Multiple import fails if "all_stores" specified as "true"

Newly added multiple import fails if user passes "all_stores" as "true"
in the request. The reason is if all_stores is specified then we are getting
stores using CONF.enabled_backends and unfortunately we are injecting
reserved stores 'os_glance_staging_store' and 'os_glance_tasks_store'
runtime. As a result import job tries to import the image in the
'os_glance_staging_store' store as well where it fails as that image
is already staged in this staging store.

Made a provision to exclude available reserved stores if "all_stores"
is specified.

Change-Id: If2616c275a969cdad5649e2cb0851275e5d0c7d2
Closes-Bug: #1863879

doc/source/admin/multistores.rst

@@ -163,6 +163,11 @@ Currently, there are two reserved stores:
     import process.  It replaces  the use of the DEPRECATED configuration
     option ``[DEFAULT]/node_staging_uri``.
 
+.. note::
+   If end user wants to retrieve all the available stores using
+   ``CONF.enabled_backeds`` then he needs to remove reserved
+   stores from that list explicitly.
+
 Configuration
 ~~~~~~~~~~~~~
 

glance/common/utils.py

@@ -44,6 +44,7 @@ from webob import exc
 
 from glance.common import exception
 from glance.common import timeutils
+from glance.common import wsgi
 from glance.i18n import _, _LE
 
 CONF = cfg.CONF
@@ -671,6 +672,17 @@ def evaluate_filter_op(value, operator, threshold):
     raise exception.InvalidFilterOperatorValue(msg)
 
 
+def _get_available_stores():
+    available_stores = CONF.enabled_backends
+    stores = []
+    # Remove reserved stores from the available stores list
+    for store in available_stores:
+        if store not in wsgi.RESERVED_STORES:
+            stores.append(store)
+
+    return stores
+
+
 def get_stores_from_request(req, body):
     """Processes a supplied request and extract stores from it
 
@@ -685,7 +697,7 @@ def get_stores_from_request(req, body):
             msg = _("All_stores parameter can't be used with "
                     "x-image-meta-store header or stores parameter")
             raise exc.HTTPBadRequest(explanation=msg)
-        stores = list(CONF.enabled_backends)
+        stores = _get_available_stores()
     else:
         try:
             stores = body['stores']

glance/tests/unit/common/test_utils.py

@@ -480,6 +480,30 @@ class TestUtils(test_utils.BaseTestCase):
                           utils.get_stores_from_request, req, body)
 
     def test_get_stores_from_request_returns_all_stores(self):
+        enabled_backends = {
+            "ceph1": "rbd",
+            "ceph2": "rbd"
+        }
+        reserved_stores = {
+            'os_glance_staging_store': 'file',
+            'os_glance_tasks_store': 'file'
+        }
+        self.config(enabled_backends=enabled_backends)
+        store.register_store_opts(CONF, reserved_stores=reserved_stores)
+        self.config(default_backend="ceph1", group="glance_store")
+        body = {"all_stores": True}
+        req = webob.Request.blank("/some_request")
+        mp = "glance.common.utils.glance_store.get_store_from_store_identifier"
+        with mock.patch(mp) as mock_get_store:
+            result = sorted(utils.get_stores_from_request(req, body))
+            self.assertEqual(["ceph1", "ceph2"], result)
+            mock_get_store.assert_any_call("ceph1")
+            mock_get_store.assert_any_call("ceph2")
+            self.assertEqual(mock_get_store.call_count, 2)
+            self.assertNotIn('os_glance_staging_store', result)
+            self.assertNotIn('os_glance_tasks_store', result)
+
+    def test_get_stores_from_request_excludes_reserved_stores(self):
         enabled_backends = {
             "ceph1": "rbd",
             "ceph2": "rbd"