network-manager renderer does not honour IPv6 default route subnet

[Louis Bouchard]

Hello,
When using the following network configuration to setup an IPv6 network :

# cat network_config.yaml
version: 2
ethernets:
    ens2:
        addresses:
        - {redacted IPv6 address}/64
        routes:
        - to: ::/0
            via: fe80::dc00:00ff:fe01:6552

The network-manager configuration generated does not honour the /0 in the to: statement and generates a configuration with a /64 subnet as can be seen here :

# cloud-init devel net-convert -p network_config.yaml -k yaml -d. -D centos -O network-manager
Read input format 'yaml' from '/tmp/network_config.yaml'.
Wrote output format 'network-manager' to './'

# cat etc/NetworkManager/system-connections/cloud-init-ens2.nmconnection
# Generated by cloud-init. Changes will be lost.

[connection]
id=cloud-init ens2
uuid=260f75fb-230a-5caa-97d0-16854e8e5a84
type=ethernet
interface-name=ens2

[user]
org.freedesktop.NetworkManager.origin=cloud-init

[ethernet]

[ipv6]
method=manual
may-fail=false
address1=2001:bc8:4e10:1:dc00:00ff:fe01:6551/64
route1=::/64,fe80::dc00:00ff:fe01:6552
         ^^^^
As seen here the subnet is /64 and not the /0 found in the configuration.

This has been tested on Debian using 22.4.2-1

[James Falcon (falcojr)]

Thanks for the bug report. I have reproduced the behavior.

[Alberto Contreras (aciba)]

Fixed here: https://github.com/canonical/cloud-init/pull/1973

[Launchpad Janitor (janitor)]

This bug was fixed in the package cloud-init - 22.4.2-0ubuntu3

---------------
cloud-init (22.4.2-0ubuntu3) lunar; urgency=medium

  * Upstream snapshot based on upstream/main at bdc7b040.
    - Bugs fixed in this snapshot: (LP: #2001737, #1998526, #2000596)
      (LP: #1851438)
  * Upstream snapshot based on upstream/main at 3b8b4692.
    - Bugs fixed in this snapshot: (LP: #1998998, #1997922, #2002969)
      (LP: #2003562, #1999680)

 -- James Falcon <email address hidden> Fri, 03 Feb 2023 15:36:12 -0600