Comment 0 for bug 1732002

I noticed that lxd (lxc list) reports that an lxc container has an ipv6 address in artful or bionic. It does not list this in xenial or zesty. I suspect this change occurred in the switch over to netplan/networkd.

This may at first seem harmless or even desired, but note that the user configuration did not request ipv6 config, so its presence is a bug.

$ for rel in xenial zesty artful bionic; do
   lxc launch ubuntu-daily:$rel $rel-demo; done
Creating xenial-demo
Starting xenial-demo
..
Creating bionic-demo
Starting bionic-demo

$ sleep 10
$ lxc list
$ lxc list
+-------------+---------+----------------------+------------------------------------------------+------------+-----------+
| NAME | STATE | IPV4 | IPV6 | TYPE | SNAPSHOTS |
+-------------+---------+----------------------+------------------------------------------------+------------+-----------+
| artful-demo | RUNNING | 10.75.205.208 (eth0) | fd42:eee5:7c43:3d62:3a42:611c:3f6f:1184 (eth0) | PERSISTENT | 0 |
+-------------+---------+----------------------+------------------------------------------------+------------+-----------+
| bionic-demo | RUNNING | 10.75.205.187 (eth0) | fd42:eee5:7c43:3d62:6f4:155b:39cc:fc3d (eth0) | PERSISTENT | 0 |
+-------------+---------+----------------------+------------------------------------------------+------------+-----------+
| xenial-demo | RUNNING | 10.75.205.143 (eth0) | | PERSISTENT | 0 |
+-------------+---------+----------------------+------------------------------------------------+------------+-----------+
| zesty-demo | RUNNING | 10.75.205.123 (eth0) | | PERSISTENT | 0 |
+-------------+---------+----------------------+------------------------------------------------+------------+-----------+

## Here is the config that was provided by lxd
$ lxc exec bionic-demo cat /var/lib/cloud/seed/nocloud-net/network-config
version: 1
config:
    - type: physical
      name: eth0
      subnets:
          - type: dhcp
            control: auto

## Here is the config that cloud-init rendered.
$ lxc exec bionic-demo -- grep -v '^#' /etc/netplan/50-cloud-init.yaml
network:
    version: 2
    ethernets:
        eth0:
            dhcp4: true

$ lxc exec bionic-demo cat /run/systemd/network/10-netplan-eth0.network
[Match]
Name=eth0

[Network]
DHCP=ipv4

[DHCP]
UseMTU=true
RouteMetric=100

$ lxc exec bionic-demo -- systemctl status --no-pager --full systemd-networkd
● systemd-networkd.service - Network Service
   Loaded: loaded (/lib/systemd/system/systemd-networkd.service; enabled; vendor preset: enabled)
   Active: active (running) since Mon 2017-11-13 18:37:34 UTC; 8min ago
     Docs: man:systemd-networkd.service(8)
 Main PID: 118 (systemd-network)
   Status: "Processing requests..."
    Tasks: 1 (limit: 4915)
   Memory: 2.0M
      CPU: 19ms
   CGroup: /system.slice/systemd-networkd.service
           └─118 /lib/systemd/systemd-networkd

Nov 13 18:37:34 bionic-demo systemd[1]: Starting Network Service...
Nov 13 18:37:34 bionic-demo systemd-networkd[118]: eth0: Gained IPv6LL
Nov 13 18:37:34 bionic-demo systemd-networkd[118]: Enumeration completed
Nov 13 18:37:34 bionic-demo systemd[1]: Started Network Service.
Nov 13 18:37:37 bionic-demo systemd-networkd[118]: eth0: DHCPv6 address fd42:eee5:7c43:3d62:6f4:155b:39cc:fc3d/128 timeout preferred 3600 valid 3600
Nov 13 18:37:37 bionic-demo systemd-networkd[118]: eth0: DHCPv4 address 10.75.205.187/24 via 10.75.205.1
Nov 13 18:37:37 bionic-demo systemd-networkd[118]: Not connected to system bus, ignoring transient hostname.
Nov 13 18:37:39 bionic-demo systemd-networkd[118]: eth0: Configured
Nov 13 18:38:09 bionic-demo systemd-networkd[118]: Could not set hostname: Method call timed out

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: nplan 0.30
ProcVersionSignature: Ubuntu 4.13.0-16.19-generic 4.13.4
Uname: Linux 4.13.0-16-generic x86_64
ApportVersion: 2.20.7-0ubuntu4
Architecture: amd64
Date: Mon Nov 13 18:27:53 2017
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 LANG=C.UTF-8
SourcePackage: nplan
UpgradeStatus: No upgrade log present (probably fresh install)