A timezone error on `python3.12` and `alembic[tz]`?

[Danipulok]

Describe the bug
Async API mode.
I used config templates from here.
I used pip install alembic[tz]:

$ pip install alembic[tz]==1.13.3
Requirement already satisfied: alembic==1.13.3 in d:\code\project\.venv\lib\site-packages (from alembic[tz]==1.13.3) (1.13.3)
Requirement already satisfied: SQLAlchemy>=1.3.0 in d:\code\project\.venv\lib\site-packages (from alembic==1.13.3->alembic[tz]==1.13.3) (2.0.36)
Requirement already satisfied: Mako in d:\code\project\.venv\lib\site-packages (from alembic==1.13.3->alembic[tz]==1.13.3) (1.3.6)
Requirement already satisfied: typing-extensions>=4 in d:\code\project\.venv\lib\site-packages (from alembic==1.13.3->alembic[tz]==1.13.3) (4.12.2)
Requirement already satisfied: greenlet!=0.4.17 in d:\code\project\.venv\lib\site-packages (from SQLAlchemy>=1.3.0->alembic==1.13.3->alembic[tz]==1.13.3) (3.1.1)     
Requirement already satisfied: MarkupSafe>=0.9.2 in d:\code\project\.venv\lib\site-packages (from Mako->alembic==1.13.3->alembic[tz]==1.13.3) (3.0.2)

But when I run alembic revision --autogenerate -m "msg", I get:

INFO  [alembic.runtime.migration] Context impl PostgresqlImpl.
INFO  [alembic.runtime.migration] Will assume transactional DDL.
INFO  [alembic.autogenerate.compare] Detected added table 'users'
INFO  [alembic.autogenerate.compare] Detected added index ''ix_users_created_at'' on '('created_at',)'
ERROR [alembic.util.messaging] Can't locate timezone: UTC
FAILED: Can't locate timezone: UTC

Expected behavior
Everything should work if I installed alembic[tz]?
But I also found this issue on SO: https://stackoverflow.com/questions/77698777/how-to-change-timezone-in-alembic-for-sqlalchemy
After I install tzdata, the same command stated working.

To Reproduce
Use this alembic.ini: https://github.com/sqlalchemy/alembic/blob/bd50ba325b10a1a9cdb452fe40c96f959825797c/alembic/templates/async/alembic.ini.mako
And add:

timezone = UTC

Versions.

• OS: Windows 10
• Python: 3.12.3
• Alembic: 1.13.3
• SQLAlchemy: 2.0.36
• Database: postgres
• DBAPI: asyncpg==0.30.0

[zzzeek]

if you're on python 3.12 the alembic[tz] target does not install anything additional, it just installs zoneinfo.

per zoneinfo: https://docs.python.org/3/library/zoneinfo.html it uses system databases if available otherwise will fall back to tzdata

@CaselIT why do we have this target in the first place and should it install tzdata on all versions?

[Danipulok]

Thanks a lot for the quick response!
Really appreciate

Hm, this seems really strange, because if I uninstall tzdata, I get the following:

$ python -c "from zoneinfo import available_timezones; print(available_timezones())"
set()

When I install tzdata again, everything's okay:

$ python -c "from zoneinfo import available_timezones; print(available_timezones())"
{'America/Puerto_Rico', 'America/Panama', 'America/Port_of_Spain', 'Pacific/Saipan', 'Europe/Bratislava', 'Pacific/Honolulu', 'Europe/Luxembourg', 'America/Recife', 'America/Cuiaba', 'America/Paramarib
o', 'Europe/Sarajevo', 'America/North_Dakota/New_Salem', 'Asia/Gaza', 'America/Ojinaga', 'Asia/Macau', 'Asia/Manila', 'Asia/Oral', 'America/Buenos_Aires', 'Europe/Ljubljana', 'Australia/North', 'Asia/C
hita', 'US/Samoa', 'Pacific/Galapagos' ...

So I think it would be useful if tzdata would always be installed on alembic[tz], if by default zoneinfo does not provide any timezones?

[CaselIT]

@CaselIT why do we have this target in the first place and should it install tzdata on all versions?

if by default zoneinfo does not provide any timezones?

I incorrectly assumed that utc etc was always included, if not then I think it makes sense to always install tzdata in the tz extra

[Danipulok]

Maybe then I should create a PR for this?
I would really like to do it

The question is should I pin the tzdata version or no?

[CaselIT]

Maybe then I should create a PR for this?

that would be great!

The question is should I pin the tzdata version or no?

I don't think we need to, unless zoneinfo requires a min version to work

[sqla-tester]

Danipulok has proposed a fix for this issue in the main branch:

fix(requirements): add tzdata to tz extras; fixes #1556 https://gerrit.sqlalchemy.org/c/sqlalchemy/alembic/+/5583

[sqla-tester]

Danipulok has proposed a fix for this issue in the main branch:

fix(requirements): add tzdata to tz extras; fixes #1556 https://gerrit.sqlalchemy.org/c/sqlalchemy/alembic/+/5583