In preparation for XenAPI support, refactor the interface between

nova.compute and the hypervisor (i.e. libvirt).

compute.node is no longer coupled tightly with libvirt.  Instead, hypervisor
connections are handled through a simple abstract interface.   This has the
additional advantage that there is no need to riddle the code with
FLAGS.fake_libvirt checks, as we now have an interface behind which we can mock.

The libvirt-specific code, and the fakevirt code used for unit tests, have
moved into nova.virt.

The fake_libvirt flag has been replaced with a connection_type flag, that will
allow us to specify different connection types.

The disk image handling (S3 or local disk image fetch) has moved into
nova.virt.images, where it will be easier to share between connection types.

The power_state values (Instance.RUNNING etc) and the INSTANCE_TYPES dictionary
have moved into their own files (nova.compute.instance_types and
nova.compute.power_state) so that we can share them without mutual
dependencies between nova.compute.node and nova.virt.libvirt_conn.

24 files changed, 667 insertions, 378 deletions

diff --git a/bin/dhcpleasor.py b/bin/dhcpleasor.py
index 07ff325f1..4a3f374d5 100755
--- a/bin/dhcpleasor.py
+++ b/bin/dhcpleasor.py
@@ -71,7 +71,7 @@ def main(argv=None):
         FLAGS.fake_rabbit = True
         FLAGS.redis_db = 8
         FLAGS.network_size = 32
-        FLAGS.fake_libvirt=True
+        FLAGS.connection_type = 'fake'
         FLAGS.fake_network=True
         FLAGS.fake_users = True
     action = argv[1]
diff --git a/docs/fakes.rst b/docs/fakes.rst
index bea8bc4e9..a993fb4c8 100644
--- a/docs/fakes.rst
+++ b/docs/fakes.rst
@@ -18,10 +18,10 @@
 Nova Fakes
 ==========
 
-The :mod:`fakevirt` Module
+The :mod:`virt.fake` Module
 --------------------------
 
-.. automodule:: nova.fakevirt
+.. automodule:: nova.virt.fake
     :members:
     :undoc-members:
     :show-inheritance:
diff --git a/nova/compute/instance_types.py b/nova/compute/instance_types.py
new file mode 100644
index 000000000..439be3c7d
--- /dev/null
+++ b/nova/compute/instance_types.py
@@ -0,0 +1,30 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2010 United States Government as represented by the
+# Administrator of the National Aeronautics and Space Administration.
+# All Rights Reserved.
+# Copyright (c) 2010 Citrix Systems, Inc.
+#
+#    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.
+
+"""
+The built-in instance properties.
+"""
+
+INSTANCE_TYPES = {}
+INSTANCE_TYPES['m1.tiny'] = {'memory_mb': 512, 'vcpus': 1, 'local_gb': 0}
+INSTANCE_TYPES['m1.small'] = {'memory_mb': 1024, 'vcpus': 1, 'local_gb': 10}
+INSTANCE_TYPES['m1.medium'] = {'memory_mb': 2048, 'vcpus': 2, 'local_gb': 10}
+INSTANCE_TYPES['m1.large'] = {'memory_mb': 4096, 'vcpus': 4, 'local_gb': 10}
+INSTANCE_TYPES['m1.xlarge'] = {'memory_mb': 8192, 'vcpus': 4, 'local_gb': 10}
+INSTANCE_TYPES['c1.medium'] = {'memory_mb': 2048, 'vcpus': 4, 'local_gb': 10}
diff --git a/nova/compute/node.py b/nova/compute/node.py
index d681ec661..7146d1279 100644
--- a/nova/compute/node.py
+++ b/nova/compute/node.py
@@ -20,93 +20,48 @@
 Compute Node:
 
     Runs on each compute node, managing the
-    hypervisor using libvirt.
+    hypervisor using the virt module.
 
 """
 
 import base64
-import json
 import logging
 import os
-import shutil
 import sys
 from twisted.internet import defer
 from twisted.internet import task
 from twisted.application import service
 
-
-try:
-    import libvirt
-except Exception, err:
-    logging.warning('no libvirt found')
-
 from nova import exception
-from nova import fakevirt
 from nova import flags
 from nova import process
 from nova import utils
-from nova.compute import disk
 from nova.compute import model
 from nova.compute import network
-from nova.objectstore import image # for image_path flag
+from nova.compute import power_state
+from nova.compute.instance_types import INSTANCE_TYPES
+from nova.virt import connection as virt_connection
 from nova.volume import storage
 
 
 FLAGS = flags.FLAGS
-flags.DEFINE_string('libvirt_xml_template',
-                        utils.abspath('compute/libvirt.xml.template'),
-                        'Libvirt XML Template')
-flags.DEFINE_bool('use_s3', True,
-                      'whether to get images from s3 or use local copy')
 flags.DEFINE_string('instances_path', utils.abspath('../instances'),
                         'where instances are stored on disk')
 
-INSTANCE_TYPES = {}
-INSTANCE_TYPES['m1.tiny'] = {'memory_mb': 512, 'vcpus': 1, 'local_gb': 0}
-INSTANCE_TYPES['m1.small'] = {'memory_mb': 1024, 'vcpus': 1, 'local_gb': 10}
-INSTANCE_TYPES['m1.medium'] = {'memory_mb': 2048, 'vcpus': 2, 'local_gb': 10}
-INSTANCE_TYPES['m1.large'] = {'memory_mb': 4096, 'vcpus': 4, 'local_gb': 10}
-INSTANCE_TYPES['m1.xlarge'] = {'memory_mb': 8192, 'vcpus': 4, 'local_gb': 10}
-INSTANCE_TYPES['c1.medium'] = {'memory_mb': 2048, 'vcpus': 4, 'local_gb': 10}
-
-
-def _image_path(path=''):
-    return os.path.join(FLAGS.images_path, path)
-
-
-def _image_url(path):
-    return "%s:%s/_images/%s" % (FLAGS.s3_host, FLAGS.s3_port, path)
-
 
 class Node(object, service.Service):
     """
     Manages the running instances.
     """
     def __init__(self):
-        """ load configuration options for this node and connect to libvirt """
+        """ load configuration options for this node and connect to the hypervisor"""
         super(Node, self).__init__()
         self._instances = {}
-        self._conn = self._get_connection()
+        self._conn = virt_connection.get_connection()
         self._pool = process.ProcessPool()
         self.instdir = model.InstanceDirectory()
         # TODO(joshua): This needs to ensure system state, specifically: modprobe aoe
 
