requirements: Upgrade to Django 4.0.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

analytics/views/activity_common.py

@@ -1,9 +1,9 @@
 import re
+import sys
 from datetime import datetime
 from html import escape
 from typing import Any, Collection, Dict, List, Optional, Sequence
 
-import pytz
 from django.conf import settings
 from django.db.backends.utils import CursorWrapper
 from django.template import loader
@@ -12,7 +12,12 @@ from markupsafe import Markup as mark_safe
 
 from zerver.models import UserActivity
 
-eastern_tz = pytz.timezone("US/Eastern")
+if sys.version_info < (3, 9):  # nocoverage
+    from backports import zoneinfo
+else:  # nocoverage
+    import zoneinfo
+
+eastern_tz = zoneinfo.ZoneInfo("America/New_York")
 
 
 if settings.BILLING_ENABLED:

requirements/common.in

@@ -3,7 +3,7 @@
 # and requirements/prod.txt.
 # See requirements/README.md for more detail.
 # Django itself
-Django[argon2]==3.2.*
+Django[argon2]==4.0.*
 
 # needed for NotRequired, ParamSpec
 typing-extensions
@@ -77,7 +77,7 @@ django-bmemcached
 python-dateutil
 
 # Needed for time zone work
-pytz
+backports.zoneinfo ; python_version < "3.9"
 
 # Needed for Redis
 redis

requirements/dev.txt

@@ -93,6 +93,26 @@ backoff-stubs==1.11.1 \
     --hash=sha256:3fd641261cfe9cd657ebb7fc8a1dc700efa3f1b63e82fe0235d74bb73f8b85da \
     --hash=sha256:8b56cf2cfaf64abc1623544bd725b21566b5b92cf790a97d33e7437fb131251e
     # via -r requirements/mypy.in
+backports.zoneinfo==0.2.1 ; python_version < "3.9" \
+    --hash=sha256:17746bd546106fa389c51dbea67c8b7c8f0d14b5526a579ca6ccf5ed72c526cf \
+    --hash=sha256:1b13e654a55cd45672cb54ed12148cd33628f672548f373963b0bff67b217328 \
+    --hash=sha256:1c5742112073a563c81f786e77514969acb58649bcdf6cdf0b4ed31a348d4546 \
+    --hash=sha256:4a0f800587060bf8880f954dbef70de6c11bbe59c673c3d818921f042f9954a6 \
+    --hash=sha256:5c144945a7752ca544b4b78c8c41544cdfaf9786f25fe5ffb10e838e19a27570 \
+    --hash=sha256:7b0a64cda4145548fed9efc10322770f929b944ce5cee6c0dfe0c87bf4c0c8c9 \
+    --hash=sha256:8439c030a11780786a2002261569bdf362264f605dfa4d65090b64b05c9f79a7 \
+    --hash=sha256:8961c0f32cd0336fb8e8ead11a1f8cd99ec07145ec2931122faaac1c8f7fd987 \
+    --hash=sha256:89a48c0d158a3cc3f654da4c2de1ceba85263fafb861b98b59040a5086259722 \
+    --hash=sha256:a76b38c52400b762e48131494ba26be363491ac4f9a04c1b7e92483d169f6582 \
+    --hash=sha256:da6013fd84a690242c310d77ddb8441a559e9cb3d3d59ebac9aca1a57b2e18bc \
+    --hash=sha256:e55b384612d93be96506932a786bbcde5a2db7a9e6a4bb4bffe8b733f5b9036b \
+    --hash=sha256:e81b76cace8eda1fca50e345242ba977f9be6ae3945af8d46326d776b4cf78d1 \
+    --hash=sha256:e8236383a20872c0cdf5a62b554b27538db7fa1bbec52429d8d106effbaeca08 \
+    --hash=sha256:f04e857b59d9d1ccc39ce2da1021d196e47234873820cbeaad210724b1ee28ac \
+    --hash=sha256:fadbfe37f74051d024037f223b8e001611eac868b5c5b06144ef4d8b799862f2
+    # via
+    #   -r requirements/common.in
+    #   django
 beautifulsoup4==4.11.1 \
     --hash=sha256:58d5c3d29f5a36ffeb94f02f0d786cd53014cf9b3b3951d42e0080d8a9498d30 \
     --hash=sha256:ad9aa55b65ef2808eb405f46cf74df7fcb7044d5cbc26487f96eb2ef2e436693
@@ -439,9 +459,9 @@ distro==1.7.0 \
