Add option to allow cross AZ attach configurable

Make check_attach() optionally check if the volume and instance
are in the same availability zone and if cross AZ attach
is configured as not allowed report error.

This does not change the current default behaviour.

DocImpact: Adds a new Nova Config option

Change-Id: Ib0e085888b1c6620869261d87cd964de302accb3

5 files changed, 23 insertions, 5 deletions

diff --git a/nova/compute/api.py b/nova/compute/api.py
index 658673e50..3337fc82e 100644
--- a/nova/compute/api.py
+++ b/nova/compute/api.py
@@ -2244,7 +2244,7 @@ class API(base.Base):
             context, device=device, instance=instance, volume_id=volume_id)
         try:
             volume = self.volume_api.get(context, volume_id)
-            self.volume_api.check_attach(context, volume)
+            self.volume_api.check_attach(context, volume, instance=instance)
             self.volume_api.reserve_volume(context, volume)
             self.compute_rpcapi.attach_volume(context, instance=instance,
                     volume_id=volume_id, mountpoint=device)
diff --git a/nova/compute/cells_api.py b/nova/compute/cells_api.py
index 50449df04..1e30331bc 100644
--- a/nova/compute/cells_api.py
+++ b/nova/compute/cells_api.py
@@ -524,7 +524,7 @@ class ComputeCellsAPI(compute_api.API):
             context, device=device, instance=instance, volume_id=volume_id)
         try:
             volume = self.volume_api.get(context, volume_id)
-            self.volume_api.check_attach(context, volume)
+            self.volume_api.check_attach(context, volume, instance=instance)
         except Exception:
             with excutils.save_and_reraise_exception():
                 self.db.block_device_mapping_destroy_by_instance_and_device(
diff --git a/nova/compute/manager.py b/nova/compute/manager.py
index 8927e682a..18b0f3ae1 100755
--- a/nova/compute/manager.py
+++ b/nova/compute/manager.py
@@ -645,7 +645,8 @@ class ComputeManager(manager.SchedulerDependentManager):
 
             if bdm['volume_id'] is not None:
                 volume = self.volume_api.get(context, bdm['volume_id'])
-                self.volume_api.check_attach(context, volume)
+                self.volume_api.check_attach(context, volume,
+                                                      instance=instance)
                 cinfo = self._attach_volume_boot(context,
                                                  instance,
                                                  volume,
diff --git a/nova/tests/fake_volume.py b/nova/tests/fake_volume.py
index c7430ee6d..0d8a502a5 100644
--- a/nova/tests/fake_volume.py
+++ b/nova/tests/fake_volume.py
@@ -17,12 +17,17 @@
 import uuid
 
 from nova import exception
+from nova.openstack.common import cfg
 from nova.openstack.common import log as logging
 from nova.openstack.common import timeutils
 
 
 LOG = logging.getLogger(__name__)
 
+CONF = cfg.CONF
+CONF.import_opt('cinder_cross_az_attach',
+                'nova.volume.cinder')
+
 
 class fake_volume():
     user_uuid = '4a3cd440-b9c2-11e1-afa6-0800200c9a66'
@@ -175,7 +180,7 @@ class API(object):
         LOG.info('deleting volume %s', volume['id'])
         self.volume_list = [v for v in self.volume_list if v != volume]
 
-    def check_attach(self, context, volume):
+    def check_attach(self, context, volume, instance=None):
         if volume['status'] != 'available':
             msg = _("status must be available")
             msg = "%s" % volume
@@ -183,6 +188,10 @@ class API(object):
         if volume['attach_status'] == 'attached':
             msg = _("already attached")
             raise exception.InvalidVolume(reason=msg)
+        if instance and not CONF.cinder_cross_az_attach:
+            if instance['availability_zone'] != volume['availability_zone']:
+                msg = _("Instance and volume not in same availability_zone")
+                raise exception.InvalidVolume(reason=msg)
 
     def check_detach(self, context, volume):
         if volume['status'] == "available":
diff --git a/nova/volume/cinder.py b/nova/volume/cinder.py
index 05918f83d..b58e63011 100644
--- a/nova/volume/cinder.py
+++ b/nova/volume/cinder.py
@@ -51,6 +51,10 @@ cinder_opts = [
     cfg.BoolOpt('cinder_api_insecure',
                default=False,
                help='Allow to perform insecure SSL requests to cinder'),
+    cfg.BoolOpt('cinder_cross_az_attach',
+               default=True,
+               help='Allow attach between instance and volume in different '
+                    'availability zones.'),
 ]
 
 CONF = cfg.CONF
@@ -195,7 +199,7 @@ class API(base.Base):
 
         return rval
 
-    def check_attach(self, context, volume):
+    def check_attach(self, context, volume, instance=None):
         # TODO(vish): abstract status checking?
         if volume['status'] != "available":
             msg = _("status must be available")
@@ -203,6 +207,10 @@ class API(base.Base):
         if volume['attach_status'] == "attached":
             msg = _("already attached")
             raise exception.InvalidVolume(reason=msg)
+        if instance and not CONF.cinder_cross_az_attach:
+            if instance['availability_zone'] != volume['availability_zone']:
+                msg = _("Instance and volume not in same availability_zone")
+                raise exception.InvalidVolume(reason=msg)
 
     def check_detach(self, context, volume):
         # TODO(vish): abstract status checking?