-    def _get_connection(self):
-        """ returns a libvirt connection object """
-        # TODO(termie): maybe lazy load after initial check for permissions
-        # TODO(termie): check whether we can be disconnected
-        if FLAGS.fake_libvirt:
-            conn = fakevirt.FakeVirtConnection.instance()
-        else:
-            auth = [[libvirt.VIR_CRED_AUTHNAME, libvirt.VIR_CRED_NOECHOPROMPT],
-                    'root',
-                    None]
-            conn = libvirt.openAuth('qemu:///system', auth, 0)
-            if conn == None:
-                logging.error('Failed to open connection to the hypervisor')
-                sys.exit(1)
-        return conn
-
     def noop(self):
         """ simple test of an AMQP message call """
         return defer.succeed('PONG')
@@ -122,8 +77,7 @@ class Node(object, service.Service):
     def adopt_instances(self):
         """ if there are instances already running, adopt them """
         return defer.succeed(0)
-        instance_names = [self._conn.lookupByID(x).name()
-                          for x in self._conn.listDomainsID()]
+        instance_names = self._conn.list_instances()
         for name in instance_names:
             try:
                 new_inst = Instance.fromName(self._conn, self._pool, name)
@@ -155,7 +109,7 @@ class Node(object, service.Service):
                 logging.exception("model server went away")
         yield
 
-    # @exception.wrap_exception
+    @exception.wrap_exception
     def run_instance(self, instance_id, **_kwargs):
         """ launch a new instance with specified options """
         logging.debug("Starting instance %s..." % (instance_id))
@@ -174,8 +128,7 @@ class Node(object, service.Service):
         logging.info("Instances current state is %s", new_inst.state)
         if new_inst.is_running():
             raise exception.Error("Instance is already running")
-        d = new_inst.spawn()
-        return d
+        new_inst.spawn()
 
     @exception.wrap_exception
     def terminate_instance(self, instance_id):
@@ -309,20 +262,6 @@ class Instance(object):
         self.datamodel.save()
         logging.debug("Finished init of Instance with id of %s" % name)
 
-    def toXml(self):
-        # TODO(termie): cache?
-        logging.debug("Starting the toXML method")
-        libvirt_xml = open(FLAGS.libvirt_xml_template).read()
-        xml_info = self.datamodel.copy()
-        # TODO(joshua): Make this xml express the attached disks as well
-
-        # TODO(termie): lazy lazy hack because xml is annoying
-        xml_info['nova'] = json.dumps(self.datamodel.copy())
-        libvirt_xml = libvirt_xml % xml_info
-        logging.debug("Finished the toXML method")
-
-        return libvirt_xml
-
     @classmethod
     def fromName(cls, conn, pool, name):
         """ use the saved data for reloading the instance """
@@ -333,7 +272,7 @@ class Instance(object):
     def set_state(self, state_code, state_description=None):
         self.datamodel['state'] = state_code
         if not state_description:
-            state_description = STATE_NAMES[state_code]
+            state_description = power_state.name(state_code)
         self.datamodel['state_description'] = state_description
         self.datamodel.save()
 
@@ -347,37 +286,29 @@ class Instance(object):
         return self.datamodel['name']
 
     def is_pending(self):
-        return (self.state == Instance.NOSTATE or self.state == 'pending')
+        return (self.state == power_state.NOSTATE or self.state == 'pending')
 
     def is_destroyed(self):
-        return self.state == Instance.SHUTOFF
+        return self.state == power_state.SHUTOFF
 
     def is_running(self):
         logging.debug("Instance state is: %s" % self.state)
-        return (self.state == Instance.RUNNING or self.state == 'running')
+        return (self.state == power_state.RUNNING or self.state == 'running')
 
     def describe(self):
         return self.datamodel
 
     def info(self):
-        logging.debug("Getting info for dom %s" % self.name)
-        virt_dom = self._conn.lookupByName(self.name)
-        (state, max_mem, mem, num_cpu, cpu_time) = virt_dom.info()
-        return {'state': state,
-                'max_mem': max_mem,
-                'mem': mem,
-                'num_cpu': num_cpu,
-                'cpu_time': cpu_time,
-                'node_name': FLAGS.node_name}
-
-    def basepath(self, path=''):
-        return os.path.abspath(os.path.join(self.datamodel['basepath'], path))
+        result = self._conn.get_info(self.name)
+        result['node_name'] = FLAGS.node_name
+        return result
 
     def update_state(self):
         self.datamodel.update(self.info())
         self.set_state(self.state)
         self.datamodel.save() # Extra, but harmless
 
+    @defer.inlineCallbacks
     @exception.wrap_exception
     def destroy(self):
         if self.is_destroyed():
@@ -385,38 +316,9 @@ class Instance(object):
             raise exception.Error('trying to destroy already destroyed'
                                   ' instance: %s' % self.name)
 
-        self.set_state(Instance.NOSTATE, 'shutting_down')
-        try:
-            virt_dom = self._conn.lookupByName(self.name)
-            virt_dom.destroy()
-        except Exception, _err:
-            pass
-            # If the instance is already terminated, we're still happy
-        d = defer.Deferred()
-        d.addCallback(lambda x: self._cleanup())
-        d.addCallback(lambda x: self.datamodel.destroy())
-        # TODO(termie): short-circuit me for tests
-        # WE'LL save this for when we do shutdown,
-        # instead of destroy - but destroy returns immediately
-        timer = task.LoopingCall(f=None)
-        def _wait_for_shutdown():
-            try:
-                self.update_state()
-                if self.state == Instance.SHUTDOWN:
-                    timer.stop()
-                    d.callback(None)
-            except Exception:
-                self.set_state(Instance.SHUTDOWN)
-                timer.stop()
-                d.callback(None)
-        timer.f = _wait_for_shutdown
-        timer.start(interval=0.5, now=True)
-        return d
-
-    def _cleanup(self):
-        target = os.path.abspath(self.datamodel['basepath'])
-        logging.info("Deleting instance files at %s", target)
-        shutil.rmtree(target)
+        self.set_state(power_state.NOSTATE, 'shutting_down')
+        yield self._conn.destroy(self)
+        self.datamodel.destroy()
 
