Add Windows Event Log handler

The Python built-in logging module already provides a Windows Event
Log handler. This change ensures that oslo.log exposes it.

Change-Id: I287260b5046c88c433dfa66064da14faf15610e0
Implements: blueprint windows-event-log

oslo_log/_options.py

@@ -108,6 +108,9 @@ generic_log_opts = [
                 default=False,
                 help='Log output to standard error. '
                      + _IGNORE_MESSAGE),
+    cfg.BoolOpt('use_eventlog',
+                default=False,
+                help='Log output to Windows Event Log.'),
 ]
 
 log_opts = [

oslo_log/log.py

@@ -361,6 +361,14 @@ def _setup_logging_from_conf(conf, project, version):
         journal = handlers.OSJournalHandler()
         log_root.addHandler(journal)
 
+    if conf.use_eventlog:
+        if platform.system() == 'Windows':
+            eventlog = logging.handlers.NTEventLogHandler(project)
+            log_root.addHandler(eventlog)
+        else:
+            raise RuntimeError(_("Windows Event Log is not available on this "
+                                 "platform."))
+
     # if None of the above are True, then fall back to standard out
     if not logpath and not conf.use_stderr and not conf.use_journal:
         # pass sys.stdout as a positional argument

oslo_log/tests/unit/test_log.py

@@ -140,6 +140,25 @@ class CommonLoggerTestsMixIn(object):
                      'info', 'debug', 'log'):
             self.assertRaises(AttributeError, getattr, log, func)
 
+    @mock.patch('platform.system', return_value='Linux')
+    def test_eventlog_missing(self, platform_mock):
+        self.config(use_eventlog=True)
+        self.assertRaises(RuntimeError,
+                          log._setup_logging_from_conf,
+                          self.CONF,
+                          'test',
+                          'test')
+
+    @mock.patch('platform.system', return_value='Windows')
+    @mock.patch('logging.handlers.NTEventLogHandler')
+    @mock.patch('oslo_log.log.getLogger')
+    def test_eventlog(self, loggers_mock, handler_mock, platform_mock):
+        self.config(use_eventlog=True)
+        log._setup_logging_from_conf(self.CONF, 'test', 'test')
+        handler_mock.assert_called_once_with('test')
+        mock_logger = loggers_mock.return_value.logger
+        mock_logger.addHandler.assert_any_call(handler_mock.return_value)
+
 
 class LoggerTestCase(CommonLoggerTestsMixIn, test_base.BaseTestCase):
     def setUp(self):

releasenotes/notes/windows-eventlog-2beb0a6010e342eb.yaml

@@ -0,0 +1,4 @@
+features:
+  - |
+    Added Windows EventLog functionality to oslo.log. Set use_eventlog to true
+    in the service's configuration file to use it.