diff --git a/nova/compute/manager.py b/nova/compute/manager.py
index 245958de79d9..3a91908af5ca 100644
--- a/nova/compute/manager.py
+++ b/nova/compute/manager.py
@@ -470,6 +470,24 @@ class ComputeManager(manager.SchedulerDependentManager):
         LOG.audit(msg)
         self.driver.inject_file(instance_ref, path, file_contents)
 
+    @exception.wrap_exception
+    @checks_instance_lock
+    def agent_update(self, context, instance_id, url, md5hash):
+        """Update agent running on an instance on this host."""
+        context = context.elevated()
+        instance_ref = self.db.instance_get(context, instance_id)
+        instance_id = instance_ref['id']
+        instance_state = instance_ref['state']
+        expected_state = power_state.RUNNING
+        if instance_state != expected_state:
+            LOG.warn(_('trying to update agent on a non-running '
+                    'instance: %(instance_id)s (state: %(instance_state)s '
+                    'expected: %(expected_state)s)') % locals())
+        nm = instance_ref['name']
+        msg = _('instance %(nm)s: updating agent to %(url)s') % locals()
+        LOG.audit(msg)
+        self.driver.agent_update(instance_ref, url, md5hash)
+
     @exception.wrap_exception
     @checks_instance_lock
     def rescue_instance(self, context, instance_id):
diff --git a/nova/tests/test_compute.py b/nova/tests/test_compute.py
index b4ac2dbc4226..dd06e5719297 100644
--- a/nova/tests/test_compute.py
+++ b/nova/tests/test_compute.py
@@ -266,6 +266,14 @@ class ComputeTestCase(test.TestCase):
                 "File Contents")
         self.compute.terminate_instance(self.context, instance_id)
 
+    def test_agent_update(self):
+        """Ensure instance can have its agent updated"""
+        instance_id = self._create_instance()
+        self.compute.run_instance(self.context, instance_id)
+        self.compute.agent_update(self.context, instance_id,
+                'http://127.0.0.1/agent', '00112233445566778899aabbccddeeff')
+        self.compute.terminate_instance(self.context, instance_id)
+
     def test_snapshot(self):
         """Ensure instance can be snapshotted"""
         instance_id = self._create_instance()
diff --git a/nova/virt/driver.py b/nova/virt/driver.py
index eb9626d0879e..2229291f2b75 100644
--- a/nova/virt/driver.py
+++ b/nova/virt/driver.py
@@ -234,6 +234,10 @@ class ComputeDriver(object):
         """
         raise NotImplementedError()
 
+    def agent_update(self, instance, url, md5hash):
+        """Update agent on the VM instance."""
+        raise NotImplementedError()
+
     def inject_network_info(self, instance):
         """inject network info for specified instance"""
         raise NotImplementedError()
diff --git a/nova/virt/fake.py b/nova/virt/fake.py
index 0225797d7dac..22fbeefd2c23 100644
--- a/nova/virt/fake.py
+++ b/nova/virt/fake.py
@@ -225,6 +225,21 @@ class FakeConnection(driver.ComputeDriver):
         """
         pass
 
+    def agent_update(self, instance, url, md5hash):
+        """
+        Update agent on the specified instance.
+
+        The first parameter is an instance of nova.compute.service.Instance,
+        and so the instance is being specified as instance.name. The second
+        parameter is the URL of the agent to be fetched and updated on the
+        instance; the third is the md5 hash of the file for verification
+        purposes.
+
+        The work will be done asynchronously.  This function returns a
+        task that allows the caller to detect when it is complete.
+        """
+        pass
+
     def rescue(self, instance):
         """
         Rescue the specified instance.