Merge pull request sonic-net#2 from pettershao-ragilenetworks/get-ser…

…ial-number-from-STATE_DB

Add serial_num field into device_info

src/sonic-py-common/sonic_py_common/device_info.py

@@ -37,6 +37,7 @@
 CHASSIS_INFO_TABLE = 'CHASSIS_INFO|chassis {}'
 CHASSIS_INFO_CARD_NUM_FIELD = 'module_num'
 CHASSIS_INFO_SERIAL_FIELD = 'serial'
+CHASSIS_INFO_SERIAL_NUM_FIELD = 'serial_num'
 CHASSIS_INFO_MODEL_FIELD = 'model'
 CHASSIS_INFO_REV_FIELD = 'revision'
 
@@ -371,7 +372,7 @@ def get_platform_info():
 
 def get_chassis_info():
     """
-    This function is used to get the Chassis serial / model / rev number
+    This function is used to get the Chassis serial / model / rev number / serial number
     """
 
     chassis_info_dict = {}
@@ -385,6 +386,7 @@ def get_chassis_info():
         chassis_info_dict['serial'] = db.get(db.STATE_DB, table, CHASSIS_INFO_SERIAL_FIELD)
         chassis_info_dict['model'] = db.get(db.STATE_DB, table, CHASSIS_INFO_MODEL_FIELD)
         chassis_info_dict['revision'] = db.get(db.STATE_DB, table, CHASSIS_INFO_REV_FIELD)
+        chassis_info_dict['serial_num'] = db.get(db.STATE_DB, table, CHASSIS_INFO_SERIAL_NUM_FIELD)
     except Exception:
         pass