Make it SOLID. Software Architecture for System Administrators

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Ole Michaelis & Sönke Ruempler | Jimdo Make it SOLID Software Architecture for System Administrators

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OSDC 2014 Ole Michaelis “Open Source Rockstar” @CodeStars github.com/nesQuick codestars.eu

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OSDC 2014 Sönke Ruempler “Chief Trolling Officer” @s0enke github.com/s0enke ruempler.eu

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OSDC 2014 Jimdo

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OSDC 2014 because infrastructure development is neither a Jenga game! S.O.L.I.D

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OSDC 2014 a little poll! http://images.fineartamerica.com/images-medium-large/live-long-mr-spock-tobias-woelki.jpg

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OSDC 2014

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OSDC 2014 S O L I D

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OSDC 2014 A dev/ops story Ole as Junior Admin Sönke as Dr. Software

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OSDC 2014 the basics

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OSDC 2014 configuration management Idempotent Declarative Convergent Abstract

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OSDC 2014 software architecture VS. 36 years >2000 years

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OSDC 2014

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OSDC 2014 node web-1 { $role = 'web-app-a' $has_apache = true; include php5 } node web-2 { $role = 'web-app-b' $has_fcgi=true include php5 } # has both enabled, but needs a special config node web-3 { $role = 'web-app-c' $has_fcgi=true $has_apache=true include php5 } Web App 1 Web App 2 Web App 3

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OSDC 2014 class php5 { if ($::has_fcgi) package { 'php5-cli' : ensure => installed } } if ($::has_apache) { package { 'php5-apache' : ensure => installed } } if ($::role == 'web-app-c') package { 'php5-web-app-c-special-module' } file { '/etc/php5/php.ini' : source => 'puppet:///modules/php5/php.ini-web-app-c' } } } Global variable! Out of Context! No abstraction

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OSDC 2014 class php5( $has_fcgi = false, $has_apache = false, $role = undef ) { if ($has_fcgi) package { 'php5-cli' : ensure => installed } } if ($has_apache) { package { 'php5-apache' : ensure => installed } } if ($role == 'web-app-c') { package { 'php5-web-app-c-special-module' } file { '/etc/php5/php.ini' : source => 'puppet:///modules/php5/php.ini-web-app-c' , require => Package[php-fcgi] } }

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OSDC 2014 node 'web-1' { $role = 'web-app-a' $has_apache = true class { 'php5' : has_apache => true, role => 'web-app-a' } } node 'web-2' { $role = 'web-app-b' $has_fcgi = true class { 'php5' : has_fcgi => true, role => 'web-app-b' } } Injection! Injection!

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OSDC 2014 Would you solder a lamp directly to the electrical wiring in a wall? Dependency Inversion

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OSDC 2014

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OSDC 2014 Stuff tends to get big Beware of god classes!

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OSDC 2014 if ($lighttpd) { package { 'php5-cgi': } configdir { '/etc/php5/cgi': require => Package['php5-cgi'] } configdir { '/etc/php5/cgi/conf.d': require => Package['php5-cgi'] } if ($testserver) { configfile { '/etc/php5/cgi/php.ini': sourcename => 'php5/cgi/php.ini-testserver', require => Package['php5-cgi'] } } else { if ($cms ) { configfile { '/etc/php5/cgi/php.ini': sourcename => 'php5/cgi/php.ini-cms', require => Package['php5-cgi'] } } else { if ($mgmt ) { configfile { '/etc/php5/cgi/php.ini': sourcename => 'php5/cgi/php.ini-mgmt', require => Package['php5-cgi'] } } else { if ($lc ) { configfile { '/etc/php5/cgi/php.ini': sourcename => 'php5/cgi/php.ini-lc. jimdo.com', require => Package['php5-cgi'] } } else { configfile { '/etc/php5/cgi/php.ini': sourcename => 'php5/cgi/php.ini', require => Package['php5-cgi'] } } } } } configfile { '/etc/php5/cgi/conf.d/pdo.ini': sourcename => 'php5/cgi/conf.d/pdo.ini', require => Package['php5-cgi'] } }

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OSDC 2014

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OSDC 2014 ?

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OSDC 2014

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OSDC 2014 rspec-puppet test-kitchen

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OSDC 2014

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OSDC 2014 describe :node => 'web-1' do it { should contain_package ('php5-fcgi') } end describe :node => 'web-2' do it { should contain_package ('php5-apache2' ) } end describe :node => 'web-3' do it { should contain_package ('php5-fcgi') } it { should contain_package ('php5-apache2' ) } end Test php5 class: Install Package ?

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OSDC 2014 describe :class => 'php5::fcgi' do it { should contain_package('php5-cli') } end describe :class => 'php5::apache' do it { should contain_package('php5-apache2') } end class php5::fgci { package { 'php5-cgi' : ensure => installed } } class php5::apache { package { 'php5-apache' : ensure => installed } }

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OSDC 2014 Just because you can, doesn’t mean you should! Single Responsibility

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OSDC 2014 describe :node => 'web-1' do it { should include_class('php5::fcgi') } it { should contain_package('php5-fcgi') } end describe :node => 'web-2' do it { should include_class('php5::apache') } it { should contain_package('php5-apache2') } end node web-1 { include php5::apache } node web-2 { include php5::fcgi } Tests Code

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OSDC 2014

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OSDC 2014 “programs […] are changed by adding new code, rather than by changing existing code” Open Close Principle

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OSDC 2014

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OSDC 2014 new requirements... now web app 1 needs a second node node web-1 { $role = 'web-app-a' include php5::apache } node web-1a { $role = 'web-app-a' include php5::apache }

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OSDC 2014

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OSDC 2014

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OSDC 2014 class role::web-app-a { include php5::apache } node web-1 { include role::web-app- a } node web-1a { include role::web-app- a } Our new role! And nodes just include it!

