Test Driven Development!for Puppet!Puppet needs software developmentGareth Rushgrove

Who (Who is this person?)

@garethr

UK Government Digital Service

The problem (This isn’t a rant, but…)

Who here is a software developer?

Gareth Rushgrove

If you’re writing Puppet code you’re a software developer

Gareth Rushgrove

As a software developer it’s your job to learn software engineering practices

Gareth Rushgrove

What is Test Driven Development

(And why should you care)

A common practice in software engineering

Gareth Rushgrove

Not just testing

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Encourages simple designs and inspires confidence

Gareth Rushgrove

First write an (initially failing) automated test case

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Then produce the minimum amount of code to pass that test

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And finally refactor the new code to acceptable standards

Gareth Rushgrove

Test Driven Design

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Gareth Rushgrove

Unit testing with RSpec and Guard (Not puppet specific)

A unit is the smallest testable part of an application

Gareth Rushgrove

Testing puppet requires a little Ruby knowledge so we’ll use Ruby examples

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class Person def say(word) end end

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First lets write a test. For this we use the RSpec testing framework

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require 'person' !describe Person, "#say" do it "should say something" do ! end end

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require 'person' !describe Person, "#say" do it "should say something" do bob = Person.new bob.say("hello").should \ eq("hello everyone") end end

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Now lets run our test. It should fail

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rspec

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Failures: 1) Person#say should say something Failure/Error: bob.say("hello").should eq("hello everyone") expected: "hello everyone" got: nil Finished in 0.00171 seconds 1 example, 1 failure

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Now lets write the implementation

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class Person def say(word) word + " everyone" end end

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And run our test again

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Person#say should say something !Finished in 0.00199 seconds 1 example, 0 failures

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Why not have tests automatically run whenever you change the code?

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That’s what Guard does

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guard :rspec, cmd: 'bundle exec rspec' do watch(%r{^spec/.+_spec\.rb$}) watch(%r{^lib/.+\.rb$}) { 'spec' } end

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guard

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Lets see a quick demo

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Why test puppet code at all

(Testing declarative languages)

Modules increasingly contain logic

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Modules increasingly take arguments

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Modules increasingly have interfaces with other modules

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Modules increasingly used in many operating system and version combinations

Gareth Rushgrove

Modules increasingly used in many Ruby and Puppet version combinations

Gareth Rushgrove

Unit testing puppet with

rspec-puppet (Finally some puppet code)

Unit testing for Puppet

A very simple puppet class

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class sample { }

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First write the test

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require 'spec_helper' !describe "sample" do it { should create_file('/tmp/sample')} end

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Then run the test

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sample should contain File[/tmp/sample] (FAILED - 1) !Finished in 0.4584 seconds 1 example, 1 failure

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And then write the (puppet) code to make the test pass

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class sample { file { "/tmp/sample": ensure => present, } }

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sample should contain File[/tmp/sample] !Finished in 0.3881 seconds 1 example, 0 failures

Gareth Rushgrove

Lets run the tests automatically whenever you change anything

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guard :rspec, cmd: 'bundle exec rspec' do watch(%r{^spec/.+_spec\.rb$}) watch(%r{^manifests/.+\.pp$}) { 'spec' } end

Gareth Rushgrove

Lets see a quick demo of that too

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You can also test hosts, defines, facts, functions, hieradata

Gareth Rushgrove

Syntax checking, linting, oh my (Creating a build process)

puppet-lint

Gareth Rushgrove

Puppet!style guide

Available!as a gem

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

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puppet-syntax

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Validate Puppet and ERB syntax

require 'puppet-syntax/tasks/puppet-syntax'

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rake syntax ---> syntax:manifests ---> syntax:templates ---> syntax:hiera:yaml

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What is Rake and why do we use it

(Still no puppet)

Rake is a Ruby!build tool

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It’s like Make but in Ruby

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It’s very easy to distribute Rake tasks as Ruby gems

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rake

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rake <command>

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rake -T

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Lets make a command to run lint, syntax and spec

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

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rake test

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Acceptance testing with

beaker (Living on the edge)

Acceptance test against real systems

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Test what actually happens, not what is meant to happen

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Build by

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Very new

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Test against different operating systems

