Add pagination to v2 image-list

* Use a recursive generator function to iterate over the image
  container. The presence of next links are indicators to
  continue pagination while their value drives the location of
  the next page.
* A user can pass in --page-size on the command line, or page_size
  when using the controller directly, to control how many images
  are requested with each subsequent paginated request. Default page
  size is 20.
* Add a flag (strict_url_check) for the FakeAPI class to control
  whether it chops off query params when trying to match a request
  to a fixture.
* Related to bp glance-client-v2.

Change-Id: Ib98e912a7af0bb570b4fd738733edd9b837d1a12

glanceclient/v2/images.py

@@ -13,19 +13,35 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+DEFAULT_PAGE_SIZE = 20
+
 
 class Controller(object):
     def __init__(self, http_client, model):
         self.http_client = http_client
         self.model = model
 
-    def list(self):
+    def list(self, page_size=DEFAULT_PAGE_SIZE):
         """Retrieve a listing of Image objects
 
+        :param page_size: Number of images to request in each paginated request
         :returns generator over list of Images
         """
-        resp, body = self.http_client.json_request('GET', '/v2/images')
+        def paginate(url):
+            resp, body = self.http_client.json_request('GET', url)
             for image in body['images']:
+                yield image
+            try:
+                next_url = body['next']
+            except KeyError:
+                return
+            else:
+                for image in paginate(next_url):
+                    yield image
+
+        url = '/v2/images?limit=%s' % page_size
+
+        for image in paginate(url):
             #NOTE(bcwaldon): remove 'self' for now until we have an elegant
             # way to pass it into the model constructor without conflict
             image.pop('self', None)

glanceclient/v2/shell.py

@@ -17,9 +17,14 @@ from glanceclient.common import utils
 from glanceclient import exc
 
 
+@utils.arg('--page-size', metavar='<SIZE>', default=None, type=int,
+           help='Number of images to request in each paginated request.')
 def do_image_list(gc, args):
     """List images."""
-    images = gc.images.list()
+    kwargs = {}
+    if args.page_size is not None:
+        kwargs['page_size'] = args.page_size
+    images = gc.images.list(**kwargs)
     columns = ['ID', 'Name']
     utils.print_list(images, columns)
 

tests/utils.py

@@ -15,14 +15,15 @@
 
 
 class FakeAPI(object):
-    def __init__(self, fixtures):
+    def __init__(self, fixtures, strict_url_check=False):
         self.fixtures = fixtures
         self.calls = []
+        self.strict_url_check = strict_url_check
 
     def _request(self, method, url, headers=None, body=None):
         call = (method, url, headers or {}, body)
         self.calls.append(call)
-        # drop any query params
+        if not self.strict_url_check:
             url = url.split('?', 1)[0]
         return self.fixtures[url][method]
 

tests/v2/test_images.py

@@ -22,7 +22,7 @@ from tests import utils
 
 
 fixtures = {
-    '/v2/images': {
+    '/v2/images?limit=20': {
         'GET': (
             {},
             {'images': [
@@ -37,6 +37,32 @@ fixtures = {
             ]},
         ),
     },
+    '/v2/images?limit=1': {
+        'GET': (
+            {},
+            {
+                'images': [
+                   {
+                        'id': '3a4560a1-e585-443e-9b39-553b46ec92d1',
+                        'name': 'image-1',
+                    },
+                ],
+                'next': ('/v2/images?limit=1&'
+                         'marker=3a4560a1-e585-443e-9b39-553b46ec92d1'),
+            },
+        ),
+    },
+    ('/v2/images?limit=1&marker=3a4560a1-e585-443e-9b39-553b46ec92d1'): {
+        'GET': (
+            {},
+            {'images': [
+                {
+                    'id': '6f99bf80-2ee6-47cf-acfe-1f1fabb7e810',
+                    'name': 'image-2',
+                },
+            ]},
+        ),
+    },
     '/v2/images/3a4560a1-e585-443e-9b39-553b46ec92d1': {
         'GET': (
             {},
@@ -58,7 +84,7 @@ FakeModel = warlock.model_factory(fake_schema)
 class TestController(unittest.TestCase):
     def setUp(self):
         super(TestController, self).setUp()
-        self.api = utils.FakeAPI(fixtures)
+        self.api = utils.FakeAPI(fixtures, strict_url_check=True)
         self.controller = images.Controller(self.api, FakeModel)
 
     def test_list_images(self):
@@ -69,6 +95,14 @@ class TestController(unittest.TestCase):
         self.assertEqual(images[1].id, '6f99bf80-2ee6-47cf-acfe-1f1fabb7e810')
         self.assertEqual(images[1].name, 'image-2')
 
+    def test_list_images_paginated(self):
+        #NOTE(bcwaldon): cast to list since the controller returns a generator
+        images = list(self.controller.list(page_size=1))
+        self.assertEqual(images[0].id, '3a4560a1-e585-443e-9b39-553b46ec92d1')
+        self.assertEqual(images[0].name, 'image-1')
+        self.assertEqual(images[1].id, '6f99bf80-2ee6-47cf-acfe-1f1fabb7e810')
+        self.assertEqual(images[1].name, 'image-2')
+
     def test_get_image(self):
         image = self.controller.get('3a4560a1-e585-443e-9b39-553b46ec92d1')
         self.assertEqual(image.id, '3a4560a1-e585-443e-9b39-553b46ec92d1')