[multi-asic] Refine [override config table] for corner cases (#2918)

Handle corner case for multi-asics:
1. when golden config file is empty for multi-asic case
2. when config format is incorrect for multi-asics, e.g. localhost or namespace is missing in golden config db

config/main.py

@@ -1894,14 +1894,24 @@ def override_config_table(db, input_config_db, dry_run):
         current_config = config_db.get_config()
         # Serialize to the same format as json input
         sonic_cfggen.FormatConverter.to_serialized(current_config)
-
-        if multi_asic.is_multi_asic():
+        ns_config_input = None
+        if multi_asic.is_multi_asic() and len(config_input):
             # Golden Config will use "localhost" to represent host name
             if ns == DEFAULT_NAMESPACE:
-                ns_config_input = config_input["localhost"]
+                if "localhost" in config_input.keys():
+                    ns_config_input = config_input["localhost"]
+                else:
+                    click.secho("Wrong config format! 'localhost' not found in host config! cannot override.. abort")
+                    sys.exit(1)
             else:
-                ns_config_input = config_input[ns]
-        else:
+                if ns in config_input.keys():
+                    ns_config_input = config_input[ns]
+                else:
+                    click.secho("Wrong config format! {} not found in asic config! cannot override.. abort".format(ns))
+                    sys.exit(1)
+        if not ns_config_input:
+            # if ns_config_input is not defined, define it
+            # it could be single-asic dut, or config_input is empty
             ns_config_input = config_input
         # Generate sysinfo if missing in ns_config_input
         generate_sysinfo(current_config, ns_config_input, ns)

tests/config_override_input/multi_asic_missing_asic.json

@@ -0,0 +1,5 @@
+{
+    "localhost": {
+        "DEVICE_METADATA": {}
+    }
+}

tests/config_override_input/multi_asic_missing_localhost.json

@@ -0,0 +1,11 @@
+{
+    "host": {
+        "DEVICE_METADATA": {}
+    },
+    "asic0": {
+        "DEVICE_METADATA": {}
+    },
+    "asic1": {
+        "DEVICE_METADATA": {}
+    }
+}

tests/config_override_test.py

@@ -24,6 +24,8 @@
 MULTI_ASIC_MACSEC_OV = os.path.join(DATA_DIR, "multi_asic_macsec_ov.json")
 MULTI_ASIC_DEVICE_METADATA_RM = os.path.join(DATA_DIR, "multi_asic_dm_rm.json")
 MULTI_ASIC_DEVICE_METADATA_GEN_SYSINFO = os.path.join(DATA_DIR, "multi_asic_dm_gen_sysinfo.json")
+MULTI_ASIC_MISSING_LOCALHOST_OV = os.path.join(DATA_DIR, "multi_asic_missing_localhost.json")
+MULTI_ASIC_MISSING_ASIC_OV = os.path.join(DATA_DIR, "multi_asic_missing_asic.json")
 
 # Load sonic-cfggen from source since /usr/local/bin/sonic-cfggen does not have .py extension.
 sonic_cfggen = load_module_from_source('sonic_cfggen', '/usr/local/bin/sonic-cfggen')
@@ -381,6 +383,39 @@ def read_json_file_side_effect(filename):
             assert platform == "multi_asic"
             assert mac == "11:22:33:44:55:66"
 
+    def test_masic_missig_localhost_override(self):
+        def read_json_file_side_effect(filename):
+            with open(MULTI_ASIC_MISSING_LOCALHOST_OV, "r") as f:
+                wrong_format = json.load(f)
+            return wrong_format
+        db = Db()
+        cfgdb_clients = db.cfgdb_clients
+
+        with mock.patch('config.main.read_json_file',
+                        mock.MagicMock(side_effect=read_json_file_side_effect)):
+            runner = CliRunner()
+            result = runner.invoke(config.config.commands["override-config-table"],
+                                   ['golden_config_db.json'], obj=db)
+            assert "'localhost' not found in host config" in result.output
+            # make sure program aborted with return code 1
+            assert result.exit_code == 1
+
+    def test_masic_missig_asic_override(self):
+        def read_json_file_side_effect(filename):
+            with open(MULTI_ASIC_MISSING_ASIC_OV, "r") as f:
+                wrong_format = json.load(f)
+            return wrong_format
+        db = Db()
+        cfgdb_clients = db.cfgdb_clients
+
+        with mock.patch('config.main.read_json_file',
+                        mock.MagicMock(side_effect=read_json_file_side_effect)):
+            runner = CliRunner()
+            result = runner.invoke(config.config.commands["override-config-table"],
+                                   ['golden_config_db.json'], obj=db)
+            assert "not found in asic config" in result.output
+            # make sure program aborted with return code 1
+            assert result.exit_code == 1
 
     @classmethod
     def teardown_class(cls):