Add an extension to show image size.

Adds image size data that is returned from Glance into the API response.
This becomes really useful for users when they take a snapshot and want
to track the storage used by it.  Since this information is already
being pulled by Nova we should display it.

DocImpact
Change-Id: I8a2d4001c21bcc54cac1a2992034dfc9fbe39d7e

2 files changed, 90 insertions, 0 deletions

diff --git a/nova/api/openstack/compute/contrib/image_size.py b/nova/api/openstack/compute/contrib/image_size.py
new file mode 100644
index 000000000..21998738f
--- /dev/null
+++ b/nova/api/openstack/compute/contrib/image_size.py
@@ -0,0 +1,88 @@
+# Copyright 2013 Rackspace Hosting
+# 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.
+
+from nova.api.openstack import extensions
+from nova.api.openstack import wsgi
+from nova.api.openstack import xmlutil
+
+authorize = extensions.soft_extension_authorizer('compute', 'image_size')
+
+
+def make_image(elem):
+    elem.set('{%s}size' % Image_size.namespace, '%s:size' % Image_size.alias)
+
+
+class ImagesSizeTemplate(xmlutil.TemplateBuilder):
+    def construct(self):
+        root = xmlutil.TemplateElement('images')
+        elem = xmlutil.SubTemplateElement(root, 'image', selector='images')
+        make_image(elem)
+        return xmlutil.SlaveTemplate(root, 1, nsmap={
+            Image_size.alias: Image_size.namespace})
+
+
+class ImageSizeTemplate(xmlutil.TemplateBuilder):
+    def construct(self):
+        root = xmlutil.TemplateElement('image', selector='image')
+        make_image(root)
+        return xmlutil.SlaveTemplate(root, 1, nsmap={
+            Image_size.alias: Image_size.namespace})
+
+
+class ImageSizeController(wsgi.Controller):
+
+    def _extend_image(self, image, image_cache):
+        key = "%s:size" % Image_size.alias
+        image[key] = image_cache['size']
+
+    @wsgi.extends
+    def show(self, req, resp_obj, id):
+        context = req.environ["nova.context"]
+        if authorize(context):
+            # Attach our slave template to the response object
+            resp_obj.attach(xml=ImageSizeTemplate())
+            image_resp = resp_obj.obj['image']
+            # image guaranteed to be in the cache due to the core API adding
+            # it in its 'show' method
+            image_cached = req.get_db_item('images', image_resp['id'])
+            self._extend_image(image_resp, image_cached)
+
+    @wsgi.extends
+    def detail(self, req, resp_obj):
+        context = req.environ['nova.context']
+        if authorize(context):
+            # Attach our slave template to the response object
+            resp_obj.attach(xml=ImagesSizeTemplate())
+            images_resp = list(resp_obj.obj['images'])
+            # images guaranteed to be in the cache due to the core API adding
+            # it in its 'detail' method
+            for image in images_resp:
+                image_cached = req.get_db_item('images', image['id'])
+                self._extend_image(image, image_cached)
+
+
+class Image_size(extensions.ExtensionDescriptor):
+    """Adds image size to image listings."""
+
+    name = "ImageSize"
+    alias = "OS-EXT-IMG-SIZE"
+    namespace = ("http://docs.openstack.org/compute/ext/"
+                 "image_size/api/v1.1")
+    updated = "2013-02-19T00:00:00+00:00"
+
+    def get_controller_extensions(self):
+        controller = ImageSizeController()
+        extension = extensions.ControllerExtension(self, 'images', controller)
+        return [extension]
diff --git a/nova/api/openstack/compute/images.py b/nova/api/openstack/compute/images.py
index 7dda64f87..703d2fe2d 100644
--- a/nova/api/openstack/compute/images.py
+++ b/nova/api/openstack/compute/images.py
@@ -144,6 +144,7 @@ class Controller(wsgi.Controller):
             explanation = _("Image not found.")
             raise webob.exc.HTTPNotFound(explanation=explanation)
 
+        req.cache_db_items('images', [image], 'id')
         return self._view_builder.show(req, image)
 
     def delete(self, req, id):
@@ -200,6 +201,7 @@ class Controller(wsgi.Controller):
         except exception.Invalid as e:
             raise webob.exc.HTTPBadRequest(explanation=str(e))
 
+        req.cache_db_items('images', images, 'id')
         return self._view_builder.detail(req, images)
 
     def create(self, *args, **kwargs):