Merge "Add a "libvirt_disk_prefix" flag to libvirt driver"

2 files changed, 54 insertions, 13 deletions

diff --git a/nova/tests/test_libvirt.py b/nova/tests/test_libvirt.py
index 61ba21692..c1fae1df2 100644
--- a/nova/tests/test_libvirt.py
+++ b/nova/tests/test_libvirt.py
@@ -357,6 +357,10 @@ class LibvirtConnTestCase(test.TestCase):
         instance_data = dict(self.test_instance)
         self._check_xml_and_container(instance_data)
 
+    def test_xml_disk_prefix(self):
+        instance_data = dict(self.test_instance)
+        self._check_xml_and_disk_prefix(instance_data)
+
     @test.skip_if(missing_libvirt(), "Test requires libvirt")
     def test_snapshot_in_ami_format(self):
         self.flags(image_service='nova.image.fake.FakeImageService')
@@ -557,6 +561,40 @@ class LibvirtConnTestCase(test.TestCase):
         target = tree.find('./devices/filesystem/source').get('dir')
         self.assertTrue(len(target) > 0)
 
+    def _check_xml_and_disk_prefix(self, instance):
+        user_context = context.RequestContext(self.user_id,
+                                              self.project_id)
+        instance_ref = db.instance_create(user_context, instance)
+
+        type_disk_map = {
+            'qemu': [
+               (lambda t: t.find('.').get('type'), 'qemu'),
+               (lambda t: t.find('./devices/disk/target').get('dev'), 'vda')],
+            'xen': [
+               (lambda t: t.find('.').get('type'), 'xen'),
+               (lambda t: t.find('./devices/disk/target').get('dev'), 'sda')],
+            'kvm': [
+               (lambda t: t.find('.').get('type'), 'kvm'),
+               (lambda t: t.find('./devices/disk/target').get('dev'), 'vda')],
+            'uml': [
+               (lambda t: t.find('.').get('type'), 'uml'),
+               (lambda t: t.find('./devices/disk/target').get('dev'), 'ubda')]
+            }
+
+        for (libvirt_type, checks) in type_disk_map.iteritems():
+            self.flags(libvirt_type=libvirt_type)
+            conn = connection.LibvirtConnection(True)
+
+            network_info = _fake_network_info(self.stubs, 1)
+            xml = conn.to_xml(instance_ref, network_info)
+            tree = xml_to_tree(xml)
+
+            for i, (check, expected_result) in enumerate(checks):
+                self.assertEqual(check(tree),
+                                 expected_result,
+                                 '%s != %s failed check %d' %
+                                 (check(tree), expected_result, i))
+
     def _check_xml_and_uri(self, instance, expect_ramdisk, expect_kernel,
                            rescue=False):
         user_context = context.RequestContext(self.user_id, self.project_id)
diff --git a/nova/virt/libvirt/connection.py b/nova/virt/libvirt/connection.py
index fb7f71ad1..71ca21d1b 100644
--- a/nova/virt/libvirt/connection.py
+++ b/nova/virt/libvirt/connection.py
@@ -29,6 +29,8 @@ Supports KVM, LXC, QEMU, UML, and XEN.
                 (default: kvm).
 :libvirt_uri:  Override for the default libvirt URI (depends on libvirt_type).
 :libvirt_xml_template:  Libvirt XML Template.
+:libvirt_disk_prefix:  Override the default disk prefix for the devices
+                       attached to a server.
 :rescue_image_id:  Rescue ami image (None = original image).
 :rescue_kernel_id:  Rescue aki image (None = original image).
 :rescue_ramdisk_id:  Rescue ari image (None = original image).
@@ -146,6 +148,11 @@ flags.DEFINE_string('default_local_format',
 flags.DEFINE_bool('libvirt_use_virtio_for_bridges',
                   False,
                   'Use virtio for bridge interfaces')
+flags.DEFINE_string('libvirt_disk_prefix',
+                    None,
+                    'Override the default disk prefix for the devices '
+                    'attached to a server, which is dependent on '
+                    'libvirt_type. (valid options are: sd, xvd, uvd, vd)')
 
 
 def get_connection(read_only):
@@ -193,6 +200,15 @@ class LibvirtConnection(driver.ComputeDriver):
             self.volume_drivers[driver_type] = driver_class(self)
         self._host_state = None
 
+        disk_prefix_map = {"lxc": "", "uml": "ubd", "xen": "sd"}
+        if FLAGS.libvirt_disk_prefix:
+            self._disk_prefix = FLAGS.libvirt_disk_prefix
+        else:
+            self._disk_prefix = disk_prefix_map.get(FLAGS.libvirt_type, 'vd')
+        self.default_root_device = self._disk_prefix + 'a'
+        self.default_local_device = self._disk_prefix + 'b'
+        self.default_swap_device = self._disk_prefix + 'c'
+
     @property
     def host_state(self):
         if not self._host_state:
@@ -1064,19 +1080,6 @@ class LibvirtConnection(driver.ComputeDriver):
         if FLAGS.libvirt_type == 'uml':
             utils.execute('chown', 'root', basepath('disk'), run_as_root=True)
 
-    if FLAGS.libvirt_type == 'uml':
-        _disk_prefix = 'ubd'
-    elif FLAGS.libvirt_type == 'xen':
-        _disk_prefix = 'sd'
-    elif FLAGS.libvirt_type == 'lxc':
-        _disk_prefix = ''
-    else:
-        _disk_prefix = 'vd'
-
-    default_root_device = _disk_prefix + 'a'
-    default_local_device = _disk_prefix + 'b'
-    default_swap_device = _disk_prefix + 'c'
-
     def _volume_in_mapping(self, mount_device, block_device_info):
         block_device_list = [block_device.strip_dev(vol['mount_device'])
                              for vol in