ZoneInfoNotFoundError: 'No time zone found with key UTC' due to missing tzdata package

[ahmed-arb]

Description

The credentials service crashes with a ZoneInfoNotFoundError when handling requests because the tzdata Python package is not installed in the Docker image. This causes a 500 error on every request, including /admin.

Error

ModuleNotFoundError: No module named 'tzdata'

Which leads to:

zoneinfo._common.ZoneInfoNotFoundError: 'No time zone found with key UTC'

The full chain is: Django's timezone context processor calls zoneinfo.ZoneInfo(settings.TIME_ZONE), which attempts to load timezone data via the tzdata package. Since the package is missing and the system tzdata files are apparently not available either, the lookup fails — even for UTC.

Steps to Reproduce

1. Run credentials service via Tutor
2. Navigate to any page (e.g. /admin)
3. Observe HTTP 500 response

Environment

• Python 3.11.9
• Django (via Open edX credentials)
• Tutor v20+

Workaround

A Tutor plugin that installs tzdata into the credentials image:

from tutor import hooks

hooks.Filters.ENV_PATCHES.add_item(
    (
        "credentials-dockerfile-post-python-requirements",
        "RUN --mount=type=cache,target=/openedx/.cache/pip,sharing=shared pip install tzdata",
    )
)

Suggested Fix

Add tzdata to the Python requirements for the credentials Docker image. On Python 3.9+ (especially on minimal/Alpine-style images that lack system timezone data), the tzdata package is the expected fallback for zoneinfo and should be an explicit dependency.