=====
Usage
=====

The interface to the `os_vif` library is very simple. To begin using the
library, first call the `os_vif.initialize()` function. This will load all
installed plugins and register the object model:

.. code-block:: python

    import os_vif

    os_vif.initialize()

Once the `os_vif` library is initialized, there are only two other library
functions: `os_vif.plug()` and `os_vif.unplug()`. Both methods accept a single
argument of type `os_vif.objects.VIF`:

.. code-block:: python

    import uuid

    from nova import objects as nova_objects
    from os_vif import exception as vif_exc
    from os_vif import objects as vif_objects
    from os_vif import vnic_types

    instance_uuid = 'd7a730ca-3c28-49c3-8f26-4662b909fe8a'
    instance = nova_objects.Instance.get_by_uuid(instance_uuid)
    instance_info = vif_objects.InstanceInfo(
        uuid=instance.uuid,
        name=instance.name,
        project_id=instance.project_id)

    subnet = vif_objects.Subnet(cidr='192.168.1.0/24')
    subnets = vif_objects.SubnetList([subnet])
    network = vif_objects.Network(label='tenantnet',
                                  subnets=subnets,
                                  multi_host=False,
                                  should_provide_vlan=False,
                                  should_provide_bridge=False)

    vif_uuid = uuid.uuid4()
    vif = vif_objects.VIFVHostUser(id=vif_uuid,
                                   address=None,
                                   network=network,
                                   plugin='vhostuser',
                                   path='/path/to/socket',
                                   mode=vif_objects.fields.VIFVHostUserMode.SERVER)

    # Now do the actual plug operations to connect the VIF to
    # the backing network interface.
    try:
        os_vif.plug(vif, instance_info)
    except vif_exc.PlugException as err:
        # Handle the failure...

    # If you are removing a virtual machine and its interfaces,
    # you would use the unplug() operation:
    try:
        os_vif.unplug(vif, instance_info)
    except vif_exc.UnplugException as err:
        # Handle the failure...
