Mute common error when deleting VPC

ocw/lib/ec2.py

@@ -325,7 +325,12 @@ def vpc_can_be_deleted(self, resource_vpc, vpc_id) -> bool:
 
     def report_cleanup_results(self, vpc_errors: list, vpc_notify: list, vpc_locked: list) -> None:
         if len(vpc_errors) > 0:
-            send_mail(f'Errors on VPC deletion in [{self._namespace}]', '\n'.join(vpc_errors))
+            # this is most common error message which we can not fix.
+            # So no point to spam us with notifications about it
+            known_error = "An error occurred (DependencyViolation) when calling the DeleteVpc operation"
+            filtered = [x for x in vpc_errors if known_error not in x]
+            if len(filtered) > 0:
+                send_mail(f'Errors on VPC deletion in [{self._namespace}]', '\n'.join(vpc_errors))
         if len(vpc_notify) > 0:
             send_mail(f'{len(vpc_notify)} VPC\'s should be deleted, skipping due vpc-notify-only=True', ','.join(vpc_notify))
         if len(vpc_locked) > 0:

ocw/lib/emailnotify.py

@@ -1,12 +1,10 @@
-from datetime import timedelta
 import smtplib
 import logging
 from email.mime.text import MIMEText
 from texttable import Texttable
 from django.urls import reverse
 from webui.PCWConfig import PCWConfig
 from webui.settings import build_absolute_uri
-from ..models import Instance
 
 logger = logging.getLogger(__name__)
 

ocw/tables.py

@@ -32,6 +32,7 @@ def render(self, record):
                                link['url'], link['title'], link['title'], static('img/openqa.svg'))
         return ""
 
+
 class TagsColumn(tables.TemplateColumn):
 
     def __init__(self, template_name=None, **extra):

tests/test_db.py

@@ -179,7 +179,6 @@ def mocked__update_provider(arg1, arg2, arg3):
     def mocked_auto_delete_instances():
         call_stack.append('auto_delete_instances')
 
-
     monkeypatch.setattr('ocw.lib.db._update_provider', mocked__update_provider)
     monkeypatch.setattr('ocw.lib.db.auto_delete_instances', mocked_auto_delete_instances)