shrynx shrynx

Optimizing Rust container builds

I'm a Rust newbie, and one of the things that I've found frustrating is that the default docker build experience is extremely slow. As it downloads crates, then dependencies, then finally my app - I often get distracted, start doing something else, then come back several minutes later and forget what I was doing

Recently, I had the idea to make it a little better by combining multistage builds with some of the amazing features from BuildKit. Specifically, cache mounts, which let a build container cache directories for compilers & package managers. Here's a quick annotated before & after from a real app I encountered.

Before

This is a standard enough multistage Dockerfile. Nothing seemingly terrible or great here - just a normal build stage, and a smaller runtime stage.

GADTs: A primer

Sketch link

This post assumes you are familiar with Algebraic Data Types (sum types/variants/tagged unions and product types: records, tuples, etc) and comfortable reading type signatures. For a brush up on ADTs and specifically on sum types/variants, refer Reason's documentation and rauschmayer's blog on variants in Reason. Also while you are at it, a quick look on phantom types wouldn't hurt 🙂.

Keybase proof

I hereby claim:

I am shrynx on github.
I am shrynx (https://keybase.io/shrynx) on keybase.
I have a public key ASDZMy6G_oMiX_f3Ckv281Z_VlsvbvrNtESV7pCiDEX1wQo

To claim this, I am signing this object:

	// options
	String imagePath = "img/desandro-avatar.jpg";
	float res = 10; // resolution, dot density
	float zoom = 3.0; // proportion to zoom image
	boolean isAdditive = true; // true = RGB, false = CMY
	float offsetAngle = 1; // affects dot pattern
	/*
	0 = no patter
	0.05 = slight offset
	1 = slight offset

	(ns gen-art.beads
	(:require [clojure2d.core :refer :all]
	[fastmath.core :as m]
	[fastmath.random :as r]
	[fastmath.fields :as f]
	[fastmath.vector :as v]
	[clojure2d.color :as c]
	[clojure2d.extra.utils :as ut]
	[clojure2d.pixels :as p])
	(:import [fastmath.vector Vec2]) )

	module type Res = {type t;};

	module Make = (R: Res) => {
	include R;

	type state =
	\| NotAsked
	\| Loading
	\| NetworkError
	\| DecodingError

	state = {
	everySecond: 0,
	every5Second: 0,
	random: 0,
	};

	incrementEverySecond = () => {
	this.setState(({ everySecond }) => ({ everySecond: everySecond + 1 }));
	};

 const CounterContext = React.createContext(0);
 class CounterProvider extends React.Component {
   state = { count: 0 };
   incrementCount = () => {
     this.setState(({ count }) => ({ count: count + 1 }));
   };
   componentDidMount() {
     setInterval(this.incrementCount, 1000);
   }

	#!/usr/bin/env osascript -l JavaScript
	const Chrome = Application('Chrome');

	// although there is ES6 support , but "run" function
	// can't use fat arrow functions.
	// https://github.com/JXA-Cookbook/JXA-Cookbook/wiki/ES6-Features-in-JXA#arrow-functions
	function run(args) {
	const url = args[0];
	const tabData = findTabForUrl(url);