ref(py): Replace usage of croniter with cronsim

We're replacing croniter with cronsim as it's bit more of a modern
library. This replaces the single usage outsode of the cron monitors
feature of sentry.

See GH-80208

src/sentry/api/helpers/deprecation.py

@@ -3,13 +3,14 @@
 import functools
 import logging
 from collections.abc import Callable
-from datetime import datetime, timedelta, timezone
+from datetime import datetime, timedelta
 from typing import Concatenate, ParamSpec, TypeVar
 
 import isodate
-from croniter import croniter
+from cronsim import CronSim, CronSimError
 from django.conf import settings
 from django.http.response import HttpResponseBase
+from django.utils import timezone
 from isodate.isoerror import ISO8601Error
 from rest_framework.request import Request
 from rest_framework.response import Response
@@ -66,17 +67,19 @@ def _should_be_blocked(deprecation_date: datetime, now: datetime, key: str) -> b
             logger.exception("Invalid ISO8601 format for blackout duration")
             return False
 
-        if not croniter.is_valid(brownout_cron):
-            logger.error("Invalid crontab for blackout schedule")
+        try:
+            # Move back one minute so we can iterate once and determine if now
+            # matches the cron schedule.
+            iter = CronSim(brownout_cron, now - timedelta(minutes=1))
+        except CronSimError:
+            logger.exception("Invalid crontab for blackout schedule")
             return False
 
-        # return True if now exactly matches the crontab
-        if croniter.match(brownout_cron, now):
+        if next(iter) == now.replace(second=0, microsecond=0):
             return True
 
-        # If not, check if now is within BROWNOUT_DURATION of the last brownout time
-        iter = croniter(brownout_cron, now)
-        brownout_start = iter.get_prev(datetime)
+        # If not, check if now is within `brownout_duration` of the last brownout time
+        brownout_start = next(CronSim(brownout_cron, now, reverse=True))
         return brownout_start <= now < brownout_start + brownout_duration
     return False
 
@@ -131,7 +134,7 @@ def endpoint_method(
             if is_self_hosted() and not settings.ENVIRONMENT == "development":
                 return func(self, request, *args, **kwargs)
 
-            now = datetime.now(timezone.utc)
+            now = timezone.now()
 
             if now > deprecation_date and _should_be_blocked(deprecation_date, now, key):
                 response: HttpResponseBase = Response(GONE_MESSAGE, status=GONE)

tests/sentry/helpers/test_deprecation.py

@@ -1,7 +1,7 @@
 from datetime import datetime, timedelta
 
 import isodate
-from croniter import croniter
+from cronsim import CronSim
 from django.http.request import HttpRequest
 from django.http.response import HttpResponse
 from rest_framework.response import Response
@@ -18,7 +18,7 @@
 
 replacement_api = "replacement-api"
 test_date = datetime.fromisoformat("2020-01-01T00:00:00+00:00:00")
-timeiter = croniter("0 12 * * *", test_date)
+timeiter = CronSim("0 12 * * *", test_date)
 default_duration = timedelta(minutes=1)
 
 custom_cron = "30 1 * * *"
@@ -86,7 +86,7 @@ def test_after_deprecation_date(self):
             with freeze_time(test_date):
                 self.assert_allowed_request("GET")
 
-            brownout_start = timeiter.get_next(datetime)
+            brownout_start = next(timeiter)
             with freeze_time(brownout_start):
                 self.assert_denied_request("GET")
 
@@ -119,13 +119,13 @@ def test_default_key(self):
             options.delete("api.deprecation.brownout-cron")
             options.delete("api.deprecation.brownout-duration")
 
-            custom_time_iter = croniter(custom_cron, test_date)
+            custom_time_iter = CronSim(custom_cron, test_date)
             custom_duration_timedelta = isodate.parse_duration(custom_duration)
-            old_brownout_start = timeiter.get_next(datetime)
+            old_brownout_start = next(timeiter)
             with freeze_time(old_brownout_start):
                 self.assert_allowed_request("GET")
 
-            new_brownout_start = custom_time_iter.get_next(datetime)
+            new_brownout_start = next(custom_time_iter)
             with freeze_time(new_brownout_start):
                 self.assert_denied_request("GET")
 
@@ -141,19 +141,19 @@ def test_custom_key(self):
         with self.settings(
             SENTRY_SELF_HOSTED=False,
         ):
-            old_brownout_start = timeiter.get_next(datetime)
+            old_brownout_start = next(timeiter)
             with freeze_time(old_brownout_start):
                 self.assert_denied_request("POST")
 
             register("override-cron", default=custom_cron)
             register("override-duration", default=custom_duration)
-            custom_time_iter = croniter(custom_cron, test_date)
+            custom_time_iter = CronSim(custom_cron, test_date)
             custom_duration_timedelta = isodate.parse_duration(custom_duration)
 
             with freeze_time(old_brownout_start):
                 self.assert_allowed_request("POST")
 
-            new_brownout_start = custom_time_iter.get_next(datetime)
+            new_brownout_start = next(custom_time_iter)
             with freeze_time(new_brownout_start):
                 self.assert_denied_request("POST")
 
@@ -162,7 +162,7 @@ def test_custom_key(self):
                 self.assert_allowed_request("POST")
 
     def test_bad_schedule_format(self):
-        brownout_start = timeiter.get_next(datetime)
+        brownout_start = next(timeiter)
         with freeze_time(brownout_start):
             with (
                 self.settings(SENTRY_SELF_HOSTED=False),