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Roles and Profiles Pattern (Methodology)

Overview

Provides a methodology for abstraction of Puppet code.

It's all about abstraction:

  • Data (parameters) gets abstracted by Hiera
  • Providers/Resources abstract the underlying OS implementation
  • Providers get abstracted by Types
  • Resources get abstracted by Classes
  • Classes get abstracted by Modules (Component Modules)
  • Modules get abstracted by Profiles
  • Profiles get abstracted by Roles

Classification/Abstraction Flow:

  1. A node is assigned a Role
  2. A Role includes one or more Profiles
  3. Profiles include Component modules, Resources combined with logic.
  4. Make calls out to Hiera for hierarchal specific data (parameters)
  5. Hiera data is passed to Component modules
  6. Component modules call Puppet Resources
  7. Puppet Resources use Types/Providers to configure setting on a node

abstraction

Profiles

Combines modules andresources to define a logical technology stack(single).

For more detail consult the documented set of guidelines

Profiles follow the following rules:

  • Technology specific
  • May include resources directly
  • May make calls to Hiera for required data (parameters)
  • Include Component module classes/resources
  • Named according to the technology they manage
    • Do NOT include environments in profile nawmes

Being technology specific does not limit the profile to managing a single application. It should include all applications and logic need to fully manage an application stack.

Example:

class profile::wordpress {

  ## Hiera lookups
  $site_name               = hiera('profiles::wordpress::site_name')
  $wordpress_user_password = hiera('profiles::wordpress::wordpress_user_password')
  $mysql_root_password     = hiera('profiles::wordpress::mysql_root_password')
  $wordpress_db_host       = hiera('profiles::wordpress::wordpress_db_host')
  $wordpress_db_name       = hiera('profiles::wordpress::wordpress_db_name')
  $wordpress_db_password   = hiera('profiles::wordpress::wordpress_db_password')
  $wordpress_user          = hiera('profiles::wordpress::wordpress_user')
  $wordpress_group         = hiera('profiles::wordpress::wordpress_group')
  $wordpress_docroot       = hiera('profiles::wordpress::wordpress_docroot')
  $wordpress_port          = hiera('profiles::wordpress::wordpress_port')

  ## Create user
  group { 'wordpress':
    ensure => present,
    name   => $wordpress_group,
  }
  user { 'wordpress':
    ensure   => present,
    gid      => $wordpress_group,
    password => $wordpress_user_password,
    name     => $wordpress_group,
    home     => $wordpress_docroot,
  }

  ## Configure mysql
  class { 'mysql::server':
    root_password => $mysql_root_password,
  }

  class { 'mysql::bindings':
    php_enable => true,
  }

  ## Configure apache
  include apache
  include apache::mod::php
  apache::vhost { $::fqdn:
    port    => $wordpress_port,
    docroot => $wordpress_docroot,
  }

  ## Configure wordpress
  class { '::wordpress':
    install_dir => $wordpress_docroot,
    db_name     => $wordpress_db_name,
    db_host     => $wordpress_db_host,
    db_password => $wordpress_db_password,
  }
}

Roles

A unquie collection (wrapper) of one or more profiles (technology stacks) to define a node

For more detail consult the documented set of guidelines

Roles follow the following rules:

  • Maps technology to a node
  • Nodes get classified with only a SINGLE role
    • A role similar, yet different, from another role is: a NEW role.
  • Do NOT include logic
  • ONLY use includes for abstracting profiles
  • Named according to the nodes purpose (business logic)

Example:

Includes the profile wordpress to install/configure wordpress and includes the base profile to configure globally common settings such as NTP and default user accounts.

class role::myblog {
  include profile::wordpress
  include profile::base
}

References

Puppet Camp 2013 Presentation Puppet Roles and Profiles Workflow (SH*% Gary Says)