     @defer.inlineCallbacks
     @exception.wrap_exception
@@ -427,136 +329,26 @@ class Instance(object):
                     'instance: %s (state: %s)' % (self.name, self.state))
 
         logging.debug('rebooting instance %s' % self.name)
-        self.set_state(Instance.NOSTATE, 'rebooting')
-        yield self._conn.lookupByName(self.name).destroy()
-        self._conn.createXML(self.toXml(), 0)
-
-        d = defer.Deferred()
-        timer = task.LoopingCall(f=None)
-        def _wait_for_reboot():
-            try:
-                self.update_state()
-                if self.is_running():
-                    logging.debug('rebooted instance %s' % self.name)
-                    timer.stop()
-                    d.callback(None)
-            except Exception:
-                self.set_state(Instance.SHUTDOWN)
-                timer.stop()
-                d.callback(None)
-        timer.f = _wait_for_reboot
-        timer.start(interval=0.5, now=True)
-        yield d
-
-    def _fetch_s3_image(self, image, path):
-        url = _image_url('%s/image' % image)
-        d = self._pool.simpleExecute('curl --silent %s -o %s' % (url, path))
-        return d
-
-    def _fetch_local_image(self, image, path):
-        source = _image_path('%s/image' % image)
-        d = self._pool.simpleExecute('cp %s %s' % (source, path))
-        return d
-
-    @defer.inlineCallbacks
-    def _create_image(self, libvirt_xml):
-        # syntactic nicety
-        data = self.datamodel
-        basepath = self.basepath
-
-        # ensure directories exist and are writable
-        yield self._pool.simpleExecute('mkdir -p %s' % basepath())
-        yield self._pool.simpleExecute('chmod 0777 %s' % basepath())
-
-
-        # TODO(termie): these are blocking calls, it would be great
-        #               if they weren't.
-        logging.info('Creating image for: %s', data['instance_id'])
-        f = open(basepath('libvirt.xml'), 'w')
-        f.write(libvirt_xml)
-        f.close()
-
-        if FLAGS.fake_libvirt:
-            logging.info('fake_libvirt, nothing to do for create_image')
-            raise defer.returnValue(None);
-
-        if FLAGS.use_s3:
-            _fetch_file = self._fetch_s3_image
-        else:
-            _fetch_file = self._fetch_local_image
-
-        if not os.path.exists(basepath('disk')):
-           yield _fetch_file(data['image_id'], basepath('disk-raw'))
-        if not os.path.exists(basepath('kernel')):
-           yield _fetch_file(data['kernel_id'], basepath('kernel'))
-        if not os.path.exists(basepath('ramdisk')):
-           yield _fetch_file(data['ramdisk_id'], basepath('ramdisk'))
-
-        execute = lambda cmd, input=None: self._pool.simpleExecute(cmd=cmd,
-                                                                   input=input,
-                                                                   error_ok=1)
-
-        key = data['key_data']
-        net = None
-        if FLAGS.simple_network:
-            with open(FLAGS.simple_network_template) as f:
-                net = f.read() % {'address': data['private_dns_name'],
-                                  'network': FLAGS.simple_network_network,
-                                  'netmask': FLAGS.simple_network_netmask,
-                                  'gateway': FLAGS.simple_network_gateway,
-                                  'broadcast': FLAGS.simple_network_broadcast,
-                                  'dns': FLAGS.simple_network_dns}
-        if key or net:
-            logging.info('Injecting data into image %s', data['image_id'])
-            yield disk.inject_data(basepath('disk-raw'), key, net, execute=execute)
-
-        if os.path.exists(basepath('disk')):
-            yield self._pool.simpleExecute('rm -f %s' % basepath('disk'))
-
-        bytes = (INSTANCE_TYPES[data['instance_type']]['local_gb']
-                 * 1024 * 1024 * 1024)
-        yield disk.partition(
-                basepath('disk-raw'), basepath('disk'), bytes, execute=execute)
+        self.set_state(power_state.NOSTATE, 'rebooting')
+        yield self._conn.reboot(self)
+        self.update_state()
 
     @defer.inlineCallbacks
     @exception.wrap_exception
     def spawn(self):
-        self.set_state(Instance.NOSTATE, 'spawning')
+        self.set_state(power_state.NOSTATE, 'spawning')
         logging.debug("Starting spawn in Instance")
-
-        xml = self.toXml()
-        self.set_state(Instance.NOSTATE, 'launching')
-        logging.info('self %s', self)
         try:
-            yield self._create_image(xml)
-            self._conn.createXML(xml, 0)
-            # TODO(termie): this should actually register
-            # a callback to check for successful boot
-            logging.debug("Instance is running")
-
-            local_d = defer.Deferred()
-            timer = task.LoopingCall(f=None)
-            def _wait_for_boot():
-                try:
-                    self.update_state()
-                    if self.is_running():
-                        logging.debug('booted instance %s' % self.name)
-                        timer.stop()
-                        local_d.callback(None)
-                except Exception:
-                    self.set_state(Instance.SHUTDOWN)
-                    logging.error('Failed to boot instance %s' % self.name)
-                    timer.stop()
-                    local_d.callback(None)
-            timer.f = _wait_for_boot
-            timer.start(interval=0.5, now=True)
+            yield self._conn.spawn(self)
         except Exception, ex:
             logging.debug(ex)
-            self.set_state(Instance.SHUTDOWN)
+            self.set_state(power_state.SHUTDOWN)
+        self.update_state()
 