     --hash=sha256:151aeccf60c216402932b52e40ee477a939f8d58898927378a02abbe852c1c39 \
     --hash=sha256:d596311d707e692c2160c37807f83e3820c5d539d5a83e87cfb6babd8ba3a06b
     # via zulip
-django[argon2]==3.2.14 \
-    --hash=sha256:677182ba8b5b285a4e072f3ac17ceee6aff1b5ce77fd173cc5b6a2d3dc022fcf \
-    --hash=sha256:a8681e098fa60f7c33a4b628d6fcd3fe983a0939ff1301ecacac21d0b38bad56
+django[argon2]==4.0.6 \
+    --hash=sha256:a67a793ff6827fd373555537dca0da293a63a316fe34cb7f367f898ccca3c3ae \
+    --hash=sha256:ca54ebedfcbc60d191391efbf02ba68fb52165b8bf6ccd6fe71f098cac1fe59e
     # via
     #   -r requirements/common.in
     #   django-auth-ldap
@@ -456,9 +476,8 @@ django-auth-ldap==4.1.0 \
     --hash=sha256:68870e7921e84b1a9867e268a9c8a3e573e8a0d95ea08bcf31be178f5826ff36 \
     --hash=sha256:77f749d3b17807ce8eb56a9c9c8e5746ff316567f81d5ba613495d9c7495a949
     # via -r requirements/common.in
-django-bitfield==2.1.0 \
-    --hash=sha256:158f1056e22cce450d0a49633ea77bfd84b85a2294b1ef03faa775a485f4065d \
-    --hash=sha256:a55859fd16ce4269d5ceed3e20cf8fc3c2df866f0a78b90c60a19a0e76aa5fd8
+django-bitfield==2.2.0 \
+    --hash=sha256:1b21262acc4ec0af3f82ed04498a056cd9d5452532ac02771e004835a34e0b1b
     # via -r requirements/common.in
 django-bmemcached==0.3.0 \
     --hash=sha256:4e4b7d97216dbae331c1de10e699ca22804b94ec3a90d2762dd5d146e6986a8a
@@ -1606,9 +1625,7 @@ pytz==2022.1 \
     --hash=sha256:1e760e2fe6a8163bc0b3d9a19c4f84342afa0a2affebfaa84b01b978a02ecaa7 \
     --hash=sha256:e68985985296d9a66a881eb3193b0906246245294a881e7c8afe623866ac6a5c
     # via
-    #   -r requirements/common.in
     #   babel
-    #   django
     #   moto
     #   twilio
 pyuca==1.2 \
@@ -2136,10 +2153,6 @@ types-python-dateutil==2.8.18 \
     --hash=sha256:8695c7d7a5b1aef4002f3ab4e1247e23b1d41cd7cc1286d4594c2d8c5593c991 \
     --hash=sha256:fd5ed97262b76ae684695ea38ace8dd7c1bc9491aba7eb4edf6654b7ecabc870
     # via -r requirements/mypy.in
-types-pytz==2022.1.1 \
-    --hash=sha256:4e7add70886dc2ee6ee7535c8184a26eeb0ac9dbafae9962cb882d74b9f67330 \
-    --hash=sha256:581467742f32f15fff1098698b11fd511057a2a8a7568d33b604083f2b03c24f
-    # via -r requirements/mypy.in
 types-pyyaml==6.0.9 \
     --hash=sha256:33ae75c84b8f61fddf0c63e9c7e557db9db1694ad3c2ee8628ec5efebb5a5e9b \
     --hash=sha256:b738e9ef120da0af8c235ba49d3b72510f56ef9bcc308fc8e7357100ff122284

requirements/mypy.in

@@ -24,7 +24,6 @@ types-Pillow
 types-psycopg2
 types-Pygments
 types-python-dateutil
-types-pytz
 types-PyYAML
 types-redis
 types-requests

requirements/mypy.txt

@@ -245,10 +245,6 @@ types-python-dateutil==2.8.18 \
     --hash=sha256:8695c7d7a5b1aef4002f3ab4e1247e23b1d41cd7cc1286d4594c2d8c5593c991 \
     --hash=sha256:fd5ed97262b76ae684695ea38ace8dd7c1bc9491aba7eb4edf6654b7ecabc870
     # via -r requirements/mypy.in
-types-pytz==2022.1.1 \
-    --hash=sha256:4e7add70886dc2ee6ee7535c8184a26eeb0ac9dbafae9962cb882d74b9f67330 \
-    --hash=sha256:581467742f32f15fff1098698b11fd511057a2a8a7568d33b604083f2b03c24f
-    # via -r requirements/mypy.in
 types-pyyaml==6.0.9 \
     --hash=sha256:33ae75c84b8f61fddf0c63e9c7e557db9db1694ad3c2ee8628ec5efebb5a5e9b \
     --hash=sha256:b738e9ef120da0af8c235ba49d3b72510f56ef9bcc308fc8e7357100ff122284

