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Auto-scaling PHP
applications using Chef
and AWS
Andy Gale
Web Consultancy
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About me
Andy Gale
Web Consultant
Hello Future
http://hellofutu.re
!
@andygale
@hellofutur3
Web Consultancy
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Hosting
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Virtual machine or cloud instance
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Traffic
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Visitors
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Crash!
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Hosting
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Dedicated machine
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Crash!
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Separate Database and Web
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Crash!
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Horizontal scaling
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Great success!
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Web Consultancy
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Auto-scaling
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• Only pay for capacity we use
• Handle huge traffic peaks
• Automatically recover from failure
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When your traffic increases, our robot will
automatically create a new web server for
you.
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• Cloud hosting provider
• Various services
• We’ll be using Elastic Load
Balancers, EC2 (Elastic Compute
Cloud) and RDS (Relational
Database Service)
What is AWS?
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Auto-scaling
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• Create new web servers
• Use ELB load balancer
• Use Amazon RDS database which
will in this example will need to be
large enough to handle our traffic
peaks
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Auto-scaling
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• We’ll need a way of setting up web
servers
• And we’ll need a way of installing
our code on to them
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• Configuration management tool
• Install packages
• Ensure services like Apache are running
• Write out configuration files from
templates
• Restart services when templates
change
What is Chef?
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Collections of recipes, templates and other
configuration attributes to get stuff done.
Chunks of Ruby code that describe what stuff we
need to do to get that stuff done.
Cookbooks
Recipes
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A virtual machine, cloud server or dedicate
server
Resource
Creates a user, expands a template, installs a
package, starts a service etc
Node
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Port number, database name, file location etc
Template
A template which you create a file from inserting
variables
Attribute
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package "ntp" do
action :install
end
!
template "/etc/ntp.conf" do
source "ntp.conf.erb"
owner "root"
group "root"
mode 0644
notifies :restart, resources(:service => "ntp")
end
!
service "ntp" do
action :start
end
Install package
Create config file
from template
Define service and
start NTP
Restart service
when config file
changes
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Let’s make a cookbook to
install our PHP application
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Our template
ServerName <%= @params[:server_name] %>
DocumentRoot <%= @params[:docroot] %>
!
>
Options FollowSymLinks
AllowOverride FileInfo Options
AllowOverride All
Order allow,deny
Allow from all
!
Options FollowSymLinks
AllowOverride None
!
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include_recipe "apache2"
include_recipe "php"
include_recipe "php::module_mysql"
include_recipe "apache2::mod_php5"
Our recipe
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web_app node['phpapp']['host'] do
template "phpapp.conf.erb"
docroot node['phpapp']['dir']
server_name node['phpapp']['host']
end
Our recipe
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gettingstartedwithchef.com
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$ knife ec2 server create --run-list "role[phpapp]" -I
ami-3d160149 --region eu-west-1 -G www,default -x ubuntu --
node-name server01 --identity-file ~/.ssh/sshkey.pem
Create EC2 instance
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Auto-scaling
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• We want to auto-scale quickly
• Our previous Chef and knife example takes
10 minutes to bootstrap our server
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Auto-scaling
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https://github.com/hellofuture-cookbooks/hf-lamp
hf-lamp
• Different recipes for installing
dependencies and setting up you
application configuration
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include_recipe "apache2"
include_recipe "php"
include_recipe "php::module_mysql"
include_recipe "apache2::mod_php5"
Auto-scaling
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Auto-scaling
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• chef-solo to create an instance with
dependencies installed
• Create an AMI image from that instance
• Use that instance in you auto-scaling
launch configuration
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When to auto-scale
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• Create CloudWatch alarms on key metrics
such as CPU load
• Scale up when a high percentage of total of
the metric is being used
• Scale down when low percentage of the
metric is being used
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When to auto-scale
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• Test things out with CloudWatch alarms to
begin with
• Scale up quickly and scale down slowly
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Amazon OpsWorks
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• Chef based
• Lots of scaling configuration options
including scaling up on a schedule
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Questions?
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