Introduce LibvirtBaseFileSystemVolumeDriver

This adds the LibvirtBaseFileSystemVolumeDriver abstract base class
which the NFS, GPFS, Scality, SMBFS, GlusterFS and Quobyte volume
drivers will extend in subsequent changes.

The initial implementation handles the common work of getting the mount
and device paths for connecting and disconnecting volumes.

Part of blueprint consolidate-libvirt-fs-volume-drivers

Change-Id: I2a8b2cb27e731ebd1711cf0cd6dbcabb42fad4c1

nova/tests/unit/virt/libvirt/volume/test_fs.py

@@ -0,0 +1,58 @@
+# Copyright 2015 IBM Corp.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import os
+
+import mock
+
+from nova import test
+from nova import utils
+from nova.virt.libvirt.volume import fs
+
+FAKE_MOUNT_POINT = '/var/lib/nova/fake-mount'
+FAKE_SHARE = 'fake-share'
+NORMALIZED_SHARE = FAKE_SHARE + '-normalized'
+HASHED_SHARE = utils.get_hash_str(NORMALIZED_SHARE)
+FAKE_DEVICE_NAME = 'fake-device'
+
+
+class FakeFileSystemVolumeDriver(fs.LibvirtBaseFileSystemVolumeDriver):
+
+    def _get_mount_point_base(self):
+        return FAKE_MOUNT_POINT
+
+    def _normalize_export(self, export):
+        return NORMALIZED_SHARE
+
+
+class LibvirtBaseFileSystemVolumeDriverTestCase(test.NoDBTestCase):
+    """Tests the basic behavior of the LibvirtBaseFileSystemVolumeDriver"""
+
+    def setUp(self):
+        super(LibvirtBaseFileSystemVolumeDriverTestCase, self).setUp()
+        self.connection = mock.Mock()
+        self.driver = FakeFileSystemVolumeDriver(self.connection)
+        self.connection_info = {
+            'data': {
+                'export': FAKE_SHARE,
+                'name': FAKE_DEVICE_NAME,
+            }
+        }
+
+    def test_get_device_path(self):
+        path = self.driver._get_device_path(self.connection_info)
+        expected_path = os.path.join(FAKE_MOUNT_POINT,
+                                     HASHED_SHARE,
+                                     FAKE_DEVICE_NAME)
+        self.assertEqual(expected_path, path)

nova/virt/libvirt/volume/fs.py

@@ -0,0 +1,95 @@
+# Copyright 2015 IBM Corp.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import abc
+import os
+
+import six
+
+from nova import utils
+from nova.virt.libvirt.volume import volume as libvirt_volume
+
+
+@six.add_metaclass(abc.ABCMeta)
+class LibvirtBaseFileSystemVolumeDriver(
+    libvirt_volume.LibvirtBaseVolumeDriver):
+    """The base class for file system type volume drivers"""
+
+    def __init__(self, connection):
+        super(LibvirtBaseFileSystemVolumeDriver,
+              self).__init__(connection, is_block_dev=False)
+
+    @abc.abstractmethod
+    def _get_mount_point_base(self):
+        """Return the mount point path prefix.
+
+        This is used to build the device path.
+
+        :returns: The mount point path prefix.
+        """
+        raise NotImplementedError('_get_mount_point_base')
+
+    def _normalize_export(self, export):
+        """Normalize the export (share) if necessary.
+
+        Subclasses should override this method if they have a non-standard
+        export value, e.g. if the export is a URL. By default this method just
+        returns the export value passed in unchanged.
+
+        :param export: The export (share) value to normalize.
+        :returns: The normalized export value.
+        """
+        return export
+
+    def _get_mount_path(self, connection_info):
+        """Returns the mount path prefix using the mount point base and share.
+
+        :param connection_info: dict of the form
+
+        ::
+
+          connection_info = {
+              'data': {
+                  'export': the file system share,
+                  ...
+              }
+              ...
+          }
+
+        :returns: The mount path prefix.
+        """
+        share = self._normalize_export(connection_info['data']['export'])
+        return os.path.join(self._get_mount_point_base(),
+                            utils.get_hash_str(share))
+
+    def _get_device_path(self, connection_info):
+        """Returns the hashed path to the device.
+
+        :param connection_info: dict of the form
+
+        ::
+
+          connection_info = {
+              'data': {
+                  'export': the file system share,
+                  'name': the name of the device,
+                  ...
+              }
+              ...
+          }
+
+        :returns: The full path to the device.
+        """
+        mount_path = self._get_mount_path(connection_info)
+        return os.path.join(mount_path, connection_info['data']['name'])