introduction to puppet scripting

Introduction to Puppet Scripting

Shawn S. SmileyLead ArchitectAchieve Internetshawn.smiley@achieveinternet.com

What is puppet?

“Puppet is IT automation software that helps system administrators manage infrastructure throughout its lifecycle, from provisioning and configuration to patch management and compliance.”

Source: www.puppetlabs.com/puppet/what-is-puppet

What does that mean?

• You can setup a new server in minutes vs. hours!

• You can be sure your server configurations are consistent.

• You can easily deploy configuration changes to multiple servers.

Image Source: http://www.forbes.com/sites/kenkrogue/2012/09/07/the-most-important-interview-question-never-asked/

Quick Demo

Image source: http://gyaniji.blogspot.com/2011/12/demo-of-ad-posting-job.html

What happened?

• Puppet analyzed the scripts to build a picture of what the server should look like.

• Puppet then compared that to what the server actually looks like.

• It then generates and executes scripts to make the server configuration match that in the puppet scripts.

How vs. What

• Why is it better to describe what a system looks like rather than how to configure a system?

• When you describe what a system looks like, you can repeatedly rerun the process without fear of breaking the system.

• Can build platform independent scripts.

What are the pieces?

• Puppet Software• Module Library• Node configuration file• [optional] Puppet Master

Modules

What are they?• Self-contained packages that describe an aspect

of a system (e.g. “Apache” or “MySQL”)

Are there existing packages I can leverage?• http://forge.puppetlabs.com• http://github.com

Where do I put them?• /usr/share/puppet/modules• /etc/puppet/modules

File Organization

• manifests• site.pp• nodes.pp

• modules• module1• manifests

init.pp

• files• templates• module2

Demo: Folder Structure

Image source: http://gyaniji.blogspot.com/2011/12/demo-of-ad-posting-job.html

Basic Syntax

• Follows basic Ruby language syntax.• Does not fully implement the Ruby language

though, only a subset is allowed in your puppet files.To define an item:

type title($arg1) { description of resource state}

To execute an item:

include “title”

type {“title”: }

type {“title”: arg1 => ‘hello’ }

Demo: Simple script

Image source: http://gyaniji.blogspot.com/2011/12/demo-of-ad-posting-job.html

Resource Types

• Are puppet libraries that are used to interact with the system.

• Puppet comes with a wide range of resource types:

• exec• package• file• service• notify

Full list: http://docs.puppetlabs.com/references/latest/type.html

Facter

What are facts?• Global variables with information about the

system that the script is running on.

How do I see the available variables?• facter -p

How do I use them?• $::variable_name

Templates

• Templates are files that use a simple markup language to insert dynamic values.

• Templates have an .erb extension• Typically used with the File resource. e.g.:

file {'ntp.conf': path => '/etc/ntp.conf', ensure => file, content => template('ntp/ntp.conf.erb'), owner => root, mode => 0644,}

Relationships

• Package[“ntp”] -> File[‘ntp.conf’] ~> Service[‘ntpd’]

• “before”, “require” • “subscribe”, “notify”

http://docs.puppetlabs.com/puppet/2.7/reference/lang_relationships.html#relationship-metaparameters

http://docs.puppetlabs.com/puppet/2.7/reference/lang_relationships.html#chaining-arrows

User-Defined Types

• Similar to functions in most languages.• Only way to do iterations currently.

• Call the Type with an array.

define apache::vhost() { $docroot = “/var/www/${name}”}

$sites = [‘site1’, ‘site2’]apache::vhost {$sites: }

References

Books• Managing Infrastructure with Puppet

(ISBN: 978-1-4493-0763-9)• Pro Puppet (ISBN: 978-1-4302-3057-1)

Websites• http://www.puppetlabs.com• http://docs.puppetlabs.com/• http://forge.puppetlabs.com/

Q&A