requirements/prod.txt

@@ -64,6 +64,26 @@ backoff==2.1.2 \
     --hash=sha256:407f1bc0f22723648a8880821b935ce5df8475cf04f7b6b5017ae264d30f6069 \
     --hash=sha256:b135e6d7c7513ba2bfd6895bc32bc8c66c6f3b0279b4c6cd866053cfd7d3126b
     # via -r requirements/common.in
+backports.zoneinfo==0.2.1 ; python_version < "3.9" \
+    --hash=sha256:17746bd546106fa389c51dbea67c8b7c8f0d14b5526a579ca6ccf5ed72c526cf \
+    --hash=sha256:1b13e654a55cd45672cb54ed12148cd33628f672548f373963b0bff67b217328 \
+    --hash=sha256:1c5742112073a563c81f786e77514969acb58649bcdf6cdf0b4ed31a348d4546 \
+    --hash=sha256:4a0f800587060bf8880f954dbef70de6c11bbe59c673c3d818921f042f9954a6 \
+    --hash=sha256:5c144945a7752ca544b4b78c8c41544cdfaf9786f25fe5ffb10e838e19a27570 \
+    --hash=sha256:7b0a64cda4145548fed9efc10322770f929b944ce5cee6c0dfe0c87bf4c0c8c9 \
+    --hash=sha256:8439c030a11780786a2002261569bdf362264f605dfa4d65090b64b05c9f79a7 \
+    --hash=sha256:8961c0f32cd0336fb8e8ead11a1f8cd99ec07145ec2931122faaac1c8f7fd987 \
+    --hash=sha256:89a48c0d158a3cc3f654da4c2de1ceba85263fafb861b98b59040a5086259722 \
+    --hash=sha256:a76b38c52400b762e48131494ba26be363491ac4f9a04c1b7e92483d169f6582 \
+    --hash=sha256:da6013fd84a690242c310d77ddb8441a559e9cb3d3d59ebac9aca1a57b2e18bc \
+    --hash=sha256:e55b384612d93be96506932a786bbcde5a2db7a9e6a4bb4bffe8b733f5b9036b \
+    --hash=sha256:e81b76cace8eda1fca50e345242ba977f9be6ae3945af8d46326d776b4cf78d1 \
+    --hash=sha256:e8236383a20872c0cdf5a62b554b27538db7fa1bbec52429d8d106effbaeca08 \
+    --hash=sha256:f04e857b59d9d1ccc39ce2da1021d196e47234873820cbeaad210724b1ee28ac \
+    --hash=sha256:fadbfe37f74051d024037f223b8e001611eac868b5c5b06144ef4d8b799862f2
+    # via
+    #   -r requirements/common.in
+    #   django
 beautifulsoup4==4.11.1 \
     --hash=sha256:58d5c3d29f5a36ffeb94f02f0d786cd53014cf9b3b3951d42e0080d8a9498d30 \
     --hash=sha256:ad9aa55b65ef2808eb405f46cf74df7fcb7044d5cbc26487f96eb2ef2e436693
@@ -272,9 +292,9 @@ distro==1.7.0 \
     --hash=sha256:151aeccf60c216402932b52e40ee477a939f8d58898927378a02abbe852c1c39 \
     --hash=sha256:d596311d707e692c2160c37807f83e3820c5d539d5a83e87cfb6babd8ba3a06b
     # via zulip
-django[argon2]==3.2.14 \
-    --hash=sha256:677182ba8b5b285a4e072f3ac17ceee6aff1b5ce77fd173cc5b6a2d3dc022fcf \
-    --hash=sha256:a8681e098fa60f7c33a4b628d6fcd3fe983a0939ff1301ecacac21d0b38bad56
+django[argon2]==4.0.6 \
+    --hash=sha256:a67a793ff6827fd373555537dca0da293a63a316fe34cb7f367f898ccca3c3ae \
+    --hash=sha256:ca54ebedfcbc60d191391efbf02ba68fb52165b8bf6ccd6fe71f098cac1fe59e
     # via
     #   -r requirements/common.in
     #   django-auth-ldap
@@ -289,9 +309,8 @@ django-auth-ldap==4.1.0 \
     --hash=sha256:68870e7921e84b1a9867e268a9c8a3e573e8a0d95ea08bcf31be178f5826ff36 \
     --hash=sha256:77f749d3b17807ce8eb56a9c9c8e5746ff316567f81d5ba613495d9c7495a949
     # via -r requirements/common.in
-django-bitfield==2.1.0 \
-    --hash=sha256:158f1056e22cce450d0a49633ea77bfd84b85a2294b1ef03faa775a485f4065d \
-    --hash=sha256:a55859fd16ce4269d5ceed3e20cf8fc3c2df866f0a78b90c60a19a0e76aa5fd8
+django-bitfield==2.2.0 \
+    --hash=sha256:1b21262acc4ec0af3f82ed04498a056cd9d5452532ac02771e004835a34e0b1b
     # via -r requirements/common.in
 django-bmemcached==0.3.0 \
     --hash=sha256:4e4b7d97216dbae331c1de10e699ca22804b94ec3a90d2762dd5d146e6986a8a
@@ -1085,10 +1104,7 @@ python3-saml==1.14.0 \
 pytz==2022.1 \
     --hash=sha256:1e760e2fe6a8163bc0b3d9a19c4f84342afa0a2affebfaa84b01b978a02ecaa7 \
     --hash=sha256:e68985985296d9a66a881eb3193b0906246245294a881e7c8afe623866ac6a5c
-    # via
-    #   -r requirements/common.in
-    #   django
-    #   twilio
+    # via twilio
 pyuca==1.2 \
     --hash=sha256:8a382fe74627f08c0d18908c0713ca4a20aad5385f077579e56208beea2893b2 \
     --hash=sha256:abaa12e1bd2c7c68ca8396ff8383bc0654a739cef3ae68fd7af58bf29af0a91e

