Improve service checker for gnmi/telemetry container (sonic-net#19153)

Why I did it
Fix sonic-net#19081
We have used gnmi container to replace telemetry container, and telemetry is still enabled after upgrade.
service_checker script reads from features table and check if the container is running, telemetry is enabled but there's no telemetry container.
It's difficult to disable telemetry in feature table for warm reboot and cold reboot, we need to check docker image in db migrator and minigraph.py.
When we use warm reboot to upgrade from 202305 to 202311, config_db still has telemetry configuration, and we can't simply remove related configuration.

Work item tracking
Microsoft ADO (number only):
How I did it
I modify service_checker script:
If there's docker-sonic-telemetry image, check telemetry container.
If there's no docker-sonic-telemetry image, check gnmi container instead.
If there's no docker-sonic-telemetry image and docker-sonic-gnmi image, do not check telemetry.

How to verify it
Run unit test and end to end test.

src/system-health/health_checker/service_checker.py

@@ -15,6 +15,19 @@
 EVENTS_PUBLISHER_SOURCE = "sonic-events-host"
 EVENTS_PUBLISHER_TAG = "process-not-running"
 
+def check_docker_image(image_name):
+    """
+    @summary: This function will check if docker image exists.
+    @return:  True if the image exists, otherwise False.
+    """
+    try:
+        DOCKER_CLIENT = docker.DockerClient(base_url='unix://var/run/docker.sock')
+        DOCKER_CLIENT.images.get(image_name)
+        return True
+    except (docker.errors.ImageNotFound, docker.errors.APIError) as err:
+        logger.log_warning("Failed to get image '{}'. Error: '{}'".format(image_name, err))
+        return False
+
 class ServiceChecker(HealthChecker):
     """
     Checker that checks critical system service status via monit service.
@@ -84,21 +97,39 @@ def get_expected_running_containers(self, feature_table):
         # it will be removed from exception list.
         run_all_instance_list = ['database', 'bgp']
 
-        for feature_name, feature_entry in feature_table.items():
+        container_list = []
+        for container_name in feature_table.keys():
+            # slim image does not have telemetry container and corresponding docker image
+            if container_name == "telemetry":
+                ret = check_docker_image("docker-sonic-telemetry")
+                if not ret:
+                    # If telemetry container image is not present, check gnmi container image
+                    # If gnmi container image is not present, ignore telemetry container check
+                    # if gnmi container image is present, check gnmi container instead of telemetry
+                    ret = check_docker_image("docker-sonic-gnmi")
+                    if not ret:
+                        logger.log_debug("Ignoring telemetry container check on image which has no corresponding docker image")
+                    else:
+                        container_list.append("gnmi")
+                    continue
+            container_list.append(container_name)
+
+        for container_name in container_list:
+            feature_entry = feature_table[container_name]
             if feature_entry["state"] not in ["disabled", "always_disabled"]:
                 if multi_asic.is_multi_asic():
                     if feature_entry.get("has_global_scope", "True") == "True":
-                        expected_running_containers.add(feature_name)
-                        container_feature_dict[feature_name] = feature_name
+                        expected_running_containers.add(container_name)
+                        container_feature_dict[container_name] = container_name
                     if feature_entry.get("has_per_asic_scope", "False") == "True":
                         num_asics = multi_asic.get_num_asics()
                         for asic_id in range(num_asics):
-                            if asic_id in asics_id_presence or feature_name in run_all_instance_list:
-                                expected_running_containers.add(feature_name + str(asic_id))
-                                container_feature_dict[feature_name + str(asic_id)] = feature_name
+                            if asic_id in asics_id_presence or container_name in run_all_instance_list:
+                                expected_running_containers.add(container_name + str(asic_id))
+                                container_feature_dict[container_name + str(asic_id)] = container_name
                 else:
-                    expected_running_containers.add(feature_name)
-                    container_feature_dict[feature_name] = feature_name
+                    expected_running_containers.add(container_name)
+                    container_feature_dict[container_name] = container_name
 
         if device_info.is_supervisor():
             expected_running_containers.add("database-chassis")

src/system-health/tests/telemetry/etc/supervisor/critical_processes

@@ -0,0 +1 @@
+program:gnmi-native

src/system-health/tests/test_system_health.py

@@ -12,6 +12,7 @@
 import copy
 import os
 import sys
+import docker
 from imp import load_source
 from swsscommon import swsscommon
 
@@ -23,6 +24,7 @@
 swsscommon.SonicV2Connector = MockConnector
 
 test_path = os.path.dirname(os.path.abspath(__file__))
+telemetry_path = os.path.join(test_path, 'telemetry')
 modules_path = os.path.dirname(test_path)
 scripts_path = os.path.join(modules_path, 'scripts')
 sys.path.insert(0, modules_path)
@@ -166,6 +168,53 @@ def test_service_checker_single_asic(mock_config_db, mock_run, mock_docker_clien
     assert origin_container_critical_processes == checker.container_critical_processes
 
 
+@patch('swsscommon.swsscommon.ConfigDBConnector.connect', MagicMock())
+@patch('health_checker.service_checker.ServiceChecker._get_container_folder', MagicMock(return_value=telemetry_path))
+@patch('sonic_py_common.multi_asic.is_multi_asic', MagicMock(return_value=False))
+@patch('docker.DockerClient')
+@patch('health_checker.utils.run_command')
+@patch('swsscommon.swsscommon.ConfigDBConnector')
+def test_service_checker_telemetry(mock_config_db, mock_run, mock_docker_client):
+    setup()
+    mock_db_data = MagicMock()
+    mock_get_table = MagicMock()
+    mock_db_data.get_table = mock_get_table
+    mock_config_db.return_value = mock_db_data
+    mock_get_table.return_value = {
+        'gnmi': {
+            'state': 'enabled',
+            'has_global_scope': 'True',
+            'has_per_asic_scope': 'False',
+
+        },
+        'telemetry': {
+            'state': 'enabled',
+            'has_global_scope': 'True',
+            'has_per_asic_scope': 'False',
+
+        }
+    }
+    mock_containers = MagicMock()
+    mock_gnmi_container = MagicMock()
+    mock_gnmi_container.name = 'gnmi'
+    mock_containers.list = MagicMock(return_value=[mock_gnmi_container])
+    mock_docker_client_object = MagicMock()
+    mock_docker_client.return_value = mock_docker_client_object
+    mock_docker_client_object.containers = mock_containers
+    mock_docker_client_object.images = MagicMock()
+    mock_docker_client_object.images.get = MagicMock()
+    except_err = docker.errors.ImageNotFound("Unit test")
+    mock_docker_client_object.images.get.side_effect = [except_err, None]
+
+    mock_run.return_value = "gnmi-native                       RUNNING   pid 67, uptime 1:03:56"
+
+    checker = ServiceChecker()
+    assert checker.get_category() == 'Services'
+    config = Config()
+    checker.check(config)
+    assert 'gnmi:gnmi-native' in checker._info
+    assert checker._info['gnmi:gnmi-native'][HealthChecker.INFO_FIELD_OBJECT_STATUS] == HealthChecker.STATUS_OK
+
 
 @patch('swsscommon.swsscommon.ConfigDBConnector.connect', MagicMock())
 @patch('health_checker.service_checker.ServiceChecker._get_container_folder', MagicMock(return_value=test_path))