[db_migrator] Add missing attribute 'weight' to route entries in APPL DB (sonic-net#2691)

Fixes: 201911 to 202205 warm upgrade failure in fpmsyncd reconciliation due to missing weight attr in routes. (sonic-net#12625)

How I did it
Check for missing attribute weight in APPLDB route entries. If found missing this attribute is added with empty value.

How to verify it
Verified on physical device. 201911 to 202205 upgrade worked fine.

Author: vaibhavhd

scripts/db_migrator.py

@@ -579,6 +579,23 @@ def migrate_port_qos_map_global(self):
             self.configDB.set_entry('PORT_QOS_MAP', 'global', {"dscp_to_tc_map": dscp_to_tc_map_table_names[0]})
             log.log_info("Created entry for global DSCP_TO_TC_MAP {}".format(dscp_to_tc_map_table_names[0]))
 
+    def migrate_route_table(self):
+        """
+        Handle route table migration. Migrations handled:
+        1. 'weight' attr in ROUTE object was introduced 202205 onwards.
+            Upgrade from older branch to 202205 will require this 'weight' attr to be added explicitly
+        """
+        route_table = self.appDB.get_table("ROUTE_TABLE")
+        for route_prefix, route_attr in route_table.items():
+            if 'weight' not in route_attr:
+                if type(route_prefix) == tuple:
+                    # IPv6 route_prefix is returned from db as tuple
+                    route_key = "ROUTE_TABLE:" + ":".join(route_prefix)
+                else:
+                    # IPv4 route_prefix is returned from db as str
+                    route_key = "ROUTE_TABLE:{}".format(route_prefix)
+                self.appDB.set(self.appDB.APPL_DB, route_key, 'weight','')
+
     def version_unknown(self):
         """
         version_unknown tracks all SONiC versions that doesn't have a version
@@ -899,6 +916,8 @@ def common_migration_ops(self):
         else:
             log.log_notice("Asic Type: {}, Hwsku: {}".format(self.asic_type, self.hwsku))
 
+        self.migrate_route_table()
+
     def migrate(self):
         version = self.get_version()
         log.log_info('Upgrading from version ' + version)

tests/db_migrator_input/appl_db/routes_migrate_expected.json

@@ -0,0 +1,12 @@
+{
+    "ROUTE_TABLE:192.168.104.0/25": {
+        "nexthop": "10.0.0.57,10.0.0.59,10.0.0.61,10.0.0.63",
+        "ifname" : "PortChannel101,PortChannel102,PortChannel103,PortChannel104",
+        "weight": ""
+      },
+    "ROUTE_TABLE:20c0:fe28:0:80::/64": {
+    "nexthop": "fc00::72,fc00::76,fc00::7a,fc00::7e",
+    "ifname" : "PortChannel101,PortChannel102,PortChannel103,PortChannel104",
+    "weight": ""
+    }
+}

tests/db_migrator_input/appl_db/routes_migrate_input.json

@@ -0,0 +1,10 @@
+{
+    "ROUTE_TABLE:192.168.104.0/25": {
+        "nexthop": "10.0.0.57,10.0.0.59,10.0.0.61,10.0.0.63",
+        "ifname" : "PortChannel101,PortChannel102,PortChannel103,PortChannel104"
+      },
+    "ROUTE_TABLE:20c0:fe28:0:80::/64": {
+    "nexthop": "fc00::72,fc00::76,fc00::7a,fc00::7e",
+    "ifname" : "PortChannel101,PortChannel102,PortChannel103,PortChannel104"
+    }
+}

tests/db_migrator_input/config_db/routes_migrate_input.json

@@ -0,0 +1,3 @@
+{
+    "VERSIONS|DATABASE": {"VERSION": "version_1_0_1"}
+}

tests/db_migrator_test.py

@@ -518,3 +518,38 @@ def test_migrate_loopback_int(self):
             expected_keys = expected_appl_db.get_all(expected_appl_db.APPL_DB, key)
             diff = DeepDiff(resulting_keys, expected_keys, ignore_order=True)
             assert not diff
+
+class TestWarmUpgrade_without_route_weights(object):
+    @classmethod
+    def setup_class(cls):
+        os.environ['UTILITIES_UNIT_TESTING'] = "2"
+
+    @classmethod
+    def teardown_class(cls):
+        os.environ['UTILITIES_UNIT_TESTING'] = "0"
+        dbconnector.dedicated_dbs['CONFIG_DB'] = None
+        dbconnector.dedicated_dbs['APPL_DB'] = None
+
+    def test_migrate_weights_for_nexthops(self):
+        dbconnector.dedicated_dbs['CONFIG_DB'] = os.path.join(mock_db_path, 'config_db', 'routes_migrate_input')
+        dbconnector.dedicated_dbs['APPL_DB'] = os.path.join(mock_db_path, 'appl_db', 'routes_migrate_input')
+
+        import db_migrator
+        dbmgtr = db_migrator.DBMigrator(None)
+        dbmgtr.migrate()
+        dbconnector.dedicated_dbs['APPL_DB'] = os.path.join(mock_db_path, 'appl_db', 'routes_migrate_expected')
+        expected_db = Db()
+
+        # verify migrated appDB
+        expected_appl_db = SonicV2Connector(host='127.0.0.1')
+        expected_appl_db.connect(expected_appl_db.APPL_DB)
+        expected_keys = expected_appl_db.keys(expected_appl_db.APPL_DB, "ROUTE_TABLE:*")
+        expected_keys.sort()
+        resulting_keys = dbmgtr.appDB.keys(dbmgtr.appDB.APPL_DB, "ROUTE_TABLE:*")
+        resulting_keys.sort()
+        assert expected_keys == resulting_keys
+        for key in expected_keys:
+            resulting_keys = dbmgtr.appDB.get_all(dbmgtr.appDB.APPL_DB, key)
+            expected_keys = expected_appl_db.get_all(expected_appl_db.APPL_DB, key)
+            diff = DeepDiff(resulting_keys, expected_keys, ignore_order=True)
+            assert not diff