[Bug 1804478] Re: netplan dhcp interface with no default route causes systemd-networkd-wait-online to hang

[Benjamin Drung]

I verified that applying commit 223932c786ada7f758a7b7878a6ad2dae0d1e5fb
from https://github.com/systemd/systemd/pull/8728 on top of systemd
237-3ubuntu10.9 solves this bug.

Therefore please include the patch in systemd for Ubuntu 18.04.

** Description changed:

- root cause in systemd bug:
- https://github.com/systemd/systemd/issues/3752
+ root cause in systemd bug fixed in Commit 223932c786ada7f758a7b7878a6ad2dae0d1e5fb:
+ https://github.com/systemd/systemd/pull/8728
  
  Environment:
  Ubuntu 18.04 LTS amd64
  systemd package version 237-3ubuntu10.9
  
  How to trigger:
  1. add netplan interface with dhcpv4 client enabled:
-         enp0s8:
-             addresses: []
-             dhcp4: true
+         enp0s8:
+             addresses: []
+             dhcp4: true
  2. configure dhcp server to NOT give a default route, or any route for that matter
  3. reboot
  4. systemd-networkd-wait-online will block until dhcp renew is triggered
  root at sensor1:~# /lib/systemd/systemd-networkd-wait-online --timeout=3
  Event loop failed: Connection timed out
  root at sensor1:~# /lib/systemd/systemd-networkd-wait-online --timeout=3 --ignore=enp0s8
  managing: enp0s3
  ignoring: lo
  ignoring: enp0s8
  
  How to fix:
  Backport upstream changes from systemd (see related systemd ticket).

** Description changed:

- root cause in systemd bug fixed in Commit 223932c786ada7f758a7b7878a6ad2dae0d1e5fb:
+ root cause in systemd bug fixed in Commit
+ 223932c786ada7f758a7b7878a6ad2dae0d1e5fb:
  https://github.com/systemd/systemd/pull/8728
  
  Environment:
  Ubuntu 18.04 LTS amd64
  systemd package version 237-3ubuntu10.9
  
  How to trigger:
  1. add netplan interface with dhcpv4 client enabled:
          enp0s8:
              addresses: []
              dhcp4: true
  2. configure dhcp server to NOT give a default route, or any route for that matter
  3. reboot
  4. systemd-networkd-wait-online will block until dhcp renew is triggered
  root at sensor1:~# /lib/systemd/systemd-networkd-wait-online --timeout=3
  Event loop failed: Connection timed out
  root at sensor1:~# /lib/systemd/systemd-networkd-wait-online --timeout=3 --ignore=enp0s8
  managing: enp0s3
  ignoring: lo
  ignoring: enp0s8
  
  How to fix:
  Backport upstream changes from systemd (see related systemd ticket).

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

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https://bugs.launchpad.net/bugs/1804478

Title:
  netplan dhcp interface with no default route causes systemd-networkd-
  wait-online to hang

Status in systemd:
  Fix Released
Status in systemd package in Ubuntu:
  Triaged

Bug description:
  root cause in systemd bug fixed in Commit
  223932c786ada7f758a7b7878a6ad2dae0d1e5fb:
  https://github.com/systemd/systemd/pull/8728

  Environment:
  Ubuntu 18.04 LTS amd64
  systemd package version 237-3ubuntu10.9

  How to trigger:
  1. add netplan interface with dhcpv4 client enabled:
          enp0s8:
              addresses: []
              dhcp4: true
  2. configure dhcp server to NOT give a default route, or any route for that matter
  3. reboot
  4. systemd-networkd-wait-online will block until dhcp renew is triggered
  root at sensor1:~# /lib/systemd/systemd-networkd-wait-online --timeout=3
  Event loop failed: Connection timed out
  root at sensor1:~# /lib/systemd/systemd-networkd-wait-online --timeout=3 --ignore=enp0s8
  managing: enp0s3
  ignoring: lo
  ignoring: enp0s8

  How to fix:
  Backport upstream changes from systemd (see related systemd ticket).

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