It seems that the issue here is networking.service does: /sbin/ifdown -a --read-environment but it should do: ifdown -a --exclude=lo
As is seen in the equivalent upstart job (/etc/init/networking.conf). $ m="ifdown -a --read-environment"; $ sed -i "s,$m, --exclude=lo," /lib/systemd/system/networking.service $ systemctl daemon-reload $ sudo poweroff Demonstration below. ## http://paste.ubuntu.com/23319833/ ## ipv6 networking is broken by ## ip link set down dev lo ## ## This seems to be the root cause of bug 1629972 (http://pad.lv/1629972) ## where system networking (networking.service) is brought down on ## shutdown and causes hang. ## ## Note, that it is the link that is the issue, there is actually ## no problem seen in 'ping6' by either: ## ip addr del 127.0.0.1/8 dev lo ## ip addr del ::1/128 dev lo $ for n in y1 y2; do lxc delete --force $n; lxc launch ubuntu-daily:yakkety $n; done error: not found Creating y1 Starting y1 error: not found Creating y2 Starting y2 $ for n in y1 y2; do lxc exec $n -- dhclient -6 -1 -v eth0; done $ lxc list y[12] +------+---------+----------------------+------------------------------------------------+------------+-----------+ | NAME | STATE | IPV4 | IPV6 | TYPE | SNAPSHOTS | +------+---------+----------------------+------------------------------------------------+------------+-----------+ | y1 | RUNNING | 10.75.205.102 (eth0) | fd42:eee5:7c43:3d62:c7fd:6ccc:6181:8d48 (eth0) | PERSISTENT | 0 | +------+---------+----------------------+------------------------------------------------+------------+-----------+ | y2 | RUNNING | 10.75.205.5 (eth0) | fd42:eee5:7c43:3d62:f285:69dd:7210:c0a5 (eth0) | PERSISTENT | 0 | +------+---------+----------------------+------------------------------------------------+------------+-----------+ $ for n in y1 y2; do lxc exec $n -- ip route add fd42:eee5:7c43:3d62::0/64 dev eth0 $ lxc exec y1 -- ping6 fd42:eee5:7c43:3d62:f285:69dd:7210:c0a5 PING fd42:eee5:7c43:3d62:f285:69dd:7210:c0a5(fd42:eee5:7c43:3d62:f285:69dd:7210:c0a5) 56 data bytes 64 bytes from fd42:eee5:7c43:3d62:f285:69dd:7210:c0a5: icmp_seq=1 ttl=64 time=0.133 ms 64 bytes from fd42:eee5:7c43:3d62:f285:69dd:7210:c0a5: icmp_seq=2 ttl=64 time=0.061 ms 64 bytes from fd42:eee5:7c43:3d62:f285:69dd:7210:c0a5: icmp_seq=3 ttl=64 time=0.069 ms ... <window 2> $ lxc exec y1 -- ip link set down dev lo immediately ping6 starts dropping packets in window1. ** Changed in: ifupdown (Ubuntu) Assignee: (unassigned) => Scott Moser (smoser) ** Changed in: ifupdown (Ubuntu Xenial) Assignee: (unassigned) => Scott Moser (smoser) -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to ifupdown in Ubuntu. https://bugs.launchpad.net/bugs/1629972 Title: networking stop incorrectly disconnects from (network) root filesystem Status in MAAS: Triaged Status in ifupdown package in Ubuntu: Confirmed Status in ifupdown source package in Xenial: Confirmed Bug description: With the switch to systemd, all support for iscsi root (and other) filesystems disappeared, since shutdown yanks the rug out from under us. Rather than just relying on /etc/iscsi/iscsi.initramfs (which d-i creates..), the DEV check should be expanded to include iscsi devices, and networking.service ExecStop should honor those checks. Related bugs: * bug 1229458: grub2 needed changes * bug 1621615: network not configured when ipv6 netbooted into cloud-init * bug 1621507: ipv6 network boot does not work [Impact] With the changes from the above, the iscsi root (at least in the ipv6 case) gets disconneceted prior to clean shutdown (ifdown downs the interface), resulting in a failure to enlist, commission, or deploy cleanly under MAAS. (and a failure to cleanly unmount the root filesystem when it is over iscsi.) [Test Case] Given a MAAS 2.0 installation, and the packages in the other bugs, attempt to enlist, commission, or deploy a host with xenial. [Regression potential] This restores the pre-xenial behavior of not shutting down the interface if there are network drives at the time that neworking is stopped (making it a no-op.) The additional change is to detect "/dev/disk/by-path/*-iscsi-*" as a network disk, replacing the check for the existence of /etc/iscsi/iscsi.initramfs, which was only created by debian-installer (and maas until recently). To manage notifications about this bug go to: https://bugs.launchpad.net/maas/+bug/1629972/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
