[Bug 2033681] Re: Calico still uses vif type tap and it causes failures with libvirt 9.5.0

[Ioana Lazea]

** Also affects: cloud-archive
   Importance: Undecided
       Status: New

** Also affects: cloud-archive/epoxy
   Importance: Undecided
       Status: New

** Also affects: cloud-archive/dalmatian
   Importance: Undecided
       Status: New

** Also affects: cloud-archive/caracal
   Importance: Undecided
       Status: New

** Also affects: cloud-archive/flamingo
   Importance: Undecided
       Status: New

** Also affects: cloud-archive/gazpacho
   Importance: Undecided
       Status: New

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https://bugs.launchpad.net/bugs/2033681

Title:
  Calico still uses vif type tap and it causes failures with libvirt
  9.5.0

Status in Ubuntu Cloud Archive:
  New
Status in Ubuntu Cloud Archive caracal series:
  New
Status in Ubuntu Cloud Archive dalmatian series:
  New
Status in Ubuntu Cloud Archive epoxy series:
  New
Status in Ubuntu Cloud Archive flamingo series:
  New
Status in Ubuntu Cloud Archive gazpacho series:
  New
Status in OpenStack Compute (nova):
  Fix Released
Status in nova package in Ubuntu:
  New
Status in nova source package in Noble:
  New
Status in nova source package in Questing:
  New
Status in nova source package in Resolute:
  New

Bug description:

  Description
  ===========
  Calico (out of tree) uses vif type tap. But libvirt doesn't like pre-existing tap devices https://github.com/libvirt/libvirt/commit/a2ae3d299cf from libvirt 9.5.0. This causes openstack clusters that run calico networking backend to fail during instance creation.

  Steps to reproduce
  ==================
  1. Configure calico
  2. Run openstack with libvirt 9.5.0 (latest in centos 9 stream)
  3. Boot a VM

  Expected result
  ===============
  The VM is able to boot without any problems

  Actual result

  Other information
  =================

  13:34:38 < sean-k-mooney> calico is apparently still using vif type
  tap
  https://github.com/projectcalico/calico/blob/cf7fa35475eba84f5afcd7f53ac7d07dcb403202/networking-
  calico/networking_calico/plugins/ml2/drivers/calico/test/lib.py#L66C31-L66C34

  13:35:06 < sean-k-mooney> vif type tap is not supported by our os-vif code so its usign the legacy fallback
  13:35:51 < sean-k-mooney> https://github.com/openstack/nova/blob/master/nova/virt/libvirt/vif.py#L595-L596
  13:36:15 < sean-k-mooney> https://github.com/openstack/nova/blob/master/nova/virt/libvirt/vif.py#L420-L430
  13:36:48 < sean-k-mooney> https://github.com/openstack/nova/blob/master/nova/virt/libvirt/designer.py#L44-L55

  13:37:40 < sean-k-mooney> zer0c00l: with that said the tap was always ment to be created by libvirt so it sound like calico might have been doing things it shoudl not have been
  13:38:03 < zer0c00l> sean-k-mooney: Thanks for looking into this. :(
  13:38:36 < sean-k-mooney> we could proably correct this with a bug fix
  13:38:52 < sean-k-mooney> jsut setting managed='no'
  13:39:13 < sean-k-mooney> here https://github.com/openstack/nova/blob/master/nova/virt/libvirt/vif.py#L427
  13:39:54 < sean-k-mooney> the problem is that the there is no way to test this really upstream
  13:40:06 < sean-k-mooney> well beyond unit/fucntional tests
  13:40:12 < sean-k-mooney> but we dont have any calico ci
  13:40:37 < sean-k-mooney> calico should be the only backend using vif_type=tap
  13:40:52 < sean-k-mooney> but im not sure if we woudl need a config option in the workarounds section for this or not

  
  Potential patch
  ===============
  diff --git a/nova/virt/libvirt/config.py b/nova/virt/libvirt/config.py
  index 47e92e3..5af3ce4 100644
  --- a/nova/virt/libvirt/config.py
  +++ b/nova/virt/libvirt/config.py
  @@ -1749,6 +1749,7 @@
           self.device_addr = None
           self.mtu = None
           self.alias = None
  +        self.managed = 'no'
   
       def __eq__(self, other):
           if not isinstance(other, LibvirtConfigGuestInterface):
  @@ -1851,7 +1852,7 @@
               dev.append(vlan_elem)
   
           if self.target_dev is not None:
  -            dev.append(etree.Element("target", dev=self.target_dev))
  +            dev.append(etree.Element("target", dev=self.target_dev, managed=self.managed))
   
           if self.vporttype is not None:
               vport = etree.Element("virtualport", type=self.vporttype)

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