TOPICS

Code vs data
Parameters
Scoping
Inheritance
Facts

Code | DATA

manifests

templates

system defined

user defined

params

top 
scope

node 
scope

child 
class

class

facter

params

scope

Specific area in puppet's code hirearchy
allows to define same param from different places
to create global/local params

top scope

node scope

```
global params
```
```
apply to all nodes
```

```
node specific
```

group lab


$color = 'blue'
$car   = 'maruti' 

node 'node1' {

  include tomcat
  
}


node 'node2' {

   $color = 'green'
   include tomcat

}

app.pp

where to use ?

```
resource names
```
```
parameter value 
```
```
template variable
```

param reference

$color

${color}

${color}

"

group lab

class tomcat::scope {

   notify{"print the scope": 
     message => "
     
       FAVOURITE COLOR :  ${color}
       FAVOURITE CAR   :  ${car}
    
    "
  }

}

class tomcat::scope

group lab

class tomcat {

  include tomcat::scope
  include tomcat::install
  include tomcat::config
  include tomcat::service 
}

class tomcat

discussion

Run puppet on node1 and node2 both

Do you see same values printed on both nodes?

```
If you see different values, why? 
```

top scope

node scope

parent class

child class

params.pp

the story of sane defaults

params.pp

dedicated class to define data/properties/params

can be also used to write logic/conditionals to separate system specific properties

created as a design pattern to define the sane defaults

Sane Defaults

group lab

class tomcat::params {

  $color = 'white' 
  $car   = 'figo'

}

tomcat::params

apply and check if the nodes pick up the properties in params.pp
how would you make properties from one class available into another

inheritance

group lab

class tomcat::scope inherits tomcat::params{

   $color = 'yellow'


   notify{"print the scope": 
     message => "
     
       FAVOURITE COLOR :  ${color}
       FAVOURITE CAR   :  ${car}
    
    "
  }

}

tomcat::scope

qualified params

$::tomcat::params::color

$::tomcat::color

$color

group exercise

Parameterizing Tomcat Configs

class tomcat

class tomcat inherits tomcat::params{

  include tomcat::scope
  include tomcat::install
  include tomcat::config
  include tomcat::service 
}

refactor classes

class tomcat::install inherits tomcat{
    
    include java
    
    package { $::tomcat::packages:
      ensure   => installed, 
      require  => Package['epel-release']
    }

}

tomcat::install

class tomcat::config inherits tomcat{

  file { $::tomcat::config_path:
    source    => 'puppet:///modules/tomcat/tomcat.conf',
    owner    => $::tomcat::user, 
    group    => $::tomcat::group, 
    mode     => '0644',
    notify   => Service['tomcat'] 
  }

}

tomcat::config

class tomcat::service inherits tomcat{

   service { $::tomcat::service_name:
     ensure   => $::tomcat::service_state, 
     enable   => true,
     require  => Class['tomcat::install'],
   }
}

tomcat::service

apply

group exercise

handle platform specific configs

cd /workspace/code/environments/production/modules

puppet module generate --skip-interview user-base

mv /workspace/base.pp base/manifests/init.pp

Generate base module

group exercise

class base{

    user {"deploy" :
      ensure    => present, 
      uid       => 5001, 
      password  => '$1$WD98.uaZ$cxx30x/K3FXQrljxsvBIu/',
      home      => '/home/deploy'
    }
    
    user {"dojo" :
      ensure  => absent, 
    }
    
    package { [ "tree", "unzip", "git", "ntp", "wget"  ]:
    
      ensure  => installed
    
    }
    
    service { "ntp": 
      ensure  => running, 
      enable  => true, 
      
    }
    
}

group exercise

class base


node 'node2' {

   include base

   $color = 'green'
   include tomcat

}

group exercise

Add the base class to node definition for node2

Failes because service "ntp" is not available on centos. It was created for ubuntu.

NTP

ubuntu

centos

package

service

ntp

ntp

ntp

ntpd

discussion

group exercise

class base::params {

  case $::os['family'] {
    'Debian': {
      $ntp_service = 'ntp'
    }
    'RedHat': {
      $ntp_service = 'ntpd'
    }
  }
  

}

create base::params class

file: modules/base/manifests/params.pp

Exercise

And to use these params, we need to

inherit base::params in base class (init.pp)
parameterize the service name

exercise

Reference to the solution

facter

```
System Profiler
```
```
Installed with puppet
```
```
Provides facts
```

system defined

attributes

Platform
Network
Kernel
Memory
CPU
Virtualization
Disk Mounts
Other system info

agent

master

facts

catalog

report

facter

facter 
facter ipaddress
facter hostname
facter memory
facter memory.system 
facter memory.system.total
facter processors
facter processors.count

system defined

attributes

 Finding facts
 about a  Node with facter

referencing

facts

attributes

system defined

$facts['hostname']

${::hostname}

${hostname}

$hostname

referencing

facts

${::ipaddress}

attributes

system defined

${::hostname}

${::memory}

${::memory['system']}

${::processors['count']}

facter 
facter ipaddress
facter hostname
facter memory
facter memory.system 
facter memory.system.total
facter processors
facter processors.count

group exercise

    file { '/etc/motd': 
      ensure   => file, 
      owner    => 'root',
      content  => "
      
         This server is a property of XYZ Inc.
         
         SYSTEM INFO 
         ============
         
         Hostname     : ${::fqdn}
         IP Address   : ${::ipaddress}
         Memory       : ${::memory['system']['total']}
         Cores        : ${::processors['count']}
         OS           : ${::os['distro']['description']}
      
      
      "
    
    }

Update base class

file: modules/base/manifests/init.pp

parameters

managing properties