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Puppet Module Reusability Learning from shipping to the Forge Gareth Rushgrove

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Who (Who is this person?)

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@garethr

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UK Government Digital Service

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Last code I wrote

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7. Gareth Rushgrove

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Last puppet module I wrote

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The Problem (Sharing modules is hard)

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Not invented here syndrome 1

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A search for puppet-apache

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145 Gareth Rushgrove

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145 Gareth Rushgrove

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Puppetlabs apache

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67 contributors Gareth Rushgrove

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281 forks Gareth Rushgrove

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281 Gareth Rushgrove

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Vendor everything pattern 2

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Not publishing to the Forge 3

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Puppet Forge

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Undocumented modules 4

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Official docs guidelines

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(Too) opinionated configuration 5

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Sometimes I just want to write nginx configuration Gareth Rushgrove

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Duplicate resources 6

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Package { 'build-essential’: ensure => installed, } Gareth Rushgrove

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Stdlib (Start here)

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Standard Library from Puppetlabs

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Fail fast Gareth Rushgrove

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Validation Gareth Rushgrove

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Useful error messages Gareth Rushgrove

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fail("${::operatingsystem} not supported") Gareth Rushgrove

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validate_string Gareth Rushgrove

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validate_string($version) Gareth Rushgrove

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validate_slength Gareth Rushgrove

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validate_re Gareth Rushgrove

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validate_hash Gareth Rushgrove

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Gareth Rushgrove validate_cmd

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validate_bool Gareth Rushgrove

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Avoid duplicate resources Gareth Rushgrove

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Package { 'build-essential’: ensure => installed, } Gareth Rushgrove

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include 'gcc' Gareth Rushgrove

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package{[ 'python-pip', 'python-ldap', ]: ensure => installed } Gareth Rushgrove

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ensure_packages Gareth Rushgrove

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ensure_packages([ 'python-pip', 'python-ldap', ]) Gareth Rushgrove

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ensure_resource Gareth Rushgrove

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Nicer interfaces Gareth Rushgrove

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str2bool Gareth Rushgrove

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any2array Gareth Rushgrove

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And much more Gareth Rushgrove

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Dependency management is everywhere (Else)

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NPM, Bundler, Pip, Mix, Leiningen Gareth Rushgrove

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Librarian Puppet

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r10k

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echo 'modules' >> .gitignore Gareth Rushgrove

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dependency 'puppetlabs/stdlib' dependency 'garethr/erlang' dependency 'maestrodev/wget' Gareth Rushgrove

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forge "http://forge.puppetlabs.com" mod 'puppetlabs/ruby' mod 'puppetlabs/ntp' mod 'puppetlabs/git' mod 'puppetlabs/vcsrepo' mod 'puppetlabs/apt' mod 'puppetlabs/gcc' Gareth Rushgrove

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librarian-puppet install Gareth Rushgrove

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A Nice Module Pattern (Structuring modules for reuse)

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R.I.Pienaar

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install, config, service, params Gareth Rushgrove

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manifests !"" config.pp !"" init.pp !"" install.pp !"" params.pp #"" service.pp Gareth Rushgrove

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class sample ( ) inherits sample::params { class { 'sample::install': } -> class { 'sample::config': } ~> class { 'sample::service': } -> Class['sample'] } Gareth Rushgrove

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anchor { 'sample::begin': } -> class { 'sample::install': } -> class { 'sample::config': } class { 'sample::service': } -> anchor { 'sample::end': } Gareth Rushgrove

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Anchor['sample::begin'] ~> Class['sample::service'] Class['sample::install'] ~> Class['sample::service'] Class['sample::config'] ~> Class['sample::service'] Gareth Rushgrove

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Puppet module tool Gareth Rushgrove

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puppet module generate name Gareth Rushgrove

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Default module skeleton Gareth Rushgrove

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In puppet source code

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!"" manifests !"" spec !"" tests !"" Modulefile !"" .gitignore #"" README Gareth Rushgrove

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Creating your own module skeleton Gareth Rushgrove

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~/.puppet/var/puppet-module/skeleton Gareth Rushgrove

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puppet module skeleton

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!"" manifests !"" spec !"" tests !"" templates !"" files !"" lib !"" Gemfile Gareth Rushgrove

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!"" Rakefile !"" .nodeset.yml !"" .fixtures.yml !"" .travis.yml !"" Modulefile !"" .gitignore #"" README.md Gareth Rushgrove

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Creates install, config, service, params classes Gareth Rushgrove

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Dependency management with Bundler Gareth Rushgrove

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Better unit testing setup using rspec- puppet-helper Gareth Rushgrove

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Adds syntax and lint checking Gareth Rushgrove

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Adds Travis CI configuration Gareth Rushgrove

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Adds integration tests with rspec-system Gareth Rushgrove

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Adds module management with maestrodev blacksmith Gareth Rushgrove

