OSDC 2011 | Advanced Puppet Topics by Ken Barber

Advanced Puppet
Topics
Ken Barber
Professional Services Engineer
Donnerstag, 14. April 2011

aka
My favourite
puppet features

Topics
• Standalone Puppet
• Ruby DSL
• extlookup
• dotty output
• External Node Classiﬁcation
• Puppetdocs

Standalone Puppet

Standalone Puppet
• The Puppet Domain Speciﬁc Language (DSL)
is a language that can be used standalone
• Works like any other script
• Requires no infrastructure

Example 1
#!/usr/bin/env puppet
file { ‘/tmp/example1.out’:
content => “Example 1n”,
}
create_ﬁle.pp:

Example 1
# chmod +x create_file.pp
# ./create_file.pp
notice: /Stage[main]//File[/tmp/example1.out]/ensure:
defined content as '{md5}8a0a86c394456fa1879929d8e1419f94'
notice: Finished catalog run in 0.08 seconds
# cat /tmp/example1.out
Example 1
#

Example 2
package { 'mysql-server':
ensure => installed,
}
file { '/etc/my.cnf':
source => 'my.cnf',
notify => Service['mysql'],
}
service { 'mysql':
ensure => running,
enable => true,
require => Package['mysql-server'],
}
setup_mysql.pp:

Example 2
# chmod +x setup_mysql.pp
# ./setup_mysql.pp
notice: /Stage[main]//Package[mysql-server]/ensure: ensure
changed 'purged' to 'present'
notice: /Stage[main]//File[/etc/mysql/my.cnf]/ensure:
defined content as '{md5}b82b1ec5fa04a2680403e94e5cda845e'
notice: /Stage[main]//Service[mysql]: Triggered 'refresh'
from 1 events
#

Example 3
# puppet apply -e "file{'/tmp/foo':content=>"foon"}"
notice: /Stage[main]//File[/tmp/foo]/ensure: defined
content as '{md5}d3b07384d113edec49eaa6238ad5ff00'
# cat /tmp/foo
foo
#

Use Cases
• Boot strapping Puppet on a machine that has
minimal facilities
• Development work
• Running Puppet in master-less mode

Ruby DSL

Why Puppet DSL?
• It’s declarative so its ideal for conﬁguration
management
• We can constrain the behaviour to only
conﬁguration management
• You don’t need to know ruby to start, and its
simpler to learn then most languages

Why Ruby DSL?
• Allows you to extend Puppet beyond normal
Puppet DSL
• No constraints
• Prototype new ideas that can potentially
become Puppet DSL later

How to use Ruby
DSL
• Puppet now recognises the ‘.rb’ extension
• standalone_script.pp -> standalone_script.rb
• manifests/site.pp -> manifests/site.rb
• <module>/manifests/init.pp -> <module>/
manifests/init.rb
• import “extras.pp” -> import “extras.rb”

How to use the
Ruby DSL
hostclass :foo do
notice ["foo"]
end
node "default" do
include “foo”
end
standalone_script.rb:

Ruby DSL - Nodes
# Puppet DSL
node "default" {
notice(“Default node”)
}
# Ruby DSL
node "default" do
notice[“Default node”]
end

Ruby DSL - Classes
# Puppet DSL
class foo {
  notice("foo")
}
node "default" {
  include foo
}
# Ruby DSL
hostclass :foo do
  notice ["foo"]
end
node "default" do
  include “foo”
end

Ruby DSL - Functions
# Puppet DSL
node "default" {
  notice("Function output")
}
# Ruby DSL
node "default" do
  notice ["Function output"]
end
# Ruby DSL - alternative
node "default" do
  call_function “notice”, ["Function output"]
end

Ruby DSL - Resources
# Puppet DSL
define myresource() {
  notice($name)
}
node "default" {
  myresource {"resource_output": }
}
# Ruby DSL
define "myresource" do
  notice [@name]
end
node "default" do
  create_resource :myresource, "resource_output"
end

Ruby DSL - Variables
# Puppet DSL
node "default" {
  $myvar = "value is here"
  notice($myvar)
}
# Ruby DSL
node "default" do
  scope.setvar("myvar", "value is here")
  a = scope.lookupvar("myvar")
  notice [a]
end

Mysql Example
require 'mysql'

hostclass :packages do
# Connect to mysql
conn = Mysql.new('localhost', 'user', 'password', 'cmdb')
# Obtain a list of mysql packages (and versions)
pkgs = conn.query('select * from packages')
# Create a package resource for each package defining the version
# for each
pkgs.each_hash { |p| package p['name'], :ensure => p['version'] }
conn.close
end

node 'default' do
include 'packages'
end

Ruby DSL - Further
Information
• Wiki Article:
• http://projects.puppetlabs.com/projects/1/wiki/
Ruby_Dsl
• Google ‘puppet ruby dsl’

extlookup()