     @exception.wrap_exception
     def console_output(self):
-        if not FLAGS.fake_libvirt:
+        # FIXME: Abstract this for Xen
+        if FLAGS.connection_type == 'libvirt':
             fname = os.path.abspath(
                     os.path.join(self.datamodel['basepath'], 'console.log'))
             with open(fname, 'r') as f:
@@ -564,13 +356,3 @@ class Instance(object):
         else:
             console = 'FAKE CONSOLE OUTPUT'
         return defer.succeed(console)
-
-STATE_NAMES = {
- Instance.NOSTATE : 'pending',
- Instance.RUNNING : 'running',
- Instance.BLOCKED : 'blocked',
- Instance.PAUSED  : 'paused',
- Instance.SHUTDOWN : 'shutdown',
- Instance.SHUTOFF : 'shutdown',
- Instance.CRASHED : 'crashed',
-}
diff --git a/nova/compute/power_state.py b/nova/compute/power_state.py
new file mode 100644
index 000000000..b27aa4677
--- /dev/null
+++ b/nova/compute/power_state.py
@@ -0,0 +1,41 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2010 United States Government as represented by the
+# Administrator of the National Aeronautics and Space Administration.
+# All Rights Reserved.
+# Copyright (c) 2010 Citrix Systems, Inc.
+#
+#    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.
+
+"""The various power states that a VM can be in."""
+
+NOSTATE = 0x00
+RUNNING = 0x01
+BLOCKED = 0x02
+PAUSED = 0x03
+SHUTDOWN = 0x04
+SHUTOFF = 0x05
+CRASHED = 0x06
+
+
+def name(code):
+    d = {
+        NOSTATE : 'pending',
+        RUNNING : 'running',
+        BLOCKED : 'blocked',
+        PAUSED  : 'paused',
+        SHUTDOWN: 'shutdown',
+        SHUTOFF : 'shutdown',
+        CRASHED : 'crashed',
+    }
+    return d[code]
diff --git a/nova/endpoint/cloud.py b/nova/endpoint/cloud.py
index 3b7b4804b..51f5c859b 100644
--- a/nova/endpoint/cloud.py
+++ b/nova/endpoint/cloud.py
@@ -39,6 +39,7 @@ from nova.auth import users
 from nova.compute import model
 from nova.compute import network
 from nova.compute import node
+from nova.compute.instance_types import INSTANCE_TYPES
 from nova.endpoint import images
 from nova.volume import storage
 
@@ -103,7 +104,7 @@ class CloudController(object):
         result = {}
         for instance in self.instdir.all:
             if instance['project_id'] == project_id:
-                line = '%s slots=%d' % (instance['private_dns_name'], node.INSTANCE_TYPES[instance['instance_type']]['vcpus'])
+                line = '%s slots=%d' % (instance['private_dns_name'], INSTANCE_TYPES[instance['instance_type']]['vcpus'])
                 if instance['key_name'] in result:
                     result[instance['key_name']].append(line)
                 else:
diff --git a/nova/fakevirt.py b/nova/fakevirt.py
deleted file mode 100644
index bcbeae548..000000000
--- a/nova/fakevirt.py
+++ /dev/null
@@ -1,112 +0,0 @@
-# vim: tabstop=4 shiftwidth=4 softtabstop=4
-
-# Copyright 2010 United States Government as represented by the
-# Administrator of the National Aeronautics and Space Administration.
-# All Rights Reserved.
-#
-#    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.
-
-"""
-A fake (in-memory) hypervisor+api. Allows nova testing w/o KVM and libvirt.
-"""
-
-import StringIO
-from xml.etree import ElementTree
-
-
-class FakeVirtConnection(object):
-    # FIXME: networkCreateXML, listNetworks don't do anything since
-    # they aren't exercised in tests yet
-
-    def __init__(self):
-        self.next_index = 0
-        self.instances = {}
-
-    @classmethod
-    def instance(cls):
-        if not hasattr(cls, '_instance'):
-            cls._instance = cls()
-        return cls._instance
-
-    def lookupByID(self, i):
-        return self.instances[str(i)]
-
-    def listDomainsID(self):
-        return self.instances.keys()
-
-    def listNetworks(self):
-        return []
-
-    def lookupByName(self, instance_id):
-        for x in self.instances.values():
-            if x.name() == instance_id:
-                return x
-        raise Exception('no instance found for instance_id: %s' % instance_id)
-
-    def networkCreateXML(self, xml):
-        pass
-
-    def createXML(self, xml, flags):
-        # parse the xml :(
-        xml_stringio = StringIO.StringIO(xml)
-
-        my_xml = ElementTree.parse(xml_stringio)
-        name = my_xml.find('name').text
-
-        fake_instance = FakeVirtInstance(conn=self,
-                                         index=str(self.next_index),
-                                         name=name,
-                                         xml=my_xml)
-        self.instances[str(self.next_index)] = fake_instance
-        self.next_index += 1
-
-    def _removeInstance(self, i):
-        self.instances.pop(str(i))
-
-
-class FakeVirtInstance(object):
-    NOSTATE = 0x00
-    RUNNING = 0x01
-    BLOCKED = 0x02
-    PAUSED = 0x03
-    SHUTDOWN = 0x04
-    SHUTOFF = 0x05
-    CRASHED = 0x06
-
-    def __init__(self, conn, index, name, xml):
-        self._conn = conn
-        self._destroyed = False
-        self._name = name
-        self._index = index
-        self._state = self.RUNNING
-
-    def name(self):
-        return self._name
-
-    def destroy(self):
-        if self._state == self.SHUTOFF:
-            raise Exception('instance already destroyed: %s' % self.name())
-        self._state = self.SHUTDOWN
-        self._conn._removeInstance(self._index)
-
-    def info(self):
-        return [self._state, 0, 2, 0, 0]
-
-    def XMLDesc(self, flags):
-        return open('fakevirtinstance.xml', 'r').read()
-
-    def blockStats(self, disk):
-        return [0L, 0L, 0L, 0L, null]
-
-    def interfaceStats(self, iface):
-        return [0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L]
diff --git a/nova/flags.py b/nova/flags.py
index 60245a349..f9ebb28f7 100644
--- a/nova/flags.py
+++ b/nova/flags.py
@@ -36,14 +36,13 @@ DEFINE_bool = DEFINE_bool
 # Define any app-specific flags in their own files, docs at:
 # http://code.google.com/p/python-gflags/source/browse/trunk/gflags.py#39
 
