[CT-2558] [Feature] Make run_started_at an aware Python datetime

[dbeatty10]

Is this your first time submitting a feature request?

• I have read the expectations for open source contributors
• I have searched the existing issues, and I could not find an existing issue for this feature
• I am requesting a straightforward extension of existing dbt functionality, rather than a Big Idea better suited to a discussion

Describe the feature

In the following source code, we can see how run_started_at is a naive(!) Python datetime representing the current time in UTC:

• dbt-core/core/dbt/context/base.py

  Line 565 in dffbb6a

  def run_started_at(self) -> Optional[datetime.datetime]:

• dbt-core/core/dbt/tracking.py

  Line 118 in dffbb6a

  self.run_started_at = datetime.now(tz=pytz.utc)

• dbt-core/core/dbt/tracking.py

  Line 453 in dffbb6a

  "run_started_at": active_user.run_started_at.isoformat(),

So that the run_started_at can be compared unambiguously with aware timestamps, it should probably be aware as well with one of the two approaches:

1. dt.now(timezone.utc).isoformat() (offset from UTC)
2. dt.now().astimezone().isoformat() (offset from system time zone)

There's a good summary here of dbt Python datetimes.

But regardless of deprecation_date for dbt model versions, the fact that it's naive is tech debt that we should pay down, IMO by upgrading run_started_at to an aware timestamp with UTC offset of +00:00.

Describe alternatives you've considered

The most obvious alternative is to leave it as-is (if it's not broke, don't fix it, right?).

I actually don't know if "fixing" this would have any unintended consequences for folks using it like either of these examples:

select
    '{{ run_started_at.strftime("%Y-%m-%d") }}' as date_day
  
from ...

select
    '{{ run_started_at.astimezone(modules.pytz.timezone("America/New_York")) }}' as run_started_est
  
from ...

I would hope that it wouldn't break in either of those cases, but I didn't try them out one way or the other.

Who will this benefit?

One place this could come into play is here:

• Model Deprecation #7562 (comment)

Are you interested in contributing this feature?

No response

Anything else?

No response