satish viswanatham satishv

Neo4j Tutorial

Fundamentals

Store any kind of data using the following graph concepts:

Node: Graph data records
Relationship: Connect nodes (has direction and a type)
Property: Stores data in key-value pair in nodes and relationships
Label: Groups nodes and relationships (optional)

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

Clarify and agree on the scope of the system

User cases (description of sequences of events that, taken together, lead to a system doing something useful)
- Who is going to use it?
- How are they going to use it?

Issues with Terraform State Management

The idea of "state" is the lynchpin of Terraform, and yet Terraform's workflow is fraught with gotchas that can lead to the loss or destruction of state. This doc is a set of notes about issues I've encountered, what caused them, and in many cases ideas about how to improve Terraform to avoid or reduce the chances of them.

Each of these scenarios has occured at least within my team. Each time one of these occurs it erodes people's confidence in Terraform, giving it a reputation for being fragile and unforgiving of errors. This this document is not written just to criticize but rather to identify ways in which the situation could be improved.

This is a mix between two sources:

basically the first resource is great but didn't work for me: I had to remove the trailing "/*" in the resource string to make it work. I also noticed that setting the policy on the source bucket was sufficient. In the end these are the exact steps I followed to copy data between two buckets on two accounts

Basically the idea there is:

we allowe the destination account to read the source bucket (in the console for the source account)
we log as the destination and start the copy

a simple git branching model (written in 2013)

This is a very simple git workflow. It (and variants) is in use by many people. I settled on it after using it very effectively at Athena. GitHub does something similar; Zach Holman mentioned it in this talk.

Update: Woah, thanks for all the attention. Didn't expect this simple rant to get popular.

Redis and Resque

What this guide will cover: the code you will need in order to include Redis and Resque in your Rails app, and the process of creating a background job with Resque.

What this guide will not cover: installing Ruby, Rails, or Redis.

Note: As of this writing I am still using Ruby 1.9.3p374, Rails 3.2.13, Redis 2.6.11, and Resque 1.24.1. I use SQLite in development and Postgres in production.

Background jobs are frustrating if you've never dealt with them before. Over the past few weeks I've had to incorporate Redis and Resque into my projects in various ways and every bit of progress I made was very painful. There are many 'gotchas' when it comes to background workers, and documentation tends to be outdated or scattered at best.

	#!/bin/bash

	function s3du(){
	bucket=`cut -d/ -f3 <<< $1`
	prefix=`awk -F/ '{for (i=4; i<NF; i++) printf $i"/"; print $NF}' <<< $1`
	aws s3api list-objects --bucket $bucket --prefix=$prefix --output json --query '[sum(Contents[].Size), length(Contents[])]' \| jq '. \|{ size:.[0],num_objects: .[1]}'
	}

	s3du $1;

	<!doctype html>
	<html>
	<head>
	<script src="//ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
	<script type="text/javascript">
	var spData = null;
	function doData(json) {
	spData = json.feed.entry;
	}

	package main

	import (
	"flag"
	"fmt"
	"strings"
	)

	const DB_REDSHIFT = "redshift"
	const DB_POSTGRES = "postgres"

	# Hosts/domain names that are valid for this site; required if DEBUG is False
	# See https://docs.djangoproject.com/en/1.5/ref/settings/#allowed-hosts
	ALLOWED_HOSTS = [
	'yourdomain.tld',
	'.compute-1.amazonaws.com', # allows viewing of instances directly
	]

	import requests
	EC2_PRIVATE_IP = None
	try: