Make the build reproducible

[lamby]

Whilst working on the Reproducible Builds I noticed that apispec could not be built reproducibly. This is due to the copyright message (configured in docs/conf.py) including the current build date. (I originally filed this in Debian as bug #988978.)

[lafrech]

This should be harmonized amongst our repos (marshmallow, webargs).

I'd go for the simplest. It could be removing the auto-date feature and bump date manually. After all, we already bump the license year manually.

@sloria ?

[lafrech]

@lamby, I suppose marshmallow (and webargs and all...) are affected, right?

@sloria, mind if I remove that dynamic part to hardcode the date just like we do in the license file? Here and in other impacted projects.

[lamby]

@lafrech Good qestion. Marshmallow may be fine as it uses the mtime of the file, but webargs needs updating too. (I would suggest using SOURCE_DATE_EPOCH for all of these, rather than mtime stuff.)

[lafrech]

Thanks. I didn't know SOURCE_DATE_EPOCH was standardised. TBH, I didn't searched and somehow assumed it was a workaround you had to implement specifically for this, hence my proposal to simplify things and spare packagers the trouble.

https://reproducible-builds.org/docs/source-date-epoch/

Before implementing this, you should scan through our checklist to see if you can avoid implementing it.

I'm still willing to simplify things, but I have no experience in Debian packaging, so if you think SOURCE_DATE_EPOCH is better than mtime and not worth hardcoding the year, then fine, let's go for it.

[lamby]

I'm still willing to simplify things, but I have no experience in Debian packaging, so if you think SOURCE_DATE_EPOCH is better than mtime and not worth hardcoding the year, then fine, let's go for it.

👍

[lafrech]

I opened equivalent PRs on marshmallow (marshmallow-code/marshmallow#1862) and webargs (marshmallow-code/webargs#631).

After we merge this, I'll change the copyright line into

    copyright = f"2014-{build_date:%Y}, Steven Loria and contributors"

to match webargs.