scripts/lib/zulip_tools.py

@@ -16,7 +16,7 @@ import subprocess
 import sys
 import time
 import uuid
-from typing import Any, Dict, List, Sequence, Set
+from typing import IO, Any, Dict, List, Sequence, Set
 from urllib.parse import SplitResult
 
 DEPLOYMENTS_DIR = "/home/zulip/deployments"
@@ -445,6 +445,20 @@ def os_families() -> Set[str]:
     return {distro_info["ID"], *distro_info.get("ID_LIKE", "").split()}
 
 
+def get_tzdata_zi() -> IO[str]:
+    if sys.version_info < (3, 9):  # nocoverage
+        from backports import zoneinfo
+    else:  # nocoverage
+        import zoneinfo
+
+    for path in zoneinfo.TZPATH:
+        filename = os.path.join(path, "tzdata.zi")
+        if os.path.exists(filename):
+            return open(filename)
+    else:
+        raise RuntimeError("Missing time zone data (tzdata.zi)")
+
+
 def files_and_string_digest(filenames: Sequence[str], extra_strings: Sequence[str]) -> str:
     # see is_digest_obsolete for more context
     sha1sum = hashlib.sha1()

tools/lib/provision_inner.py

@@ -10,13 +10,13 @@ ZULIP_PATH = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__f
 
 sys.path.append(ZULIP_PATH)
 import pygments
-from pytz import VERSION as timezones_version
 
 from scripts.lib import clean_unused_caches
 from scripts.lib.zulip_tools import (
     ENDC,
     OKBLUE,
     get_dev_uuid_var_path,
+    get_tzdata_zi,
     is_digest_obsolete,
     run,
     run_as_root,
@@ -28,6 +28,11 @@ from version import PROVISION_VERSION
 VENV_PATH = "/srv/zulip-py3-venv"
 UUID_VAR_PATH = get_dev_uuid_var_path()
 
+with get_tzdata_zi() as f:
+    line = f.readline()
+    assert line.startswith("# version ")
+    timezones_version = line[len("# version ") :]
+
 
 def create_var_directories() -> None:
     # create var/coverage, var/log, etc.

tools/setup/build_timezone_values

@@ -3,7 +3,10 @@ import json
 import os
 import sys
 
-import pytz
+if sys.version_info < (3, 9):
+    from backports import zoneinfo
+else:
+    import zoneinfo
 
 ZULIP_PATH = os.path.join(os.path.dirname(os.path.abspath(__file__)), "../../")
 sys.path.insert(0, ZULIP_PATH)
@@ -13,4 +16,13 @@ from zerver.lib.timezone import get_canonical_timezone_map
 OUT_PATH = os.path.join(ZULIP_PATH, "static", "generated", "timezones.json")
 
 with open(OUT_PATH, "w") as f:
-    json.dump({"timezones": sorted(pytz.all_timezones_set - set(get_canonical_timezone_map()))}, f)
+    json.dump(
+        {
+            "timezones": sorted(
+                zoneinfo.available_timezones()
+                - {"Factory", "localtime"}
+                - set(get_canonical_timezone_map())
+            )
+        },
+        f,
+    )

version.py

@@ -48,4 +48,4 @@ API_FEATURE_LEVEL = 132
 #   historical commits sharing the same major version, in which case a
 #   minor version bump suffices.
 
