Greenfield PuppetDavid Danzilio

@djdanzilio

$(whoami)

What’s this all about?

A collection of wisdom that I wish I had available when I first started using Puppet

This could change in future releases

Don’t just take my word for it

– Wikipedia

“a greenfield is a project that lacks any constraints imposed by prior work”

A (not so) hypothetical scenario…

Department of BasketweavingFU

Foo University

class apache {! package { [‘apache2’, ‘rails’, ‘libapache2-mod-passenger’]:! ensure => present,! }! file { ‘/etc/apache2/sites-enabled/bw-app.conf’:! ensure => file,! source => ‘puppet:///apache/bw-app.conf',! require => Package[‘apache2’],! }! file { ‘/var/www/bw-app’:! ensure => directory,! owner => www-data,! group => www-data,! source => ‘puppet:///apache/bw-app',! recurse => true,! require => File[‘/etc/apache2/sites-enabled/bw-app.conf’]! }! service { ‘apache2’:! ensure => running,! require => [! File[‘/var/www/bw-app’],! Package[’rails’, ‘libapache2-mod-passenger’],! ]! }!}

I want to use Graphitefor all my!

basket data

OH NOES!

–Doug McIlroy

“Write programs that do one thing and do it well. Write programs to work together.”

Modules

Don’t write modules unless you absolutely have to!

Check the Forge first

2,617

Don’t customize Forge modules!

Use the Roles and Profiles pattern

Roles and Profiles

Craig Dunn’s blog post: “Designing Puppet – Roles

and Profiles”

A node includes one role

node db01.example.com { include role::db::server } !

node db02.example.com { include role::db::server::dev }

A role includes one or more profiles

class role::base { include profile::base } !class role::db::server inherits role::base { include profile::mysql include profile::application::database } !class role::db::server::dev inherits role::base { include profile::mysql include profile::percona }

A profile manages modules

class profile::mysql { ! $mysql_version = hiera(‘mysql_version’) ! class { ‘mysql::server’: package_ensure => $mysql_version } ! class { ‘mysql::backup’: } class { ‘nagios::mysql’: } !}

Like MVC for Puppet

The Forge

Look for modules with lots of downloads and recent

updates

Lots of downloadsRecent update

Do some background research on the author of the

module

Give priority to modules written by Puppet Labs

Be weary of modules with strange dependencies

WHY!??!?!

Don’t use a module without vetting it

Puppet Deployment

Have a solid deployment pipeline

Use librarian-puppet or r10k to deploy your code to your

Puppet masters

Reliable metadata is key to a successful Puppet deployment

$ cat /etc/facter/facts.d/metadata.json { "datacenter": "Boston", "rack": "R23", "role": "webserver", "cluster": "C89" }

Use environments to keep your nodes safe

Understand the lifecycle of a module

Use Hiera from the start

Don’t get too crazy with your hierarchy

:hierarchy: - “%{::app}/%{::environment}/%{::datacenter}/%{::fqdn}” - “%{::app}/%{::environment}/%{::datacenter}” - “%{::app}/%{::environment}” - “%{::app}” - “%{::cluster}/%{::environment}/%{::datacenter}/%{::fqdn}” - “%{::cluster}/%{::environment}/%{::datacenter}” - “%{::cluster}/%{::environment}” - “%{::cluster}” - “%{::environment}/%{::datacenter}/%{::fqdn}” - “%{::environment}/%{::datacenter}” - “%{::environment}” - “%{::realm}/%{::region}/%{::datacenter}/%{::fqdn}” - “%{::realm}/%{::region}/%{::datacenter}” - “%{::realm}/%{::region}” - “%{::realm}” - “%{::region}” - “%{::datacenter}/%{::rack}/%{::cluster}/%{::fqdn}” - “%{::datacenter}/%{::rack}/%{::cluster}” - “%{::datacenter}/%{::rack}” - “%{::datacenter}” - “%{::rack}” - “%{::cluster}”

Puppet Development

Puppet code is real code

Puppet is Ruby

Puppet modules need a design specification

rspec-puppet for TDD

Design modules with other people in mind

Fail fast

fail(“${::osfamily} is not supported by this module.”)

Public classes should expose a stable API

Semantic Versioning is your friend

Major.Minor.Patch

X.0.0

0.X.0

0.0.X

Remember the UNIX philosophy

Share your custom modules with the community!

