From 75d38d59f1743ad594831ce5bc1a123be263495a Mon Sep 17 00:00:00 2001
From: Michael Still <mikal@stillhq.com>
Date: Tue, 14 Feb 2012 19:17:12 +1100
Subject: Resolve bug/927714 -- get instance names from db.

I thought when I wrote the imagecache code for libvirt that the
instance names were of a fixed format. That is not correct. First
off the format is set in the instance_name_template flag. Worse
than that, it can change over time and old instances are not
renamed. So, now I check the database to see if the directory
name is a valid instance name (for this machine).

Change-Id: I318215aef5a10cee32959fd947ad628edff293a2
---
 nova/tests/test_imagecache.py   | 38 +++++++++++++++++++++++++++++++++++---
 nova/virt/libvirt/imagecache.py | 12 +++++++++++-
 2 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/nova/tests/test_imagecache.py b/nova/tests/test_imagecache.py
index f9d0e2103..70b9042b0 100644
--- a/nova/tests/test_imagecache.py
+++ b/nova/tests/test_imagecache.py
@@ -40,6 +40,13 @@ LOG = logging.getLogger(__name__)
 
 class ImageCacheManagerTestCase(test.TestCase):
 
+    def setUp(self):
+        super(ImageCacheManagerTestCase, self).setUp()
+        self.stock_instance_names = {'instance-00000001': '123',
+                                     'instance-00000002': '456',
+                                     'instance-00000003': '789',
+                                     'banana-42-hamster': '444'}
+
     def test_read_stored_checksum_missing(self):
         self.stubs.Set(os.path, 'exists', lambda x: False)
 
@@ -113,13 +120,16 @@ class ImageCacheManagerTestCase(test.TestCase):
         self.stubs.Set(db, 'instance_get_all',
                        lambda x: [{'image_ref': 'image-1',
                                    'host': FLAGS.host,
-                                   'name': 'inst-1'},
+                                   'name': 'inst-1',
+                                   'uuid': '123'},
                                   {'image_ref': 'image-2',
                                    'host': FLAGS.host,
-                                   'name': 'inst-2'},
+                                   'name': 'inst-2',
+                                   'uuid': '456'},
                                   {'image_ref': 'image-2',
                                    'host': 'remotehost',
-                                   'name': 'inst-3'}])
+                                   'name': 'inst-3',
+                                   'uuid': '789'}])
 
         image_cache_manager = imagecache.ImageCacheManager()
 
@@ -150,6 +160,7 @@ class ImageCacheManagerTestCase(test.TestCase):
 
         image_cache_manager = imagecache.ImageCacheManager()
         image_cache_manager.unexplained_images = [found]
+        image_cache_manager.instance_names = self.stock_instance_names
 
         inuse_images = image_cache_manager._list_backing_images()
 
@@ -172,6 +183,27 @@ class ImageCacheManagerTestCase(test.TestCase):
 
         image_cache_manager = imagecache.ImageCacheManager()
         image_cache_manager.unexplained_images = [found]
+        image_cache_manager.instance_names = self.stock_instance_names
+
+        inuse_images = image_cache_manager._list_backing_images()
+
+        self.assertEquals(inuse_images, [found])
+        self.assertEquals(len(image_cache_manager.unexplained_images), 0)
+
+    def test_list_backing_images_instancename(self):
+        self.stubs.Set(os, 'listdir',
+                       lambda x: ['_base', 'banana-42-hamster'])
+        self.stubs.Set(os.path, 'exists',
+                       lambda x: x.find('banana-42-hamster') != -1)
+        self.stubs.Set(virtutils, 'get_disk_backing_file',
+                       lambda x: 'e97222e91fc4241f49a7f520d1dcf446751129b3_sm')
+
+        found = os.path.join(FLAGS.instances_path, '_base',
+                             'e97222e91fc4241f49a7f520d1dcf446751129b3_sm')
+
+        image_cache_manager = imagecache.ImageCacheManager()
+        image_cache_manager.unexplained_images = [found]
+        image_cache_manager.instance_names = self.stock_instance_names
 
         inuse_images = image_cache_manager._list_backing_images()
 
diff --git a/nova/virt/libvirt/imagecache.py b/nova/virt/libvirt/imagecache.py
index d98644487..e8d448337 100644
--- a/nova/virt/libvirt/imagecache.py
+++ b/nova/virt/libvirt/imagecache.py
@@ -82,6 +82,11 @@ class ImageCacheManager(object):
         self.unexplained_images = []
         self.originals = []
 
+        # These are populated by a call to _list_running_instances()
+        self.used_images = {}
+        self.image_popularity = {}
+        self.instance_names = {}
+
     def _store_image(self, base_dir, ent, original=False):
         """Store a base image for later examination."""
         entpath = os.path.join(base_dir, ent)
@@ -112,9 +117,12 @@ class ImageCacheManager(object):
         """List running instances (on all compute nodes)."""
         self.used_images = {}
         self.image_popularity = {}
+        self.instance_names = {}
 
         instances = db.instance_get_all(context)
         for instance in instances:
+            self.instance_names[instance['name']] = instance['uuid']
+
             image_ref_str = str(instance['image_ref'])
             local, remote, insts = self.used_images.get(image_ref_str,
                                                         (0, 0, []))
@@ -132,9 +140,11 @@ class ImageCacheManager(object):
         """List the backing images currently in use."""
         inuse_images = []
         for ent in os.listdir(FLAGS.instances_path):
-            if ent.startswith('instance-'):
+            if ent in self.instance_names:
+                LOG.debug(_('%s is a valid instance name'), ent)
                 disk_path = os.path.join(FLAGS.instances_path, ent, 'disk')
                 if os.path.exists(disk_path):
+                    LOG.debug(_('%s has a disk file'), ent)
                     backing_file = virtutils.get_disk_backing_file(disk_path)
                     LOG.debug(_('Instance %(instance)s is backed by '
                                 '%(backing)s'),
-- 
cgit