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[Sam Betts <sam@xxxxxxxxxxxxxx>]

** Also affects: neutron
   Importance: Undecided
       Status: New

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https://bugs.launchpad.net/bugs/1334447

Title:
  Potential race between neutron port update and node pxe boot

Status in OpenStack Bare Metal Provisioning Service (Ironic):
  Triaged
Status in OpenStack Neutron (virtual network service):
  New

Bug description:
  Splitting off a new bug from Bug #1300589 to track progress on one
  specific issue.

  There is a potential race condition in the pxe driver where it will
  update neutron ports with DHCP data for a soon-to-be-booted ironic
  node.  This data sets, among other things, the tftp next server
  address.  The update is asynchronous on the Neutron side.  After the
  update request is sent, the node is immediately powered on.  If using
  the ssh power driver with fast booting virtual machines, there is a
  potential race where the node attempts pxe boot before the neutron
  agents have processed the updates and reconfigured DHCP servers
  appropriately.  Copying from the original bug, Robert describes the
  specific issues in the driver:

  This is the problem:
         _create_token_file(task, node)
          _update_neutron(task, node)
          manager_utils.node_set_boot_device(task, node, 'pxe', persistent=True)
          manager_utils.node_power_action(task, node, states.REBOOT)

  There's no synchronisation with neutron (neither poll nor call-back)
  to know that (all) the dnsmasq processes serving that port have been
  updated - and a VM that boots quickly may DHCP before the dnsmasq is
  hupped.

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