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[Alan Pevec <1103260@xxxxxxxxxxxxxxxxxx>]

** Changed in: nova/folsom
       Status: Fix Committed => Fix Released

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https://bugs.launchpad.net/bugs/1103260

Title:
  fixed_ips cannot reliably be released on instance termination

Status in OpenStack Compute (Nova):
  Fix Released
Status in OpenStack Compute (nova) folsom series:
  Fix Released

Bug description:
  On rare occasion we have noticed that using nova-network and the
  VlanManage fixed_ip aren't always marked as free during instance
  termination until the _disassociate_stale_fixed_ips periodic job is
  run.

  The issue occurs as a result of dnsmasq is restarted. On restart the
  nova-dhcpbridge command is called with the init arguement to populate
  the dnsmasq lease DB. The lease time, is presently being calculated by
  taking instances.updated_at or instances.created_at and adding
  CONF.dhcp_lease_time. Unfortunately these fields are not updated by
  normal DHCP actions. At dnsmasq start time the old leases are loaded
  and immediately expired. As a result of this nova-dhcpbridge is called
  with the del action and fixed_ips.leased is marked as 0 in the DB even
  though a VM has a valid lease.

  If a termination is issued while in this state dnsmasq will receive
  the release packet and drop it claiming the lease is unknown. As a
  result nova-dhcpbridge is not called to free the lease in the DB and
  the IP remains in a partially freed state until the
  _disassociate_stale_fixed_ips periodic job is run.

  During normal DHCP operations the fixed_ips.updated_at field is
  updated on a lease request or renewal. As such the dnsmasq lease DB
  should be initialized from fixed_ips.updated_at or
  fixed_ips.created_at instead of the values from the instances table.

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