Use osapi_glance_link_prefix for image location header

When an image is created the location header returned is generated based
on the request url that nova-api receives.  If SSL termination happens
upstream the request url is an http request, and the location header is
wrongly generated with that.  The osapi_glance_link_prefix config option
is available for almost precisely this purpose, so let's use it.

Change-Id: I24e46ed8fc0763f9ddeec65e0d79590dd7b86bef
Closes-bug: 1298005

nova/api/openstack/compute/servers.py

@@ -1466,7 +1466,9 @@ class Controller(wsgi.Controller):
 
         # build location of newly-created image entity
         image_id = str(image['id'])
-        image_ref = os.path.join(req.application_url,
+        url_prefix = self._view_builder._update_glance_link_prefix(
+                req.application_url)
+        image_ref = os.path.join(url_prefix,
                                  context.project_id,
                                  'images',
                                  image_id)

nova/tests/api/openstack/compute/test_server_actions.py

@@ -981,6 +981,20 @@ class ServerActionsControllerTest(test.TestCase):
         location = response.headers['Location']
         self.assertEqual('http://localhost/v2/fake/images/123', location)
 
+    def test_create_image_glance_link_prefix(self):
+        self.flags(osapi_glance_link_prefix='https://glancehost')
+        body = {
+            'createImage': {
+                'name': 'Snapshot 1',
+            },
+        }
+
+        req = fakes.HTTPRequest.blank(self.url)
+        response = self.controller._action_create_image(req, FAKE_UUID, body)
+
+        location = response.headers['Location']
+        self.assertEqual('https://glancehost/v2/fake/images/123', location)
+
     def test_create_image_name_too_long(self):
         long_name = 'a' * 260
         body = {