[202211] chassisd: Fix crash on exit on linecard (#352)

* Chassisd do an explicit stop of the config_manager (#328)

* Fix to explicit stop the config_manager
* Add tests for chassisd run method.

* chassisd: Fix crash on exit on linecard

Set the `config_manager` variable to `None` if we are running on a
linecard and thus don't need to set up the config manager.

During cleanup, the chassid service tries to clean up the
`config_manager`, but the `config_manager` variable is only ever
initialized if we are on the supervisor. Thus, checking if it is
`None` is insufficient because this results in an `UnboundLocalError`
that prevents the cleanup from succeeding on a linecard.

---------

Co-authored-by: judyjoseph <53951155+judyjoseph@users.noreply.github.com>

sonic-chassisd/scripts/chassisd

@@ -435,6 +435,8 @@ class ChassisdDaemon(daemon_base.DaemonBase):
         if self.module_updater.supervisor_slot == self.module_updater.my_slot:
             config_manager = ConfigManagerTask()
             config_manager.task_run()
+        else:
+            config_manager = None
 
         # Start main loop
         self.log_info("Start daemon main loop")
@@ -445,6 +447,9 @@ class ChassisdDaemon(daemon_base.DaemonBase):
 
         self.log_info("Stop daemon main loop")
 
+        if config_manager is not None:
+            config_manager.task_stop()
+
         # Delete all the information from DB and then exit
         self.module_updater.deinit()
 

sonic-chassisd/tests/mock_swsscommon.py

@@ -7,7 +7,8 @@ def __init__(self, db, table_name):
         self.mock_dict = {}
 
     def _del(self, key):
-        del self.mock_dict[key]
+        if key in self.mock_dict:
+            del self.mock_dict[key]
         pass
 
     def set(self, key, fvs):
@@ -29,3 +30,18 @@ class FieldValuePairs:
     def __init__(self, fvs):
         self.fv_dict = dict(fvs)
         pass
+
+class Select:
+    TIMEOUT = 1
+
+    def addSelectable(self, selectable):
+        pass
+
+    def removeSelectable(self, selectable):
+        pass
+
+    def select(self, timeout=-1, interrupt_on_signal=False):
+        return self.TIMEOUT, None
+
+class SubscriberStateTable(Table):
+    pass

sonic-chassisd/tests/mocked_libs/sonic_platform/__init__.py

@@ -0,0 +1,6 @@
+"""
+    Mock implementation of sonic_platform package for unit testing
+"""
+
+from . import chassis
+from . import platform

sonic-chassisd/tests/mocked_libs/sonic_platform/chassis.py

@@ -0,0 +1,26 @@
+"""
+    Mock implementation of sonic_platform package for unit testing
+"""
+
+import sys
+if sys.version_info.major == 3:
+    from unittest import mock
+else:
+    import mock
+
+from sonic_platform_base.chassis_base import ChassisBase
+
+
+class Chassis(ChassisBase):
+    def __init__(self):
+        ChassisBase.__init__(self)
+        self.eeprom = mock.MagicMock()
+
+    def get_eeprom(self):
+        return self.eeprom
+
+    def get_my_slot(self):
+        return 1
+
+    def get_supervisor_slot(self):
+        return 1

sonic-chassisd/tests/mocked_libs/sonic_platform/platform.py

@@ -0,0 +1,12 @@
+"""
+    Mock implementation of sonic_platform package for unit testing
+"""
+
+from sonic_platform_base.platform_base import PlatformBase
+from sonic_platform.chassis import Chassis
+
+
+class Platform(PlatformBase):
+    def __init__(self):
+        PlatformBase.__init__(self)
+        self._chassis = Chassis()

sonic-chassisd/tests/test_chassisd.py

@@ -14,6 +14,11 @@
 daemon_base.db_connect = MagicMock()
 
 test_path = os.path.dirname(os.path.abspath(__file__))
+
+# Add mocked_libs path so that the file under test can load mocked modules from there
+mocked_libs_path = os.path.join(test_path, 'mocked_libs')
+sys.path.insert(0, mocked_libs_path)
+
 modules_path = os.path.dirname(test_path)
 scripts_path = os.path.join(modules_path, "scripts")
 sys.path.insert(0, modules_path)
@@ -501,3 +506,21 @@ def test_signal_handler():
     assert daemon_chassisd.log_info.call_count == 0
     assert daemon_chassisd.stop.set.call_count == 0
     assert exit_code == 0
+
+def test_daemon_run_supervisor():
+    # Test the chassisd run
+    daemon_chassisd = ChassisdDaemon(SYSLOG_IDENTIFIER)
+    daemon_chassisd.stop = MagicMock()
+    daemon_chassisd.stop.wait.return_value = True
+    daemon_chassisd.run()
+
+def test_daemon_run_linecard():
+    # Test the chassisd run
+    daemon_chassisd = ChassisdDaemon(SYSLOG_IDENTIFIER)
+    daemon_chassisd.stop = MagicMock()
+    daemon_chassisd.stop.wait.return_value = True
+
+    import sonic_platform.platform
+    with patch.object(sonic_platform.platform.Chassis, 'get_my_slot') as mock:
+       mock.return_value = sonic_platform.platform.Platform().get_chassis().get_supervisor_slot() + 1
+       daemon_chassisd.run()