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Focus on the interface Gareth Rushgrove

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Minimize number of entry points Gareth Rushgrove

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Allow overriding provided templates Gareth Rushgrove

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Multi-OS Support (Where to abstract the differences)

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Vary default parameters Gareth Rushgrove

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Keep logic in one place Gareth Rushgrove

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case $::osfamily { 'Debian': { } 'RedHat', 'Amazon': { } default: { fail("${::operatingsystem} not su } Gareth Rushgrove

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ARM-9 Data in Modules

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garethr-erlang

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0.0.x supported Ubuntu only Gareth Rushgrove

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0.1.x supports Ubuntu, Debian, Redhat, Suse Gareth Rushgrove

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Gareth Rushgrove

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Pull requests to the rescue

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Insist on tests with open source contributions Gareth Rushgrove

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Module Testing (Code should have tests)

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Why test a declarative language? Gareth Rushgrove

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Modules increasingly contain logic Gareth Rushgrove

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Modules increasingly take arguments Gareth Rushgrove

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Modules increasingly have interfaces with other modules Gareth Rushgrove

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Modules increasingly used in many Ruby and Puppet version combinations Gareth Rushgrove

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Good news. The tools got better Gareth Rushgrove

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puppet-lint Gareth Rushgrove

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Puppet style guide

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Available as a gem

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puppet-lint --with-filename /etc/puppet/modules foo/manifests/bar.pp: trailing whitespace found on line 1 apache/manifests/server.pp: variable not enclosed in {} on line 56 Gareth Rushgrove

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puppet-syntax Gareth Rushgrove

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Validate Puppet and ERB syntax

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require 'puppet-syntax/tasks/puppet-syntax' Gareth Rushgrove

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bundle exec rake syntax ---> syntax:manifests ---> syntax:templates Gareth Rushgrove

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rspec-puppet Gareth Rushgrove

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Unit testing for Puppet

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context "epel enabled" do let(:params) {{ :epel_enable => true }} it { should contain_class('epel') } end Gareth Rushgrove

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context "epel disabled" do let(:params) {{ :epel_enable => false }} it { should_not contain_class('epel') } end Gareth Rushgrove

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Fixtures, matchers

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Test the interface not the implementation Gareth Rushgrove

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All of the above Gareth Rushgrove

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task :test => [ :syntax, :lint, :spec, ] Gareth Rushgrove

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bundle exec rake test Gareth Rushgrove

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Gareth Rushgrove

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Nice continuous integration

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Test pull request branches too

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--- language: ruby before_install: rm Gemfile.lock || true rvm: - 1.8.7 - 1.9.3 script: bundle exec rake test env: matrix: - PUPPET_VERSION="~> 2.7.0" - PUPPET_VERSION="~> 3.1.0" - PUPPET_VERSION="~> 3.2.0" Gareth Rushgrove

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A matrix of possibilities Gareth Rushgrove

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rspec-system Gareth Rushgrove

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Integration test against real systems

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Puppet helpers for rspec-system

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Vagrant driver

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VSphere provider

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Test that Puppet runs without errors Gareth Rushgrove

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it 'should run without errors' do pp = "class { 'sample': }" puppet_apply(pp) do |r| r.exit_code.should == 2 end end Gareth Rushgrove

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Test runs are idempotent Gareth Rushgrove

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it 'should run without errors' do pp = "class { 'sample': }" puppet_apply(pp) do |r| r.exit_code.should == 2 r.refresh r.exit_code.should be_zero end end Gareth Rushgrove

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Test that the module installs relevant binaries Gareth Rushgrove

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it 'should install the erl binary' do shell 'which erl' do |r| r.stdout.should =~ /\/usr\/bin\/e r.stderr.should be_empty r.exit_code.should be_zero end end Gareth Rushgrove

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Test against different operating systems Gareth Rushgrove

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default_set: 'centos-64-x64' sets: 'centos-64-x64': nodes: "main.foo.vm": prefab: 'centos-64-x64' 'fedora-18-x64': nodes: "main.foo.vm": prefab: 'fedora-18-x64' 'debian-607-x64': nodes: "main.foo.vm": Gareth Rushgrove

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Room for improvements (Making reuse easier in Puppet)

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Run your own Forge 1

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A more secure Forge 2

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Bless a dependency management tool 3

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Optional dependencies 4

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dependency 'puppetlabs/stdlib' optional_dependency 'puppetlabs/apache' Gareth Rushgrove

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Private classes 5

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private class elixir::install { Gareth Rushgrove

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Parameter naming conventions 6

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example42 Proposal

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Interfaces in Puppet 7

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interface packageandservice { $version $enable $package_name $template } Gareth Rushgrove

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class diamond ( $version, $enable, $package_name, $template, ) { implements packageandservice Gareth Rushgrove

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Questions? (And thanks for listening)