[subinterface]Avoid removing the subinterface when last configured ip is removed (sonic-net#2181)

* Avoid removing the subinterface when last configured ip is removed
Signed-off-by: Sudharsan Dhamal Gopalarathnam <[email protected]>

Author: dgsudharsan

config/main.py

@@ -4277,7 +4277,8 @@ def remove(ctx, interface_name, ip_addr):
     remove_router_interface_ip_address(config_db, interface_name, ip_address)
     interface_addresses = get_interface_ipaddresses(config_db, interface_name)
     if len(interface_addresses) == 0 and is_interface_bind_to_vrf(config_db, interface_name) is False and get_intf_ipv6_link_local_mode(ctx, interface_name, table_name) != "enable":
-        config_db.set_entry(table_name, interface_name, None)
+        if table_name != "VLAN_SUB_INTERFACE":
+            config_db.set_entry(table_name, interface_name, None)
 
     if multi_asic.is_multi_asic():
         command = "sudo ip netns exec {} ip neigh flush dev {} {}".format(ctx.obj['namespace'], interface_name, str(ip_address))

tests/config_int_ip_test.py

@@ -105,6 +105,36 @@ def test_config_int_ip_rem_static(
             assert result.exit_code == 0
             assert mock_run_command.call_count == 1
 
+    @pytest.mark.parametrize('setup_single_bgp_instance',
+                             ['ip_route_for_int_ip'], indirect=['setup_single_bgp_instance'])
+    def test_config_int_ip_rem_sub_intf(
+            self,
+            get_cmd_module,
+            setup_single_bgp_instance):
+        (config, _) = get_cmd_module
+        jsonfile_config = os.path.join(mock_db_path, "config_db")
+        from .mock_tables import dbconnector
+        dbconnector.dedicated_dbs['CONFIG_DB'] = jsonfile_config
+
+        runner = CliRunner()
+        db = Db()
+        obj = {'config_db': db.cfgdb}
+
+        # remove vlan IP`s
+        with mock.patch('utilities_common.cli.run_command') as mock_run_command:
+            print(db.cfgdb.get_table('INTERFACE'))
+            assert ('Ethernet16.16', '16.1.1.1/16') in db.cfgdb.get_table('VLAN_SUB_INTERFACE')
+            assert 'Ethernet16.16' in db.cfgdb.get_table('VLAN_SUB_INTERFACE')
+            result = runner.invoke(config.config.commands["interface"].commands["ip"].commands["remove"],
+                                   ["Ethernet16.16", "16.1.1.1/16"], obj=obj)
+            print(result.exit_code, result.output)
+            assert result.exit_code == 0
+            assert mock_run_command.call_count == 1
+            # removing IP should only remove the INTERFACE,IP key. The regular INTERFACE key should still exists for sub interface
+            assert ('Ethernet16.16', '16.1.1.1/16') not in db.cfgdb.get_table('VLAN_SUB_INTERFACE')
+            assert 'Ethernet16.16' in db.cfgdb.get_table('VLAN_SUB_INTERFACE')
+
+
 class TestIntIpMultiasic(object):
     @pytest.fixture(scope="class", autouse=True)
     def setup_class(cls):

tests/int_ip_input/config_db.json

@@ -37,5 +37,11 @@
     },
     "VLAN_INTERFACE|Vlan2|192.168.1.1/21": {
         "NULL": "NULL"
+    },
+    "VLAN_SUB_INTERFACE|Ethernet16.16": {
+        "admin_status": "up"
+    },
+    "VLAN_SUB_INTERFACE|Ethernet16.16|16.1.1.1/16": {
+        "NULL": "NULL"
     }
 }