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HOSTS: ubuntu-server-12042-x64: roles: - master platform: ubuntu-server-12.04-amd64 box: ubuntu-server-12042-x64-vbox4210-nocm box_url: http://puppet-vagrant-boxes.puppetlabs.com/ubuntu-server-12042-x64-vbox4210-nocm.box hypervisor: vagrant !CONFIG: log_level: verbose type: foss

Gareth Rushgrove

HOSTS: centos-64-x64: roles: - master platform: el-6-x86_64 box : centos-64-x64-vbox4210-nocm box_url : http://puppet-vagrant-boxes.puppetlabs.com/centos-64-x64-vbox4210-nocm.box hypervisor : vagrant !CONFIG: log_level: verbose type: foss

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Supports multiple hypervisors

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Vagrant hypervisor

VSphere hypervisor

Helpers to install puppet and modules

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install_puppet

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puppet('module', 'install', 'puppetlabs-stdlib')

Gareth Rushgrove

Test that Puppet runs without errors

Gareth Rushgrove

context 'default parameters' do it 'should work with no errors' do pp = “class { 'sample': }” ! expect(apply_manifest(pp).exit_code).to_not eq(1) end end

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Test runs are idempotent

Gareth Rushgrove

context 'default parameters' do it 'should work with no errors' do pp = “class { 'sample': }” ! expect(apply_manifest(pp).exit_code).to_not eq(1) expect(apply_manifest(pp).exit_code).to eq(0) end end

Gareth Rushgrove

Test that the module installs packages, run services, etc.

Gareth Rushgrove

Gareth Rushgrove

describe package('nginx') do it { should be_installed } end !describe service('nginx') do it { should be_enabled } it { should be_running } end !describe port(80) do it { should be_listening} end

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Other useful tools (and what we’re still missing)

Fixtures, matchers

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Nice continuous integration

Test pull request branches too

--- language: ruby bundler_args: --without development before_install: rm Gemfile.lock || true rvm: - 1.8.7 - 1.9.3 - 2.0.0 script: bundle exec rake test env: - PUPPET_VERSION="~> 2.7.0" - PUPPET_VERSION="~> 3.1.0" - PUPPET_VERSION="~> 3.2.0" - PUPPET_VERSION="~> 3.3.0" - PUPPET_VERSION="~> 3.4.0"

Gareth Rushgrove

Official!ruby support

matrix: exclude: - rvm: 2.0.0 env: PUPPET_VERSION="~> 2.7.0" - rvm: 2.0.0 env: PUPPET_VERSION="~> 3.1.0" - rvm: 1.9.3 env: PUPPET_VERSION="~> 2.7.0"

Gareth Rushgrove

Experimental code coverage support in rspec-puppet master

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at_exit { RSpec::Puppet::Coverage.report! }

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Total resources: 24 Touched resources: 8 Resource coverage: 33.33% !Untouched resources: Class[Nginx] File[preferences.d] Anchor[apt::update] Class[Apt::Params] File[sources.list] Exec[Required packages: 'debian-keyring debian-archive-keyring' for nginx] Anchor[apt::source::nginx] Class[Apt::Update] File[configure-apt-proxy] Apt::Key[Add key: 7BD9BF62 from Apt::Source nginx] Anchor[apt::key/Add key: 7BD9BF62 from Apt::Source nginx] Anchor[apt::key 7BD9BF62 present] File[nginx.list] Exec[apt_update]

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A puppet module skeleton with everything working out of the box

Gareth Rushgrove

puppet module skeleton

puppet module generate sample

Gareth Rushgrove

A pretty complete example

(The Docker module)

Gareth Rushgrove

Gareth Rushgrove

Featured on the Forge

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50 pull request and counting

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Contributing guidelines

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Gareth Rushgrove

Currently has 121 tests

6 classes, 2 defines, 413 lines of puppet code, 387 lines of test code

Gareth Rushgrove

Take away (If all you remember is…)

Infrastructure as code

Gareth Rushgrove

The first test is the hardest

Gareth Rushgrove

Politely demand tests for contributions

Gareth Rushgrove

Test the interface not the implementation

Gareth Rushgrove

Questions? (And thanks for listening)