puppet training

Date: December 2015

ToC

1. What is puppet
2. manifests
3. resources
4. syntax
5. templates
6. conditions
7. expressions & operators
8. classes
9. defined resource types
10. run stages
11. modules
12. hiera
13. environments

Content

Stuff to be teached, explained or otherwise delivered.
In short: Concept

What is puppet

homogeneous way to manage heterogeneous networks

develop your infrastructure

• enforces states
• configuration management
• allows simple server scaling
• quick server setup

manifests

• file*.pp*
• execute/ test via $ puppet apply file.pp

resources

• functions to be used
• describe server/ service state
• execution
• http://docs.puppetlabs.com/references/latest/type.html

syntax

# comment
<RESOURCE> { '<TITLE>':
  <ATTRIBUTE> => <VALUE>,
}

real world example

# ensure /etc/passwd is present and root-rw-able only
file {'/etc/passwd':
  ensure => file,
  owner => 'root',
  group => 'root',
  mode => '0600',
}

• title needs to be unique
• parameterized
• allow metaparameters : https://docs.puppetlabs.com/references/latest/metaparameter.html

templates

• erb-syntax
• <%= @fqdn %>

more: https://docs.puppetlabs.com/puppet/latest/reference/lang_template_erb.html

syntax

<%# Non-printing tag ↓ -%>
<% if @keys_enable -%>
<%# Expression-printing tag ↓ -%>
keys <%= @keys_file %>
<% unless @keys_trusted.empty? -%>
trustedkey <%= @keys_trusted.join(' ') %>
<% end -%>
<% if @keys_requestkey != '' -%>
requestkey <%= @keys_requestkey %>
<% end -%>
<% if @keys_controlkey != '' -%>
controlkey <%= @keys_controlkey %>
<% end -%>

<% end -%>

tags

• <%= EXPRESSION %> — Inserts the value of an expression.
• With -%> — Trims the following line break.
• <% CODE %> — Executes code, but does not insert a value.
• With <%- — Trims the preceding indentation.
• With -%> — Trims the following line break.
• <%# COMMENT %> — Removed from the final output.
• With -%> — Trims the following line break.
• <%% or %%> — A literal <% or %>, respectively.

conditions

• if, elseif, else
• unless (inverse if)
• case
• selectors (for variables)
• allows regexp

expressions & operators

see more: http://docs.puppetlabs.com/puppet/latest/reference/lang_expressions.html

classes

• executed only once
• can have parameters/ header

defined resource types

• catalog n-n defined resource type
• catalog n-n use of defined resource type

syntax

define apache::vhost (Integer $port, String[1] $docroot, String[1] $servername = $title, String $vhost_name = '*') {
  include apache # contains Package['httpd'] and Service['httpd']
  include apache::params # contains common config settings
  $vhost_dir = $apache::params::vhost_dir
  file { "${vhost_dir}/${servername}.conf":
    content => template('apache/vhost-default.conf.erb'),
      # This template can access all of the parameters and variables from above.
    owner   => 'www',
    group   => 'www',
    mode    => '644',
    require => Package['httpd'],
    notify  => Service['httpd'],
  }
}

run stages

• easy sorting
• ensure preconditions for services are met

# define stages
stage { 'First': }

stage { 'Second':
  before => Stage['main'],
}

# connect classes to stages
class {'apt-keys':
  stage => First, # metaparameter
}

class {'middleware':
  stage => Second, # metaparameter
}

# Sort stages
Stage['First'] -> Stage['Second']

more: https://docs.puppetlabs.com/puppet/latest/reference/lang_run_stages.html

modules

• separated directory
• structure manifests
• own templates, libs, manifests
• needs init.pp

hiera

• database
• hierarchical
• supports multiple backends
  • yaml
  • eyaml (encrypted yaml)
  • databases
  • ...

$demo = hiera('value')

environments

• per folder
• no hierarchy -> exclusive
• allows easy testing
• server n-1 environment