Manage your dependencies with care

Keep artifacts out of your Puppet modules

Embedding data makes your modules less modular

class foo ( $pkg_version = $foo::params::pkg_version, $pkg_name = $foo::params::pkg_name, ) inherits foo::params { ! ... !}

Keep business logic out of templates

<% if @app == ‘foo’ %> ... <% else %> ... <% end %>

$template = ? $app { ‘foo’ => ‘foo.conf.erb’, default => ‘generic.conf.erb’, } !file { ‘/path/to/app.conf’: ensure => file, content => template(“module/${template}”), }

Standard Library

Use the standard library to level-up your modules

Avoid duplicate resources with ensure_packages and ensure_resource

package { ‘apache2’: ensure => present, }

ensure_packages([‘apache2’])

Validate inputs with validate_array, validate_bool, validate_hash, validate_re, and validate_string

Protect private classes with private

Modules should be easy to use and hard to abuse

StyleSubstance

Style is important

puppet-lint

puppet-syntax

source 'https://rubygems.org' !

gem 'rake' gem 'puppet' gem 'puppet-lint' gem 'puppet-syntax'

require 'puppet-lint/tasks/puppet-lint' require 'puppet-syntax/tasks/puppet-syntax' !exclude_paths = [ "pkg/**/*", "vendor/**/*", "spec/**/*", ] !PuppetLint.configuration.ignore_paths = exclude_paths PuppetSyntax.exclude_paths = exclude_paths

$ bundle install Fetching gem metadata from https://rubygems.org/........ Resolving dependencies... Installing rake 10.3.2 Installing CFPropertyList 2.2.8 Installing facter 2.1.0 Installing json_pure 1.8.1 Installing hiera 1.3.4 Installing rgen 0.6.6 Installing puppet 3.6.2 Installing puppet-lint 0.3.2 Installing puppet-syntax 1.3.0 Using bundler 1.6.2 Your bundle is complete! Use `bundle show [gemname]` to see where a bundled gem is installed.

$ bundle exec rake -T rake lint # Run puppet-lint rake syntax # Syntax check Puppet manifests and templates rake syntax:hiera # Syntax check Hiera config files rake syntax:manifests # Syntax check Puppet manifests rake syntax:templates # Syntax check Puppet templates

Documentation is important

We’re all Keynesians now.developers

Keeping Up

Puppet is evolving really fast

There is a fantastic community out there

Pay attention to thought leaders

Refactor your code as the language evolves

Contribute to modules on the Forge!

Questions?

Thank you!

Image Credits• http://officeimg.vo.msecnd.net/en-us/images/MP900430517.jpg • http://imgur.com/gallery/YNI5wud • http://www.reddit.com/r/funny/comments/1jgxtq/new_york_and_boston_the_difference/ • http://openclipart.org/detail/195046/ubuntu-geek-by-stephencuyos-195046 • http://design.ubuntu.com/downloads?metadata=element-logo+brand-ubuntu • http://commons.wikimedia.org/wiki/File:Ruby_on_Rails-logo.png • https://github.com/phusion/passenger • http://kaleidos.net/weapons/apache-webserver/ • http://puppetlabs.com/company/news/media-kit • http://copiousnotes.bloginky.com/2014/06/17/summer-classic-dr-strangelove-2/ • http://imgur.com/iWKad22 • http://cheezburger.com/6230961920 • http://www.craigdunn.org/stuff/puppet_big.png • http://www.quickmeme.com/meme/362un7 • http://programmerryangosling.tumblr.com/image/22790837971 • http://www.quickmeme.com/meme/3sogf9 • http://wall.alphacoders.com/big.php?i=238266

Further Reading• http://www.craigdunn.org/2012/05/239/ • https://www.youtube.com/user/PuppetLabsInc/playlists • https://github.com/puppetlabs/puppetlabs-stdlib • http://continuousdelivery.com • http://www.slideshare.net/PuppetLabs/tddforpuppet • http://www.slideshare.net/PuppetLabs/roles-rofiles • http://www.slideshare.net/PuppetLabs/steamlining-

puppetdevelopmentpuppetconfny2014 • http://garylarizza.com/blog/2013/12/08/when-to-hiera/ • http://www.devco.net/archives/2013/12/09/the-problem-with-params-pp.php • http://www.devco.net/archives/2013/12/08/better-puppet-modules-using-hiera-data.php • http://puppet-lint.com • https://github.com/gds-operations/puppet-syntax