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###Let's install Vagrant###

• Install VirtualBox: https://www.virtualbox.org/
• Install Vagrant: http://vagrantup.com/

###Select a Vagrant Box from https://vagrantcloud.com###

#add it to your list of boxes
vagrant box add hashicorp/precise32
#create a new folder for your project & init vagrant

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###SSH into a remote machine###

ssh user@mydomain.com
#or by ip address
ssh user@192.168.1.1

exit: exit ###Install Something###

#If it's a new server, update apt-get first thing

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upstream project {
  server 22.22.22.2:3000;
  server 22.22.22.3:3000;
  server 22.22.22.5:3000;
}

server {
  listen 80;

  location / {

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##what are generators##

• They're pausable functions, pausable iterable functions, to be more precise
• They're defined with the *
• every time you yield a value, the function pauses until .next(modifiedYieldValue) is called

var myGen = function*() {
  var one = yield 1;
  var two = yield 2;
  var three = yield 3;
 console.log(one, two, three);

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###Doing Express.js Async With Generators###

Using Co library, run generators as responses by wrapping Co and adding an extra function to handle errors

• Because Co always runs the last argument as a callback...so it would always runs next() by default
• This function only runs next if there's an error

//assign this to the Co module somewhere in application bootstrapping, 
//so you can do var ce = require('co').coExpress in each router file
co.coExpress = (generator) => {
  return (...args) => {

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##The Good, The Bad, & The Ugly Ways of handling Async Operations With Javascript## #####Callbacks < Promises < Generators#####

---

###An Example: 5 in-sequence Async Operations### (also see parallel-sequence example: https://gist.github.com/willrstern/af3a3308fc5864cf48f8)

---

###The Ugly Way: Callbacks### After each function takes place, handle any errors & do the next thing - It's easy to walk through the code and understand what's going on...but it's ugly as sin

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##Example Task: Make 2 parallel (simultaneous) async calls, then one async call when they've resolved##

##The Good Way: Promises##

//with bluebird library
var parallelCalls = [
  getUrl('/api/profile'),
  getUrl('/api/accounts')
];
//spread is like .then(), except it apply()s the array of responses as individual arguments

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Here's all you have to do to add clustering to your node.js application.

• save this code as cluster.js, and run cluster.js instead of server.js (or /bin/www, or whatever it's called for your project)
• the only line you'll need to change is the last line - it needs to point to the location of your server.js file

var cluster = require('cluster');

if (cluster.isMaster) {
  // Count the machine's CPUs
 var cpuCount = require('os').cpus().length;

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(wherever it says url.com, use your server's domain or IP)

Login to new server as root, then add a deploy user

sudo useradd --create-home -s /bin/bash deploy
sudo adduser deploy sudo
sudo passwd deploy

And Update the new password

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##Setup your server (this would ideally be done with automated provisioning)

• add a deploy user with password-less ssh see this gist
• install forever npm install -g forever

##Install flightplan

• npm install -g flightplan
• in your project folder npm install flightplan --save-dev
• create a flightplan.js file