-PROVISION_VERSION = "194.0"
+PROVISION_VERSION = "195.0"

zerver/lib/compatibility.py

@@ -3,7 +3,6 @@ import os
 import re
 from typing import List, Optional, Tuple
 
-import pytz
 from django.conf import settings
 from django.utils.timezone import now as timezone_now
 
@@ -16,7 +15,7 @@ from zerver.signals import get_device_browser
 if settings.PRODUCTION:  # nocoverage
     timestamp = os.path.basename(os.path.abspath(settings.DEPLOY_ROOT))
     LAST_SERVER_UPGRADE_TIME = datetime.datetime.strptime(timestamp, "%Y-%m-%d-%H-%M-%S").replace(
-        tzinfo=pytz.utc
+        tzinfo=datetime.timezone.utc
     )
 else:
     LAST_SERVER_UPGRADE_TIME = timezone_now()
@@ -31,7 +30,7 @@ def is_outdated_server(user_profile: Optional[UserProfile]) -> bool:
     git_version_path = os.path.join(settings.DEPLOY_ROOT, "version.py")
     release_build_time = datetime.datetime.utcfromtimestamp(
         os.path.getmtime(git_version_path)
-    ).replace(tzinfo=pytz.utc)
+    ).replace(tzinfo=datetime.timezone.utc)
 
     version_no_newer_than = min(LAST_SERVER_UPGRADE_TIME, release_build_time)
     deadline = version_no_newer_than + datetime.timedelta(

zerver/lib/email_notifications.py

@@ -11,7 +11,6 @@ from email.headerregistry import Address
 from typing import Any, Dict, Iterable, List, Optional, Tuple
 
 import lxml.html
-import pytz
 from bs4 import BeautifulSoup
 from django.conf import settings
 from django.contrib.auth import get_backends
@@ -46,6 +45,11 @@ from zerver.models import (
     get_user_profile_by_id,
 )
 
+if sys.version_info < (3, 9):  # nocoverage
+    from backports import zoneinfo
+else:  # nocoverage
+    import zoneinfo
+
 logger = logging.getLogger(__name__)
 
 
@@ -620,7 +624,7 @@ def followup_day2_email_delay(user: UserProfile) -> timedelta:
     user_tz = user.timezone
     if user_tz == "":
         user_tz = "UTC"
-    signup_day = user.date_joined.astimezone(pytz.timezone(user_tz)).isoweekday()
+    signup_day = user.date_joined.astimezone(zoneinfo.ZoneInfo(user_tz)).isoweekday()
     if signup_day == 5:
         # If the day is Friday then delay should be till Monday
         days_to_delay = 3

zerver/lib/test_runner.py

@@ -102,7 +102,7 @@ def process_instrumented_calls(func: Callable[[Dict[str, Any]], None]) -> None:
 
 
 SerializedSubsuite = Tuple[Type[TestSuite], List[str]]
-SubsuiteArgs = Tuple[Type["RemoteTestRunner"], int, SerializedSubsuite, bool]
+SubsuiteArgs = Tuple[Type["RemoteTestRunner"], int, SerializedSubsuite, bool, bool]
 
 
 def run_subsuite(args: SubsuiteArgs) -> Tuple[int, Any]:
@@ -110,8 +110,8 @@ def run_subsuite(args: SubsuiteArgs) -> Tuple[int, Any]:
     test_helpers.INSTRUMENTED_CALLS = []
     # The first argument is the test runner class but we don't need it
     # because we run our own version of the runner class.
-    _, subsuite_index, subsuite, failfast = args
-    runner = RemoteTestRunner(failfast=failfast)
+    _, subsuite_index, subsuite, failfast, buffer = args
+    runner = RemoteTestRunner(failfast=failfast, buffer=buffer)
     result = runner.run(deserialize_suite(subsuite))
     # Now we send instrumentation related events. This data will be
     # appended to the data structure in the main thread. For Mypy,
@@ -237,8 +237,14 @@ class ParallelTestSuite(django_runner.ParallelTestSuite):
     run_subsuite = run_subsuite
     init_worker = init_worker
 
