libvirt: remove volume_drivers config param

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commit I1f884f36e24fe478922671ca3eaf6b7c21fd8a5a

The 'volumes_drivers' parameter does the same job as the
'vif_driver' parameter, but for volumes instead of vifs.

The API for the LibvirtBaseVolumeDriver class is not
considered to be a public extension point. As such it
is not required or expected to remain compatible across
releases.

The main reason for its existance is for people who are
developing new cinder drivers, to be able to write out
of tree nova volume drivers. The recommended practice
is to instead work in-tree to nova on a branch. This is
an approach that would be required in order to submit
the work for review and eventual merge in any case.

commit I1f884f36e24fe478922671ca3eaf6b7c21fd8a5a
deprecated it and during the discussion the actually target
is Kilo. But it's K-3 so more reasonable target is
Liberty.

DocImpact: libvirt.volume_drivers config param is removed.

Closes-Bug: #1371175

Change-Id: I832820499ec3304132379ad9b9d1ee92c5a75b61

nova/tests/unit/virt/libvirt/test_driver.py

@@ -574,16 +574,16 @@ class LibvirtConnTestCase(test.NoDBTestCase):
                 return FakeVirtDomain()
 
         # Creating mocks
-        volume_driver = ('iscsi=nova.tests.unit.virt.libvirt.test_driver'
-                         '.FakeVolumeDriver')
-        self.flags(volume_drivers=[volume_driver],
-                   group='libvirt')
+        volume_driver = ['iscsi=nova.tests.unit.virt.libvirt.test_driver'
+                         '.FakeVolumeDriver']
         fake = FakeLibvirtDriver()
         # Customizing above fake if necessary
         for key, val in kwargs.items():
             fake.__setattr__(key, val)
 
         self.stubs.Set(libvirt_driver.LibvirtDriver, '_conn', fake)
+        self.stubs.Set(libvirt_driver.LibvirtDriver, '_get_volume_drivers',
+            lambda x: volume_driver)
         self.stubs.Set(host.Host, 'get_connection', lambda x: fake)
 
     def fake_lookup(self, instance_name):

nova/virt/libvirt/driver.py

@@ -162,31 +162,6 @@ libvirt_opts = [
                help='Snapshot image format (valid options are : '
                     'raw, qcow2, vmdk, vdi). '
                     'Defaults to same as source image'),
-    cfg.ListOpt('volume_drivers',
-                default=[
-                  'iscsi=nova.virt.libvirt.volume.LibvirtISCSIVolumeDriver',
-                  'iser=nova.virt.libvirt.volume.LibvirtISERVolumeDriver',
-                  'local=nova.virt.libvirt.volume.LibvirtVolumeDriver',
-                  'fake=nova.virt.libvirt.volume.LibvirtFakeVolumeDriver',
-                  'rbd=nova.virt.libvirt.volume.LibvirtNetVolumeDriver',
-                  'sheepdog=nova.virt.libvirt.volume.LibvirtNetVolumeDriver',
-                  'nfs=nova.virt.libvirt.volume.LibvirtNFSVolumeDriver',
-                  'smbfs=nova.virt.libvirt.volume.LibvirtSMBFSVolumeDriver',
-                  'aoe=nova.virt.libvirt.volume.LibvirtAOEVolumeDriver',
-                  'glusterfs='
-                      'nova.virt.libvirt.volume.LibvirtGlusterfsVolumeDriver',
-                  'fibre_channel=nova.virt.libvirt.volume.'
-                      'LibvirtFibreChannelVolumeDriver',
-                  'scality='
-                      'nova.virt.libvirt.volume.LibvirtScalityVolumeDriver',
-                  'gpfs='
-                      'nova.virt.libvirt.volume.LibvirtGPFSVolumeDriver',
-                  'quobyte='
-                      'nova.virt.libvirt.volume.LibvirtQuobyteVolumeDriver',
-                  ],
-                help='DEPRECATED. Libvirt handlers for remote volumes. '
-                     'This option is deprecated and will be removed in the '
-                     'Kilo release.'),
     cfg.StrOpt('disk_prefix',
                help='Override the default disk prefix for the devices attached'
                     ' to a server, which is dependent on virt_type. '
@@ -295,6 +270,23 @@ CONSOLE = "console=tty0 console=ttyS0"
 GuestNumaConfig = collections.namedtuple(
     'GuestNumaConfig', ['cpuset', 'cputune', 'numaconfig', 'numatune'])
 
+libvirt_volume_drivers = [
+    'iscsi=nova.virt.libvirt.volume.LibvirtISCSIVolumeDriver',
+    'iser=nova.virt.libvirt.volume.LibvirtISERVolumeDriver',
+    'local=nova.virt.libvirt.volume.LibvirtVolumeDriver',
+    'fake=nova.virt.libvirt.volume.LibvirtFakeVolumeDriver',
+    'rbd=nova.virt.libvirt.volume.LibvirtNetVolumeDriver',
+    'sheepdog=nova.virt.libvirt.volume.LibvirtNetVolumeDriver',
+    'nfs=nova.virt.libvirt.volume.LibvirtNFSVolumeDriver',
+    'smbfs=nova.virt.libvirt.volume.LibvirtSMBFSVolumeDriver',
+    'aoe=nova.virt.libvirt.volume.LibvirtAOEVolumeDriver',
+    'glusterfs=nova.virt.libvirt.volume.LibvirtGlusterfsVolumeDriver',
+    'fibre_channel=nova.virt.libvirt.volume.LibvirtFibreChannelVolumeDriver',
+    'scality=nova.virt.libvirt.volume.LibvirtScalityVolumeDriver',
+    'gpfs=nova.virt.libvirt.volume.LibvirtGPFSVolumeDriver',
+    'quobyte=nova.virt.libvirt.volume.LibvirtQuobyteVolumeDriver',
+]
+
 
 def patch_tpool_proxy():
     """eventlet.tpool.Proxy doesn't work with old-style class in __str__()
@@ -411,7 +403,7 @@ class LibvirtDriver(driver.ComputeDriver):
         self.vif_driver = libvirt_vif.LibvirtGenericVIFDriver()
 
         self.volume_drivers = driver.driver_dict_from_config(
-            CONF.libvirt.volume_drivers, self)
+            self._get_volume_drivers(), self)
 
         self._disk_cachemode = None
         self.image_cache_manager = imagecache.ImageCacheManager()
@@ -467,6 +459,9 @@ class LibvirtDriver(driver.ComputeDriver):
                    'expect': ', '.join("'%s'" % k for k in
                                        sysinfo_serial_funcs.keys())})
 
+    def _get_volume_drivers(self):
+        return libvirt_volume_drivers
+
     @property
     def disk_cachemode(self):
         if self._disk_cachemode is None: