Migrate from pytz to zoneinfo, list (close to) all time zones

https://listman.redhat.com/archives/anaconda-devel-list/2021-February/msg00020.html

Python's zoneinfo does not have any concept of "common timezones".
Hence, we show all zones with slash in them, except some weird Etc ones.

This effectively adds about 17% of zones, today, that means:

    Africa/Asmera
    Africa/Timbuktu
    America/Argentina/ComodRivadavia
    America/Atka
    America/Buenos_Aires
    America/Catamarca
    America/Coral_Harbour
    America/Cordoba
    America/Ensenada
    America/Fort_Wayne
    America/Godthab
    America/Indianapolis
    America/Jujuy
    America/Knox_IN
    America/Louisville
    America/Mendoza
    America/Montreal
    America/Porto_Acre
    America/Rosario
    America/Santa_Isabel
    America/Shiprock
    America/Virgin
    Antarctica/South_Pole
    Asia/Ashkhabad
    Asia/Calcutta
    Asia/Chongqing
    Asia/Chungking
    Asia/Dacca
    Asia/Harbin
    Asia/Istanbul
    Asia/Kashgar
    Asia/Katmandu
    Asia/Macao
    Asia/Rangoon
    Asia/Saigon
    Asia/Tel_Aviv
    Asia/Thimbu
    Asia/Ujung_Pandang
    Asia/Ulan_Bator
    Atlantic/Faeroe
    Atlantic/Jan_Mayen
    Australia/ACT
    Australia/Canberra
    Australia/Currie
    Australia/LHI
    Australia/NSW
    Australia/North
    Australia/Queensland
    Australia/South
    Australia/Tasmania
    Australia/Victoria
    Australia/West
    Australia/Yancowinna
    Brazil/Acre
    Brazil/DeNoronha
    Brazil/East
    Brazil/West
    Canada/Saskatchewan
    Canada/Yukon
    Chile/Continental
    Chile/EasterIsland
    Europe/Belfast
    Europe/Nicosia
    Europe/Tiraspol
    Mexico/BajaNorte
    Mexico/BajaSur
    Mexico/General
    Pacific/Johnston
    Pacific/Ponape
    Pacific/Samoa
    Pacific/Truk
    Pacific/Yap
    US/Aleutian
    US/East-Indiana
    US/Indiana-Starke
    US/Michigan
    US/Samoa

See also rhinstaller#3167 (comment) for why is that OK.

anaconda.spec.in

@@ -108,7 +108,6 @@ Requires: subscription-manager >= %{subscriptionmanagerver}
 # which is apparently great for containers but unhelpful for the rest of us
 Requires: cracklib-dicts
 
-Requires: python3-pytz
 Requires: teamd
 %ifarch s390 s390x
 Requires: openssh

pyanaconda/isys/__init__.py

@@ -28,7 +28,7 @@
 import blivet.arch
 import time
 import datetime
-import pytz
+import zoneinfo
 
 from pyanaconda.anaconda_loggers import get_module_logger
 log = get_module_logger(__name__)
@@ -88,7 +88,7 @@ def set_system_date_time(year=None, month=None, day=None, hour=None, minute=None
 
     """
 
-    utc = pytz.UTC
+    utc = zoneinfo.ZoneInfo(key='UTC')
     # If no timezone is set, use UTC
     if not tz:
         tz = utc
@@ -104,13 +104,12 @@ def set_system_date_time(year=None, month=None, day=None, hour=None, minute=None
     minute = minute if minute is not None else now.minute
     second = second if second is not None else now.second
 
-    set_date = tz.localize(datetime.datetime(year, month, day, hour, minute, second))
+    set_date = datetime.datetime(year, month, day, hour, minute, second, tzinfo=tz)
 
     # Calculate the number of seconds between this time and timestamp 0
-    # see pytz docs, search for "Converting between timezones"
     # pylint bug here: https://github.com/PyCQA/pylint/issues/1104
     # pylint: disable=no-value-for-parameter
-    epoch = utc.localize(datetime.datetime.utcfromtimestamp(0)).astimezone(tz)
+    epoch = datetime.datetime.fromtimestamp(0, tz=utc).astimezone(tz)
     timestamp = (set_date - epoch).total_seconds()
 
     set_system_time(int(timestamp))

pyanaconda/timezone.py

@@ -22,9 +22,10 @@
 
 """
 
-import pytz
 import langtable
+import zoneinfo
 from collections import OrderedDict
+from functools import cache
 
 from pyanaconda.core import util
 from pyanaconda.core.constants import THREAD_STORAGE
@@ -38,8 +39,7 @@
 from pyanaconda.anaconda_loggers import get_module_logger
 log = get_module_logger(__name__)
 
-# The following zones are not in pytz.common_timezones and
-# Etc category in pytz.all_timezones includes some more,
+# The Etc category in zoneinfo.available_timezones() includes some more,
 # however confusing ones (like UCT, GMT+0, GMT-0,...)
 ETC_ZONES = ['GMT+1', 'GMT+2', 'GMT+3', 'GMT+4', 'GMT+5', 'GMT+6', 'GMT+7',
              'GMT+8', 'GMT+9', 'GMT+10', 'GMT+11', 'GMT+12',
@@ -126,6 +126,18 @@ def get_preferred_timezone(territory):
     return timezones[0]
 
 
+@cache
+def all_timezones():
+    """
+    Get all timezones, but with the Etc zones reduced. Cached.
+
+    :rtype: set
+
+    """
+    etc_zones = {"Etc/" + zone for zone in ETC_ZONES}
+    return zoneinfo.available_timezones() | etc_zones
+
+
 def get_all_regions_and_timezones():
     """
     Get a dictionary mapping the regions to the list of their timezones.
@@ -136,15 +148,14 @@ def get_all_regions_and_timezones():
 
     result = OrderedDict()
 
-    for tz in pytz.common_timezones:
+    for tz in sorted(all_timezones()):
         parts = tz.split("/", 1)
 
         if len(parts) > 1:
             if parts[0] not in result:
                 result[parts[0]] = set()
             result[parts[0]].add(parts[1])
 
-    result["Etc"] = set(ETC_ZONES)
     return result
 
 
@@ -157,9 +168,7 @@ def is_valid_timezone(timezone):
 
     """
 
-    etc_zones = ["Etc/" + zone for zone in ETC_ZONES]
-
-    return timezone in pytz.common_timezones + etc_zones
+    return timezone in all_timezones()
 
 
 def get_timezone(timezone):
@@ -170,4 +179,4 @@ def get_timezone(timezone):
     :rtype: datetime.tzinfo
     """
 
-    return pytz.timezone(timezone)
+    return zoneinfo.ZoneInfo(timezone)