modules

CHAPTER 4

TOPICS

modules
classes
ordering
node classification
notification and handlers

modules

modules are the packages with manifests and supporting files

```
have 1:1 mapping with the applications
```

let you create a library of  reusable code

anatomy

manifests

files

templates

data

spec

examples

metadata.json

README.MD

modulepath

Modules are stored on Puppet Master
Puppet Master has a code directory to store modules and rest of the configurations
The default code dir needs to be changed in case want to point to a custom path.

   master-code-dir: /etc/puppetlabs/code

   master-code-dir:  /workspace/code

cp -r /etc/puppetlabs/code /workspace/code

   master-code-dir: /etc/puppetlabs/code

   master-code-dir: /workspace/code

service puppetserver restart

Edit File : /etc/puppetlabs/puppetserver/conf.d/puppetserver.conf

Copy existing structure to our workspace

Change from

Change to

Restart Puppet Master

Group exercise

You have been asked to deploy a java application server with tomcat. You have been tasked to create automation code with puppet to set it up.

Problem Statement

APP server

modules

Group exercise

We would create a module to setup tomcat server and apply it to automate the task
As a prerequisite, we also need to install Java. We will create a module to install openjdk.

Solution:

tasks

Group exercise

Generate modules for java and tomcat
Create class to install java and
Create a node definition to apply the classes
Create classes to install tomcat and start the service, apply
Write classes to manage configuration files

auto generating modules

puppet module is a utility  which comes with code generator

it can let you create, search install, upload modules (to and from puppet forge)

root@puppet:/workspace# puppet help module                                                  
                                                                                            
                                                                                            
USAGE: puppet module <action> [--environment production ] [--modulepath  ]    

ACTIONS:                                                                                    
  build        Build a module release package.                                              
  changes      Show modified files of an installed module.                                  
  generate     Generate boilerplate for a new module.                                       
  install      Install a module from the Puppet Forge or a release archive.                 
  list         List installed modules                                                       
  search       Search the Puppet Forge for a module.                                        
  uninstall    Uninstall a puppet module.                                                   
  upgrade      Upgrade a puppet module.

generating modules Skeleton

Group exercise

cd /workspace/code/environments/production/modules

puppet module generate --skip-interview user-java

puppet module generate --skip-interview  user-tomcat


|-- java                                                                                    
|   |-- Gemfile                                                                             
|   |-- README.md                                                                           
|   |-- Rakefile                                                                            
|   |-- examples                                                                            
|   |   `-- init.pp                                                                         
|   |-- manifests                                                                           
|   |   `-- init.pp                                                                         
|   |-- metadata.json                                                                       
|   `-- spec                                                                                
|       |-- classes                                                                         
|       |   `-- init_spec.rb                                                                
|       `-- spec_helper.rb

-- java                                                                                    
|   |-- Gemfile                                                                             
|   |-- README.md                                                                           
|   |-- Rakefile                                                                            
|   |-- examples                                                                            
|   |   `-- init.pp                                                                         
|   |-- manifests                                                                           
|   |   `-- init.pp                                                                         
|   |-- metadata.json                                                                       
|   `-- spec                                                                                
|       |-- classes                                                                         
|       |   `-- init_spec.rb                                                                
|       `-- spec_helper.rb

modules

tomcat

manifests

init.pp

puppet module generator creates a scaffolding required to write manifests
it also generates the default manifest (init.pp)
additional manifests can be added to modules/xxx/manifest directory

????

writing manifests

modules

tomcat

manifests

init.pp

each manifest contains a class, a named container, which encompasses one or more resources
"::" is added to class names to separate the namespaces
namespaces must map to the module structure

abc.pp

xyz.pp

classes

class tomcat::abc

class tomcat::xyz

subdir

pqr.pp

class tomcat::subdir::pqr

modules

tomcat

manifests

init.pp

every feature gets its own class, and in turns a manifest
create a separate classes for each phase of application lifecycle. This provides more granular control

install.pp

config.pp

strategies

service.pp

deploy.pp

ssl.pp

tomcat

example

Group exercise

install packages to setup web server application and pre requisites
manage configurations for web servers
start/stop service

phases

tomcat::service

tomcat::config

tomcat::install

classes

java

module

Group exercise

install packages to setup openjdk

phases

java::install

classes

java manifest

Group exercise

class java::install {

  package { [ 'epel-release', 'java-1.7.0-openjdk'] : 
    ensure => installed,
  }

