Should use glanceclient to get images

Getting images from Novaclient is refered as proxy API
and was deprecated to use in nova. We should use
Glanceclient to get images instead.

Closes-bug: #1655516
Change-Id: Ie7d89e857d149e11b3c9b44c980b0be5cb0cc35f

watcher/common/nova_helper.py

@@ -23,6 +23,7 @@ import time
 from oslo_log import log
 
 import cinderclient.exceptions as ciexceptions
+import glanceclient.exc as glexceptions
 import novaclient.exceptions as nvexceptions
 
 from watcher.common import clients
@@ -142,7 +143,7 @@ class NovaHelper(object):
                 # We'll use the same name for the new instance.
                 imagedict = getattr(instance, "image")
                 image_id = imagedict["id"]
-                image = self.nova.images.get(image_id)
+                image = self.glance.images.get(image_id)
                 new_image_name = getattr(image, "name")
 
             instance_name = getattr(instance, "name")
@@ -575,8 +576,8 @@ class NovaHelper(object):
             return
 
         try:
-            image = self.nova.images.get(image_id)
-        except nvexceptions.NotFound:
+            image = self.glance.images.get(image_id)
+        except glexceptions.NotFound:
             LOG.debug("Image '%s' not found " % image_id)
             return