Fix TypeError on agent lookup failure

Agent lookups can fail as we presently use logging.exception,
better known in our code as LOG.exception, which can also generate
other fun issues on journald based systems where additional errors
could be raised resulting in us being unable to troubleshoot the
the actual issue.

Because of the mis-use of LOG.exception and the default behavior
of the backoff retry handler, the retry logic was also not
functional as any error no matter how small caused IPA to
just exit.

Change-Id: Ic4608b7c6ff9773d1403926efb3d59869c71343b
Story: 2007968
Task: 40465

ironic_python_agent/ironic_api_client.py

@@ -167,12 +167,41 @@ class APIClient(object):
                 'GET', self.lookup_api,
                 headers=self._get_ironic_api_version_header(),
                 params=params)
-        except Exception as err:
-            LOG.exception(
-                'Unhandled error looking up node with addresses %r at %s: %s',
-                params['addresses'], self.api_url, err,
+        except (requests.exceptions.Timeout,
+                requests.exceptions.ConnectTimeout,
+                requests.exceptions.ConnectionError,
+                requests.exceptions.ReadTimeout,
+                requests.exceptions.HTTPError) as err:
+            LOG.warning(
+                'Error detected while attempting to perform lookup '
+                'with %s, retrying. Error: %s', self.api_url, err
             )
             return False
+        except Exception as err:
+            # NOTE(TheJulia): If you're looking here, and you're wondering
+            # why the retry logic is not working or your investigating a weird
+            # error or even IPA just exiting,
+            # See https://storyboard.openstack.org/#!/story/2007968
+            # To be clear, we're going to try to provide as much detail as
+            # possible in the exit handling
+            msg = ('Unhandled error looking up node with addresses {} at '
+                   '{}: {}'.format(params['addresses'], self.api_url, err))
+            # No matter what we do at this point, IPA is going to exit.
+            # This is because we don't know why the exception occured and
+            # we likely should not try to retry as such.
+            # We will attempt to provide as much detail to the logs as
+            # possible as to what occured, although depending on the logging
+            # subsystem, additional errors can occur, thus the additional
+            # handling below.
+            try:
+                LOG.exception(msg)
+                return False
+            except Exception as exc_err:
+                LOG.error(msg)
+                exc_msg = ('Unexpected exception occured while trying to '
+                           'log additional detail. Error: {}'.format(exc_err))
+                LOG.error(exc_msg)
+                raise errors.LookupNodeError(msg)
 
         if response.status_code != requests.codes.OK:
             LOG.warning(

ironic_python_agent/tests/unit/test_ironic_api_client.py

@@ -16,6 +16,7 @@ from unittest import mock
 
 from oslo_serialization import jsonutils
 from oslo_service import loopingcall
+import requests
 
 from ironic_python_agent import errors
 from ironic_python_agent import hardware
@@ -312,6 +313,47 @@ class TestBaseIronicPythonAgent(base.IronicAgentTest):
                           'node_uuid': 'someuuid'},
                          params)
 
+    @mock.patch.object(ironic_api_client, 'LOG', autospec=True)
+    def test_do_lookup_transient_exceptions(self, mock_log):
+        exc_list = [requests.exceptions.ConnectionError,
+                    requests.exceptions.ReadTimeout,
+                    requests.exceptions.HTTPError,
+                    requests.exceptions.Timeout,
+                    requests.exceptions.ConnectTimeout]
+        self.api_client.session.request = mock.Mock()
+        for exc in exc_list:
+            self.api_client.session.request.reset_mock()
+            mock_log.reset_mock()
+            self.api_client.session.request.side_effect = exc
+            error = self.api_client._do_lookup(self.hardware_info,
+                                               node_uuid=None)
+            self.assertFalse(error)
+            mock_log.error.assert_has_calls([])
+            self.assertEqual(1, mock_log.warning.call_count)
+
+    @mock.patch.object(ironic_api_client, 'LOG', autospec=True)
+    def test_do_lookup_unknown_exception(self, mock_log):
+        self.api_client.session.request = mock.Mock()
+        self.api_client.session.request.side_effect = \
+            requests.exceptions.RequestException('meow')
+        self.assertFalse(
+            self.api_client._do_lookup(self.hardware_info,
+                                       node_uuid=None))
+        self.assertEqual(1, mock_log.exception.call_count)
+
+    @mock.patch.object(ironic_api_client, 'LOG', autospec=True)
+    def test_do_lookup_unknown_exception_fallback(self, mock_log):
+        mock_log.exception.side_effect = TypeError
+        self.api_client.session.request = mock.Mock()
+        self.api_client.session.request.side_effect = \
+            requests.exceptions.RequestException('meow')
+        self.assertRaises(errors.LookupNodeError,
+                          self.api_client._do_lookup,
+                          self.hardware_info,
+                          node_uuid=None)
+        self.assertEqual(1, mock_log.exception.call_count)
+        self.assertEqual(2, mock_log.error.call_count)
+
     def test_do_lookup_bad_response_code(self):
         response = FakeResponse(status_code=400, content={
             'node': {

releasenotes/notes/fixes-agent-lookup-retries-1b4bb90b8e783aca.yaml

@@ -0,0 +1,9 @@
+---
+fixes:
+  - |
+    Fixes retry logic issues with the Agent Lookup which can result in
+    the lookup failing prematurely before being completed, typically
+    resulting in an abrupt end to the agent logging and potentially
+    weird errors like TypeError being reported on the agent process
+    standard error output. For more information see
+    `bug 2007968 <https://storyboard.openstack.org/#!/story/2007968>`_.