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Elixir Supervision Trees Made Easy

I started with Elixir just a couple weeks after the switch from 1.4 to 1.5, so the bulk of online resources were out of date (or at least resulted in deprecation warnings). This guide is for defining Elixir 1.5 supervised modules.

It's not actually terribly complicated. It's just sometimes unclear from examples what's implemented by the language and what you actually have to implement yourself.

Say we want a supervision tree like this (where each atom is a process):

:a

/ \

AWS S3 bucket and IAM policy recipes

Anonymous GET access
Anonymous GET access - match HTTP referrer
Full access for specific IAM user/role
GET/PUT/DELETE access to specific path within a bucket
Restricted LIST & PUT/DELETE access to specific path within a bucket
Full access (and S3 console) for specific IAM users
Reference

Anonymous GET access

What is your folder-structure preference for a large-scale Node.js project?

0: Starting from Rails

This is the reference point. All the other options are based off this.

|-- app
|   |-- controllers
|   |   |-- admin

	var AWS = require('aws-sdk');
	var cloudwatch = new AWS.CloudWatch({ region: 'us-east-1'});

	exports.handler = function (event, context) {

	var ElasticSearchHost = 'elasticsearch.example:9200';
	var Environment = 'int';
	var EndTime = new Date;
	var StartTime = new Date(EndTime - 15601000);
	var Metrics = {

	# This demonstrates that, when using async/await, a crash in the task will crash the caller
	defmodule Tasker do
	def good(message) do
	IO.puts message
	end

	def bad(message) do
	IO.puts message
	raise "I'm BAD!"
	end