I am also affected by this issue. In my case both network.target and network-online.target are reached too early, which results in sssd and autofs to start before network interfaces are up; autofs then fails to obtain mount maps and does not attempt to retry; it is necessary to restart autofs manually after network has started fully.
Similarly as the bug reporter, I run Ubuntu 16.04 server, and I use static addresses only, configured in /etc/network/interfaces. The root cause is ifup exiting with success before network interfaces start operating. However, ifup behaved the same way in Ubuntu 14.04, and there it did not cause the problem. Apparently Upstart and its network- related units were able to deal with this issue correctly. In contrast, systemd configuration files packaged in ifupdown Xenial package are causing the "async" behavior of ifup to surface and create problems. During system boot there are two attempts to start physical network interfaces by ifup: in [email protected] (one service per interface) and in networking.service. All these services start in parallel and call ifup in parallel, but ifup uses a lock to prevent its concurrent execution (per interface), effectively serializing [email protected](s) and networking.service. In my tests, ifup@ services always win this race. This actually works fine if all interfaces are configured successfully. If not, networking.service performs a second attempt after [email protected] failed, which may be problematic (see below). Targets network.target and network-online.target are reached when networking.service finishes. This happens after interfaces are configured by ifup. Interfaces became operable significantly later. The problem may be worked around in a particular configuration in several ways: 1. We can make ifup wait for the interface to come up, for example by including a loop in post-up command in /etc/network/interfaces, checking /sys/class/net/$INTERFACE/operstate. This would require using some timeout, after which the command would fail, to deal with situations such as a disconnected cable. In such a case, the delay would be twice as long as the specified timeout, because that timeout will have to be reached in both [email protected] and networking service. If we do not configure any virtual interfaces, we can deal with this by disabling networking.service. 2. We can modify [email protected] to wait for the interface to come up, similarly as above. It will also be necessary to change the type of this service from "simple" to "oneshot", to make it wait for its ExecStart command before exiting. 3. We can also modify networking.service to wait in a similar manner. 4. We can introduce an additional service which will wait for all or some interfaces to come up, and will delay network.target and network- online.target until it is done. It would be advantageous to wait on all interfaces in parallel, and I am not sure if that would be easy to implement in one service. 5. An active waiting in a loop is obviously not the most beautiful solution, so perhaps a cleaner way could be found? -- 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/1588915 Title: ifup does not block for interface to be up with static addresses Status in ifupdown package in Ubuntu: Confirmed Bug description: Description: Ubuntu 16.04 LTS (server) Release: 16.04 systemd: Installed: 229-4ubuntu6 Candidate: 229-4ubuntu6 Version table: *** 229-4ubuntu6 500 500 http://us.archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages 100 /var/lib/dpkg/status 229-4ubuntu4 500 500 http://us.archive.ubuntu.com/ubuntu xenial/main amd64 Packages This issue is more about systemd integration then an issue with systemd package itself. The general problem is the distinction between the network being configured and the network being up and what that means for services that depend on the network. upstream systemd has network.target (network is configured) and network-online.target (network is up), however xenial server (dunno about desktop) doesn't seem to use network-online.target. The result of which is, as soon as the network is configured both network.target and network-online.target are considered complete. At which point services dependent on either of those will get started. However this can lead to problems if the services in question are actually dependent on the network (ie dns lookups) when they are starting up. Here's an example of what I mean. If you install openntpd and add the -s option there is a race on boot if it will or wont be able to do the initial sync. Jun 02 16:58:02 xenial64 systemd[1]: Reached target Network. Jun 02 16:58:02 xenial64 systemd[1]: Starting OpenNTPd Network Time Protocol... Jun 02 16:58:02 xenial64 systemd[1]: Reached target Network is Online. Jun 02 16:58:02 xenial64 ntpd[920]: constraint certificate verification turned off Jun 02 16:58:02 xenial64 ntpd[928]: ntp engine ready Jun 02 16:58:02 xenial64 kernel: tg3 0000:02:00.0 enp2s0: Link is down Jun 02 16:58:05 xenial64 kernel: tg3 0000:02:00.0 enp2s0: Link is up at 1000 Mbps, full duplex Jun 02 16:58:05 xenial64 kernel: tg3 0000:02:00.0 enp2s0: Flow control is on for TX and on for RX Jun 02 16:58:05 xenial64 kernel: IPv6: ADDRCONF(NETDEV_CHANGE): enp2s0: link becomes ready Jun 02 16:58:17 xenial64 ntpd[920]: no reply received in time, skipping initial time setting openntpd was started 3 seconds before the interface even got link. I believe this issue is only going to effect physical servers with static ips. vm's interfaces will instantly have link when they are brought up and dhcp, the interface will already be up or else they wouldn't have been able to get an ip. thanks jim To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ifupdown/+bug/1588915/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
