Cache boot time roles for vendordata.

Some external vendordata services want to provide metadata
based on the role of the user who started the instance. It
would be confusing if the metadata returned changed later
if the role of the user changed, so we cache the boot time
roles and then pass those to the external vendordata
service.

Change-Id: Ieb84c945f4f9a21c2b7b892f9b1ead84dca441e9

nova/api/metadata/vendordata_dynamic.py

@@ -78,7 +78,9 @@ class DynamicVendorData(vendordata.VendorDataDriver):
                     'image-id': self.instance.image_ref,
                     'user-data': self.instance.user_data,
                     'hostname': self.instance.hostname,
-                    'metadata': self.instance.metadata}
+                    'metadata': self.instance.metadata,
+                    'boot-roles': self.instance.system_metadata.get(
+                                      'boot_roles', '')}
             headers = {'Content-Type': 'application/json',
                        'Accept': 'application/json',
                        'User-Agent': 'openstack-nova-vendordata'}

nova/compute/manager.py

@@ -1887,6 +1887,11 @@ class ComputeManager(manager.Manager):
             action=fields.NotificationAction.CREATE,
             phase=fields.NotificationPhase.START)
 
+        # NOTE(mikal): cache the keystone roles associated with the instance
+        # at boot time for later reference
+        instance.system_metadata.update(
+            {'boot_roles': ','.join(context.roles)})
+
         self._check_device_tagging(requested_networks, block_device_mapping)
 
         try:

nova/tests/unit/compute/test_compute.py

@@ -8232,12 +8232,14 @@ class ComputeAPITestCase(BaseTestCase):
             self.assertEqual(instance.task_state, task_states.REBUILDING)
             sys_meta = {k: v for k, v in instance.system_metadata.items()
                         if not k.startswith('instance_type')}
-            self.assertEqual(sys_meta,
+            self.assertEqual(
                     {'image_kernel_id': uuids.kernel_id,
-                    'image_min_disk': '1',
-                    'image_ramdisk_id': uuids.ramdisk_id,
-                    'image_something_else': 'meow',
-                    'preserved': 'preserve this!'})
+                     'image_min_disk': '1',
+                     'image_ramdisk_id': uuids.ramdisk_id,
+                     'image_something_else': 'meow',
+                     'preserved': 'preserve this!',
+                     'boot_roles': ''},
+                    sys_meta)
 
     def test_rebuild(self):
         self._test_rebuild(vm_state=vm_states.ACTIVE)

releasenotes/notes/vendordata-reboot-cache-boot-roles-6051fabcd4981928.yaml

@@ -0,0 +1,8 @@
+---
+features:
+  - |
+    The vendordata metadata system now caches boot time roles.  Some external
+    vendordata services want to provide metadata based on the role of the user
+    who started the instance. It would be confusing if the metadata returned
+    changed later if the role of the user changed, so we cache the boot time
+    roles and then pass those to the external vendordata service.