[Bug 1732002] Re: cloud images in lxc get ipv6 address
Ryan Harper
1732002 at bugs.launchpad.net
Mon Mar 19 20:36:55 UTC 2018
After some discussion, it appears that networkd is kinda of making a
boolean (on|off) for IPV6 RA, when it's really a tri-state
(on|off|kernel).
Upstream networkd indicates there is a tri-state; like so:
Enable or disable IPv6 Router Advertisement (RA) reception support for
the interface. Takes a boolean parameter. If true, RAs are accepted; if
false, RAs are ignored, independently of the local forwarding state.
When not set, the kernel default is used, and RAs are accepted only when
local forwarding is disabled for that interface. When RAs are accepted,
they may trigger the start of the DHCPv6 client if the relevant flags
are set in the RA data, or if no routers are found on the link.
While in netplan, we've only a boolean, which could be fine, except
netplan defaults to AcceptRA=True which means we have no way of allowing
the kernel configuration to work.
Netplan needs to know if the yaml includes an accept-ra key, and if so,
uses the value set (off or on); but if the yaml does not specify an
accept-ra key, it should *NOT* render a default value.
This allows hosts to defer the the kernel settings. This key was
introduced as away to resolve a bug where "unconfigured" interfaces got
an IPV6 address due to kernel setting and an IPV6 router present.
https://bugs.launchpad.net/maas/+bug/1655440
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https://bugs.launchpad.net/bugs/1732002
Title:
cloud images in lxc get ipv6 address
Status in nplan package in Ubuntu:
New
Status in systemd package in Ubuntu:
New
Bug description:
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)
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