DRBD connector class

Our DRBD block storage driver for Cinder can be used to make
Nova directly connect to the DRBD 9 storage servers, instead
of needing an iSCSI hop.

Blueprint: https://blueprints.launchpad.net/cinder/+spec/drbd-transport

Please see
  http://drbd.linbit.com/users-guide-9.0/s-openstack-transport-protocol.html
for more details

Change-Id: I7c02850ba1e9626b99a295c72175815b3dd1bdf3

etc/os-brick/rootwrap.d/os-brick.filters

@@ -58,6 +58,9 @@ drv_cfg: CommandFilter, /opt/emc/scaleio/sdc/bin/drv_cfg, root, /opt/emc/scaleio
 # initiator/connector.py
 sds_cli: CommandFilter, /usr/local/bin/sds/sds_cli, root
 
+# initiator/connector.py
+drbdadm: CommandFilter, drbdadm, root
+
 # initiator/connector.py: 'vgc-cluster', 'domain-list', '-l'
 # initiator/connector.py: 'vgc-cluster', 'space-set-apphosts', '-n'...
 vgc-cluster: CommandFilter, vgc-cluster, root

os_brick/initiator/connector.py

@@ -30,6 +30,7 @@ import re
 import requests
 import socket
 import sys
+import tempfile
 import time
 
 from oslo_concurrency import lockutils
@@ -66,6 +67,7 @@ ISCSI = "ISCSI"
 ISER = "ISER"
 FIBRE_CHANNEL = "FIBRE_CHANNEL"
 AOE = "AOE"
+DRBD = "DRBD"
 NFS = "NFS"
 GLUSTERFS = "GLUSTERFS"
 LOCAL = "LOCAL"
@@ -201,6 +203,11 @@ class InitiatorConnector(executor.Executor):
                                      execute=execute,
                                      device_scan_attempts=device_scan_attempts,
                                      *args, **kwargs)
+        elif protocol == DRBD:
+            return DRBDConnector(root_helper=root_helper,
+                                 driver=driver,
+                                 execute=execute,
+                                 *args, **kwargs)
         elif protocol == LOCAL:
             return LocalConnector(root_helper=root_helper,
                                   driver=driver,
@@ -1479,6 +1486,83 @@ class LocalConnector(InitiatorConnector):
         pass
 
 
+class DRBDConnector(InitiatorConnector):
+    """"Connector class to attach/detach DRBD resources."""
+
+    def __init__(self, root_helper, driver=None,
+                 execute=putils.execute, *args, **kwargs):
+
+        super(DRBDConnector, self).__init__(root_helper, driver=driver,
+                                            execute=execute, *args, **kwargs)
+
+        self._execute = execute
+        self._root_helper = root_helper
+
+    def check_valid_device(self, path, run_as_root=True):
+        """Verify an existing volume."""
+        # TODO(linbit): check via drbdsetup first, to avoid blocking/hanging
+        # in case of network problems?
+
+        return super(DRBDConnector, self).check_valid_device(path, run_as_root)
+
+    def get_all_available_volumes(self, connection_properties=None):
+
+        base = "/dev/"
+        blkdev_list = []
+
+        for e in os.listdir(base):
+            path = base + e
+            if os.path.isblk(path):
+                blkdev_list.append(path)
+
+        return blkdev_list
+
+    def _drbdadm_command(self, cmd, data_dict, sh_secret):
+        # TODO(linbit): Write that resource file to a permanent location?
+        tmp = tempfile.NamedTemporaryFile(suffix="res", delete=False, mode="w")
+        try:
+            kv = {'shared-secret': sh_secret}
+            tmp.write(data_dict['config'] % kv)
+            tmp.close()
+
+            (out, err) = self._execute('drbdadm', cmd,
+                                       "-c", tmp.name,
+                                       data_dict['name'],
+                                       run_as_root=True,
+                                       root_helper=self._root_helper)
+        finally:
+            os.unlink(tmp.name)
+
+        return (out, err)
+
+    def connect_volume(self, connection_properties):
+        """Attach the volume."""
+
+        self._drbdadm_command("adjust", connection_properties,
+                              connection_properties['provider_auth'])
+
+        device_info = {
+            'type': 'block',
+            'path': connection_properties['device'],
+        }
+
+        return device_info
+
+    def disconnect_volume(self, connection_properties, device_info):
+        """Detach the volume."""
+
+        self._drbdadm_command("down", connection_properties,
+                              connection_properties['provider_auth'])
+
+    def get_volume_paths(self, connection_properties):
+        path = connection_properties['device']
+        return [path]
+
+    def get_search_path(self):
+        # TODO(linbit): is it allowed to return "/dev", or is that too broad?
+        return None
+
+
 class HuaweiStorHyperConnector(InitiatorConnector):
     """"Connector class to attach/detach SDSHypervisor volumes."""
     attached_success_code = 0

os_brick/tests/initiator/test_connector.py

@@ -1756,6 +1756,66 @@ class RBDConnectorTestCase(ConnectorTestCase):
         self.assertEqual(1, volume_close.call_count)
 
 
+class DRBDConnectorTestCase(ConnectorTestCase):
+
+    RESOURCE_TEMPLATE = '''
+        resource r0 {
+            on host1 {
+            }
+            net {
+                shared-secret "%(shared-secret)s";
+            }
+        }
+'''
+
+    def setUp(self):
+        super(DRBDConnectorTestCase, self).setUp()
+
+        self.connector = connector.DRBDConnector(
+            None, execute=self._fake_exec)
+
+        self.execs = []
+
+    def _fake_exec(self, *cmd, **kwargs):
+        self.execs.append(cmd)
+
+        # out, err
+        return ('', '')
+
+    def test_connect_volume(self):
+        """Test connect_volume."""
+
+        cprop = {
+            'provider_auth': 'my-secret',
+            'config': self.RESOURCE_TEMPLATE,
+            'name': 'my-precious',
+            'device': '/dev/drbd951722',
+            'data': {},
+        }
+
+        res = self.connector.connect_volume(cprop)
+
+        self.assertEqual(cprop['device'], res['path'])
+        self.assertEqual('adjust', self.execs[0][1])
+        self.assertEqual(cprop['name'], self.execs[0][4])
+
+    def test_disconnect_volume(self):
+        """Test the disconnect volume case."""
+
+        cprop = {
+            'provider_auth': 'my-secret',
+            'config': self.RESOURCE_TEMPLATE,
+            'name': 'my-precious',
+            'device': '/dev/drbd951722',
+            'data': {},
+        }
+        dev_info = {}
+
+        self.connector.disconnect_volume(cprop, dev_info)
+
+        self.assertEqual('down', self.execs[0][1])
+
+
 class ScaleIOConnectorTestCase(ConnectorTestCase):
     """Test cases for ScaleIO connector"""
     # Fake volume information