[Bug 1887177] Re: [SRU] ovsdb-server.service needs a depedency on local-fs.target

[Brian Turek]

I checked proposed and the amd64 versions finally built.  I installed
v2.13.1-0ubuntu0.20.04.1, removed my temporary fix, rebooted, and am
pleased to report that ovsdb-server is now waiting for ZFS to mount.
Manual inspection using "systemctl list-dependencies ovsdb-
server.service --after" shows dependencies on the relevant ZFS mounts as
well.

** Tags removed: verification-needed-focal
** Tags added: verification-done-focal

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Title:
  [SRU] ovsdb-server.service needs a depedency on local-fs.target

Status in openvswitch package in Ubuntu:
  Fix Released
Status in openvswitch source package in Focal:
  Fix Committed
Status in openvswitch source package in Groovy:
  Fix Released

Bug description:
  [Impact]
  When /var is on a separate filesystem (ZFS), ovsdb-server crashes on start if it is triggered before that filesystem is ready.

  I recently just did a from-scratch install of Ubuntu 20.04 server
  edition and ran into issues with Open vSwitch and ZFS.  I attempted to
  use ZFS for all of /var only to find that ovsdb-server pre-empted my
  ZFS /var mount which caused it to crash when trying to read its
  configuration DB at/var/lib/openvswitch/conf.db  After much
  troubleshooting, the problem basically boils down to ovsdb-
  server.service needing a requirement on local-fs.target

  I then found a blog post on Open Cloud Blog
  (https://www.opencloudblog.com/?p=240) that contained a fix:

  The "After" line /lib/systemd/system/ovsdb-server.service needs the
  following changes:

      [Unit]
      Description=Open vSwitch Database Unit
      After=syslog.target network-pre.target dpdk.service local-fs.target
      Before=network.target networking.service
      PartOf=openvswitch-switch.service
      DefaultDependencies=no

      [Service]
      LimitNOFILE=1048576
      Type=forking
      Restart=on-failure
      EnvironmentFile=-/etc/default/openvswitch
      ExecStart=/usr/share/openvswitch/scripts/ovs-ctl \
                --no-ovs-vswitchd --no-monitor --system-id=random \
                start $OPTIONS
      ExecStop=/usr/share/openvswitch/scripts/ovs-ctl --no-ovs-vswitchd stop
      ExecReload=/usr/share/openvswitch/scripts/ovs-ctl --no-ovs-vswitchd \
                 --no-monitor restart $OPTIONS
      RuntimeDirectory=openvswitch
      RuntimeDirectoryMode=0755

  [Test Case]

  Install ZFS on a machine, configure /var to be mounted on ZFS, install
  Open vSwitch, restart the server. The OpenvSwitch process should wait
  on the ZFS mount to start.

  [Regression Potential]

  Low. The only change in this is to defer the ovsdb-server startup
  until after the local-fs Systemd target has started. The only risk I
  can forsee is if the local-fs target didn't come up.

  [racb] Service dependency and thus ordering is being adjusted, so if
  there is a regression it might manifest in users with unusual or
  different service installations from the norm, or in users with
  customised service configurations. There might also be unrelated
  latent issues or race conditions revealed as a result of changing the
  order of service startups.

  [Discussion]

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