Slides from a talk I gave at PuppetCamp Boston 2014. I this talk I share some tips for newcomers to Puppet.

1. Greenfield Puppet
David Danzilio
@djdanzilio

2. $(whoami)

3. What’s this all about?

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

5. This could change in future
releases

6. Don’t just take my word for it

8. – Wikipedia
“a greenfield is a project that lacks any constraints
imposed by prior work”

10. A (not so) hypothetical
scenario…

11. Department of
BasketweavingFUFoo University

12. 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’],!
]!
}!
}

13. I want to use
Graphite
for all my!
basket data

14. OH NOES!

16. –Doug McIlroy
“Write programs that do one thing and do it
well. Write programs to work together.”

17. Modules

18. Don’t write modules unless
you absolutely have to!

20. Check the Forge first

21. 2,617

22. Don’t customize Forge
modules!

23. Use the Roles and Profiles
pattern

24. Roles and Profiles

25. Craig Dunn’s blog post:
“Designing Puppet – Roles
and Profiles”

26. A node includes one role

27. node db01.example.com {
include role::db::server
}
!
node db02.example.com {
include role::db::server::dev
}

28. A role includes one or more
profiles

29. 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
}

30. A profile manages modules

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

32. Like MVC for Puppet

33. The Forge

34. Look for modules with lots of
downloads and recent
updates

35. Lots of downloads
Recent update

36. Do some background
research on the author of the
module

37. Give priority to modules
written by Puppet Labs

38. Be weary of modules with
strange dependencies

39. WHY!??!?!

40. Don’t use a module without
vetting it

42. Puppet Deployment

43. Have a solid deployment
pipeline

45. Use librarian-puppet or r10k
to deploy your code to your
Puppet masters

46. Reliable metadata is key to a
successful Puppet deployment

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

48. Use environments to keep
your nodes safe

49. Understand the lifecycle of a
module

50. Use Hiera from the start

51. Don’t get too crazy with your
hierarchy

52. :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}”

53. Puppet Development

54. Puppet code is real code

55. Puppet is Ruby

57. Puppet modules need a
design specification

58. rspec-puppet for TDD

59. Design modules with other
people in mind

60. Fail fast

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

62. Public classes should expose
a stable API

63. Semantic Versioning is your
friend

64. Major.Minor.Patch

65. X.0.0

66. 0.X.0

67. 0.0.X

68. Remember the UNIX
philosophy

69. Share your custom modules
with the community!

70. Manage your dependencies
with care

71. Keep artifacts out of your
Puppet modules

72. Embedding data makes your
modules less modular

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

74. Keep business logic out of
templates

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

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

77. Standard Library

78. Use the standard library to
level-up your modules

79. Avoid duplicate resources with
ensure_packages and
ensure_resource

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

81. ensure_packages([‘apache2’])

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

83. Protect private classes with
private

85. Modules should be easy to
use and hard to abuse

86. Style
Substance

87. Style is important

88. puppet-lint

89. puppet-syntax

90. source 'https://rubygems.org'
!
gem 'rake'
gem 'puppet'
gem 'puppet-lint'
gem 'puppet-syntax'

91. 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

92. $ 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.

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

94. Documentation is important

97. We’re all Keynesians now.
developers

98. Keeping Up

99. Puppet is evolving really fast

100. There is a fantastic
community out there

101. Pay attention to thought
leaders

103. Refactor your code as the
language evolves

105. Contribute to modules on the
Forge!

106. Questions?

107. Thank you!

108. 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

109. 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