automatic blacklisting of openvswitch packages for auto-update

[James Page]

Restarting openvswitch as part of a package upgrade will cause a minor disruption to networking flows until the neutron-openvswitch agent re-programs the ovs daemons; In order to avoid automatic updates causing this type of problem in charm based deployments we should create a blacklist file for the openvswitch packages to prevent them from being upgraded by auto-updates:

   https://help.ubuntu.com/lts/serverguide/automatic-updates.html

Suggest /etc/apt/apt.conf.d/99{charm_name}-openvswitch file is created with content:

  Unattended-Upgrade::Package-Blacklist {
        "openvswitch-common";
        "openvswitch-switch";
  };

[James Page (james-page)]

We might also want to take a similar approach for the ceph charms; package updates should always be managed.

[Paul Collins (pjdc)]

I believe this is addressed by bug 1383674, at least for liberty and above.

However, as the operators of a large icehouse-based cloud, we're still interested in avoiding restarts as much as possible - when you have 64 compute hosts and complex software stacks deployed on them, even a minor disruption adds up quite quickly to a major one.

[Paul Collins (pjdc)]

Oh, of course it's not fixed by bug 1383674, which was for neutron-openvswitch-agent restarts.