Check that Glance returns image data before processing it

Now if Glance v2 cannot find image data it returns an empty
response with 204 status code, instead of raising an error.

Glance client handles this situation and wraps the response
with a RequestIdProxy object, whose 'wrapped' attribute is
None.

But when openstack client tries to parse this object using
glanceclient's save_image util function, it fails with
"NoneType object is not iterable" message, for the
object doesn't contain any data.

This patch adds additional check to prevent such behaviour
and raises SystemExit exception if no data was returned from
the server.

Glance v1 is not affected, because it raises an error if can't
find an image data.

Change-Id: I016a60462ba586f9fa7585c2cfafffd7be38de7b
Closes-Bug: #1741223

openstackclient/image/v2/image.py

@@ -17,6 +17,7 @@
 
 import argparse
 import logging
+import sys
 
 from glanceclient.common import utils as gc_utils
 from osc_lib.cli import parseractions
@@ -649,6 +650,12 @@ class SaveImage(command.Command):
         )
         data = image_client.images.data(image.id)
 
+        if data.wrapped is None:
+            msg = _('Image %s has no data.') % image.id
+            LOG.error(msg)
+            sys.stdout.write(msg + '\n')
+            raise SystemExit
+
         gc_utils.save_image(data, parsed_args.file)
 
 

openstackclient/tests/unit/image/v2/test_image.py

@@ -15,6 +15,7 @@
 
 import copy
 
+from glanceclient.common import utils as glanceclient_utils
 from glanceclient.v2 import schemas
 import mock
 from osc_lib import exceptions
@@ -1505,3 +1506,53 @@ class TestImageUnset(TestImage):
             self.image.id, 'test'
         )
         self.assertIsNone(result)
+
+
+class TestImageSave(TestImage):
+
+    image = image_fakes.FakeImage.create_one_image({})
+
+    def setUp(self):
+        super(TestImageSave, self).setUp()
+
+        # Generate a request id
+        self.resp = mock.MagicMock()
+        self.resp.headers['x-openstack-request-id'] = 'req_id'
+
+        # Get the command object to test
+        self.cmd = image.SaveImage(self.app, None)
+
+    def test_save_data(self):
+        req_id_proxy = glanceclient_utils.RequestIdProxy(
+            ['some_data', self.resp]
+        )
+        self.images_mock.data.return_value = req_id_proxy
+
+        arglist = ['--file', '/path/to/file', self.image.id]
+
+        verifylist = [
+            ('file', '/path/to/file'),
+            ('image', self.image.id)
+        ]
+        parsed_args = self.check_parser(self.cmd, arglist, verifylist)
+
+        with mock.patch('glanceclient.common.utils.save_image') as mocked_save:
+            self.cmd.take_action(parsed_args)
+            mocked_save.assert_called_once_with(req_id_proxy, '/path/to/file')
+
+    def test_save_no_data(self):
+        req_id_proxy = glanceclient_utils.RequestIdProxy(
+            [None, self.resp]
+        )
+        self.images_mock.data.return_value = req_id_proxy
+
+        arglist = ['--file', '/path/to/file', self.image.id]
+
+        verifylist = [
+            ('file', '/path/to/file'),
+            ('image', self.image.id)
+        ]
+        parsed_args = self.check_parser(self.cmd, arglist, verifylist)
+
+        # Raise SystemExit if no data was provided.
+        self.assertRaises(SystemExit, self.cmd.take_action, parsed_args)

releasenotes/notes/bug-1741223-7a5c5b6e7f232628.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    'NoneType' object is not iterable when Glance cannot find image data in its
+    backend.
+    [Bug `1741223 <https://bugs.launchpad.net/ironic/+bug/1741223>`_]