Add release atteststions

[orf]

Hello!

First, thanks for this fantastic project - it’s a great help to the community and ecosystem at large.

I would like to suggest adding artifact attestations to the releases.

This would enable supply chain verification for these builds, and provide a layer of validation above just verifying the signature.

it’s pretty simple to add: just a single step, with no configuration or changes required in the binary itself.

what do you think?

[zanieb]

Yeah these seem reasonable, were you interested in contributing this?

[orf]

Absolutely! I’m currently travelling and away from my laptop so it will have to be next week, but I can take a look at it when I’m back.

[chludwig-haufe]

I see there is an open PR #371, but no further activity. Is there anything blocking the creation of the attestations?

Since I didn't see this mentioned in the documentation: How is the integrity of the Python sources and dependencies used in the build verified?

[indygreg]

We pin and verify the sha256 and file size of all downloaded assets. See downloads.py.

[zanieb]

@chludwig-haufe there's a blocking comment at #371 (comment)

[orf]

@chludwig-haufe there's a blocking comment at #371 (comment)

Yep! I have this PR in my backlog, but some personal stuff has come up.

We should indeed only attest on main (or anything that actually publishes), adding the relevant if: blocks should be all that is needed.

[zanieb]

I presume we need to attest the artifacts in .github/workflows/release.yml too? We create several derived artifacts.

[chludwig-haufe]

Please pardon my ignorance (I am not an active user of GitHub actions) – but Verifying artifact attestations with the GitHub CLI made me assume I could verify the integrity of a downloaded package as follows:

$ curl -LO https://github.com/astral-sh/python-build-standalone/releases/download/20250115/cpython-3.10.16+20250115-aarch64-apple-darwin-install_only.tar.gz
$ export GH_TOKEN="GitHub personal access token w/ read privileges"
$ gh attestation verify cpython-3.10.16+20250115-aarch64-apple-darwin-install_only.tar.gz -R astral-sh/python-build-standalone
Loaded digest sha256:21dba90e7a0b879fdc475411fc8c39e0567c6f5c92112956b63de7f83ee433ad for file://cpython-3.10.16+20250115-aarch64-apple-darwin-install_only.tar.gz
✗ Loading attestations from GitHub API failed

Error: failed to fetch attestations from astral-sh/python-build-standalone: HTTP 404: Not Found (https://api.github.com/repos/astral-sh/python-build-standalone/attestations/sha256:21dba90e7a0b879fdc475411fc8c39e0567c6f5c92112956b63de7f83ee433ad?per_page=30)

What am I missing?

[zanieb]

The -install_only archives are derived, as I mentioned in #343 (comment)