In concept why can’t the full set of files in a release be a single, one-way hash value, with both adding or releasing changing the hash value?
(Also: we’d need to determine what it even means to hash a set of files. Do we order by canonicalized filename, by upload time, etc. Each of these has surprising implications!)
Edit: to be clear, it’s not ideal or fully intentional that uploads to PyPI are not atomic. But it’s the status quo and any change will take years.
Aren’t releases versioned, using semantic versioning?
If not, why shouldn’t a change in dependencies not trigger a new release version?
If it is versioned and if there’s a corresponding hash to the release, why wouldn’t I also expect that to change when the version and dependencies change?
I can understand that there may be historical reasons that this scheme will break how PyPI releases are built and distributed, but I also hope you understand that it violates the principle of least surprise.
I’m not sure what you mean by “change in dependencies”: every release has zero or more distributions (“files”), and each distribution in a release can specify its own dependencies. For example, a macOS-specific wheel might depend on something that Linux-specific wheels don’t need or vice versa.
> but I also hope you understand that it violates the principle of least surprise.
I think it’s fair to say that virtually everything about Python packaging violates POLA :-)
If it weren’t for AI, Python would have died as a language ecosystem due to their perpetual neglect of this area. The python community clearly had no ability to solve this problem themselves. I got sick and left and started using better tools.
It’s only now that they’re the cornerstone of the world economy that other people are coming in and cleaning up their messes for them. It’s pitiful. Python failed and needed to be saved from itself.
You lock to the distribution instead of the release so your build doesn't have to download distributions for platforms you're not using.
PyPi just decided to do what VCSes already did, worse
The response is that there is hash pinning but only at the constituent levels. Which clearly isn’t what the OP meant.
2. There are hashes in the HTML served by PyPI. These are updated at the whim of both the index and the publisher. Even though they are checked by pip during install, they are worthless.
3. There are many ways to install packages that work around (2). Custom index server doesn't have to provide hashes, and pip will happily install that. You can install from sources, from a package you've downloaded somewhere, form VCS, you can build it during install, all without even prompting the user to confirm the very scary choices.
NB. I have no idea how do you make the leap from "adding files to release" to "not modifying the release". To me, adding file to release is sure as hell modifying it. Here's a very simple malicious example:
I release package "innocent" with an empty "scripts" section. Then, in the subsequent modification to this release, I add the "scripts" section with a script named "notebook". Now, whenever my user wants to run Jupyter notebook, they will call my "notebook" program, not the one from Jupyter package.
1. “Wheel” signatures (e.g. RECORD.jws) were specified but never actually implemented in any major packaging installer, to the best of my knowledge. In that sense it’s not really meaningful to ask whether they’re “still” supported, since nothing ever did support them unfortunately. The reasons for that are multifaceted, but a single easily identifiable reason is that they don’t solve the key/identity distribution problem.
2. The primary benefit of index-supplied hashing is for lockfiles. Specifically, they make lockfiles like uv.lock and pylock.toml useful/meaningful.
3. Is the source distribution problem, and is sort of fundamental to any packaging system that has any amount of dynamism in it. There’s a good argument to be made for reducing unnecessary dynamism (e.g. via wheels), but a nontrivial percent of Python users actually want this behavior.
Re: files: I think you’re getting confused about distribution files (sdists and wheels) versus the individual contents therein. You can’t modify distribution files on PyPI, you can only add new, unique ones. And this is now restricted to 14 days for each release.
2. Lock files are hilariously wrong in Python. They don't accomplish what they claim because the only tool that in principle could do that and that is actually used with Python deployment / development is conda, and to the best of my knowledge conda's environment doesn't support locks. All other installers don't even guarantee that successfully running them will produce an environment with all dependencies met. But, not only that, they don't prevent users from becoming victims of manipulations that happen index-side because they don't store the checksums.
3. "nontrivial percent of Python users actually want this behavior." I'm yet to find one. Most Python users simply don't understand how any of their packaging works and come up with absurdly bad ideas and "solutions" to their problems. They may tell you they want something in the same sense as a drug addict may tell you they want more drugs, but the "actually" isn't there. They "actually" don't know what they want most of the time.
> You can’t modify distribution files on PyPI, you can only add new, unique ones.
I just gave an example of how this modifies the package. Not sure what problem do you see with it.
We also figured out 20 years ago that SHA1 was not quite as strong as initially estimated, and not quite 10 years ago that generating two colliding documents was merely a matter of some serious computing power. A few projects went ahead and changed the name of their master branch, but SHA256 preference remains elusive.
The release consists of one sdist and zero or more wheels. Until now you were able to upload additional wheels at later time.
(This doesn’t change your observations at all! Just as a demonstration of how Python packaging’s data model can be unintuitive.)
Something that I wish was included in PEP-694 is the notion of a "tombstone" invalid/empty sdist artifact to deal with that case, to make it easier for package managers to interpret and surface those different failure classes.
Like, sure, this is a package manager UX problem, but it's been happening for long enough that I feel like it might be time for PyPI to help managers do better.