mirrord VS Cargo

So, you've been using mirrord to simplify your development process (if you haven’t, go here!). Naturally, you want the traffic from the app you're debugging to go through the cluster environment, so your app can communicate with its clustery pals. There is a problem though: your latest change adds some new columns to the database, and you don’t want to modify the database in the cluster and affect everyone else working on it. You do have a local instance of the database that you can modify, so your app can use that, but you still want it to talk to all the other components in the cluster. So what now? The new outgoing traffic filter feature is here to solve exactly this type of problem!

I had the pleasure of talking to Eyal @ CTO at Metalbear and the maintainer of Mirrord. I got some crazy insights.

If you want to take mirrord for a spin, check out the quick start guide. We’d love to hear about your experience or just general thoughts - chat us up on our Discord or open an issue or discussion on GitHub.

We're building an open-source tool called mirrord which lets you run a local process in the context of a pod in your cloud environment. We often get asked how mirrord is different from Telepresence and so we decided to write a short blog post about it, which we hope would be valuable to those interested in local Kubernetes development:

Hands-on tutorial of mirrord.dev with the creators and Rawkode!

if you are interested in k8s, iptables, hooking libc, asm etc https://github.com/metalbear-co/mirrord

I gave my first CNCF talk in Toronto yesterday, talking about https://github.com/metalbear-co/mirrord , how all the features work, and how it's engineered!

Dependency Management in Other Languages: We've discussed Python and Node.js in this article, but dependency management is a universal concept in programming. Exploring how you handle dependencies in other languages like Java, C#, or Rust could be beneficial. (I think Rust's cargo is an excellent example of a package manager.)

Nice hack! Would it have been possible back then to use cargo to pull in some dependencies?

The clean solution of cargo script is here: https://github.com/rust-lang/cargo/issues/12207

Yes, I am sure this is going to be a part of Rust 1.77.0 and it will release on 21st March. I say that because of the tag in the PR (https://github.com/rust-lang/cargo/pull/13257#event-11505613...).

I'm no expert on Rust compiler development, but my understanding is that all code that is merged into master is available on nightly. If they're not behind a feature flag (this one isn't), they'll be available in a full release within 12 weeks of being merged. Larger features that need a lot more testing remain behind feature flags. Once they are merged into master, they remain on nightly until they're sufficiently tested. The multi-threaded frontend (https://blog.rust-lang.org/2023/11/09/parallel-rustc.html) is an example of such a feature. It'll remain nightly only for several months.

Again, I'm not an expert. This is based on what I've observed of Rust development.

The author provides very surface-level criticism of two Rust tools, but they don't look into why those choices were made.

With about five minutes of my time, I found out:

wrap_comments was introduced in 2019 [0]. There are bugs in the implementation (it breaks Markdown tables), so the option hasn't been marked as stable. Progress on the issue has been spotty.

--no-merge-sources is not trivial to re-implement [1]. The author has already explained why the flag no longer works -- Cargo integrated the command, but not all of the flags. This commit [2] explains why this functionality was removed in the first place.

Rust is open source, so the author of this blog post could improve the state of the software they care about by championing these issues. The --no-merge-sources error message even encourages you to open an issue, presumably so that the authors of Cargo can gauge the importance of certain flags/features.

You could even do something much simpler, like adding a comment to the related issues mentioning that you ran into these rough edges and that it made your life a little worse, or with a workaround that you found.

Alternatively, you can continue to write about how much free software sucks.

[0]: https://github.com/rust-lang/rustfmt/issues/3347

[1]: https://github.com/rust-lang/cargo/pull/10344

[2]: https://github.com/rust-lang/cargo/commit/3842d8e6f20067f716...

You try to use it as a part of multi-language project, with an external build tool to tie it all together, and you discover that --out-dir flag is still not stabilized over some future compatibility concerns.

To create a new application we'll use cargo (a build tool and also a package manager for Rust. It is used for scaffolding new library/binary projects). So in your projects folder, you can run this command in your terminal:

> ...but at the end of the day Cargo is the reason that Rust is popular.

FWIW, maybe that's true for you, but there are numerous other advantages to the language for which many people choose to use Rust--some even "despite" Cargo: you see Google having had to put in way way WAY too much work to get Bazel working for Rust :/--that it honestly feels a bit like belittling an extremely important language to make this claim so flippantly.

> You can set a default build target for a Cargo project with two lines of configuration, no nightly features necessary...

This doesn't work as, as soon as you start setting target-specific options, it infects the host build, as they incorrectly modelled the problem as some kind of map from targets to flags. If you don't believe me, on your Linux computer, try cross-compile something complicated that will runs on a "least common denominator" Linux distribution, such as CentOS 7.

> Can you clarify what this is referring to?

Sure. I've Googled rust cargo target host bugs for you (which, FWIW, finds a number of bugs I've filed or have talked about, but it isn't as if I have a list anywhere). Note that one of these bugs is "closed", but I still provide them for context as a patch might have been merged but (as you'll find out if you read through all of these) it isn't stable.

https://github.com/rust-lang/cargo/issues/8147

https://github.com/rust-lang/cargo/issues/3349

https://github.com/rust-lang/cargo/pull/9322

https://github.com/rust-lang/cargo/issues/9453

https://github.com/rust-lang/cargo/pull/9753

The result of this work being left incomplete is that increasingly large numbers of "serious" projects--things I'd expect people in packaging land to have heard of, such as BuildRoot--are being forced to set the ridiculous environment variable __CARGO_TEST_CHANNEL_OVERRIDE_DO_NOT_USE_THIS="nightly" in order to get access to a flag that makes Cargo sort of work.

(And yet, I often see people surprised at how long it is taking for various of the more important clients to fully get into using Rust, as the safety issues are so severe from continuing to use C/C++: as you made the contention that you believe the reason why people use Rust is Cargo, I will say the opposite: the reason why we don't see more Rust is also Cargo.)

What has worked for me so far:

https://doc.rust-lang.org/book/

(do the exercises!)

plus a little bit of:

https://doc.rust-lang.org/cargo/

and

https://doc.rust-lang.org/std/index.html

(There's no need to remember the last URL -- just google "rust xxx" and you will get the right page.)

I'm looking forward to reading this:

https://nnethercote.github.io/perf-book/introduction.html

Sprinkle some blog posts on top:

https://xxchan.me/cs/2023/02/17/optimize-rust-comptime-en.ht...

https://matklad.github.io/2021/05/31/how-to-test.html

https://matklad.github.io/2021/08/22/large-rust-workspaces.h...

https://fasterthanli.me/articles/a-half-hour-to-learn-rust

https://fasterthanli.me/articles/working-with-strings-in-rus...

... and the rest is just a matter of applying enough sweat :)