[LLDP]: Update init_db to load global database config (sonic-net#166)

[LLDP]: Update init_db to load global database config
before initializing SonicV2Connector class.
LLDPLocManAddrUpdater requires information from host database hence uses init_db() to initialize the host db.
For unit-testing multi-asic code path, there are mock db files provided for global_db and namespace specific dbs.
As init_db did not load global database config, unit-test mock db was not loading global_db database files for LLDPLocManAddrUpdater unit-testing. Fixed this by loading global database config in init_db function. Fixed by:
Loading global database config in init_db()
unit-test: Loading mock db files from "global_db" director for multi-asic platform if namespace is empty or None.

Author: SuvarnaMeenakshi

src/sonic_ax_impl/mibs/__init__.py

@@ -181,6 +181,7 @@ def init_db():
     Connects to DB
     :return: db_conn
     """
+    SonicDBConfig.load_sonic_global_db_config()
     # SyncD database connector. THIS MUST BE INITIALIZED ON A PER-THREAD BASIS.
     # Redis PubSub objects (such as those within swsssdk) are NOT thread-safe.
     db_conn = SonicV2Connector(**redis_kwargs)

tests/mock_tables/asic0/appl_db.json

@@ -27,6 +27,15 @@
     "lldp_rem_port_id": "Ethernet2",
     "lldp_rem_man_addr": "fe80::268a:7ff:fe3f:834c"
   },
+  "LLDP_LOC_CHASSIS": {
+    "lldp_loc_chassis_id_subtype": "5",
+    "lldp_loc_chassis_id": "00:11:22:AB:CD:EF",
+    "lldp_loc_sys_name": "SONiC",
+    "lldp_loc_sys_desc": "Gotta go Fast!",
+    "lldp_loc_sys_cap_enabled": "28 00",
+    "lldp_loc_sys_cap_supported": "28 00",
+    "lldp_loc_man_addr": "10.224.25.36,fe80::ce37:abff:feec:de9c"
+  },
   "PORT_TABLE:Ethernet0": {
     "description": "snowflake",
     "alias": "etp1",

tests/mock_tables/asic1/appl_db.json

@@ -34,7 +34,7 @@
     "lldp_loc_sys_desc": "Gotta go Fast!",
     "lldp_loc_sys_cap_enabled": "28 00",
     "lldp_loc_sys_cap_supported": "28 00",
-    "lldp_loc_man_addr": "10.224.25.26,fe80::ce37:abff:feec:de9c"
+    "lldp_loc_man_addr": "10.224.25.36,fe80::ce37:abff:feec:de9c"
   },
   "PORT_TABLE:Ethernet8": {
     "description": "snowflake",

tests/mock_tables/asic2/appl_db.json

@@ -6,7 +6,7 @@
     "lldp_loc_sys_desc": "Gotta go Fast!",
     "lldp_loc_sys_cap_enabled": "28 00",
     "lldp_loc_sys_cap_supported": "28 00",
-    "lldp_loc_man_addr": "10.224.25.26,fe80::ce37:abff:feec:de9c"
+    "lldp_loc_man_addr": "10.224.25.36,fe80::ce37:abff:feec:de9c"
   },
   "PORT_TABLE:Ethernet-BP16": {
     "description": "backplane",

tests/mock_tables/dbconnector.py

@@ -46,7 +46,7 @@ def connect_SonicV2Connector(self, db_name, retry_on=True):
     # In case of multiple namespaces, namespace string passed to
     # SonicV2Connector will specify the namespace or can be empty.
     # Empty namespace represents global or host namespace.
-    if len(ns_list) > 1 and self.namespace == "":
+    if len(ns_list) > 1 and (self.namespace == "" or self.namespace == None):
         self.dbintf.redis_kwargs['namespace'] = "global_db"
     else:
         self.dbintf.redis_kwargs['namespace'] = self.namespace

tests/mock_tables/global_db/appl_db.json

@@ -20,6 +20,6 @@
     "lldp_loc_sys_desc": "Gotta go Fast!",
     "lldp_loc_sys_cap_enabled": "28 00",
     "lldp_loc_sys_cap_supported": "28 00",
-    "lldp_loc_man_addr": "10.224.25.26,fe80::ce37:abff:feec:de9c"
+    "lldp_loc_man_addr": "10.224.25.36,fe80::ce37:abff:feec:de9c"
   }
 }

tests/namespace/test_lldp.py

@@ -118,6 +118,7 @@ def test_subtype_lldp_loc_man_addr_table(self):
 
         response = get_pdu.make_response(self.lut)
         value0 = response.values[0]
+        self.assertEqual(str(value0.name), str(ObjectIdentifier(13, 0, 1, 0, (1, 0, 8802, 1, 1, 2, 1, 3, 8, 1, 3, 1, 4, 10, 224, 25, 36))))
         self.assertEqual(value0.type_, ValueType.INTEGER)
         self.assertEqual(value0.data, 5)
 

tests/test_lldp.py

@@ -97,6 +97,7 @@ def test_subtype_lldp_loc_man_addr_table(self):
 
         response = get_pdu.make_response(self.lut)
         value0 = response.values[0]
+        self.assertEqual(str(value0.name), str(ObjectIdentifier(13, 0, 1, 0, (1, 0, 8802, 1, 1, 2, 1, 3, 8, 1, 3, 1, 4, 10, 224, 25, 26))))
         self.assertEqual(value0.type_, ValueType.INTEGER)
         self.assertEqual(value0.data, 5)
 
@@ -224,4 +225,4 @@ def test_getnextpdu_lldpRemSysCapEnabled(self):
         value0 = response.values[0]
         self.assertEqual(value0.type_, ValueType.OCTET_STRING)
         self.assertEqual(str(value0.name), str(ObjectIdentifier(12, 0, 1, 0, (1, 0, 8802, 1, 1, 2, 1, 4, 1, 1, 12, 1, 1))))
-        self.assertEqual(str(value0.data), "\x28\x00")
+        self.assertEqual(str(value0.data), "\x28\x00")