+DEFINE_string('connection_type', 'libvirt', 'libvirt or fake')
 DEFINE_integer('s3_port', 3333, 's3 port')
 DEFINE_integer('s3_internal_port', 3334, 's3 port')
 DEFINE_string('s3_host', '127.0.0.1', 's3 host')
 #DEFINE_string('cloud_topic', 'cloud', 'the topic clouds listen on')
 DEFINE_string('compute_topic', 'compute', 'the topic compute nodes listen on')
 DEFINE_string('storage_topic', 'storage', 'the topic storage nodes listen on')
-DEFINE_bool('fake_libvirt', False,
-                  'whether to use a fake libvirt or not')
 DEFINE_bool('verbose', False, 'show debug output')
 DEFINE_boolean('fake_rabbit', False, 'use a fake rabbit')
 DEFINE_bool('fake_network', False, 'should we use fake network devices and addresses')
diff --git a/nova/tests/access_unittest.py b/nova/tests/access_unittest.py
index 8500dd0cb..6cf7e893d 100644
--- a/nova/tests/access_unittest.py
+++ b/nova/tests/access_unittest.py
@@ -33,7 +33,7 @@ class Context(object):
 class AccessTestCase(test.BaseTestCase):
     def setUp(self):
         super(AccessTestCase, self).setUp()
-        FLAGS.fake_libvirt = True
+        FLAGS.connection_type = 'fake'
         FLAGS.fake_storage = True
         um = UserManager.instance()
         # Make test users
diff --git a/nova/tests/cloud_unittest.py b/nova/tests/cloud_unittest.py
index b8614fdc8..8040f6331 100644
--- a/nova/tests/cloud_unittest.py
+++ b/nova/tests/cloud_unittest.py
@@ -39,7 +39,7 @@ FLAGS = flags.FLAGS
 class CloudTestCase(test.BaseTestCase):
     def setUp(self):
         super(CloudTestCase, self).setUp()
-        self.flags(fake_libvirt=True,
+        self.flags(connection_type='fake',
                    fake_storage=True,
                    fake_users=True)
 
@@ -72,7 +72,7 @@ class CloudTestCase(test.BaseTestCase):
         users.UserManager.instance().delete_user('admin')
 
     def test_console_output(self):
-        if FLAGS.fake_libvirt:
+        if FLAGS.connection_type == 'fake':
             logging.debug("Can't test instances without a real virtual env.")
             return
         instance_id = 'foo'
@@ -83,7 +83,7 @@ class CloudTestCase(test.BaseTestCase):
         rv = yield self.node.terminate_instance(instance_id)
 
     def test_run_instances(self):
-        if FLAGS.fake_libvirt:
+        if FLAGS.connection_type == 'fake':
             logging.debug("Can't test instances without a real virtual env.")
             return
         image_id = FLAGS.default_image
@@ -104,7 +104,7 @@ class CloudTestCase(test.BaseTestCase):
                 break
         self.assert_(rv)
 
-        if not FLAGS.fake_libvirt:
+        if connection_type != 'fake':
             time.sleep(45) # Should use boto for polling here
         for reservations in rv['reservationSet']:
             # for res_id in reservations.keys():
diff --git a/nova/tests/fake_flags.py b/nova/tests/fake_flags.py
index d32f40d8f..5fcd2bcac 100644
--- a/nova/tests/fake_flags.py
+++ b/nova/tests/fake_flags.py
@@ -20,7 +20,7 @@ from nova import flags
 
 FLAGS = flags.FLAGS
 
-FLAGS.fake_libvirt = True
+FLAGS.connection_type = 'fake'
 FLAGS.fake_storage = True
 FLAGS.fake_rabbit = True
 FLAGS.fake_network = True
diff --git a/nova/tests/future_unittest.py b/nova/tests/future_unittest.py
index da5470ffe..31ec83065 100644
--- a/nova/tests/future_unittest.py
+++ b/nova/tests/future_unittest.py
@@ -39,7 +39,7 @@ FLAGS = flags.FLAGS
 class AdminTestCase(test.BaseTestCase):
     def setUp(self):
         super(AdminTestCase, self).setUp()
-        self.flags(fake_libvirt=True,
+        self.flags(connection_type='fake',
                    fake_rabbit=True)
 
         self.conn = rpc.Connection.instance()
diff --git a/nova/tests/model_unittest.py b/nova/tests/model_unittest.py
index 1bd7e527f..b9eb2ac96 100644
--- a/nova/tests/model_unittest.py
+++ b/nova/tests/model_unittest.py
@@ -34,7 +34,7 @@ FLAGS = flags.FLAGS
 class ModelTestCase(test.TrialTestCase):
     def setUp(self):
         super(ModelTestCase, self).setUp()
-        self.flags(fake_libvirt=True,
+        self.flags(connection_type='fake',
                    fake_storage=True,
                    fake_users=True)
 
diff --git a/nova/tests/network_unittest.py b/nova/tests/network_unittest.py
index a822cc1d9..45ee6dbc7 100644
--- a/nova/tests/network_unittest.py
+++ b/nova/tests/network_unittest.py
@@ -33,7 +33,7 @@ from nova import utils
 class NetworkTestCase(test.TrialTestCase):
     def setUp(self):
         super(NetworkTestCase, self).setUp()
-        self.flags(fake_libvirt=True,
+        self.flags(connection_type='fake',
                    fake_storage=True,
                    fake_network=True,
                    network_size=32)
diff --git a/nova/tests/node_unittest.py b/nova/tests/node_unittest.py
index 93942d79e..86d9775fd 100644
--- a/nova/tests/node_unittest.py
+++ b/nova/tests/node_unittest.py
@@ -57,7 +57,7 @@ class NodeConnectionTestCase(test.TrialTestCase):
     def setUp(self):
         logging.getLogger().setLevel(logging.DEBUG)
         super(NodeConnectionTestCase, self).setUp()
-        self.flags(fake_libvirt=True,
+        self.flags(connection_type='fake',
                    fake_storage=True,
                    fake_users=True)
         self.node = node.Node()
diff --git a/nova/tests/objectstore_unittest.py b/nova/tests/objectstore_unittest.py
index f47ca7f00..f22256aaf 100644
--- a/nova/tests/objectstore_unittest.py
+++ b/nova/tests/objectstore_unittest.py
@@ -25,6 +25,8 @@ import tempfile
 
 from nova import flags
 from nova import objectstore
+from nova.objectstore import bucket # for buckets_path flag
+from nova.objectstore import image # for images_path flag
 from nova import test
 from nova.auth import users
 
diff --git a/nova/tests/real_flags.py b/nova/tests/real_flags.py
index 9e106f227..690fb640a 100644
--- a/nova/tests/real_flags.py
+++ b/nova/tests/real_flags.py
@@ -20,7 +20,7 @@ from nova import flags
 
