Delete NSG if no resources associated with it (#1358)

Co-authored-by: stas <statis@microsoft.com>

src/api-service/__app__/onefuzzlib/azure/nsg.py

@@ -5,7 +5,7 @@
 
 import logging
 import os
-from typing import Dict, List, Optional, Union, cast
+from typing import Dict, List, Optional, Set, Union, cast
 
 from azure.core.exceptions import HttpResponseError, ResourceNotFoundError
 from azure.mgmt.network.models import (
@@ -72,6 +72,12 @@ def create_nsg(name: str, location: Region) -> Union[None, Error]:
     return None
 
 
+def list_nsgs() -> List[NetworkSecurityGroup]:
+    resource_group = get_base_resource_group()
+    network_client = get_network_client()
+    return list(network_client.network_security_groups.list(resource_group))
+
+
 def update_nsg(nsg: NetworkSecurityGroup) -> Union[None, Error]:
     resource_group = get_base_resource_group()
 
@@ -95,6 +101,10 @@ def update_nsg(nsg: NetworkSecurityGroup) -> Union[None, Error]:
     return None
 
 
+def ok_to_delete(active_regions: Set[Region], nsg_region: str, nsg_name: str) -> bool:
+    return nsg_region not in active_regions and nsg_region == nsg_name
+
+
 def delete_nsg(name: str) -> bool:
     # NSG can be only deleted if no other resource is associated with it
     resource_group = get_base_resource_group()

src/api-service/__app__/timer_proxy/__init__.py

@@ -8,6 +8,7 @@ import logging
 import azure.functions as func
 from onefuzztypes.enums import VmState
 
+from ..onefuzzlib.azure.nsg import delete_nsg, list_nsgs, ok_to_delete
 from ..onefuzzlib.orm import process_state_updates
 from ..onefuzzlib.proxy import PROXY_LOG_PREFIX, Proxy
 from ..onefuzzlib.workers.scalesets import Scaleset
@@ -50,3 +51,10 @@ def main(mytimer: func.TimerRequest) -> None:  # noqa: F841
     for region in regions:
         if all(x.outdated for x in proxies if x.region == region):
             Proxy.get_or_create(region)
+
+    # if there are NSGs with name same as the region that they are allocated
+    # and have no NIC associated with it then delete the NSG
+    for nsg in list_nsgs():
+        if ok_to_delete(regions, nsg.location, nsg.name):
+            if nsg.network_interfaces is None:
+                delete_nsg(nsg.name)

src/api-service/tests/test_nsg.py

@@ -0,0 +1,32 @@
+#!/usr/bin/env python
+#
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
+from typing import Set, Tuple
+
+import pytest
+from onefuzztypes.primitives import Region
+
+from __app__.onefuzzlib.azure.nsg import ok_to_delete
+
+# Active regions, NSG region, NSG name, expected result
+NsgOkToDeleteTestCase = Tuple[Set[Region], str, str, bool]
+
+NSG_OK_TO_DELETE_TEST_CASES = [
+    # OK to delete
+    (set([Region("def"), Region("ghk")]), "abc", "abc", True),
+    # Not OK to delete
+    # region set has same region as NSG
+    (set([Region("abc"), Region("def"), Region("ghk")]), "abc", "abc", False),
+    # NSG region does not match it's name
+    (set([Region("abc"), Region("def"), Region("ghk")]), "abc", "cba", False),
+    (set([Region("def"), Region("ghk")]), "abc", "cba", False),
+]
+
+
+@pytest.mark.parametrize("nsg_ok_to_delete_test_case", NSG_OK_TO_DELETE_TEST_CASES)
+def test_is_ok_to_delete_nsg(nsg_ok_to_delete_test_case: NsgOkToDeleteTestCase) -> None:
+    regions, nsg_location, nsg_name, expected = nsg_ok_to_delete_test_case
+    result = ok_to_delete(regions, nsg_location, nsg_name)
+    assert result == expected