deprecate "file transfer" feature for Glance images

In August 2013 the blueprint "image-multiple-location" got merged
with commit 6f9ed56. This commit introduced another way of
downloading images from glance, despite the normal way via HTTP.

After discussing this in IRC, we believe that this feature was never
used in any production environment (it was designed for a Rackspace
use case which never made it to reality) and that the plugin mechanism
of image downloaders isn't the way to go, this change will deprecate
the feature.

Change-Id: I67e2cbf956286132da90ad6a4c6d5075d99177a9

nova/conf/image_file_url.py

@@ -23,6 +23,10 @@
 
 filesystems = cfg.ListOpt(
     name='filesystems',
+    deprecated_for_removal=True,
+    deprecated_reason='The feature to download images from glance via '
+                      'filesystem is not used and will be removed in the '
+                      'future.',
     default=[],
     help=_('List of file systems that are configured '
            'in this file in the '
@@ -37,9 +41,17 @@
                 help=_('A unique ID given to each file system.  This is '
                        'value is set in Glance and agreed upon here so '
                        'that the operator knowns they are dealing with '
-                       'the same file system.')),
+                       'the same file system.'),
+                deprecated_for_removal=True,
+                deprecated_reason='The feature to download images from glance '
+                                  'via filesystem is not used and will be '
+                                  'removed in the future.'),
      cfg.StrOpt('mountpoint',
-                help=_('The path at which the file system is mounted.')),
+                help=_('The path at which the file system is mounted.'),
+                deprecated_for_removal=True,
+                deprecated_reason='The feature to download images from glance '
+                                  'via filesystem is not used and will be '
+                                  'removed in the future.'),
 ]
 
 ALL_OPTS = [filesystems]

releasenotes/notes/deprecate-config-image-file-url-46c20999756afce0.yaml

@@ -0,0 +1,8 @@
+---
+deprecations:
+  - The feature to download *Glance* images via file transfer instead
+    of HTTP is now deprecated and may be removed as early as the 15.0.0
+    release. The config options ``filesystems`` in the section
+    ``image_file_url`` are affected as well as the derived sections
+    ``image_file_url:<list entry name>`` and their config options
+    ``id`` and ``mountpoint``.