Use zoneinfo instead of pytz if available

The zoneinfo module was introduced in Python 3.9. We can use that
built-in module instead of the 3rd party library (pytz).

This is based on change I1f88bdadc68bfa726eac1da1c5824c1ed352ad98 in
oslo.utils.

Change-Id: If6aeb6c837d413c9d9a544a80c4c736efc8455fc

aodh/api/controllers/v2/alarms.py

@@ -30,14 +30,20 @@ from oslo_utils import timeutils
 from oslo_utils import uuidutils
 import pecan
 from pecan import rest
-import pytz
-import pytz.exceptions
 from stevedore import extension
 from urllib import parse as urlparse
 import wsme
 from wsme import types as wtypes
 import wsmeext.pecan as wsme_pecan
 
+try:
+    import zoneinfo
+except ImportError:
+    # zoneinfo is available in Python >= 3.9
+    import pytz
+    import pytz.exceptions
+    zoneinfo = None
+
 import aodh
 from aodh.api.controllers.v2 import base
 from aodh.api.controllers.v2 import utils as v2_utils
@@ -176,9 +182,12 @@ class AlarmTimeConstraint(base.Base):
     @staticmethod
     def validate(tc):
         if tc.timezone:
+            checker = zoneinfo.ZoneInfo if zoneinfo else pytz.timezone
+            exc = (zoneinfo.ZoneInfoNotFoundError if zoneinfo else
+                   pytz.exceptions.UnknownTimeZoneError)
             try:
-                pytz.timezone(tc.timezone)
-            except pytz.exceptions.UnknownTimeZoneError:
+                checker(tc.timezone)
+            except exc:
                 raise base.ClientSideError(_("Timezone %s is not valid")
                                            % tc.timezone)
         return tc

aodh/evaluator/__init__.py

@@ -27,9 +27,15 @@ from oslo_config import cfg
 from oslo_log import log
 from oslo_utils import timeutils
 from oslo_utils import uuidutils
-import pytz
 from stevedore import extension
 
+try:
+    import zoneinfo
+except ImportError:
+    # zoneinfo is available in Python >= 3.9
+    import pytz
+    zoneinfo = None
+
 import aodh
 from aodh import coordination
 from aodh import keystone_client
@@ -148,9 +154,13 @@ class Evaluator(object, metaclass=abc.ABCMeta):
         if not alarm.time_constraints:
             return True
 
-        now_utc = timeutils.utcnow().replace(tzinfo=pytz.utc)
+        now_utc = timeutils.utcnow().replace(tzinfo=datetime.timezone.utc)
         for tc in alarm.time_constraints:
-            tz = pytz.timezone(tc['timezone']) if tc['timezone'] else None
+            if zoneinfo:
+                tz = (zoneinfo.ZoneInfo(tc['timezone'])
+                      if tc['timezone'] else None)
+            else:
+                tz = pytz.timezone(tc['timezone']) if tc['timezone'] else None
             now_tz = now_utc.astimezone(tz) if tz else now_utc
             start_cron = croniter.croniter(tc['start'], now_tz)
             if cls._is_exact_match(start_cron, now_tz):

aodh/tests/unit/evaluator/test_gnocchi.py

@@ -22,7 +22,13 @@ from unittest import mock
 from gnocchiclient import exceptions
 from oslo_utils import timeutils
 from oslo_utils import uuidutils
-import pytz
+
+try:
+    import zoneinfo
+except ImportError:
+    # zoneinfo is available in Python >= 3.9
+    import pytz
+    zoneinfo = None
 
 from aodh.evaluator import gnocchi
 from aodh import messaging
@@ -351,9 +357,12 @@ class TestGnocchiResourceThresholdEvaluate(TestGnocchiEvaluatorBase):
              'duration': 10800,  # 3 hours
              'timezone': 'Europe/Ljubljana'}
         ]
-        dt = datetime.datetime(2014, 1, 1, 15, 0, 0,
-                               tzinfo=pytz.timezone('Europe/Ljubljana'))
-        mock_utcnow.return_value = dt.astimezone(pytz.UTC)
+        if zoneinfo:
+            tzinfo = zoneinfo.ZoneInfo('Europe/Ljubljana')
+        else:
+            tzinfo = pytz.timezone('Europe/Ljubljana')
+        dt = datetime.datetime(2014, 1, 1, 15, 0, 0, tzinfo=tzinfo)
+        mock_utcnow.return_value = dt.astimezone(datetime.timezone.utc)
         self.client.metric.get_measures.return_value = []
         self._evaluate_all_alarms()
         self._assert_all_alarms('ok')
@@ -373,9 +382,12 @@ class TestGnocchiResourceThresholdEvaluate(TestGnocchiEvaluatorBase):
              'duration': 10800,  # 3 hours
              'timezone': 'Europe/Ljubljana'}
         ]
-        dt = datetime.datetime(2014, 1, 1, 12, 0, 0,
-                               tzinfo=pytz.timezone('Europe/Ljubljana'))
-        mock_utcnow.return_value = dt.astimezone(pytz.UTC)
+        if zoneinfo:
+            tzinfo = zoneinfo.ZoneInfo('Europe/Ljubljana')
+        else:
+            tzinfo = pytz.timezone('Europe/Ljubljana')
+        dt = datetime.datetime(2014, 1, 1, 12, 0, 0, tzinfo=tzinfo)
+        mock_utcnow.return_value = dt.astimezone(datetime.timezone.utc)
         self.client.metric.get_measures.return_value = []
         self._evaluate_all_alarms()
         self._assert_all_alarms('insufficient data')

requirements.txt

@@ -19,7 +19,7 @@ oslo.messaging>=5.2.0 # Apache-2.0
 oslo.middleware>=3.22.0 # Apache-2.0
 oslo.utils>=3.5.0 # Apache-2.0
 python-keystoneclient>=1.6.0
-pytz>=2013.6
+pytz>=2013.6;python_version<"3.9" # MIT
 requests>=2.5.2
 stevedore>=1.5.0 # Apache-2.0
 SQLAlchemy>=1.4.1
@@ -34,3 +34,4 @@ python-observabilityclient>=0.0.4
 python-octaviaclient>=1.8.0
 python-dateutil>=2.8.2  # BSD
 python-heatclient>=1.17.0
+tzdata>=2022.4;python_version>="3.9" # MIT