From 96072a1ef1a5822d57e18ba65ce3ba50af062b23 Mon Sep 17 00:00:00 2001
From: Balazs Gibizer <balazs.gibizer@est.tech>
Date: Mon, 25 Jan 2021 18:00:03 +0100
Subject: [PATCH] libvirt: parse alias out from device config

Libvirt assigns a device alias for each device in the domain and uses
this identifier in the events related to these devices, like device
detach.

This patch extends the LibvirtConfigGuestInterface and the
LibvirtConfigGuestDisk config object to parse the alias back from the
domain config. The alias is intentionally not used during domain XML
generation as it is expected that libvirt will populate and persist
this field.

This is part of the longer series trying to transform the existing
device detach handling to use libvirt events.

Change-Id: I16e7df6932bb7dff243706ee49338ba6b3782085
Related-Bug: #1882521
---
 nova/tests/unit/virt/libvirt/test_config.py | 30 +++++++++++++++++++++
 nova/virt/libvirt/config.py                 |  6 +++++
 2 files changed, 36 insertions(+)

diff --git a/nova/tests/unit/virt/libvirt/test_config.py b/nova/tests/unit/virt/libvirt/test_config.py
index 13e5c63c10c3..16d6a58d04ff 100644
--- a/nova/tests/unit/virt/libvirt/test_config.py
+++ b/nova/tests/unit/virt/libvirt/test_config.py
@@ -2285,6 +2285,21 @@ class LibvirtConfigGuestInterfaceTest(LibvirtConfigBaseTest):
         self.assertNotIsInstance(obj.device_addr,
                              config.LibvirtConfigGuestDeviceAddressDrive)
 
+    def test_config_interface_alias(self):
+        xml = """
+            <interface type='network'>
+                <mac address='52:54:00:14:6f:50'/>
+                <source network='default' bridge='virbr0'/>
+                <target dev='vnet0'/>
+                <model type='virtio'/>
+                <alias name='net0'/>
+            </interface>"""
+
+        obj = config.LibvirtConfigGuestInterface()
+        obj.parse_str(xml)
+
+        self.assertEqual('net0', obj.alias)
+
 
 class LibvirtConfigGuestFeatureTest(LibvirtConfigBaseTest):
 
@@ -2813,6 +2828,21 @@ class LibvirtConfigGuestSnapshotTest(LibvirtConfigBaseTest):
 
         self.assertTrue(obj.driver_iommu)
 
+    def test_config_alias_parse(self):
+        xml = """
+            <disk type="file" device="disk">
+              <source file="/tmp/hello.qcow2"/>
+              <target bus="virtio" dev="/dev/sda"/>
+              <serial>7a97c4a3-6f59-41d4-bf47-191d7f97f8e9</serial>
+               <alias name='virtio-disk0'/>
+            </disk>"""
+        xmldoc = etree.fromstring(xml)
+
+        obj = config.LibvirtConfigGuestDisk()
+        obj.parse_dom(xmldoc)
+
+        self.assertEqual('virtio-disk0', obj.alias)
+
 
 class LibvirtConfigNodeDeviceTest(LibvirtConfigBaseTest):
 
diff --git a/nova/virt/libvirt/config.py b/nova/virt/libvirt/config.py
index f30c49e25ec6..2c155d46ef93 100644
--- a/nova/virt/libvirt/config.py
+++ b/nova/virt/libvirt/config.py
@@ -1037,6 +1037,7 @@ class LibvirtConfigGuestDisk(LibvirtConfigGuestDevice):
         self.boot_order = None
         self.mirror = None
         self.encryption = None
+        self.alias = None
 
     def _format_iotune(self, dev):
         iotune = etree.Element("iotune")
@@ -1246,6 +1247,8 @@ class LibvirtConfigGuestDisk(LibvirtConfigGuestDevice):
                 e = LibvirtConfigGuestDiskEncryption()
                 e.parse_dom(c)
                 self.encryption = e
+            elif c.tag == 'alias':
+                self.alias = c.get('name')
 
 
 class LibvirtConfigGuestDiskBackingStore(LibvirtConfigObject):
@@ -1688,6 +1691,7 @@ class LibvirtConfigGuestInterface(LibvirtConfigGuestDevice):
         self.vlan = None
         self.device_addr = None
         self.mtu = None
+        self.alias = None
 
     def __eq__(self, other):
         if not isinstance(other, LibvirtConfigGuestInterface):
@@ -1914,6 +1918,8 @@ class LibvirtConfigGuestInterface(LibvirtConfigGuestDevice):
                 self.device_addr = obj
             elif c.tag == 'mtu':
                 self.mtu = int(c.get('size'))
+            elif c.tag == 'alias':
+                self.alias = c.get('name')
 
     def add_filter_param(self, key, value):
         self.filterparams.append({'key': key, 'value': value})