Use default auth for StackdriverStatsExporter

contrib/opencensus-ext-stackdriver/opencensus/ext/stackdriver/stats_exporter/__init__.py

@@ -22,6 +22,7 @@
 
 from google.api_core.gapic_v1 import client_info
 from google.cloud import monitoring_v3
+import google.auth
 
 from opencensus.common import utils
 from opencensus.common.monitored_resource import monitored_resource
@@ -365,12 +366,16 @@ def get_user_agent_slug():
     return "opencensus-python/{}".format(__version__)
 
 
-def new_stats_exporter(options, interval=None):
+def new_stats_exporter(options=None, interval=None):
     """Get a stats exporter and running transport thread.
 
     Create a new `StackdriverStatsExporter` with the given options and start
     periodically exporting stats to stackdriver in the background.
 
+    Fall back to default auth if `options` is null. This will raise
+    `google.auth.exceptions.DefaultCredentialsError` if default credentials
+    aren't configured.
+
     See `opencensus.metrics.transport.get_exporter_thread` for details on the
     transport thread.
 
@@ -380,9 +385,12 @@ def new_stats_exporter(options, interval=None):
     :type interval: int or float
     :param interval: Seconds between export calls.
 
-    :rtype: :class:`StackdriverStatsExporter` and :class:`PeriodicTask`
-    :return: A tuple of the exporter and transport thread.
+    :rtype: :class:`StackdriverStatsExporter`
+    :return: The newly-created exporter.
     """
+    if options is None:
+        _, project_id = google.auth.default()
+        options = Options(project_id=project_id)
     if str(options.project_id).strip() == "":
         raise ValueError(ERROR_BLANK_PROJECT_ID)
 

contrib/opencensus-ext-stackdriver/tests/test_stackdriver_stats.py

@@ -17,6 +17,7 @@
 import unittest
 
 from google.cloud import monitoring_v3
+import google.auth
 
 from opencensus.common import utils
 from opencensus.common.version import __version__
@@ -115,6 +116,32 @@ def test_constructor_param(self):
                 default_monitoring_labels=default_labels))
         self.assertEqual(exporter.options.project_id, project_id)
 
+    def test_null_options(self):
+        # Check that we don't suppress auth errors
+        auth_error = google.auth.exceptions.DefaultCredentialsError
+        mock_auth_error = mock.Mock()
+        mock_auth_error.side_effect = auth_error
+        with mock.patch('opencensus.ext.stackdriver.stats_exporter'
+                        '.google.auth.default', mock_auth_error):
+            with self.assertRaises(auth_error):
+                stackdriver.new_stats_exporter()
+
+        # Check that we get the default credentials' project ID
+        mock_auth_ok = mock.Mock()
+        mock_auth_ok.return_value = (None, 123)
+        with mock.patch('opencensus.ext.stackdriver.stats_exporter'
+                        '.google.auth.default', mock_auth_ok):
+            sdse = stackdriver.new_stats_exporter()
+        self.assertEqual(sdse.options.project_id, 123)
+
+        # Check that we raise if auth works but the project is empty
+        mock_auth_no_project = mock.Mock()
+        mock_auth_no_project.return_value = (None, '')
+        with mock.patch('opencensus.ext.stackdriver.stats_exporter'
+                        '.google.auth.default', mock_auth_no_project):
+            with self.assertRaises(ValueError):
+                stackdriver.new_stats_exporter()
+
     def test_blank_project(self):
         self.assertRaises(ValueError, stackdriver.new_stats_exporter,
                           stackdriver.Options(project_id=""))