 FLAGS = flags.FLAGS
 
-FLAGS.fake_libvirt = False
+FLAGS.connection_type = 'libvirt'
 FLAGS.fake_storage = False
 FLAGS.fake_rabbit = False
 FLAGS.fake_network = False
diff --git a/nova/tests/storage_unittest.py b/nova/tests/storage_unittest.py
index 60576d74f..f400cd2fd 100644
--- a/nova/tests/storage_unittest.py
+++ b/nova/tests/storage_unittest.py
@@ -34,7 +34,7 @@ class StorageTestCase(test.TrialTestCase):
         super(StorageTestCase, self).setUp()
         self.mynode = node.Node()
         self.mystorage = None
-        self.flags(fake_libvirt=True,
+        self.flags(connection_type='fake',
                    fake_storage=True)
         self.mystorage = storage.BlockStore()
 
diff --git a/nova/tests/users_unittest.py b/nova/tests/users_unittest.py
index 301721075..824d5cff6 100644
--- a/nova/tests/users_unittest.py
+++ b/nova/tests/users_unittest.py
@@ -35,7 +35,7 @@ class UserTestCase(test.BaseTestCase):
     flush_db = False
     def setUp(self):
         super(UserTestCase, self).setUp()
-        self.flags(fake_libvirt=True,
+        self.flags(connection_type='fake',
                    fake_storage=True)
         self.users = users.UserManager.instance()
 
