live migrations do not update dnsmasq entries or setup networking on destination node when using multi_host

I discussed this a bit offline with the networking team. It seems a little challenging to do the correct implementation for essex, but here is the basic plan:

Notes below from Trey Morris:

we'll need to pull the network_setup functionality out of ip allocation/deallocation and add a callable trigger to that functionality to the network api. It looks like for allocate_ip the functionality is already split out into the _setup_network() function. We need to do something similar for deallocate_ip, like _teardown_network(), and create a setup_networks() function with a corresponding network_api call.

setup/unsetup_all could be optimized into one function with a default parameter, something like:

def setup_networks(self, context, teardown=False, **kwargs):
    if teardown:
        call_func = self._teardown_network
    else:
        call_func = self._setup_network

    *pull instance variables from kwargs*
     nw_info = self.get_instance_nw_info(instance_stuff...)
     for vif in nw_info:
         self.call_func(context, vif['network'])

The flow as I see it (from compute) would be
def live_migrate():
    self.network_api.setup_networks(instance, teardown=True)
    perform migrate as it was before
    self.network_api.setup_networks(instance)

allocate_fixed_ip would still call self._setup_network(context, network) and the single network would be configured just as it was before, and deallocate could do the same, only it would call self._teardown_network(context, network) instead of performing the teradown in-function.

My only addition might be that you would want to teardown the network on the old host after the migrate, which means you might have to pass the host in the call somewhere.

In the meantime the above patch will at least make things work.

apparently this affects resize as well. And tr3buchet also discovered that deallocate is not working properly

Fix proposed to branch: master
Review: https://review.openstack.org/4635

Fix proposed to branch: master
Review: https://review.openstack.org/4646

Reviewed: https://review.openstack.org/4646
Committed: http://github.com/openstack/nova/commit/0c7a54b3b44f849bf397bb4068ab16c576c3559c
Submitter: Jenkins
Branch: master

commit 0c7a54b3b44f849bf397bb4068ab16c576c3559c
Author: Trey Morris <email address hidden>
Date: Mon Feb 27 19:07:31 2012 -0600

    Setup and teardown networks during migration

    * fixes lp939060
    * live migration and resize nova appropriately setup
      and teardown networking related to network hosts
    * deallocate_fixed_ip is now run on the correct host
      resulting in the network structures being torn down
      correctly

    Change-Id: I2c86989ab7c6593bf346611cde8c043116d55bc5

Fix proposed to branch: master
Review: https://review.openstack.org/5038

Fix proposed to branch: master
Review: https://review.openstack.org/5097

Reviewed: https://review.openstack.org/5097
Committed: http://github.com/openstack/nova/commit/81c1d70754543360e11e3aaba2ed403872b21302
Submitter: Jenkins
Branch: master

commit 81c1d70754543360e11e3aaba2ed403872b21302
Author: Vishvananda Ishaya <email address hidden>
Date: Thu Mar 8 12:51:36 2012 -0800

    Clean up setup and teardown for dhcp managers

     * use update_dhcp on teardown, not release_dhcp
     * clean up setup / teardown to not require vif and address
     * make dnsmasq only configure allocated ips
     * prepares the fix for bug 939060

    Change-Id: Ie85860c5549339befee74c951ccb0d72a92f6d6c

Hrm, is this really still in progress or did the bot drink too much ?

Reviewed: https://review.openstack.org/5038
Committed: http://github.com/openstack/nova/commit/33def9e714fbd13a6dc4b755ade4841c971f7ae5
Submitter: Jenkins
Branch: master

commit 33def9e714fbd13a6dc4b755ade4841c971f7ae5
Author: Vishvananda Ishaya <email address hidden>
Date: Thu Mar 8 12:53:44 2012 -0800

    Fix live-migration in multi_host network

     * call teardown after live migration
     * call update a second time after migration for dhcp
     * moves the instance state update into post_live_migrate
     * completes the fix for bug 939060
     * fixes bug 947326

    Change-Id: I042567573b9bb46381c5447aa08e83cd1916b225