Remove dependency on pytz

pytz will be removed from RHEL/CentOS 10 because of the built-in
zoneinfo[1].

Because the current usage of pytz can be very easily replaced, this
removes the dependency on pytz.

[1] https://issues.redhat.com/browse/RHEL-219

Change-Id: Ib90acd5ebb9a0c2cffd643bda0ecdafa97552008

keystone/common/sql/core.py

@@ -20,7 +20,6 @@ CONF() because it sets up configuration options.
 """
 import datetime
 import functools
-import pytz
 
 from oslo_db import exception as db_exception
 from oslo_db import options as db_options
@@ -148,7 +147,7 @@ class DateTimeInt(sql_types.TypeDecorator):
     """
 
     impl = sql.BigInteger
-    epoch = datetime.datetime.fromtimestamp(0, tz=pytz.UTC)
+    epoch = datetime.datetime.fromtimestamp(0, tz=datetime.timezone.utc)
     # NOTE(ralonsoh): set to True as any other TypeDecorator in SQLAlchemy
     # https://docs.sqlalchemy.org/en/14/core/custom_types.html# \
     #   sqlalchemy.types.TypeDecorator.cache_ok
@@ -163,7 +162,7 @@ class DateTimeInt(sql_types.TypeDecorator):
                 raise ValueError(_('Programming Error: value to be stored '
                                    'must be a datetime object.'))
             value = timeutils.normalize_time(value)
-            value = value.replace(tzinfo=pytz.UTC)
+            value = value.replace(tzinfo=datetime.timezone.utc)
             # NOTE(morgan): We are casting this to an int, and ensuring we
             # preserve microsecond data by moving the decimal. This is easier
             # than being concerned with the differences in Numeric types in
@@ -177,9 +176,11 @@ class DateTimeInt(sql_types.TypeDecorator):
             # Convert from INT to appropriate micro-second float (microseconds
             # after the decimal) from what was stored to the DB
             value = float(value) / 1000000
-            # NOTE(morgan): Explictly use timezone "pytz.UTC" to ensure we are
-            # not adjusting the actual datetime object from what we stored.
-            dt_obj = datetime.datetime.fromtimestamp(value, tz=pytz.UTC)
+            # NOTE(morgan): Explictly use timezone "datetime.timezone.utc" to
+            # ensure we are not adjusting the actual datetime object from what
+            # we stored.
+            dt_obj = datetime.datetime.fromtimestamp(value,
+                                                     tz=datetime.timezone.utc)
             # Return non-tz aware datetime object (as keystone expects)
             return timeutils.normalize_time(dt_obj)
 

requirements.txt

@@ -38,4 +38,3 @@ jsonschema>=3.2.0 # MIT
 pycadf!=2.0.0,>=1.1.0 # Apache-2.0
 msgpack>=0.5.0 # Apache-2.0
 osprofiler>=1.4.0 # Apache-2.0
-pytz>=2013.6 # MIT

test-requirements.txt

@@ -3,7 +3,6 @@ flake8-docstrings
 bashate~=2.1.0 # Apache-2.0
 stestr>=1.0.0 # Apache-2.0
 freezegun>=0.3.6 # Apache-2.0
-pytz>=2013.6 # MIT
 
 # Include drivers for opportunistic testing.
 oslo.db[fixtures,mysql,postgresql]>=6.0.0 # Apache-2.0