diff --git a/nova/virt/__init__.py b/nova/virt/__init__.py
new file mode 100644
index 000000000..3d598c463
--- /dev/null
+++ b/nova/virt/__init__.py
@@ -0,0 +1,15 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright (c) 2010 Citrix Systems, Inc.
+#
+#    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.
diff --git a/nova/virt/connection.py b/nova/virt/connection.py
new file mode 100644
index 000000000..25c817415
--- /dev/null
+++ b/nova/virt/connection.py
@@ -0,0 +1,42 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2010 United States Government as represented by the
+# Administrator of the National Aeronautics and Space Administration.
+# All Rights Reserved.
+# Copyright (c) 2010 Citrix Systems, Inc.
+#
+#    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.
+
+from nova import flags
+from nova.virt import fake
+from nova.virt import libvirt_conn
+
+
+FLAGS = flags.FLAGS
+
+
+def get_connection(read_only=False):
+    # TODO(termie): maybe lazy load after initial check for permissions
+    # TODO(termie): check whether we can be disconnected
+    t = FLAGS.connection_type
+    if t == 'fake':
+        conn = fake.get_connection(read_only)
+    elif t == 'libvirt':
+        conn = libvirt_conn.get_connection(read_only)
+    else:
+        raise Exception('Unknown connection type "%s"' % t)
+
+    if conn is None:
+        logging.error('Failed to open connection to the hypervisor')
+        sys.exit(1)
+    return conn
diff --git a/nova/virt/fake.py b/nova/virt/fake.py
new file mode 100644
index 000000000..d9ae5ac96
--- /dev/null
+++ b/nova/virt/fake.py
@@ -0,0 +1,81 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2010 United States Government as represented by the
+# Administrator of the National Aeronautics and Space Administration.
+# All Rights Reserved.
+# Copyright (c) 2010 Citrix Systems, Inc.
+#
+#    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.
+
+"""
+A fake (in-memory) hypervisor+api. Allows nova testing w/o a hypervisor.
+"""
+
+import logging
+
+from nova.compute import power_state
+
+
+def get_connection(_):
+    # The read_only parameter is ignored.
+    return FakeConnection.instance()
+
+
+class FakeConnection(object):
+    def __init__(self):
+        self.instances = {}
+
+    @classmethod
+    def instance(cls):
+        if not hasattr(cls, '_instance'):
+            cls._instance = cls()
+        return cls._instance
+
+    def list_instances(self):
+        return self.instances.keys()
+
+    def spawn(self, instance):
+        fake_instance = FakeInstance()
+        self.instances[instance.name] = fake_instance
+        fake_instance._state = power_state.RUNNING
+
+    def reboot(self, instance):
+        pass
+       
+    def destroy(self, instance):
+        del self.instances[instance.name]
+
+    def get_info(self, instance_id):
+        i = self.instances[instance_id]
+        return {'state': i._state,
+                'max_mem': 0,
+                'mem': 0,
+                'num_cpu': 2,
+                'cpu_time': 0}
+
+    def list_disks(self, instance_id):
+        return ['A_DISK']
+
+    def list_interfaces(self, instance_id):
+        return ['A_VIF']
+
+    def block_stats(self, instance_id, disk_id):
+        return [0L, 0L, 0L, 0L, null]
+
+    def interface_stats(self, instance_id, iface_id):
+        return [0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L]
+
+
+class FakeInstance(object):
+    def __init__(self):
+        self._state = power_state.NOSTATE
diff --git a/nova/virt/images.py b/nova/virt/images.py
new file mode 100644
index 000000000..0b11c134e
--- /dev/null
+++ b/nova/virt/images.py
@@ -0,0 +1,55 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2010 United States Government as represented by the
+# Administrator of the National Aeronautics and Space Administration.
+# All Rights Reserved.
+# Copyright (c) 2010 Citrix Systems, Inc.
+#
+#    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.
+
+"""
+Handling of VM disk images.
+"""
+
+import os.path
+
+from nova import flags
+
+FLAGS = flags.FLAGS
+
+flags.DEFINE_bool('use_s3', True,
+                  'whether to get images from s3 or use local copy')
+
+
+def fetch(pool, image, path):
+    if FLAGS.use_s3:
+        f = _fetch_s3_image
+    else:
+        f = _fetch_local_image
+    return f(pool, image, path)
+
+def _fetch_s3_image(pool, image, path):
+    url = _image_url('%s/image' % image)
+    d = pool.simpleExecute('curl --silent %s -o %s' % (url, path))
+    return d
+
+def _fetch_local_image(pool, image, path):
+    source = _image_path('%s/image' % image)
+    d = pool.simpleExecute('cp %s %s' % (source, path))
+    return d
+
+def _image_path(path):
+    return os.path.join(FLAGS.images_path, path)
+
+def _image_url(path):
+    return "%s:%s/_images/%s" % (FLAGS.s3_host, FLAGS.s3_port, path)
diff --git a/nova/virt/libvirt_conn.py b/nova/virt/libvirt_conn.py
new file mode 100644
index 000000000..74fec650e
--- /dev/null
+++ b/nova/virt/libvirt_conn.py
@@ -0,0 +1,353 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2010 United States Government as represented by the
+# Administrator of the National Aeronautics and Space Administration.
+# All Rights Reserved.
+# Copyright (c) 2010 Citrix Systems, Inc.
+#
+#    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.
+
+"""
+A connection to a hypervisor (e.g. KVM) through libvirt.
+"""
+
+import json
+import logging
+import os.path
+import shutil
+import sys
+
+from twisted.internet import defer
+from twisted.internet import task
+
+from nova import exception
+from nova import flags
+from nova import process
+from nova import utils
+from nova.compute import disk
+from nova.compute import instance_types
+from nova.compute import power_state
+from nova.virt import images
+
+libvirt = None
+libxml2 = None
+
+FLAGS = flags.FLAGS
+flags.DEFINE_string('libvirt_xml_template',
+                    utils.abspath('compute/libvirt.xml.template'),
+                    'Libvirt XML Template')
+
+def get_connection(read_only):
+    # These are loaded late so that there's no need to install these
+    # libraries when not using libvirt.
+    global libvirt
+    global libxml2
+    if libvirt is None:
+        libvirt = __import__('libvirt')
+    if libxml2 is None:
+        libxml2 = __import__('libxml2')
+    return LibvirtConnection(read_only)
+
+
+class LibvirtConnection(object):
+    def __init__(self, read_only):
+        auth = [[libvirt.VIR_CRED_AUTHNAME, libvirt.VIR_CRED_NOECHOPROMPT],
+                'root',
+                None]
+        if read_only:
+            self._conn = libvirt.openReadOnly('qemu:///system')
+        else:
+            self._conn = libvirt.openAuth('qemu:///system', auth, 0)
+        self._pool = process.ProcessPool()
+
+
+    def list_instances(self):
+        return [self._conn.lookupByID(x).name()
+                for x in self._conn.listDomainsID()]
+
+
+    def destroy(self, instance):
+        try:
+            virt_dom = self._conn.lookupByName(instance.name)
+            virt_dom.destroy()
+        except Exception, _err:
+            pass
+            # If the instance is already terminated, we're still happy
+        d = defer.Deferred()
+        d.addCallback(lambda x: self._cleanup())
+        # FIXME: What does this comment mean?
+        # TODO(termie): short-circuit me for tests
+        # WE'LL save this for when we do shutdown,
+        # instead of destroy - but destroy returns immediately
+        timer = task.LoopingCall(f=None)
+        def _wait_for_shutdown():
+            try:
+                instance.update_state()
+                if instance.state == power_state.SHUTDOWN:
+                    timer.stop()
+                    d.callback(None)
+            except Exception:
+                instance.set_state(power_state.SHUTDOWN)
+                timer.stop()
+                d.callback(None)
+        timer.f = _wait_for_shutdown
+        timer.start(interval=0.5, now=True)
+        return d
+
+
+    def _cleanup(self, instance):
+        target = os.path.abspath(instance.datamodel['basepath'])
+        logging.info("Deleting instance files at %s", target)
+        shutil.rmtree(target)
+
+
+    @defer.inlineCallbacks
+    @exception.wrap_exception
+    def reboot(self, instance):
+        xml = self.toXml(instance)
+        yield self._conn.lookupByName(instance.name).destroy()
