Articles tagged #rust

Deconstructing color image compression

Here's a picture of a colorful rose. It's 1200 by 800 pixels, and what you're seeing is decoded from a JPEG file that's about 200 kibibytes.

And here's a much worse version of that picture, that’s barely recognizable:

...but, that’s the point! Because that one is just 21 bytes. Those bytes. That’s .0005% of the original image.

Extra credit

We've achieved our goals already with this series: we have a web service written in Rust, built into a Docker image with nix, with a nice dev shell, that we can deploy to fly.io.

But there's always room for improvement, and so I wanted to talk about a few things we didn't bother doing in the previous chapters.

Making clash-geoip available in the dev shell

Generating a docker image with nix

There it is. The final installment.

Over the course of this series, we've built a very useful Rust web service that shows us colored ASCII art cats, and we've packaged it with docker, and deployed it to https://fly.io.

We did all that without using nix at all, and then in the last few chapters, we've learned to use nix, and now it's time to tell goodbye, along with this whole-ass :

Doing geo-location and keeping analytics

I sold you on some additional functionality for catscii last chapter, and we got caught up in private registry / docker shenanigans, so, now, let's resume web development as promised.

Adding geolocation

We kinda left the locat crate stubby, it doesn't actually do any IP to location lookups. It doesn't even have a dependency on a crate that do that.

Using the Shipyard private crate registry with Docker
Bear

Wait wait wait, so we're not talking about nix yet?

Well, no! The service we have is pretty simple, and I want to complicate things a bit, to show how things would work in both the Dockerfile and the nix scenario.

And because I don't like contrived examples, we're going to do something somewhat real-world: we're going to geo-locate visitors, and track how many visits we get from each country.

Deploying catscii to fly.io

Disclaimer:

Because I used to work for fly.io, I still benefit from an employee discount at the time of this writing: I don't have to pay for anything deployed there for now.

fly.io is still sponsoring me for developing hring, but this isn't a sponsored post. It's just a good fit for what we're doing here, with a generous free tier.

Writing a Dockerfile for catscii

Now that our service is production-ready, it's time to deploy it somewhere.

There's a lot of ways to approach this: what we are going to do, though, is build a docker image. Or, I should say, an OCI image.

This is still a series about Nix, but again: because the best way to see the benefits of Nix is to do it without Nix first, we'll use only Docker's tooling to build the image.

Serving ASCII cats over HTTP

Our catscii program does everything we want it to do, except that it's a command-line application rather than a web server. Let's fix that.

Enter axum

The documentation for the axum crate tells us how to make a basic web server, and we honestly don't need much more than that.

So let's add axum:

Shell session
amos@miles:~/catscii$ cargo add axum@0.6
    Updating crates.io index
      Adding axum =0.6 to dependencies.
             Features:
             + form
             + http1
             + json
             + matched-path
             + original-uri
             + query
             + tokio
             + tower-log
             - __private_docs
             - headers
             - http2
             - macros
             - multipart
             - w

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