Add GlusterFS libvirt volume connector

This is to support GlusterFS as a storage backend for Cinder,
which works similarly to the NFS backend.

Change-Id: I047d58ba74d27273ba8f2639bcc77999f8be0f30

3 files changed, 92 insertions, 2 deletions

diff --git a/nova/tests/test_libvirt_volume.py b/nova/tests/test_libvirt_volume.py
index c0fa53506..0098215b2 100644
--- a/nova/tests/test_libvirt_volume.py
+++ b/nova/tests/test_libvirt_volume.py
@@ -392,3 +392,31 @@ class LibvirtVolumeTestCase(test.TestCase):
         self.assertEqual(tree.get('type'), 'block')
         self.assertEqual(tree.find('./source').get('dev'), aoedevpath)
         libvirt_driver.disconnect_volume(connection_info, "vde")
+
+    def test_libvirt_glusterfs_driver(self):
+        mnt_base = '/mnt'
+        self.flags(glusterfs_mount_point_base=mnt_base)
+
+        libvirt_driver = volume.LibvirtGlusterfsVolumeDriver(self.fake_conn)
+        export_string = '192.168.1.1:/volume-00001'
+        name = 'volume-00001'
+        export_mnt_base = os.path.join(mnt_base,
+                libvirt_driver.get_hash_str(export_string))
+        file_path = os.path.join(export_mnt_base, name)
+
+        connection_info = {'data': {'export': export_string, 'name': name}}
+        disk_info = {
+            "bus": "virtio",
+            "dev": "vde",
+            "type": "disk",
+            }
+        conf = libvirt_driver.connect_volume(connection_info, disk_info)
+        tree = conf.format_dom()
+        self.assertEqual(tree.get('type'), 'file')
+        self.assertEqual(tree.find('./source').get('file'), file_path)
+        libvirt_driver.disconnect_volume(connection_info, "vde")
+
+        expected_commands = [
+            ('stat', export_mnt_base),
+            ('mount', '-t', 'glusterfs', export_string, export_mnt_base)]
+        self.assertEqual(self.executes, expected_commands)
diff --git a/nova/virt/libvirt/driver.py b/nova/virt/libvirt/driver.py
index bdb875ed3..4e2fb9d39 100755
--- a/nova/virt/libvirt/driver.py
+++ b/nova/virt/libvirt/driver.py
@@ -152,7 +152,9 @@ libvirt_opts = [
                   'rbd=nova.virt.libvirt.volume.LibvirtNetVolumeDriver',
                   'sheepdog=nova.virt.libvirt.volume.LibvirtNetVolumeDriver',
                   'nfs=nova.virt.libvirt.volume.LibvirtNFSVolumeDriver',
-                  'aoe=nova.virt.libvirt.volume.LibvirtAOEVolumeDriver'
+                  'aoe=nova.virt.libvirt.volume.LibvirtAOEVolumeDriver',
+                  'glusterfs='
+                      'nova.virt.libvirt.volume.LibvirtGlusterfsVolumeDriver'
                   ],
                 help='Libvirt handlers for remote volumes.'),
     cfg.StrOpt('libvirt_disk_prefix',
diff --git a/nova/virt/libvirt/volume.py b/nova/virt/libvirt/volume.py
index 9ec8f6bcb..c368f66f6 100644
--- a/nova/virt/libvirt/volume.py
+++ b/nova/virt/libvirt/volume.py
@@ -52,7 +52,11 @@ volume_opts = [
                     'of the nfs man page for details'),
     cfg.StrOpt('num_aoe_discover_tries',
                default=3,
-               help='number of times to rediscover AoE target to find volume')
+               help='number of times to rediscover AoE target to find volume'),
+    cfg.StrOpt('glusterfs_mount_point_base',
+                default=paths.state_path_def('mnt'),
+                help='Dir where the glusterfs volume is mounted on the '
+                      'compute node'),
     ]
 
 CONF = cfg.CONF
@@ -390,3 +394,59 @@ class LibvirtAOEVolumeDriver(LibvirtBaseVolumeDriver):
         conf.source_type = "block"
         conf.source_path = aoedevpath
         return conf
+
+
+class LibvirtGlusterfsVolumeDriver(LibvirtBaseVolumeDriver):
+    """Class implements libvirt part of volume driver for GlusterFS."""
+
+    def __init__(self, connection):
+        """Create back-end to glusterfs."""
+        super(LibvirtGlusterfsVolumeDriver,
+              self).__init__(connection, is_block_dev=False)
+
+    def connect_volume(self, connection_info, mount_device):
+        """Connect the volume. Returns xml for libvirt."""
+        conf = super(LibvirtGlusterfsVolumeDriver,
+                     self).connect_volume(connection_info, mount_device)
+        path = self._ensure_mounted(connection_info['data']['export'])
+        path = os.path.join(path, connection_info['data']['name'])
+        conf.source_type = 'file'
+        conf.source_path = path
+        return conf
+
+    def _ensure_mounted(self, glusterfs_export):
+        """
+        @type glusterfs_export: string
+        """
+        mount_path = os.path.join(CONF.glusterfs_mount_point_base,
+                                  self.get_hash_str(glusterfs_export))
+        self._mount_glusterfs(mount_path, glusterfs_export, ensure=True)
+        return mount_path
+
+    def _mount_glusterfs(self, mount_path, glusterfs_share, ensure=False):
+        """Mount glusterfs export to mount path."""
+        if not self._path_exists(mount_path):
+            utils.execute('mkdir', '-p', mount_path)
+
+        try:
+            utils.execute('mount', '-t', 'glusterfs', glusterfs_share,
+                          mount_path,
+                          run_as_root=True)
+        except exception.ProcessExecutionError as exc:
+            if ensure and 'already mounted' in exc.message:
+                LOG.warn(_("%s is already mounted"), glusterfs_share)
+            else:
+                raise
+
+    @staticmethod
+    def get_hash_str(base_str):
+        """returns string that represents hash of base_str (in hex format)."""
+        return hashlib.md5(base_str).hexdigest()
+
+    @staticmethod
+    def _path_exists(path):
+        """Check path."""
+        try:
+            return utils.execute('stat', path, run_as_root=True)
+        except exception.ProcessExecutionError:
+            return False