Julien Ma julienma

UPS Shutdown Scripts

This documents everything I needed to get my Proxmox instance to listen to my UPS Server and initiate a shutdown script that would shutdown my UDM Pro. This is needed as the UDM Pro does not have the ability to listen to a NUT server on it's own (what the hell ubiquiti).

I'm using a Synology NAS as a NUT server, but you can point your NUT client to any supported UPS. It's set to alert any clients subscribed to it when the UPS connected to it is in low battery. This all applies regardless of what machine you have a NUT server on, it does not have to be Synology.

Additionally these install steps were on my Proxmox machine, but these steps will probably work on any Debian GNU/Linux OS with little to no modification. YMMV

High level summary of the steps:

Install the NUT client on Proxmox

Rails 7 new features. Before and After

Add ComparisonValidator
PostgreSQL generated columns
PostgreSQL custom enum types
Add tracking of belongs_to association
association_previously_changed? method
Add invert_where method
Add associated method
Add missing method
Active Record Encryption

The dokku-push action requires an SSH key with push access to the Dokku instance. Here's how to do that.

Replace APPNAME with the name of the app (e.g. this is a good idea to use the same name used on Dokku's).

Generate a new SSH keypair

We want each repo to have its own SSH key, so it's easier to rotate/invalidate them if required, without affecting all the repos. Let's generate a new key on your computer (see GitHub help):

How to setup a practically free CDN using Backblaze B2 and Cloudflare

⚠️ Note 2023-01-21
Some things have changed since I originally wrote this in 2016. I have updated a few minor details, and the advice is still broadly the same, but there are some new Cloudflare features you can (and should) take advantage of. In particular, pay attention to Trevor Stevens' comment here from 22 January 2022, and Matt Stenson's useful caching advice. In addition, Backblaze, with whom Cloudflare are a Bandwidth Alliance partner, have published their own guide detailing how to use Cloudflare's Web Workers to cache content from B2 private buckets. That is worth reading,

Sinatra & Web Development Cheat Sheet

This is a cheat sheet I developed for students while teaching an Intro to Web Development course through Lighthouse Labs. If you're interested in learning to code, you should definitely check them out.

Fix Ubuntu package cache

Had problem with Ubuntu package cache.

➜  sources.list.d sudo apt-get update                   
Hit:1 http://fi.archive.ubuntu.com/ubuntu xenial InRelease
Hit:2 http://fi.archive.ubuntu.com/ubuntu xenial-updates InRelease                                                                   
Hit:3 http://fi.archive.ubuntu.com/ubuntu xenial-backports InRelease                                                                 
Hit:4 http://security.ubuntu.com/ubuntu xenial-security InRelease

Let’s Encrypt + Heroku

Step 1: Setup certificate

$ sudo letsencrypt certonly --manual -d <domain>

You'll need to deploy a verification file to your current website.

	ruby '2.7.1'

	gem 'rails', github: 'rails/rails'
	gem 'tzinfo-data', '>= 1.2016.7' # Don't rely on OSX/Linux timezone data

	# Action Text
	gem 'actiontext', github: 'basecamp/actiontext', ref: 'okra'
	gem 'okra', github: 'basecamp/okra'

	# Drivers

	-- Script for DEVONthink 3
	-- Run OCRmyPDF on PDFs without OCR
	-- Requires https://github.com/jbarlow83/OCRmyPDF to be installed e.g. with brew

	on performSmartRule(theRecords)
	tell application id "DNtp"
	set strExportPath to "PATH=/opt/homebrew/bin:$PATH "
	set intRecordsCount to count of theRecords
	show progress indicator "Adding OCR to PDF..." steps intRecordsCount
	repeat with theRecord in theRecords

	(Dijkstra and plain A* are generally not included here as there are thousands of
	implementations, though I've made an exception for rare Ruby and Crystal versions,
	and for Thor, Mapzen's enhanced A*. )

	A* Ruby https://github.com/georgian-se/shortest-path
	A* Crystal https://github.com/petoem/a-star.cr
	A* (bidirectional with shortcuts) C++ https://github.com/valhalla/valhalla
	NBA* JS https://github.com/anvaka/ngraph.path
	NBA* Java https://github.com/coderodde/GraphSearchPal
	NBA* Java https://github.com/coderodde/FunkyPathfinding