setting the timestamp in the hatch configuration for reproducible builds

[jhgit]

I see that I can set SOURCE_DATE_EPOCH in my environment when building sdists or wheels. I'd like to put that timestamp into a file committed in my project repository when I tag a release (say in pyproject.toml or some file that could get ingested not unlike _version.py perhaps). I don't want every released tarball to have a date for all files of 2020/02/02 UTC whether it's release 0.0.1 or 5.5.5. I DO want a reproducible build for a particular version (e.g., the day and time I decide to finalize the release), but just not the same timestamp for all release versions.

And I'd rather have that timestamp checked into the repository than relying out-of-band build scripts to set SOURCE_DATE_EPOCH in the environment.

I don't see a way to set that as a simple build configuration setting the way that utils.py:get_reproducible_timestamp() is implemented right now. So I think I'd have to create a build hook. Maybe I'm missing something.

Has anyone done this? Or might have a simple suggestion?

[ofek]

That would be a feature request for now, however I would be hesitant to add that as an option because environment variables are used near ubiquitously in build environments compared to files.

[jhgit]

What about just a setting that one could write into the [tools.hatch.build] section of pyproject.toml? Even overloading the 'reproducible' option so that it can be true/false or a timestamp? Or if that is distasteful, then make it a separate option that only takes effect if 'reproducible' is true.