-    def __init__(self, suite: TestSuite, processes: int, failfast: bool) -> None:
-        super().__init__(suite, processes, failfast)
+    def __init__(
+        self,
+        subsuites: List[TestSuite],
+        processes: int,
+        failfast: bool = False,
+        buffer: bool = False,
+    ) -> None:
+        super().__init__(subsuites=subsuites, processes=processes, failfast=failfast, buffer=buffer)
         # We can't specify a consistent type for self.subsuites, since
         # the whole idea here is to monkey-patch that so we can use
         # most of django_runner.ParallelTestSuite with our own suite

zerver/lib/timezone.py

@@ -1,16 +1,13 @@
 from functools import lru_cache
-from io import TextIOWrapper
 from typing import Dict
 
-import pytz
+from scripts.lib.zulip_tools import get_tzdata_zi
 
 
 @lru_cache(maxsize=None)
 def get_canonical_timezone_map() -> Dict[str, str]:
     canonical = {}
-    with TextIOWrapper(
-        pytz.open_resource("tzdata.zi")  # type: ignore[attr-defined] # Unclear if this is part of the public pytz API
-    ) as f:
+    with get_tzdata_zi() as f:
         for line in f:
             if line.startswith("L "):
                 l, name, alias = line.split()

zerver/lib/validator.py

@@ -28,6 +28,7 @@ for any particular type of object.
 
 """
 import re
+import sys
 from dataclasses import dataclass
 from datetime import datetime
 from decimal import Decimal
@@ -49,7 +50,6 @@ from typing import (
 )
 
 import orjson
-import pytz
 from django.core.exceptions import ValidationError
 from django.core.validators import URLValidator, validate_email
 from django.utils.translation import gettext as _
@@ -58,6 +58,11 @@ from zerver.lib.exceptions import InvalidJSONError, JsonableError
 from zerver.lib.timezone import canonicalize_timezone
 from zerver.lib.types import ProfileFieldData, Validator
 
+if sys.version_info < (3, 9):  # nocoverage
+    from backports import zoneinfo
+else:  # nocoverage
+    import zoneinfo
+
 ResultT = TypeVar("ResultT")
 
 
@@ -127,6 +132,17 @@ def check_long_string(var_name: str, val: object) -> str:
     return check_capped_string(500)(var_name, val)
 
 
+def check_timezone(var_name: str, val: object) -> str:
+    s = check_string(var_name, val)
+    try:
+        zoneinfo.ZoneInfo(s)
+    except (ValueError, zoneinfo.ZoneInfoNotFoundError):
+        raise ValidationError(
+            _("{var_name} is not a recognized time zone").format(var_name=var_name)
+        )
+    return s
+
+
 def check_date(var_name: str, val: object) -> str:
     if not isinstance(val, str):
         raise ValidationError(_("{var_name} is not a string").format(var_name=var_name))
@@ -564,10 +580,12 @@ def to_decimal(var_name: str, s: str) -> Decimal:
 
 
 def to_timezone_or_empty(var_name: str, s: str) -> str:
-    if s in pytz.all_timezones_set:
-        return canonicalize_timezone(s)
-    else:
+    try:
+        zoneinfo.ZoneInfo(s)
+    except (ValueError, zoneinfo.ZoneInfoNotFoundError):
         return ""
+    else:
+        return canonicalize_timezone(s)
 
 
 def to_converted_or_fallback(

zerver/models.py

@@ -1810,7 +1810,7 @@ class UserProfile(AbstractBaseUser, PermissionsMixin, UserBaseSettings):
     )
     default_all_public_streams: bool = models.BooleanField(default=False)
 
-    # A time zone name from the `tzdata` database, as found in pytz.all_timezones.
+    # A time zone name from the `tzdata` database, as found in zoneinfo.available_timezones().
     #
     # The longest existing name is 32 characters long, so max_length=40 seems
     # like a safe choice.

zerver/signals.py

@@ -1,6 +1,6 @@
+import sys
 from typing import Any, Optional
 
-import pytz
 from django.conf import settings
 from django.contrib.auth.signals import user_logged_in, user_logged_out
 from django.dispatch import receiver
@@ -13,6 +13,11 @@ from zerver.lib.queue import queue_json_publish
 from zerver.lib.send_email import FromAddress
 from zerver.models import UserProfile
 
+if sys.version_info < (3, 9):  # nocoverage
+    from backports import zoneinfo
+else:  # nocoverage
+    import zoneinfo
+
 JUST_CREATED_THRESHOLD = 60
 
