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Comment by pdimitar | Hacker News Reader

This might be a little side-topic but IMO Alpine is famous for having a small byte size footprint.

I love Rust to tears but it produces fairly huge binaries even in release mode and even with some symbols stripping.

So if Alpine also plans to include various Rust tools I'd hope that this will prompt the core team to also work on reducing the sizes of the final Rust binaries.

I don't want to sound entitled! I am very thankful to the entire Rust team. And Rust is hugely important nowadays. It's just that when it comes to distributing stuff in Dockerfiles (and fly.io, and several others) the Rust binaries stick out like a sore thumb. :\ They're fairly big.

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This is definitely an area it would be great to see more work in. On Fuchsia we started linking the rust stdlib dynamically, but there are some significant ABI constraints to doing this in a traditional Unix shared library ecosystem that we're able to avoid due to the isolated and storage-deduplicated nature of the package system.

If you do link rusts stdlib dynamically, then you end up with binaries that are equivalent to C++ binary sizes with an external libc++, where rusts stdlib is approximately the same size as libc++, and the release mode stripped binaries are also comparable (within ~1kb of each other, and in the range of 10kb for a standard unix pipeline style application which does some basic stream processing of IO).

Is dynamically linking Rust's standard library officially-supported or did you have to hack around that? I know static-linking is the default but I've never looked into doing otherwise

The flag to dynamically link dependencies exists, and is part of the compiler's stable flags, but I'm not sure how much it's actually used, or how well it actually works.

Hmm, an LWN comment posted on the Debian wiki claims there are ABI stability issues, but they are being worked on:

https://lwn.net/Articles/797616/ https://wiki.debian.org/StaticLinking#Rust

Correct, the ABI is not stable. Given that they build a base system with a single rustc, that's not an immediate concern, though of course, a more stable ABI helps dynamic linking be more relevant.

The problem they'll have is that they don't update the whole system atomically, so the generations of different packages may be different.

A distribution like Clear or Nix could probably wrangle things appropriately.

Rust's stable ABI is the C ABI. I don't really see this changing in the foreseeable future.

It works well in terms of programs working. It has similar challenges to C++ that various commonly used abstractions end up producing a lot of code on the program side regardless. It's nonetheless worthwhile, if you have enough programs and resource constraints.

I am definitely not as well-versed as you -- but for now I'd stick with Rust's statically linking nature. What I am more looking for is to have some very aggressive tree-shaking at the final phases of Rust compilation/linking where the tooling can prove that in your program, say, 73% of the stdlib isn't used at all so it can just remove it from the final binary.

It's my view that as deployment moves more and more to containers and even to the "microkernel + your app only" model then being able to fit binaries in CPU caches will become crucial for the viability of such cloud hosting. (Although to be fair, when we're talking about Rust + the Linux kernel, running something in 25ms vs 5ms can't be a huge deal for 98% of all apps, right?)

Pretty sure LTO already provides that functionality(I wish Rust had LTO on by default but it's fairly straightforward to flip on).

You can set LTO units to 1 which is what I do because it leads to some final binary size reduction -- but it isn't much. :(

I am aware that we have to start being more mindful of our dependencies but in commercial this is a luxury that you often don't have.

Not sure why I am eating the down arrows but I'd like to specify: I just tested on a few projects of mine and the binary size reduction is definitely more aggressive and better-looking compared to a year ago. Very happy with the gains! I am leaving my original comment above anyway since there's IMO still some room for improvement.

For comparison, without LTO and stripping I've had a fairly small hobby project easily compile to ~3MB and with them it's now ~800KB which is nearly 400% improvement. Nice.

Is alpine really going for “small” though?

I’m not saying they’re not small and haven’t done a fantastic job, but my impression is that this is due to being mostly minimal in the default install;

The reason I say this (and I could be wrong) is because the use of musl for the libc means each binary kinda needs to include it’s own libc statically.

This must make the binaries huge!

Also, you can easily make small rust binaries, it’s Golang (of the two) that produces very large binaries.

If you just follow the first two bits of advice from: https://github.com/johnthagen/min-sized-rust you’ll reduce your binary sizes to near C++ levels.

> the use of musl for the libc means each binary kinda needs to include it’s own libc statically.

This is factually incorrect. Musl supports dynamic linking and if you run `ldd` on any binary in Alpine you can see that it dynamically links against musl libc.

Ah, fair enough. I did a little more digging and it seems you can dynamically link rust binaries too now: https://github.com/rust-lang/compiler-team/issues/422

In your link, I really enjoyed this link on creating a 45-byte executable: http://www.muppetlabs.com/~breadbox/software/tiny/teensy.htm...

Trust in open-source's ability to populate all niches. If Rust is added, and it significantly bloats up the Alpine image, someone will come along and make Alpine-Classic or Montane Linux or something.

Maybe I'm misunderstanding but from what I understood, this isn't about adding rust to the base alpine packaging. It's about showing it to be installed from the main repository. Currently it's available in the community repository.

Ah, you understand me (and the post) just fine -- hence I mentioned that my comment is a bit out there and not exactly on topic.

I am simply wondering if this would prompt more interest in reducing Rust's final binary sizes, that's all.

Docker acts as late linker for dynamically linked apps, bundling shared libs and executable together. Statically linked Rust apps certainly go against the grain in that model but can often be made significantly smaller with some build and dependency tweaking.

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