igorjs

Tutorial: scheduled start/stop of EC2 instances managed by Auto Scaling Groups

If your EC2 instances in AWS are managed through Auto Scaling Groups, it is easy to schedule startup and shutdown of those instances, e.g. to save money.

This tutorial walks you through setting up an AWS Lambda function that is triggered by CloudWatch Events and automatically changes the min, max and desired instances in your Auto Scaling Group(s).

The idea is to toggle between 0 (stop) and a specifed min, max and desired amount of instances (start), so you only need a single Lambda function. The premise is that you do not touch these Auto Scaling Group settings manually, or you might make your EC2 instances nocturnal.

Create new Lambda function and Start Event

igorjs

function keepTrying(otherArgs, promise) {
	promise = promise||new Promise();
	
	// try doing the important thing
	
	if(success) {
		promise.resolve(result);
	} else {
		setTimeout(function() {
			keepTrying(otherArgs, promise);

igorjs

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igorjs

Einstein Riddle solver

http://www.theguardian.com/science/alexs-adventures-in-numberland/2015/may/04/einsteins-election-riddle-are-you-in-the-two-per-cent-that-can-solve-it

igorjs

/**
 * BTC-e JavaScript Trading API
 * https://btc-e.com/api/documentation
 *
 * Author: jsCoin
 * BTC : 151vumzopVBZMV9CtswFiumQBbEHcULPnG
 * LTC : Laoq3qsLvQFCnnbfcFGpQyjy5kcK58bpen
 *
 * Dependencies:
 *   jQuery - http://jquery.com/

igorjs

image: dnxsolutions/musketeers:1.1.1-ecr

services:
  - docker:18.03.1-ce-dind # needs to match gitlab runner version

variables:
  DOCKER_HOST: tcp://docker:2375/
  DOCKER_DRIVER: overlay2
  AWS_DEFAULT_REGION: ap-southeast-2
  AWS_HOSTED_ZONE: dev.cloud.example.com.au

igorjs

Not using yarn ? see the corresponding pnpm action gist

Why

While @setup/node has a built-in cache parameter for popular package managers, it discards the cache on every lock file update. This composite action allows to run install with (almost always) warm cache. Depending on repo usage, that might reduces the monthly ci-time and decrease the carbon emissions. See also actions/setup-node#325.

Bench

Based on the nextjs-monorepo-example. A cold cache install on the ci is more than 2 minutes. With warmed cache: 1 minute. Crafted from benchmarks results in https://gist.github.com/belgattitude/0ecd26155b47e7be1be6163ecfbb0f0b. Depending on repo (renovatebot...), the slight complexity increase in ci setup might worth it.

igorjs

(To be improved)

Requirements

• httpie (which provides the http command) — pip install httpie

Setup

• Save the git-branch-protection.sh as git-branch-protection somewhere in your path (something like ~/bin or ~/.local/bin if you already use it)
• Generate a GitHub token and save it as ~/.config/github_token.

igorjs

If you're using a high-end bluetooth headset on your Macbook Pro it's likely your mac is using an audio codec which favors battery efficiency over high quality. This results in a drastic degradation of sound, the SBC codec is the likely culprit, read more about it here.

Find out what codec you're using

1. Play a song on your headphones
2. Option (⌥) click the Bluetooth button at the top of your screen
3. If you're using AAC or aptX, you can stop here—those are the highest quality codecs.

Change your codec to AAC or aptX

igorjs

Provider	Singleton	Instantiable	Configurable
Constant	Yes	No	No
Value	Yes	No	No
Service	Yes	No	No
Factory	Yes	Yes	No
Decorator	Yes	No?	No
Provider	Yes	Yes	Yes

Constant