/scalability-tutorial

Sample stack for the LA Scalability Meetup

Primary LanguageJavaScript

Introduction

This repo contains configuration examples for setting up a stack according to the architecture Jeff Su proposed in on the January 10th, 2012 LA High Scalability Meetup. It is intended to be the bare minimum for setting up load balancing, throttling, statistics tracking and caching in front of a web application.

Architecture

There are 4 basic principles behind this architecture. 1) Setting up easy load balancing and fault tolerance with haproxy 2) Using varnish to cache both static and semi-dynamic requests 3) Using Node.js to handle some stateful business logic and then proxy requests. 4) Using Redis to sync up Node.js servers

Installation

It is assumed that these are installed

  1. redis: [http://redis.io/download]
  2. Nodejs: [https://github.com/joyent/node/wiki/Installing-Node.js-via-package-manager]
  3. varnish: [https://www.varnish-cache.org/trac/wiki/Installation]
  4. haproxy
  5. rails

If you want to run the app, it is recommended that you install rails via (rvm)[http://beginrescueend.com/rvm/install/]. Then run:

rvm install 1.9.2
rvm use 1.9.2
gem install bundler
bundle install

Starting Up

Do this in separate terminals:

# start haproxy
haproxy -f ./haproxy/haproxy.cfg

# start varnish
sudo varnishd -d -f ./varnish/default.vcl -a 127.0.0.1:4001
# then type "start" <enter>

# start Node
Node nodejs/server.js

# start rails
cd app; rails s -p 3001

Architecture

HAProxy

HAProxy is used to load balance every layer of the stack. It will listen these ports:

  • 8000 public port
  • 5000 Node distributed port
  • 4000 caching distributed port
  • 3000 app distributed port

Each layer (except for the app) has a fallback option for availability.

Nodejs

Nodejs is a layer used for handling simple/global cases. It is currently used for ip throttling, and ip/url statistics gathering, but could be used for things like authentication, permissions and routing.

Varnish

Varnish is the caching layer. It scales very well and should be used wherever caching is allowed.

In the varnish config, there is a 1s cache time on all "dynamic" content. This allows us to utilize the caching against many concurrent requests while still maintaining dynamic-ish behavior.

Rails

Rails is used as a highly agile but slow application layer.

Links