Comment by skydhash
3 months ago
Vendoring is nice. Using the system version is nicer. If you can’t run on $current_debian, that’s very much a you problem. If postgres and nginx can do it, you can too.
3 months ago
Vendoring is nice. Using the system version is nicer. If you can’t run on $current_debian, that’s very much a you problem. If postgres and nginx can do it, you can too.
The system package manager and the language package/dependency managers do a very different task.
The distro package manager delivers applications (like Firefox) and a coherent set of libraries needed to run those applications.
Most distro package managers (except Nix and its kin) don't allow you to install multiple versions of a library, have libs with different compile time options enabled (or they need separate packages for that). Once you need a different version of some library than, say, Firefox does, you're out of luck.
A language package manager by contrast delivers your dependency graph, pinned to certain versions you control, to build your application. It can install many different versions of a lib, possibly even link them in the same application.
But I don’t really want your version of the application, I want the one that is aligned to my system. If some feature is really critical to the application, you can detect them at runtime and bailout (in C at least). Most developers are too aggressive on version pinning.
> Most distro package managers (except Nix and its kin) don't allow you to install multiple versions of a library
They do, but most distro only supports one or two versions in the official repos.
Maybe you want that, but I generally want the version of the application that the devs have tested the most. I've dealt with many issues due to slight differences between dependency versions, and I'd rather not provoke them. (That said, I do like debian for boring infrastructure, because they can keep things patched without changing things, but for complex desktop apps, nah, give me the upstream versions please. And for things I'm developing myself the distro is but a vehicle for a static binary or self-contained folder)
> If you can’t run on $current_debian, that’s very much a you problem.
This is a reasonable position for most software, but definitely not all, especially when you fix a bug or add a feature in your dependent library and your Debian users (reasonably!) don't want to wait months or years for Debian to update their packages to get the benefits. This probably happens rarely for stable system software like postgres and nginx, but for less well-established usecases like running modern video games on Linux, it definitely comes up fairly often.
Something I have seen that recently have become much more common is the software upstream authors providing a Debian repository for the latest versions of their software, including backports for old Debian releases.
Yes, mainly because such repositories don't have to follow debian's policies, and so it's a lot easier to package a version that vendors in dependencies in a version/configuration you're willing to support (and it's better to point users there than at an official debian version because if debian breaks something you'll be getting the bug reports no matter how much people try to tell users to report to the distribution first)
That is an impossible task in practice for most developers.
Many distros, and Debian in particular, apply extensive patches to upstream packages. Asking a developer to depend on every possible variation of such packages, across many distros, is a tall order. Postgres and Nginx might be able to do it, but those are established projects with large teams behind them and plenty of leverage. They might even be able to influence distro maintainers to their will, since no distro will want to miss out on carrying such popular packages.
So vendoring is in practice the only sane choice for smaller teams and projects.
Besides, distro package managers carrying libraries for all programming languages is an insane practice that is impossible to scale and maintain. It exists in this weird unspecified state that can technically be useful for end users, but is completely useless for developers. Are they supposed to develop on a specific distro for some reason? Should it carry sources or only binaries? Is the dependency resolution the same for all languages? Should language tooling support them? It's an entirely ridiculous practice that should be abandoned altogether.
Yes, it's also silly that every language has to reinvent the wheel for managing dependencies, and that it can introduce novel supply chain attack vectors, but the alternative is a far more ludicrous proposition.
> distro package managers carrying libraries for all programming languages is an insane practice that is impossible to scale and maintain.
That's not the idea. If a software is packaged for a distro, then the distro will have the libraries needed for that software.
If you're developing a new software and wants some new library not yet packaged, I believe you can figure how to get them on your system. The thread is about the user's system, not yours. When I want to run your code, you don't have to say:
It's not reasonable to expect every software in existence to work with a compatible set of dependencies. So no, the distro can't supply all the libraries.
What happens is that distro developers spend their time patching the upstream so it works with the set included on the distro. This has some arguable benefits to any user that wants to rebuild their software, at the cost of random problems added by that patching that flies under the radar of the upstream developers.
Instead, the GPs proposal of vendoring the dependencies solves that problem, without breaking the compilation, and adds another set of issues that may or may not be a problem. I do argue that it's a good option to keep on one's mind to apply when necessary.
4 replies →
Right. Build and runtime dependencies are a separate matter. But for runtime dependencies, it's easier for developers to supply an OCI image, AppImage, or equivalent, with the exact versions of all dependencies baked in, than to support every possible package manager on every distro, and all possible dependency and environment permutations.
This is also much easier for the user, since they only need to download and run a single self-contained artifact, that was previously (hopefully) tested to be working as intended.
This has its own problems, of course, but it is the equivalent of vendoring build time dependencies.
The last part of my previous comment was specifically about the practice of distros carrying build time libraries. This might've been acceptable for C/C++ that have historically lacked a dependency manager, but modern languages don't have this problem. It's a burden that distro maintainers shouldn't have to worry about.
2 replies →
You do not depends on a package, you depends on its API. Implementation details shouldn't matter if behavior stays the same. Why do you care if the distro reimplemented ffmpeg or libcurl, or use an alternative version built with musl? Either the library is there or it's not. Or the minimum version you want is there or it's not. You've already provided the code and the requirement list, it's up to the distro maintainer or the user to meet them. If the latter patch the code, why do you care that much?
And if a library have a feature flags, check them before using the part that is gated.
There's no guarantee that software/library vX.Y.Z packaged by distro A will be identical in behavior to one packaged by distro B. Sure, distro maintainers have all sorts of guidelines, but in reality, mistakes happen, and there can be incompatibilities between the version a developer has been testing against, and one the end user is using.
Relying on feature flags is a pie in the sky solution, and realistically developers shouldn't have to be concerned with such environmental issues. Dependency declarations should be relied on to work 100% of the time, whether they're specified as version numbers or checksums. Since they're not reliable in practice, vendoring build and runtime dependencies is the only failproof method.
This isn't to say that larger teams shouldn't support specific distros directly, but my point is that smaller teams simply don't have the resources to do so.
3 replies →
But that would lock me in to say whatever $debian provides. And some dependencies only exist as source because they are not packaged for $distribution.
Of course, if possible, just saying "hey, I need these dependencies from the system" is nicer, but also not error-free. If a system suddenly uses an older or newer version of a dependency, you might also run into trouble.
In either case, you run into either an a) trust problem or b) a maintenance problem. And in that scenario I tend to prefer option b), at least I know exactly whom to blame and who is in charge of fixing it: me.
Also comes down to the language I guess. Common Lisp has a tendency to use source packages anyway.
> If a system suddenly uses an older or newer version of a dependency, you might also run into trouble.
You won't. The user may. On his system.
Aware of that. So how is that different from any other Debian package? If you rely on a certain set of packages, you are always at the end at fault. You either trust a certain base or you vet it.