[VxLAN]Fix Vxlan delete command to throw error when there are references (sonic-net#2404)

*Check for VNET references for vxlan before deleting vxlan object

Author: dgsudharsan

config/vxlan.py

@@ -38,6 +38,10 @@ def del_vxlan(db, vxlan_name):
     """Del VXLAN"""
     ctx = click.get_current_context()
 
+    vxlan_keys = db.cfgdb.get_keys('VXLAN_TUNNEL')
+    if vxlan_name not in vxlan_keys:
+        ctx.fail("Vxlan tunnel {} does not exist".format(vxlan_name))
+
     vxlan_keys = db.cfgdb.get_keys('VXLAN_EVPN_NVO')
     if not vxlan_keys:
       vxlan_count = 0
@@ -56,6 +60,12 @@ def del_vxlan(db, vxlan_name):
     if(vxlan_count > 0):
         ctx.fail("Please delete all VLAN VNI mappings.")  
 
+    vnet_table = db.cfgdb.get_table('VNET')
+    vnet_keys = vnet_table.keys()
+    for vnet_key in vnet_keys:
+        if ('vxlan_tunnel' in vnet_table[vnet_key] and vnet_table[vnet_key]['vxlan_tunnel'] == vxlan_name):
+            ctx.fail("Please delete all VNET configuration referencing the tunnel " + vxlan_name)
+
     db.cfgdb.set_entry('VXLAN_TUNNEL', vxlan_name, None)
 
 @vxlan.group('evpn_nvo')

tests/vnet_input/config_db.json

@@ -0,0 +1,10 @@
+{
+    "VNET|Vnet_2000": {
+        "peer_list": "",
+        "vni": "2000",
+        "vxlan_tunnel": "tunnel1"
+    },
+    "VXLAN_TUNNEL|tunnel1": {
+        "src_ip": "10.10.10.10"
+    }
+}

tests/vxlan_test.py

@@ -7,6 +7,10 @@
 import config.main as config
 import show.main as show
 from utilities_common.db import Db
+from .mock_tables import dbconnector
+
+test_path = os.path.dirname(os.path.abspath(__file__))
+mock_db_path = os.path.join(test_path, "vnet_input")
 
 show_vxlan_interface_output="""\
 VTEP Information:
@@ -247,6 +251,24 @@ def test_config_vxlan_add(self):
         assert result.exit_code == 0
         assert result.output == show_vxlan_vlanvnimap_output
 
+    def test_config_vxlan_del(self):
+        dbconnector.dedicated_dbs['CONFIG_DB'] = os.path.join(mock_db_path, 'config_db')
+        db = Db()
+        runner = CliRunner()
+
+        result = runner.invoke(config.config.commands["vxlan"].commands["del"], ["tunnel_invalid"], obj=db)
+        print(result.exit_code)
+        print(result.output)
+        assert result.exit_code != 0
+        assert "Error: Vxlan tunnel tunnel_invalid does not exist" in result.output
+
+        result = runner.invoke(config.config.commands["vxlan"].commands["del"], ["tunnel1"], obj=db)
+        dbconnector.dedicated_dbs = {}
+        print(result.exit_code)
+        print(result.output)
+        assert result.exit_code != 0
+        assert "Please delete all VNET configuration referencing the tunnel" in result.output
+
     @classmethod
     def teardown_class(cls):
         os.environ['UTILITIES_UNIT_TESTING'] = "0"