config: allow golden config to override mac, platform, asic_id (#291)

Currently generate_sysinfo() unconditionally overwrites mac, platform,
and asic_id in the golden config with values from the running config or
hardware detection. This prevents users from intentionally overriding
these fields via 'config load_minigraph -o' or 'config override-config-table'.

Change generate_sysinfo() to only backfill these fields when they are
not explicitly present in the golden config input. If the golden config
provides mac/platform/asic_id, those values are preserved.

Add unit test to verify explicit sysinfo values in golden config are
not overwritten by hardware-detected values.

Signed-off-by: securely1g <securely1g@users.noreply.github.com>
Co-authored-by: securely1g <securely1g@users.noreply.github.com>

Author: securely1g

config/main.py

@@ -2244,8 +2244,11 @@ def generate_sysinfo(cur_config, config_input, ns=None):
     if not platform:
         platform = device_info.get_platform()
 
-    device_metadata['localhost']['mac'] = mac
-    device_metadata['localhost']['platform'] = platform
+    # Only backfill sysinfo fields if not explicitly provided in golden config
+    if 'mac' not in device_metadata['localhost']:
+        device_metadata['localhost']['mac'] = mac
+    if 'platform' not in device_metadata['localhost']:
+        device_metadata['localhost']['platform'] = platform
 
     return
 

tests/config_override_input/multi_asic_dm_explicit_sysinfo.json

@@ -0,0 +1,61 @@
+{
+    "localhost": {
+        "DEVICE_METADATA": {
+            "localhost": {
+                "default_bgp_status": "down",
+                "default_pfcwd_status": "enable",
+                "deployment_id": "1",
+                "docker_routing_config_mode": "separated",
+                "hostname": "sonic-switch",
+                "hwsku": "Mellanox-SN3800-D112C8",
+                "peer_switch": "sonic-switch",
+                "type": "ToRRouter",
+                "suppress-fib-pending": "enabled",
+                "mac": "aa:bb:cc:dd:ee:ff",
+                "platform": "custom-platform"
+            }
+        }
+    },
+    "asic0": {
+        "DEVICE_METADATA": {
+            "localhost": {
+                "asic_name": "asic0",
+                "bgp_asn": "65100",
+                "cloudtype": "None",
+                "default_bgp_status": "down",
+                "default_pfcwd_status": "enable",
+                "deployment_id": "None",
+                "docker_routing_config_mode": "separated",
+                "hostname": "sonic",
+                "hwsku": "multi_asic",
+                "region": "None",
+                "sub_role": "FrontEnd",
+                "type": "LeafRouter",
+                "mac": "aa:bb:cc:dd:ee:ff",
+                "platform": "custom-platform",
+                "asic_id": "ff:00:00"
+            }
+        }
+    },
+    "asic1": {
+        "DEVICE_METADATA": {
+            "localhost": {
+                "asic_name": "asic1",
+                "bgp_asn": "65100",
+                "cloudtype": "None",
+                "default_bgp_status": "down",
+                "default_pfcwd_status": "enable",
+                "deployment_id": "None",
+                "docker_routing_config_mode": "separated",
+                "hostname": "sonic",
+                "hwsku": "multi_asic",
+                "region": "None",
+                "sub_role": "BackEnd",
+                "type": "LeafRouter",
+                "mac": "aa:bb:cc:dd:ee:ff",
+                "platform": "custom-platform",
+                "asic_id": "ff:00:00"
+            }
+        }
+    }
+}

tests/config_override_test.py

@@ -24,6 +24,7 @@
 MULTI_ASIC_MACSEC_OV = os.path.join(DATA_DIR, "multi_asic_macsec_ov.json")
 MULTI_ASIC_FEATURE_RM = os.path.join(DATA_DIR, "multi_asic_feature_rm.json")
 MULTI_ASIC_DEVICE_METADATA_GEN_SYSINFO = os.path.join(DATA_DIR, "multi_asic_dm_gen_sysinfo.json")
+MULTI_ASIC_DEVICE_METADATA_EXPLICIT_SYSINFO = os.path.join(DATA_DIR, "multi_asic_dm_explicit_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")
 
@@ -401,6 +402,41 @@ def read_json_file_side_effect(filename):
             assert platform == "multi_asic"
             assert mac == "11:22:33:44:55:66"
 
+    def test_device_metadata_explicit_sysinfo_override(self):
+        """Test that explicit mac/platform/asic_id in golden config are preserved."""
+        def read_json_file_side_effect(filename):
+            with open(MULTI_ASIC_DEVICE_METADATA_EXPLICIT_SYSINFO, "r") as f:
+                device_metadata = json.load(f)
+            return device_metadata
+        db = Db()
+        cfgdb_clients = db.cfgdb_clients
+
+        with mock.patch('config.main.read_json_file',
+                        mock.MagicMock(side_effect=read_json_file_side_effect)),\
+             mock.patch('sonic_py_common.device_info.get_platform',
+                        return_value="multi_asic"),\
+             mock.patch('sonic_py_common.device_info.get_system_mac',
+                        return_value="11:22:33:44:55:66\n"),\
+             mock.patch('sonic_py_common.multi_asic.get_asic_device_id',
+                        return_value="06:00:00\n"):
+            runner = CliRunner()
+            result = runner.invoke(config.config.commands["override-config-table"],
+                                   ['golden_config_db.json'], obj=db)
+            assert result.exit_code == 0
+
+        for ns, config_db in cfgdb_clients.items():
+            mac = config_db.get_config()['DEVICE_METADATA']['localhost'].get('mac')
+            platform = config_db.get_config()['DEVICE_METADATA']['localhost'].get('platform')
+            # Golden config explicit values should be preserved, not overwritten
+            assert mac == "aa:bb:cc:dd:ee:ff", \
+                f"Expected golden config mac 'aa:bb:cc:dd:ee:ff' but got '{mac}' for namespace '{ns}'"
+            assert platform == "custom-platform", \
+                f"Expected golden config platform 'custom-platform' but got '{platform}' for namespace '{ns}'"
+            if ns != config.DEFAULT_NAMESPACE and ns != HOST_NAMESPACE:
+                asic_id = config_db.get_config()['DEVICE_METADATA']['localhost'].get('asic_id')
+                assert asic_id == "ff:00:00", \
+                    f"Expected golden config asic_id 'ff:00:00' but got '{asic_id}' for namespace '{ns}'"
+
     def test_masic_missig_localhost_override(self):
         def read_json_file_side_effect(filename):
             with open(MULTI_ASIC_MISSING_LOCALHOST_OV, "r") as f: