Don't delete container_cidr key when overriding

Commit f426eb98d1 added a global_override
deletion mechanism, but did not account for the automatically-created
container_cidr key.

This change ensures the key is skipped in deletion, and adds further
tests for the _parse_gloabl_variables function.

Change-Id: I5c48adea5920c1524be75939a75af6bed3a9743a
Closes-Bug: #1649632

lib/generate.py

@@ -793,9 +793,12 @@ def _parse_global_variables(user_cidr, inventory, user_defined_config):
             )
             logger.debug("Applied global_overrides")
 
+            kept_vars = user_defined_config['global_overrides'].keys()
+            kept_vars.append('container_cidr')
+
             # Remove global overrides that were deleted from inventory, too
             for key in inventory['all']['vars'].keys():
-                if key not in user_defined_config['global_overrides']:
+                if key not in kept_vars:
                     logger.debug("Deleting key %s from inventory", key)
                     del inventory['all']['vars'][key]
 

releasenotes/notes/container_cidr_key_restored-4d232fff46ec00b9.yaml

@@ -0,0 +1,8 @@
+---
+fixes:
+  - The 'container_cidr' key has been restored back to openstack_inventory.json
+
+    The fix to remove deleted global override keys mistakenly deleted the
+    'container_cidr' key, as well. This was used by downstream consumers,
+    and cannot be reconstructed with other information inside the inventory
+    file. Regression tests were also added.

tests/test_inventory.py

@@ -832,6 +832,33 @@ class TestGlobalOverridesConfigDeletion(TestConfigCheckBase):
 
         self.assertEqual('bar', self.inventory['all']['vars']['foo'])
 
+    def test_container_cidr_key_retained(self):
+        user_cidr = self.user_defined_config['cidr_networks']['container']
+        di._parse_global_variables(user_cidr, self.inventory,
+                                   self.user_defined_config)
+        self.assertIn('container_cidr', self.inventory['all']['vars'])
+        self.assertEqual(self.inventory['all']['vars']['container_cidr'],
+                         user_cidr)
+
+    def test_only_old_vars_deleted(self):
+        self.inventory['all']['vars']['foo'] = 'bar'
+
+        di._parse_global_variables('', self.inventory,
+                                   self.user_defined_config)
+
+        self.assertNotIn('foo', self.inventory['all']['vars'])
+
+    def test_empty_vars(self):
+        del self.inventory['all']
+
+        di._parse_global_variables('', self.inventory,
+                                   self.user_defined_config)
+
+        self.assertIn('container_cidr', self.inventory['all']['vars'])
+
+        for key in self.user_defined_config['global_overrides']:
+            self.assertIn(key, self.inventory['all']['vars'])
+
 
 class TestEnsureInventoryUptoDate(unittest.TestCase):
     def setUp(self):