Andrew Johnston billywhizz

☁️ How I got off the cloud and migrated everything from AWS to a VPS in Hetzner

This is an opinionated handbook on how I migrated all my Rails apps off the cloud and into VPS.

This is how I manage real production loads for my Rails apps. It assumes:

Rails 7+
Ruby 3+
PostgreSQL
Ubuntu Server 24.04
Capistrano, Puma, Nginx

THE PROBLEM

🌲 Invert a binary tree! 🌲

Except with 3 catches:

It must invert the keys ("bit-reversal permutation")
It must be a dependency-free, pure recursive function
It must have type Bit -> Tree -> Tree (i.e., a direct recursion with max 1 bit state)

hi, i'm daniel. i'm a 15-year-old with some programming experience and i do a little bug hunting in my free time. here's the insane story of how I found a single bug that affected over half of all Fortune 500 companies:

say hello to zendesk

If you've spent some time online, you’ve probably come across Zendesk.

Zendesk is a customer service tool used by some of the world’s top companies. It’s easy to set up: you link it to your company’s support email (like [email protected]), and Zendesk starts managing incoming emails and creating tickets. You can handle these tickets yourself or have a support team do it for you. Zendesk is a billion-dollar company, trusted by big names like Cloudflare.

Personally, I’ve always found it surprising that these massive companies, worth billions, rely on third-party tools like Zendesk instead of building their own in-house ticketing systems.

your weakest link

Building Chrome V8 on Windows

In order to be able to build v8 from scratch on Windows for x64, please follow the following steps.

These instructions were updated to work with Windows 11 Build 10.0.22621, but this should also work on WInodws 10

NOTE: While the Chrome team does provide decent documentation, there are some nuances and other additional steps that must be done for v8 to compile on Windows.

Documentation:

https://chromium.googlesource.com/chromium/src/+/master/docs/windows_build_instructions.md#Setting-up-Windows

BLAKE2

BLAKE2 is an improved version of the SHA-3 finalist BLAKE, and was designed by a team of experts in cryptanalysis, implementation, and cryptographic engineering; namely Jean-Philippe Aumasson, Samuel Neves, Zooko Wilcox-O'Hearn and Christian Winnerlein.
BLAKE2s (the one checksum currently uses) computes a message digest that is 256 bits long, and represented as a 64-character hexadecimal number, e.g. 4264cb256d94533b6e152da59256638bc6adfda3efc5550d7607d4e6e45592fc.

Types

BLAKE2b (or just BLAKE2) is optimized for 64-bit platforms and produces digests of any size between 1 and 64 bytes.

	WITH RECURSIVE transitive_dependencies AS (
	SELECT package_id AS dependency_id, package_id AS root_id
	FROM dependencies
	WHERE kind = 'runtime'
	UNION ALL
	SELECT d.package_id, td.root_id
	FROM dependencies d
	JOIN transitive_dependencies td ON td.dependency_id = d.package_id AND td.dependency_id <> td.root_id -- Avoid self-joins
	WHERE d.kind = 'runtime'
	),

	<%@ language="Javascript" %>

	<script language="javascript" runat="server" src='json2.js'></script>
	<script language="javascript" runat="server" src='stringExtensions.js'></script>
	<script language="javascript" runat="server" src='contentNego.js'></script>
	<script language="javascript" runat="server">

	(function() {

	// In an ASP scenario, this fn gets "exported"

	// will be called via bun-parallel-setup.ts

	let i = 0;

	Bun.serve({
	port: process.env.PORT \|\| 8000,
	development: false,

	// Share the same port across multiple processes
	// This is the important part!

	""" Trains an agent with (stochastic) Policy Gradients on Pong. Uses OpenAI Gym. """
	import numpy as np
	import cPickle as pickle
	import gym

	# hyperparameters
	H = 200 # number of hidden layer neurons
	batch_size = 10 # every how many episodes to do a param update?
	learning_rate = 1e-4
	gamma = 0.99 # discount factor for reward

	#!/usr/bin/env bash
	set -euo pipefail

	help() {
	cat <<EOF
	vmctl [COMMAND] [ARGS]

	Launch firecracker VMs from configuration templates with networks
	managed by CNI. VM configuration is stored in $VM_CONFIG_DIR
	and network configuration is stored in $NET_CONFIG_DIR