
  1. Configure a machine with a DHCPv4 lease on a network with a DHCPv4 server.
  2. Place machine under unusual load sufficient to cause a timeout on netlink requests.
  3. Observe the interface failing with the following logs:

  systemd-networkd[139370]: eth0: Could not set DHCPv4 address: Connection timed out
  systemd-networkd[139370]: eth0: Failed

  
  The error seems to come from here: https://github.com/systemd/systemd/blob/v245.4/src/network/networkd-dhcp4.c#L781

  Expected behavior
  The DHCPv4 client should retry the lease refresh when the issue is a timeout, eventually succeeding in these scenarios.

  Actual behavior
  Permanent loss of connectivity on the affected interface.

  Additional info:
  $ lsb_release -rd
  Description:    Ubuntu 20.04.6 LTS
  Release:        20.04

  $ apt-cache policy systemd
  systemd:
    Installed: 245.4-4ubuntu3.23
    Candidate: 245.4-4ubuntu3.23
    Version table:
   *** 245.4-4ubuntu3.23 500
          500 http://ap-southeast-2.ec2.archive.ubuntu.com/ubuntu focal-updates/main amd64 Packages
          500 mirror+file:/etc/apt/source-mirrors.txt focal-updates/main amd64 Packages
          100 /var/lib/dpkg/status
       245.4-4ubuntu3.20 500
          500 http://security.ubuntu.com/ubuntu focal-security/main amd64 Packages
          500 mirror+file:/etc/apt/source-mirrors.txt focal-security/main amd64 Packages
       245.4-4ubuntu3 500
          500 http://ap-southeast-2.ec2.archive.ubuntu.com/ubuntu focal/main amd64 Packages
          500 mirror+file:/etc/apt/source-mirrors.txt focal/main amd64 Packages

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