[libvirt-users] Fwd: Re: Attach libvirt guest to an existing openvswitch port

[Ivan Borodin]

Thank you, Laine for you time and patience to give me a detailed answer.
I missed the interfaceid parameter in the docs, but now I didn't manage
to get it working.

> http://www.libvirt.org/formatdomain.html
The docs state:

"The Open vSwitch type virtualport accepts two parameters in its
<parameters> element - an interfaceid which is a standard uuid used to
uniquely identify this particular interface to Open vSwitch (if you do
not specify one, a random interfaceid will be generated for you when you
first define the interface[...]"

This interfaceid doesn't seem to have anything to do with ovsdb values.
$ ovs-vsctl find  Port 'name=vm_test'
_uuid               : f0f06327-6fcc-4073-b8c8-3f42944d43ca
bond_downdelay      : 0
bond_fake_iface     : false
bond_mode           : []
bond_updelay        : 0
external_ids        : {}
fake_bridge         : false
interfaces          : [eb7fad6e-3728-4bf7-b31e-4a1693e2ec4b]
lacp                : []
mac                 : []
name                : "vm_test"
other_config        : {}
qos                 : []
statistics          : {}
status              : {}
tag                 : []
trunks              : []
vlan_mode           : []

The "_uuid" is ovsdb internal id of a record. If you take "interfaces"
value for "interfaceid", libvirt will silently create its own new ovs
port, with its own new uuid and defining a libvirt guest's interface
with a unique uuid in "interfaceid"... Libvirt will create a new ovs
port, and the ovsdb-"interfaces" value will be the interfaceid... And I
could not find anything specific about this ovsdb/Port/interfaces.

Actually, my point was to find a way to control ovs vlans outside
libvirt. Since virsh doesn't have capabilities to edit interface's vlan
options, the only way to do it is editing domains' xml-configs through
virsh-edit, which is a bit tiresome. (By the way, there must be some
technical reason(beyond virt-xml-validate) for designing libvirt writing
it's own configuration files instead of reading them...)

There should be.. There must be a way to do this. Port parameters are
ovs authority. If there is no such way, could you, please, tell me the
reason.

On 11/21/2016 09:46 PM, Laine Stump wrote:
> On 11/13/2016 01:23 PM, Ivan Borodin wrote:
>> Somehow with interface types 'bridge' and 'network', libvirt does attach
>> domain to the existing port specified in <target dev=''/>, wiping the
>> exixting settings and always deletes this port upon domain shutdown,
>> thus making me loose ovs configuration.