[system-health] No longer check critical process/service status via monit (#9068)

HLD updated here: sonic-net/SONiC#887

#### Why I did it

Command `monit summary -B` can no longer display the status for each critical process, system-health should not depend on it and need find a way to monitor the status of critical processes. The PR is to address that. monit is still used by system-health to do file system check as well as customize check.

#### How I did it

1.	Get container names from FEATURE table
2.	For each container, collect critical process names from file critical_processes
3.	Use “docker exec -it <container_name> bash -c ‘supervisorctl status’” to get processes status inside container, parse the output and check if any critical processes exit

#### How to verify it

1. Add unit test case to cover it
2. Adjust sonic-mgmt cases to cover it
3. Manual test

Author: Junchao-Mellanox

rules/system-health.mk

@@ -4,6 +4,7 @@ SYSTEM_HEALTH = system_health-1.0-py3-none-any.whl
 $(SYSTEM_HEALTH)_SRC_PATH = $(SRC_PATH)/system-health
 $(SYSTEM_HEALTH)_PYTHON_VERSION = 3
 $(SYSTEM_HEALTH)_DEPENDS = $(SONIC_PY_COMMON_PY3) $(SONIC_CONFIG_ENGINE_PY3)
+$(SYSTEM_HEALTH)_DEBS_DEPENDS = $(LIBSWSSCOMMON) $(PYTHON3_SWSSCOMMON)
 SONIC_PYTHON_WHEELS += $(SYSTEM_HEALTH)
 
 export system_health_py3_wheel_path="$(addprefix $(PYTHON_WHEELS_PATH)/,$(SYSTEM_HEALTH))"

src/system-health/health_checker/manager.py

@@ -1,3 +1,11 @@
+from . import utils
+from .config import Config
+from .health_checker import HealthChecker
+from .service_checker import ServiceChecker
+from .hardware_checker import HardwareChecker
+from .user_defined_checker import UserDefinedChecker
+
+
 class HealthCheckerManager(object):
     """
     Manage all system health checkers and system health configuration.
@@ -10,7 +18,6 @@ def __init__(self):
         self._checkers = []
         self._state = self.STATE_BOOTING
 
-        from .config import Config
         self.config = Config()
         self.initialize()
 
@@ -19,8 +26,6 @@ def initialize(self):
         Initialize the manager. Create service checker and hardware checker by default.
         :return:
         """
-        from .service_checker import ServiceChecker
-        from .hardware_checker import HardwareChecker
         self._checkers.append(ServiceChecker())
         self._checkers.append(HardwareChecker())
 
@@ -31,7 +36,6 @@ def check(self, chassis):
         :return: A tuple. The first element indicate the status of the checker; the second element is a dictionary that
         contains the status for all objects that was checked.
         """
-        from .health_checker import HealthChecker
         HealthChecker.summary = HealthChecker.STATUS_OK
         stats = {}
         self.config.load_config()
@@ -45,7 +49,6 @@ def check(self, chassis):
             self._do_check(checker, stats)
 
         if self.config.user_defined_checkers:
-            from .user_defined_checker import UserDefinedChecker
             for udc in self.config.user_defined_checkers:
                 checker = UserDefinedChecker(udc)
                 self._do_check(checker, stats)
@@ -71,20 +74,20 @@ def _do_check(self, checker, stats):
             else:
                 stats[category].update(info)
         except Exception as e:
-            from .health_checker import HealthChecker
+            HealthChecker.summary = HealthChecker.STATUS_NOT_OK
             error_msg = 'Failed to perform health check for {} due to exception - {}'.format(checker, repr(e))
             entry = {str(checker): {
                 HealthChecker.INFO_FIELD_OBJECT_STATUS: HealthChecker.STATUS_NOT_OK,
-                HealthChecker.INFO_FIELD_OBJECT_MSG: error_msg
+                HealthChecker.INFO_FIELD_OBJECT_MSG: error_msg,
+                HealthChecker.INFO_FIELD_OBJECT_TYPE: "Internal"
             }}
             if 'Internal' not in stats:
                 stats['Internal'] = entry
             else:
                 stats['Internal'].update(entry)
 
     def _is_system_booting(self):
-        from .utils import get_uptime
-        uptime = get_uptime()
+        uptime = utils.get_uptime()
         if not self.boot_timeout:
             self.boot_timeout = self.config.get_bootup_timeout()
         booting = uptime < self.boot_timeout