** Also affects: cloud-archive/mitaka Importance: Undecided Status: New
** Changed in: cloud-archive/mitaka Status: New => In Progress ** Changed in: cloud-archive/mitaka Assignee: (unassigned) => Matthew Ruffell (mruffell) ** Changed in: cloud-archive Assignee: Matthew Ruffell (mruffell) => (unassigned) ** Changed in: cloud-archive Status: In Progress => Invalid -- You received this bug notification because you are a member of नेपाली भाषा समायोजकहरुको समूह, which is subscribed to Xenial. Matching subscriptions: Ubuntu 16.04 Bugs https://bugs.launchpad.net/bugs/1829823 Title: libvirt-bin: during shutdown libvirt-bin is stopped before libvirt- guests causing hang Status in Ubuntu Cloud Archive: Invalid Status in Ubuntu Cloud Archive mitaka series: In Progress Status in libvirt package in Ubuntu: Invalid Status in libvirt source package in Xenial: Triaged Bug description: [Impact] * libvirt-bin, in: libvirt-1.3.1-1ubuntu10.24~cloud0 in trusty mitaka uca and the parent package in xenial, libvirt-1.3.1-1ubuntu10.24 are affected. * When you shutdown a system in trusty which is running some kvm virtual machines, the libvirt-bin service is stopped before libvirt-guests. libvirt-guests tries to connect to the libvirt socket to send shutdown commands to the running vms, which cannot happen since libvirtd is not running. * On some machines, the qemu processes behind the virtual machines are not killed and are left behind as defunct processes, which can cause the system to hang on them not being terminated. * The bug is caused by the libvirt-bin upstart script [1] calling a non-existant script, /usr/lib/libvirt/libvirt-stop-guests [2]. This script used to exist in the upstart script itself in version 1.2.2-0ubuntu13.1.27 [3], the version in the trusty archives. In liberty UCA, version 1.2.16-2ubuntu11.15.10.4~cloud0 [4], the script was separated out into /usr/lib/libvirt/libvirt-stop-guests [2]. In the mitaka release, the libvirt-stop-guests script was removed and rewritten as /etc/init.d/libvirt-guests [5], but the script in [1] was never updated to point to it. [1] http://paste.ubuntu.com/p/GxxBczkCmk [2] http://paste.ubuntu.com/p/fKCDQh46vh [3] http://paste.ubuntu.com/p/QrKXqK2Bvz [4] http://paste.ubuntu.com/p/W8DgQwpYv3 [5] http://paste.ubuntu.com/p/Z28Sp2fPd6 * Since the upstart script was never updated to point to it, libvirt-bin stops without stopping libvirt-guests first. When libvirt-guests is stopped later, it cannot access the libvirt socket, cannot shut down the machines, causing the bug. * The fix is to change the upstart script to point to the new libvirt- guests script. [Test Case] * You can reproduce this in trusty with the mitaka UCA enabled. 1) Enable mitaka UCA and install libvirt0 and libvirt-bin $ sudo add-apt-repository cloud-archive:mitaka $ sudo apt update $ sudo apt install libvirt0 libvirt-bin 2) Install a virtual machine, either by using virt-install or virt-manager. I used a bionic VM. 3) Enable debugging on libvirt-guests so you can see what is going on Modify /etc/init.d/libvirt-guests and add "-x" to the end of "!/bin/sh" 4) With the vm running, shut down the system $ sudo shutdown -h now 5) Check /var/log/upstart/libvirt-bin.log, on reboot. It will say "No such file or directory: /usr/lib/libvirt/libvirt-stop-guests" 6) During that shutdown, you will see messages like: error: failed to connect to the hypervisor error: no valid connection error: Failed to connect socket to '/var/run/libvirt/libvirt-sock': No such file or directory What should happen: If you follow the same steps with the fixed package, when you look at /var/log/upstart/libvirt-bin.log, you will see output of libvirt-guests connecting to and shutting down the virtual machines which looks a little like this: https://paste.ubuntu.com/p/s4jyJX2y9F/ [Regression Potential] * There is only one file modified, the upstart script for libvirt-bin. Currently this upstart file references a file which doesn't exist, so fixing it will restore the behavior in a way which aligns with exactly what took place in previous versions. * In xenial, all of this isn't used at all - see below at "Other Info" * This change only effects systems during shutdown while they still have virtual machines running, and do not effect starting and stopping services while the machine is running normally. * I believe the regression potential is low. [Other Info] * Xenial is not effected by this bug even though it ships the exact same packages. This is because xenial uses insserv to generate service dependency files ".depend.boot" ".depend.start" ".depend.stop" which parse the scripts in /etc/init.d/ and systemd respects the dependency ordering in these files. libvirt-guests reports a dependency on libvirt-bin in the script header, so systemd will always stop libvirt-guests before libvirt-bin, avoiding the problem seen in trusty. * The fix is needed in trusty mitaka UCA and xenial will likely need the SRU as part of the process. * We'd never have uploaded that change alone for xenial (being a no-op causing MBs to download and an upgrade. But we will bundle it with an actual change - so it can "ride along" to eventually help Trusty-Mitaka. 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