+        yield self._conn.createXML(xml, 0)
+
+        d = defer.Deferred()
+        timer = task.LoopingCall(f=None)
+        def _wait_for_reboot():
+            try:
+                instance.update_state()
+                if instance.is_running():
+                    logging.debug('rebooted instance %s' % instance.name)
+                    timer.stop()
+                    d.callback(None)
+            except Exception, exn:
+                logging.error('_wait_for_reboot failed: %s' % exn)
+                instance.set_state(power_state.SHUTDOWN)
+                timer.stop()
+                d.callback(None)
+        timer.f = _wait_for_reboot
+        timer.start(interval=0.5, now=True)
+        yield d
+
+
+    @defer.inlineCallbacks
+    @exception.wrap_exception
+    def spawn(self, instance):
+        xml = self.toXml(instance)
+        instance.set_state(power_state.NOSTATE, 'launching')
+        yield self._create_image(instance, xml)
+        yield self._conn.createXML(xml, 0)
+        # TODO(termie): this should actually register
+        # a callback to check for successful boot
+        logging.debug("Instance is running")
+
+        local_d = defer.Deferred()
+        timer = task.LoopingCall(f=None)
+        def _wait_for_boot():
+            try:
+                instance.update_state()
+                if instance.is_running():
+                    logging.debug('booted instance %s' % instance.name)
+                    timer.stop()
+                    local_d.callback(None)
+            except Exception, exn:
+                logging.error("_wait_for_boot exception %s" % exn)
+                self.set_state(power_state.SHUTDOWN)
+                logging.error('Failed to boot instance %s' % instance.name)
+                timer.stop()
+                local_d.callback(None)
+        timer.f = _wait_for_boot
+        timer.start(interval=0.5, now=True)
+        yield local_d
+
+
+    @defer.inlineCallbacks
+    def _create_image(self, instance, libvirt_xml):
+        # syntactic nicety
+        data = instance.datamodel
+        basepath = lambda x='': self.basepath(instance, x)
+
+        # ensure directories exist and are writable
+        yield self._pool.simpleExecute('mkdir -p %s' % basepath())
+        yield self._pool.simpleExecute('chmod 0777 %s' % basepath())
+
+
+        # TODO(termie): these are blocking calls, it would be great
+        #               if they weren't.
+        logging.info('Creating image for: %s', data['instance_id'])
+        f = open(basepath('libvirt.xml'), 'w')
+        f.write(libvirt_xml)
+        f.close()
+
+        if not os.path.exists(basepath('disk')):
+           yield images.fetch(self._pool, data['image_id'], basepath('disk-raw'))
+        if not os.path.exists(basepath('kernel')):
+           yield images.fetch(self._pool, data['kernel_id'], basepath('kernel'))
+        if not os.path.exists(basepath('ramdisk')):
+           yield images.fetch(self._pool, data['ramdisk_id'], basepath('ramdisk'))
+
+        execute = lambda cmd, input=None: self._pool.simpleExecute(cmd=cmd,
+                                                                   input=input,
+                                                                   error_ok=1)
+
+        key = data['key_data']
+        net = None
+        if FLAGS.simple_network:
+            with open(FLAGS.simple_network_template) as f:
+                net = f.read() % {'address': data['private_dns_name'],
+                                  'network': FLAGS.simple_network_network,
+                                  'netmask': FLAGS.simple_network_netmask,
+                                  'gateway': FLAGS.simple_network_gateway,
+                                  'broadcast': FLAGS.simple_network_broadcast,
+                                  'dns': FLAGS.simple_network_dns}
+        if key or net:
+            logging.info('Injecting data into image %s', data['image_id'])
+            yield disk.inject_data(basepath('disk-raw'), key, net, execute=execute)
+
+        if os.path.exists(basepath('disk')):
+            yield self._pool.simpleExecute('rm -f %s' % basepath('disk'))
+
+        bytes = (instance_types.INSTANCE_TYPES[data['instance_type']]['local_gb']
+                 * 1024 * 1024 * 1024)
+        yield disk.partition(
+                basepath('disk-raw'), basepath('disk'), bytes, execute=execute)
+
+
+    def basepath(self, instance, path=''):
+        return os.path.abspath(os.path.join(instance.datamodel['basepath'], path))
+
+
+    def toXml(self, instance):
+        # TODO(termie): cache?
+        logging.debug("Starting the toXML method")
+        libvirt_xml = open(FLAGS.libvirt_xml_template).read()
+        xml_info = instance.datamodel.copy()
+        # TODO(joshua): Make this xml express the attached disks as well
+
+        # TODO(termie): lazy lazy hack because xml is annoying
+        xml_info['nova'] = json.dumps(instance.datamodel.copy())
+        libvirt_xml = libvirt_xml % xml_info
+        logging.debug("Finished the toXML method")
+
+        return libvirt_xml
+
+
+    def get_info(self, instance_id):
+        virt_dom = self._conn.lookupByName(instance_id)
+        (state, max_mem, mem, num_cpu, cpu_time) = virt_dom.info()
+        return {'state': state,
+                'max_mem': max_mem,
+                'mem': mem,
+                'num_cpu': num_cpu,
+                'cpu_time': cpu_time}
+
+
+    def get_disks(self, instance_id):
+        """
+        Note that this function takes an instance ID, not an Instance, so
+        that it can be called by monitor.
+        
+        Returns a list of all block devices for this domain.
+        """
+        domain = self._conn.lookupByName(instance_id)
+        # TODO(devcamcar): Replace libxml2 with etree.
+        xml = domain.XMLDesc(0)
+        doc = None
+
+        try:
+            doc = libxml2.parseDoc(xml)
+        except:
+            return []
+
+        ctx = doc.xpathNewContext()
+        disks = []
+
+        try:
+            ret = ctx.xpathEval('/domain/devices/disk')
+
+            for node in ret:
+                devdst = None
+
+                for child in node.children:
+                    if child.name == 'target':
+                        devdst = child.prop('dev')
+
+                if devdst == None:
+                    continue
+
+                disks.append(devdst)
+        finally:
+            if ctx != None:
+                ctx.xpathFreeContext()
+            if doc != None:
+                doc.freeDoc()
+
+        return disks
+
+
+    def get_interfaces(self, instance_id):
+        """
+        Note that this function takes an instance ID, not an Instance, so
+        that it can be called by monitor.
+        
+        Returns a list of all network interfaces for this instance.
+        """
+        domain = self._conn.lookupByName(instance_id)
+        # TODO(devcamcar): Replace libxml2 with etree.
+        xml = domain.XMLDesc(0)
+        doc = None
+
+        try:
+            doc = libxml2.parseDoc(xml)
+        except:
+            return []
+
+        ctx = doc.xpathNewContext()
+        interfaces = []
+
+        try:
+            ret = ctx.xpathEval('/domain/devices/interface')
+
+            for node in ret:
+                devdst = None
+
+                for child in node.children:
+                    if child.name == 'target':
+                        devdst = child.prop('dev')
+
+                if devdst == None:
+                    continue
+
+                interfaces.append(devdst)
+        finally:
+            if ctx != None:
+                ctx.xpathFreeContext()
+            if doc != None:
+                doc.freeDoc()
+
+        return interfaces
+
+
+    def block_stats(self, instance_id, disk):
+        """
+        Note that this function takes an instance ID, not an Instance, so
+        that it can be called by monitor.
+        """        
+        domain = self._conn.lookupByName(instance_id)
+        return domain.blockStats(disk)
+
+
+    def interface_stats(self, instance_id, interface):
+        """
+        Note that this function takes an instance ID, not an Instance, so
+        that it can be called by monitor.
+        """        
+        domain = self._conn.lookupByName(instance_id)
+        return domain.interfaceStats(interface)