'iscsiadm -m session' failure handling

Sometimes 'iscsiadm -m session' outputs warnings on stderr, but
still serves its purpose (usable stdout). We should not give up on
it when stderr is non-empty - instead, rely on the exit status, log
the stderr as a warning, and move on.

This change also removes 1 (ISCSI_ERR) from the list of acceptable
exit codes for the iscsiadm command, to ensure that failures get
caught.

Change-Id: Id8183cf3d8baf2f8ba6a00a47fa2ad7cc2a96aa5
Closes-Bug: #1732199

os_brick/initiator/connectors/iscsi.py

@@ -118,9 +118,8 @@ class ISCSIConnector(base.BaseLinuxConnector, base_iscsi.BaseISCSIConnector):
         """
         out, err = self._run_iscsi_session()
         if err:
-            LOG.warning("Couldn't find iscsi sessions because "
-                        "iscsiadm err: %s", err)
-            return []
+            LOG.warning("iscsiadm stderr output when getting sessions: %s",
+                        err)
 
         # Parse and clean the output from iscsiadm, which is in the form of:
         # transport_name: [session_id] ip_address:port,tpgt iqn node_type
@@ -1091,7 +1090,7 @@ class ISCSIConnector(base.BaseLinuxConnector, base_iscsi.BaseISCSIConnector):
 
     def _run_iscsi_session(self):
         (out, err) = self._run_iscsiadm_bare(('-m', 'session'),
-                                             check_exit_code=[0, 1, 21, 255])
+                                             check_exit_code=[0, 21, 255])
         LOG.debug("iscsi session list stdout=%(out)s stderr=%(err)s",
                   {'out': out, 'err': err})
         return (out, err)

os_brick/tests/initiator/connectors/test_iscsi.py

@@ -70,12 +70,17 @@ class ISCSIConnectorTestCase(test_connector.ConnectorTestCase):
                     ('tcp:', 'session3', 'ip3:port3', '1', 'tgt3')]
         self.assertListEqual(expected, res)
 
-    @mock.patch.object(iscsi.ISCSIConnector, '_run_iscsi_session',
-                       return_value=(None, 'error'))
-    def test_get_iscsi_sessions_full_error(self, sessions_mock):
+    @mock.patch.object(iscsi.ISCSIConnector, '_run_iscsi_session')
+    def test_get_iscsi_sessions_full_stderr(self, sessions_mock):
+        iscsiadm_result = ('tcp: [session1] ip1:port1,1 tgt1 (non-flash)\n'
+                           'tcp: [session2] ip2:port2,-1 tgt2 (non-flash)\n'
+                           'tcp: [session3] ip3:port3,1 tgt3\n')
+        sessions_mock.return_value = (iscsiadm_result, 'error')
         res = self.connector._get_iscsi_sessions_full()
-        self.assertEqual([], res)
-        sessions_mock.assert_called()
+        expected = [('tcp:', 'session1', 'ip1:port1', '1', 'tgt1'),
+                    ('tcp:', 'session2', 'ip2:port2', '-1', 'tgt2'),
+                    ('tcp:', 'session3', 'ip3:port3', '1', 'tgt3')]
+        self.assertListEqual(expected, res)
 
     @mock.patch.object(iscsi.ISCSIConnector, '_get_iscsi_sessions_full')
     def test_get_iscsi_sessions(self, sessions_mock):