Ender Kaylebor

Arel Cheatsheet on Steroids

A (more) complete cheatsheet for Arel, including NamedFunction functions, raw SQL and window functions.

Tables

posts = Arel::Table.new(:posts)
posts = Post.arel_table # ActiveRecord

Table alias

Magit forge for Gitlab in Doom Emacs

This guide assumes you're working on a Unix-like environment. I'm using Linux Mint (Ubuntu). It should work on Macs, and might on Windows.

These are the four steps you can use as a checklist, see the headings below for the details on each step.

Enable forge support
Create a Gitlab API key
Add your gitlab credentials to ~/.authinfo.gpg
Set-up forge in emacs

macOS Yosemite and above utilize AWDL (Apple Wireless Direct Link) to handle data transfers to other AWDL-enabled devices (Macs, Macbooks, iPhones, etc.) over the Wifi Radio, without the need for a common underlying Access Point.

However, whenever AWDL is active (Bonjour discovery and any Airdrop, Airplay, and GameKit links and transfers), it will lock the Wifi radio for small intervals. For Bonjour discovery specifically, this comes to an effective packet spooling time of about 50-100ms, once per second (active transfers will be higher).

Obviously, this will create unacceptable latency spikes for low-latency desktop streaming apps. To disable the AWDL interface, use the following command in Applications > Utilities > Terminal (this requires you to be logged in as an Administrator and enter your password):

sudo ifconfig awdl0 down

Native Secure Enclave backed ssh keys on MacOS

It turns out that MacOS Tahoe can generate and use secure-enclave backed SSH keys! This replaces projects like https://github.com/maxgoedjen/secretive

There is a shared library /usr/lib/ssh-keychain.dylib that traditionally has been used to add smartcard support to ssh by implementing PKCS11Provider interface. However since recently it also implements SecurityKeyProivder which supports loading keys directly from the secure enclave! SecurityKeyProvider is what is normally used to talk to FIDO2 devices (e.g. libfido2 can be used to talk to your Yubikey). However you can now use it to talk to your Secure Enclave instead!

TPM2-Based SSH Key Setup with Automatic Unlock

Complete guide for storing SSH keys in a TPM2 module with automatic loading via systemd and KWallet integration on KDE Plasma.

Overview

This setup provides:

Hardware-backed SSH keys stored in TPM2 (can't be extracted)
Automatic unlock at KDE login using KWallet
PIN protection (not passwordless, but PIN cached per session)

	HTTP status code symbols for Rails

	Thanks to Cody Fauser for this list of HTTP responce codes and their Ruby on Rails symbol mappings.

	Status Code Symbol
	1xx Informational
	100 :continue
	101 :switching_protocols
	102 :processing