Config vs Code
• Node Classifiers
• External Node Classifiers
• Large lookup tables in Puppet DSL
• External data like CSV tables

Usage
# Configure extlookup data directory and precedence
$extlookup_datadir = "."
$extlookup_precedence = [
"%{fqdn}",
"location_%{location}",
"county_%{country}",
"common"
]
# Fetch extlookup and print the results
notice(extlookup("snmp_trap_host"))

Example - common
snmp_trap_host,1.1.1.1
common.csv:
# ./example1.pp
notice: Scope(Class[main]): 1.1.1.1
#

Example - country
common.csv:
# ./example1.pp
#
country_de.csv:

Example - location
common.csv:
# ./example1.pp
#
country_de.csv:
location_holidayinn.csv:

dotty output

dotty output
• Puppet deﬁnes every artifact as a resources
• Resources are related to each other through
dependency
• Internally, these dependencies are mapped as
a graph
• These graphs can be output in dotty format

dotty: Tools
• Graphviz - open source, very ﬂexible,
widely used
• Gephi - free, java based, powerful graph
support
• Omnigraffle - commercial, more then just
graphs

dotty output
Traditional Way:
With new Puppet Interfaces:
puppet --noop --graph --graphdir /vagrant/graphs relationships.pp
puppet catalog --format dot ﬁnd localhost > ~/Desktop/catalog.dot

dotty Example 1
file { '/files':
ensure => directory
}
file { '/files/001.txt':
ensure => file,
content => '001',
require => File['/files'],
}

dotty Example 1

dotty Example 2
package { ‘myapp’:
ensure => installed
}
ﬁle { ‘/etc/myapp.cfg’:
content => template(‘myapp/myapp.cfg’),
require => Package[‘myapp’],
}
service { ‘myapp’:
ensure => running,
require => File[‘/etc/myapp.cfg’],
}

dotty Example 2

dotty Example 3
package { 'myapp':
}
ﬁle { '/etc/myapp1.cfg':
content => 'myapp1',
require => Package['myapp'],
}
}
service { 'myapp':
ensure => running,
}

dotty Example 3

dotty Example 3
package { 'myapp':
}
notify => Service[‘myapp’],
}
notify => Service[‘myapp’],
}
service { 'myapp':
ensure => running,
}

dotty - big example

External Node
Classiﬁcation

Nodes - normally
node “app1” {
$snmp_trap_host = “traps.puppetlabs.com”
$dns_server = “1.1.1.1”
include tomcat
include myapp
include resolver
include snmpd
}
node “db1” {
$dns_server = “1.1.1.1”
$mysql_dbs = [“db1”]
include mysql
include resolver
include snmpd
}

Why ENC?
• Allows you to store node deﬁnitions outside of
Puppet
• Provides Conﬁguration / Code separation
• You can provide information from another
information store such as a CMDB or asset
database

Conﬁguration
[main]
external_nodes = /usr/local/bin/puppet_node_classifier
node_terminus = exec
/etc/puppet/puppet.conf:

API
• First argument passed to the external script is the
hostname
• The script must return valid YAML on standard out
• The script returns 0 for success or non-zero to
indicate the node is ‘not found’

YAML Returnednode “app1” {
$dns_server = “1.1.1.1”
include tomcat
include myapp
include resolver
include snmpd
}
---
environment: production
parameters:
snmp_trap_host: traps.puppetlabs.com
dns_server: 1.1.1.1
classes:
- tomcat
- myapp
- resolver
- snmpd
Text
Puppet:
YAML:

Good ENC’s
• Puppet Dashboard
• The Foreman

Puppetdocs

Puppetdocs
• Works in a similar way to ruby docs or
Perl docs
• Documentation should be close to code
• Can be setup to auto-generate code
from VCS using CI tools like Jenkins
• Supports markdown format

Format - Class
# Description of class.
#
# ==Variables
#
# None
#
# == Examples
#
# include myclass
#
# == Authors
#
# Ken Barber <ken@puppetlabs.com>
#
# == Copyright
#
# Copyright© 2011 Puppetlabs Inc, unless otherwise noted.
#
class myclass {
....
}

Format - Resource# Description of resource.
#
# == Parameters
#
# [param1]
# Parameter 1 does something magical
#
# == Examples
#
# myresource { ‘myname’:
# param1 => ‘value’,
# }
#
# == Authors
#
# Ken Barber <ken@puppetlabs.com>
#
# == Copyright
#
# Copyright (C) 2011 Puppetlabs Inc, unless otherwise noted.
#
deﬁne myresource($param1) {
....
}

Example
• Webserver: http://localhost:8888/
puppetdoc

Any
Questions?

OSDC 2011 | Advanced Puppet Topics by Ken Barber

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OSDC 2011 | Advanced Puppet Topics by Ken Barber