Merge "Handle when allowed_units is None"

src/reactive/vault_handlers.py

@@ -255,7 +255,8 @@ def configure_vault_psql(psql):
 @when('shared-db.available')
 @when('vault.ssl.configured')
 def configure_vault_mysql(mysql):
-    if local_unit() not in mysql.allowed_units():
+    if (not mysql.allowed_units() or
+            local_unit() not in mysql.allowed_units()):
         log("Deferring vault configuration until"
             " MySQL access is granted", level=DEBUG)
         return

unit_tests/test_reactive_vault_handlers.py

@@ -188,6 +188,18 @@ class TestHandlers(unit_tests.test_utils.CharmTestCase):
             'storage_name': 'mysql',
             'mysql_db_relation': mysql})
 
+        # Not ready
+        configure_vault.reset_mock()
+        mysql.allowed_units.return_value = None
+        handlers.configure_vault_mysql(mysql)
+        configure_vault.assert_not_called()
+
+        # Not ready
+        configure_vault.reset_mock()
+        mysql.allowed_units.return_value = ['vault/382']
+        handlers.configure_vault_mysql(mysql)
+        configure_vault.assert_not_called()
+
     @patch.object(handlers, 'base64')
     @patch.object(handlers, 'write_file')
     @patch.object(handlers, 'configure_vault')