AMBARI-13568. RU - Downgrade from 2.3 to 2.2 may fail if configs were not back'ed up (dlysnichenko)

ambari-server/src/main/resources/custom_actions/scripts/ru_set_all.py

@@ -128,21 +128,19 @@ class UpgradeSetAll(Script):
 
     :original_conf_directory: the original conf directory that was made into a symlink (/etc/component/conf)
     """
-    if not os.path.islink(original_conf_directory):
-      Logger.info("Skipping the unlink of {0}; it is not a symlink or does not exist".format(original_conf_directory))
-      return
-
     # calculate the parent and backup directories
     original_conf_parent_directory = os.path.abspath(os.path.join(original_conf_directory, os.pardir))
     backup_conf_directory = os.path.join(original_conf_parent_directory, "conf.backup")
-
-    Logger.info("Unlinking {0} and restoring {1}".format(original_conf_directory, backup_conf_directory))
-
-    # remove the old symlink
-    Execute(("rm", original_conf_directory), sudo=True)
-
-    # rename the backup to the original name
-    Execute(("mv", backup_conf_directory, original_conf_directory), sudo=True)
+    if not os.path.isdir(backup_conf_directory):
+      Logger.info("Skipping restoring config from backup {0} since it does not exist".format(backup_conf_directory))
+    elif not os.path.islink(original_conf_directory):
+      Logger.info("Skipping the unlink of {0}; it is not a symlink or does not exist".format(original_conf_directory))
+    else:
+      Logger.info("Unlinking {0} and restoring {1}".format(original_conf_directory, backup_conf_directory))
+      # remove the old symlink
+      Execute(("rm", original_conf_directory), sudo=True)
+      # rename the backup to the original name
+      Execute(("mv", backup_conf_directory, original_conf_directory), sudo=True)
 
 
 def link_config(old_conf, link_conf):

ambari-server/src/test/python/custom_actions/test_ru_set_all.py

@@ -26,6 +26,7 @@ from mock.mock import patch
 from mock.mock import MagicMock
 
 # Module imports
+import subprocess
 from stacks.utils.RMFTestCase import *
 from resource_management import Script, ConfigDictionary
 from resource_management.libraries.functions.default import default
@@ -34,6 +35,8 @@ from resource_management.core.logger import Logger
 from ambari_agent.AmbariConfig import AmbariConfig
 from ambari_agent.FileCache import FileCache
 from ambari_commons.os_check import OSCheck
+from resource_management.core import shell
+import pprint
 
 
 def fake_call(command, **kwargs):
@@ -133,15 +136,19 @@ class TestRUSetAll(RMFTestCase):
 
 
   @patch("os.path.islink")
+  @patch("os.path.isdir")
   @patch("resource_management.core.shell.call")
   @patch.object(Script, 'get_config')
   @patch.object(OSCheck, 'is_redhat_family')
-  def test_downgrade_unlink_configs(self, family_mock, get_config_mock, call_mock, islink_mock):
+  def test_downgrade_unlink_configs(self, family_mock, get_config_mock, call_mock,
+                                    isdir_mock, islink_mock):
     """
     Tests downgrading from 2.3 to 2.2 to ensure that conf symlinks are removed and the backup
     directories restored.
     """
 
+    isdir_mock.return_value = True
+
     # required for the test to run since the Execute calls need this
     from resource_management.core.environment import Environment
     env = Environment(test_mode=True)
@@ -237,3 +244,37 @@ class TestRUSetAll(RMFTestCase):
 
     # ensure it wasn't called this time
     self.assertFalse(islink_mock.called)
+
+
+  @patch("os.path.isdir")
+  @patch("os.path.islink")
+  def test_unlink_configs_missing_backup(self, islink_mock, isdir_mock):
+
+    # required for the test to run since the Execute calls need this
+    from resource_management.core.environment import Environment
+    env = Environment(test_mode=True)
+    env._instances.append(env)
+
+    # Case: missing backup directory
+    isdir_mock.return_value = False
+    ru_execute = UpgradeSetAll()
+    self.assertEqual(len(env.resource_list), 0)
+    # Case: missing symlink
+    isdir_mock.reset_mock()
+    isdir_mock.return_value = True
+    islink_mock.return_value = False
+    ru_execute._unlink_config("/fake/config")
+    self.assertEqual(len(env.resource_list), 0)
+    # Case: missing symlink
+    isdir_mock.reset_mock()
+    isdir_mock.return_value = True
+    islink_mock.reset_mock()
+    islink_mock.return_value = True
+
+    ru_execute._unlink_config("/fake/config")
+    self.assertEqual(pprint.pformat(env.resource_list),
+                     "[Execute[('rm', '/fake/config')],\n"
+                     " Execute[('mv', '/fake/conf.backup', "
+                     "'/fake/config')]]")
+
+