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OSDC 2014 >

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OSDC 2014

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OSDC 2014 ? class php5::fcgi($role = undef) { if ($role == 'web-app-c') { package { 'php5-web-app-c-special-module' } file { '/etc/php5/php.ini' : source => 'puppet:///modules/php5/php.ini-web-app-c', require => Package[php-fcgi] } } }

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OSDC 2014 Don’t call us, we call you! Hollywood Principle

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OSDC 2014 class role::web-app-c::special-php-stuff { package { 'php5-web-app-c-special-module' } file { '/etc/php5/php.ini' : source => 'puppet:///modules/php5/php.ini-web-app-c' } } 1. Split out the special case into its own class.

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OSDC 2014 class php5::fcgi($include_after_package_install = undef) { package { 'php5-fcgi' : ensure => installed } if ($include_after_package_install) include $include_after_package_install Package['php5-fcgi'] -> Class[$include_after_package_install] } } 2. Make the special case pluggable and reusable. 2a. And name it abstract.

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OSDC 2014 class role::web-app-c { include php5::apache class { 'php5::fcgi' : include_after_package_install => 'profile::web-app-c::special-php-stuff' } } 3. Pass the special case as dependency in our web-app-c.

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OSDC 2014

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OSDC 2014 class profile::web-app-c::special-php-stuff { package { 'php5-web-app-c-special-module' } file { '/etc/php5/php.ini' : source => 'puppet:///modules/php5/php.ini-web-app-c' } } ?

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OSDC 2014 define php5::specialconfig( $ensure = present, $sapi, $module, $key, $value, $section = undef, $path = '/etc/php5/%s/conf.d/%s.ini' ) { ini_setting { $title: ensure => $ensure, path => sprintf($path, $sapi, $module), section => $section, setting => $key, value => $value, require => Package["php5-${sapi}"] } }

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OSDC 2014

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OSDC 2014 ?

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OSDC 2014 “puppet separate code and data” I’m feeling lucky

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OSDC 2014 # /etc/puppet/hieradata/web1.yaml --- classes: - profile::web-app-a # /etc/puppet/hieradata/web1a.yaml --- classes: - profile::web-app-a # /etc/puppet/hieradata/web2.yaml --- classes: - profile::web-app-c # /etc/puppet/hieradata/web3.yaml --- classes: - profile::web-app-c puppet-hiera example in YAML

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OSDC 2014 node default { hiera_include('classes') } node web-1 { include role::web-app-a } node web-1a { include role::web-app-a } node web-2 { include role::web-app-b } node web-3 { include role::web-app-c }

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OSDC 2014 hiera AWS/Cloudformation LDAP DNS your selfwritten stuff

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OSDC 2014

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OSDC 2014

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OSDC 2014

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OSDC 2014 What about I and L in SOLID?

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OSDC 2014 You want me to plug this in, where? Interface Segregation

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OSDC 2014 If it looks like a duck, quacks like a duck, but need batteries - you probably have the wrong abstraction! Liskov Substitution

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OSDC 2014 S O L I D

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OSDC 2014

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OSDC 2014 Structure your code! Node Profile Profiles Role Profile Modules Resources

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OSDC 2014 Puppet forge puppet module registry

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OSDC 2014 Librarian Puppet r10k Berkshelf (chef)

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OSDC 2014 stdmod https://github.com/stdmod

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OSDC 2014 sandboxed development https://github.com/mlafeldt/skeleton-cookbook https://github.com/Jimdo/puppet-skeleton

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OSDC 2014 server spec http://serverspec.org/ beaker (puppet) https://github.com/puppetlabs/beaker

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OSDC 2014 Thank you!

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OSDC 2014 @CodeStars [email protected] @s0enke [email protected] Questions?

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OSDC 2014 *I ’m just a blank slide*

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OSDC 2014 Sources • http://www.slideshare.net/PuppetLabs/garethrushgrove-puppetconf • http://www.slideshare.net/PuppetLabs/alessandro-franceschi-new • https://github.com/jedi4ever/stop-the-fork • http://lostechies.com/derickbailey/2009/02/11/solid-development-principles-in-motivational- pictures/ • https://speakerdeck.com/jfryman/refactoring-puppet • http://www.clker.com/cliparts/e/2/a/d/1206574733930851359Ryan_Taylor_Green_Tick.svg.med. png • http://www.craigdunn.org/2012/05/239/ • http://cdn.slashgear.com/wp-content/uploads/2012/10/google-datacenter-tech-13.jpg • http://deviq.com/Media/Default/Article/Dont-Call-Us-Well-Call-You-Jun-2013.png • http://www.timeshighereducation.co.uk/Pictures/web/g/q/g/copy_paste_keyboard_button_450.jpg • http://sanremo.com.au/wp-content/uploads/2013/05/lasagna.jpg • http://4.bp.blogspot. com/_9kQQgQD35rY/SaV5p8YBGhI/AAAAAAAAAkg/HOvlhIo7yGI/s400/06_Red_Green_Refactor. JPG • http://www.thelolshop.com/wp-content/uploads/2012/11/20121126-101937.jpg •