How can I find Time Zone Database version when using `arrow` or `dateutil`?

Question

I am using arrow module for Python for time zone manipulations. As far as I understand it, it relies on dateutil module for time zone information. dateutil claims:

Internal up-to-date world timezone information based on Olson's database.

I have only found c:\Python34\Lib\site-packages\dateutil\zoneinfo\dateutil-zoneinfo.tar.gz which seems to be used. I have deducted that it is downloaded from http://www.iana.org/time-zones, however it still does not give any hints what version of the database it is.

Is there a way to find what version of Olson's database is being used by arrow module?

To get access to the tz database in Python, use `pytz` module (`pytz.OLSEN_VERSION`). `arrow` and `dateutil` have known issues with handling timezones. — jfs, Feb 02 '15 at 17:59
sure, here's [couple](https://gist.github.com/zed/3838828) of [examples](https://gist.github.com/zed/4127162) — jfs, Feb 03 '15 at 11:04
update for Python 3.9's zoneinfo module: [How to get timezone rules version used by datetime?](https://stackoverflow.com/q/70807339/10197418) — FObersteiner, Jan 22 '22 at 15:14

score 3 · Accepted Answer · answered Feb 02 '15 at 17:56

Yes, arrow depends on dateutil for tz data.

Unfortunately, dateutil doesn't keep the tzdb version number when it builds its data file, so it is not available at run time.

Walking through the dateutil source code:

The version number can be seen in tzdata_file in zonefile_metadata.json.
In updatezinfo.py, the filename is passed from the metadata into the rebuild function,
In the rebuild function, you can see that the data from the file is loaded, but the filename itself is not retained, nor is the VERSION constant read from the tzdata makefile.

If this feature is important to you, I suggest opening a feature request in the dateutil issue tracker.

How can I find Time Zone Database version when using `arrow` or `dateutil`?

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