 
@@ -81,7 +86,7 @@ def email_on_new_login(sender: Any, user: UserProfile, request: Any, **kwargs: A
         user_tz = user.timezone
         if user_tz == "":
             user_tz = timezone_get_current_timezone_name()
-        local_time = timezone_now().astimezone(pytz.timezone(user_tz))
+        local_time = timezone_now().astimezone(zoneinfo.ZoneInfo(user_tz))
         if user.twenty_four_hour_time:
             hhmm_string = local_time.strftime("%H:%M")
         else:

zerver/tests/test_home.py

@@ -6,7 +6,6 @@ from typing import TYPE_CHECKING, Any
 from unittest.mock import patch
 
 import orjson
-import pytz
 from django.conf import settings
 from django.test import override_settings
 from django.utils.timezone import now as timezone_now
@@ -878,7 +877,7 @@ class HomeTest(ZulipTestCase):
         # Check when server_upgrade_nag_deadline > last_server_upgrade_time
         hamlet = self.example_user("hamlet")
         iago = self.example_user("iago")
-        now = LAST_SERVER_UPGRADE_TIME.replace(tzinfo=pytz.utc)
+        now = LAST_SERVER_UPGRADE_TIME.replace(tzinfo=datetime.timezone.utc)
         with patch("zerver.lib.compatibility.timezone_now", return_value=now + timedelta(days=10)):
             self.assertEqual(is_outdated_server(iago), False)
             self.assertEqual(is_outdated_server(hamlet), False)

zerver/tests/test_message_send.py

@@ -1,9 +1,9 @@
 import datetime
+import sys
 from typing import TYPE_CHECKING, Any, List, Mapping, Optional, Set
 from unittest import mock
 
 import orjson
-import pytz
 from django.conf import settings
 from django.db.models import Q
 from django.test import override_settings
@@ -65,6 +65,11 @@ from zerver.models import (
 )
 from zerver.views.message_send import InvalidMirrorInput
 
+if sys.version_info < (3, 9):  # nocoverage
+    from backports import zoneinfo
+else:  # nocoverage
+    import zoneinfo
+
 if TYPE_CHECKING:
     from django.test.client import _MonkeyPatchedWSGIResponse as TestHttpResponse
 
@@ -1432,8 +1437,8 @@ class ScheduledMessageTest(ZulipTestCase):
         message = self.last_scheduled_message()
         self.assert_json_success(result)
         self.assertEqual(message.content, "Test message 6")
-        local_tz = pytz.timezone(tz_guess)
-        utz_defer_until = local_tz.normalize(local_tz.localize(defer_until))
+        local_tz = zoneinfo.ZoneInfo(tz_guess)
+        utz_defer_until = defer_until.replace(tzinfo=local_tz)
         self.assertEqual(message.scheduled_timestamp, convert_to_UTC(utz_defer_until))
         self.assertEqual(message.delivery_type, ScheduledMessage.SEND_LATER)
 
@@ -1446,8 +1451,8 @@ class ScheduledMessageTest(ZulipTestCase):
         message = self.last_scheduled_message()
         self.assert_json_success(result)
         self.assertEqual(message.content, "Test message 7")
-        local_tz = pytz.timezone(user.timezone)
-        utz_defer_until = local_tz.normalize(local_tz.localize(defer_until))
+        local_tz = zoneinfo.ZoneInfo(user.timezone)
+        utz_defer_until = defer_until.replace(tzinfo=local_tz)
         self.assertEqual(message.scheduled_timestamp, convert_to_UTC(utz_defer_until))
         self.assertEqual(message.delivery_type, ScheduledMessage.SEND_LATER)
 

zerver/tests/test_new_users.py

@@ -1,8 +1,8 @@
 import datetime
+import sys
 from typing import Sequence
 from unittest import mock
 
-import pytz
 from django.conf import settings
 from django.core import mail
 from django.test import override_settings
@@ -16,6 +16,11 @@ from zerver.lib.test_classes import ZulipTestCase
 from zerver.models import Message, Realm, Recipient, Stream, UserProfile, get_realm
 from zerver.signals import JUST_CREATED_THRESHOLD, get_device_browser, get_device_os
 
+if sys.version_info < (3, 9):  # nocoverage
+    from backports import zoneinfo
+else:  # nocoverage
+    import zoneinfo
+
 
 class SendLoginEmailTest(ZulipTestCase):
     """
@@ -47,7 +52,7 @@ class SendLoginEmailTest(ZulipTestCase):
             firefox_windows = (
                 "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:47.0) Gecko/20100101 Firefox/47.0"
             )
-            user_tz = pytz.timezone(user.timezone)
+            user_tz = zoneinfo.ZoneInfo(user.timezone)
             mock_time = datetime.datetime(year=2018, month=1, day=1, tzinfo=datetime.timezone.utc)
             reference_time = mock_time.astimezone(user_tz).strftime("%A, %B %d, %Y at %I:%M%p %Z")
             with mock.patch("zerver.signals.timezone_now", return_value=mock_time):

zerver/tests/test_settings.py

@@ -410,6 +410,8 @@ class ChangeSettingsTest(ZulipTestCase):
             expected_error_msg = f"Invalid {setting_name}"
             if setting_name == "notification_sound":
                 expected_error_msg = f"Invalid notification sound '{invalid_value}'"
+            elif setting_name == "timezone":
+                expected_error_msg = "timezone is not a recognized time zone"
             self.assert_json_error(result, expected_error_msg)
             hamlet = self.example_user("hamlet")
             self.assertNotEqual(getattr(hamlet, setting_name), invalid_value)

zerver/tests/test_timezone.py

@@ -1,11 +1,16 @@
+import sys
 from datetime import datetime
 
-import pytz
 from django.utils.timezone import now as timezone_now
 
 from zerver.lib.test_classes import ZulipTestCase
 from zerver.lib.timezone import canonicalize_timezone, common_timezones
 
+if sys.version_info < (3, 9):  # nocoverage
+    from backports import zoneinfo
+else:  # nocoverage
+    import zoneinfo
+
 
 class TimeZoneTest(ZulipTestCase):
     def test_canonicalize_timezone(self) -> None:
@@ -32,10 +37,11 @@ class TimeZoneTest(ZulipTestCase):
         now = timezone_now()
         dates = [datetime(now.year, 6, 21), datetime(now.year, 12, 21)]
         extra = {*common_timezones.items(), *ambiguous_abbrevs}
-        for name in pytz.all_timezones:
-            tz = pytz.timezone(name)
+        for name in zoneinfo.available_timezones():
+            tz = zoneinfo.ZoneInfo(name)
             for date in dates:
                 abbrev = tz.tzname(date)
+                assert abbrev is not None
                 if abbrev.startswith(("-", "+")):
                     continue
                 delta = tz.utcoffset(date)

zerver/views/message_send.py

@@ -1,6 +1,6 @@
+import sys
 from typing import Iterable, Optional, Sequence, Union, cast
 
-import pytz
 from dateutil.parser import parse as dateparser
 from django.core import validators
 from django.core.exceptions import ValidationError
@@ -36,6 +36,11 @@ from zerver.models import (
     get_user_including_cross_realm,
 )
 
+if sys.version_info < (3, 9):  # nocoverage
+    from backports import zoneinfo
+else:  # nocoverage
+    import zoneinfo
+
 
 class InvalidMirrorInput(Exception):
     pass
@@ -159,8 +164,8 @@ def handle_deferred_message(
 
     deliver_at_usertz = deliver_at
     if deliver_at_usertz.tzinfo is None:
-        user_tz = pytz.timezone(local_tz)
-        deliver_at_usertz = user_tz.normalize(user_tz.localize(deliver_at))
+        user_tz = zoneinfo.ZoneInfo(local_tz)
+        deliver_at_usertz = deliver_at.replace(tzinfo=user_tz)
     deliver_at = convert_to_UTC(deliver_at_usertz)
 
     if deliver_at <= timezone_now():

zerver/views/user_settings.py

@@ -1,6 +1,5 @@
 from typing import Any, Dict, Optional
 
-import pytz
 from django.conf import settings
 from django.contrib.auth import authenticate, update_session_auth_hash
 from django.core.exceptions import ValidationError
@@ -42,7 +41,13 @@ from zerver.lib.response import json_success
 from zerver.lib.send_email import FromAddress, send_email
 from zerver.lib.sounds import get_available_notification_sounds
 from zerver.lib.upload import upload_avatar_image
-from zerver.lib.validator import check_bool, check_int, check_int_in, check_string_in
+from zerver.lib.validator import (
+    check_bool,
+    check_int,
+    check_int_in,
+    check_string_in,
+    check_timezone,
+)
 from zerver.models import (
     EmailChangeStatus,
     UserProfile,
@@ -164,9 +169,7 @@ def json_change_settings(
     demote_inactive_streams: Optional[int] = REQ(
         json_validator=check_int_in(UserProfile.DEMOTE_STREAMS_CHOICES), default=None
     ),
-    timezone: Optional[str] = REQ(
-        str_validator=check_string_in(pytz.all_timezones_set), default=None
-    ),
+    timezone: Optional[str] = REQ(str_validator=check_timezone, default=None),
     email_notifications_batching_period_seconds: Optional[int] = REQ(
         json_validator=check_int, default=None
     ),