}

file: modules/java/manifests/install.pp

tasks

Generate modules for java and tomcat
Create class to install java and
Create a node definition to apply the classes
Create classes to install tomcat and start the service, apply
Write classes to manage configuration files

now that we have written the class, lets learn how to apply it, in a client server model

node definition

node

list of classes

node 'nodename' {

    include class1
    include class2
    include class3, class4

    class { 'class3':

       param1 => val1,
       param2 => val2,
       param3 => val3,
    

    }

}

node 'app1.example.io', 'app2.example.io', 'app3.example.io' {
  include class1
  include class2
}


node /^(app|web)\.blr\d+\.example\.io$/ {
  include class1
  include class2
}

node definition

groups

regex

simple

classifying nodes

node definition provides a mapping between nodes and a  list of classes to apply

node definition resides on the puppet master

its the simplest way of classifying nodes

there are more options available for node classification

ENC

Puppet Entperprise

node definition territory

code

environments

xxx

manifests

xxx.pp

webservers.pp

db.pp

modules

code

environments

production

manifests

app.pp

node definition territory

create a node definition

node 'node1' {

   include java::install

}

file: environments/production/manifests/app.pp

Group exercise

pull and apply from node 1

ssh devops@node1

sudo su

puppet agent -t

Group exercise

ssh devops@node2

sudo su

puppet agent -t

apply on node 2

Group exercise

app.codespace.io

app.codespace

app

default

default block

DEFAULT BLOCK

node default {

  notify{'checkpoint_1':
  
    message => '
    
        CHECKPOINT_1
        
        DEFAULT BLOCK APPLIED
        Looks like there is no node definition for this host
    
    '
  }
}

Group exercise

file: production/manifests/site.pp

PRO TIP

notify{'checkpoint_1':
  
    message => '
    
        CHECKPOINT_1
        
        DEFAULT BLOCK APPLIED
        Looks like there is no node definition for this host
    
    '
}

notify

notify is a resource and a metaparameter (will talk about this later)
as a resource, can be used for checkpointing
prints a message in the run log
useful to check if a particular block of code is being called or not

pro tip

notify{'checkpoint_1':}

Create a node definition for node2
Include the same java class that you applied earlier for node1
Apply and validate on node2

LAB exercise

discussion


  package { 'httpd':
    ensure => absent,
  }

  package {'nginx':
    ensure => $nginx_version,
    require => Package['httpd'],
  }

What would this code do?

why ?

how ?

ordering

package

service

before B

require A

ordering

file

service

notify D

subscribe C

ordering with

notification



package { 'nginx':
  ensure  => installed,
  before  => Service["nginx"],
}

file { 'nginx.conf':
  ensure  => file,
  mode    => '0644',
  notify  => Service["nginx"],
}

service { 'nginx':
  ensure      => running,
  enable      => true,
  hasrestart  => true,
  hasstatus   => true,
  require     => [ Package["nginx"], File["nginx.conf"] ]
  subscribe   => File["nginx.conf"],
}

Package["nginx"] -> File["nginx.conf"] ~> Service["nginx"]

sample ordering.pp

sample

Type['title']

CAPS

before

require

notify

subscribe

PARAMETERS

meta -

Meta Parameters                                                                           
---------------                                                                           
    alias, audit, before, consume, export,
    loglevel, noop, notify, require,               
    schedule, stage, subscribe, tag

puppet describe -sm package

tasks

Generate modules for java and tomcat
Create class to install java and
Create a node definition to apply the classes
Create classes to install tomcat and start the service, apply
Write classes to manage configuration files

lab exercise

LAB exercise

create a tomcat::service recipe to start and enable tomcat service

Service should depends on package tomcat

create a tomcat::install recipe to install tomcat along with example apps. Packages to install are

tomcat
tomcat-webapps

Install

Service

Create and apply the following recipes for tomcat

lab

Expected Output

You should be able to browse to http://ipaddress:8081 port in the browser
Tomcat home page is the expected output

http://IPADDR:8081

LAB exercise

simplify node definition

Group exercise

class tomcat {

  include java::install
  include tomcat::install
  include tomcat::service 

}

Lets call all other manifests from init.pp

node 'node1' {

  include tomcat
  
}


node 'node2' {

   include tomcat

}

Group exercise

we included java cookbook in tomcat init.pp
We would also add dependency in metadata.json of tomcat module that depends on java

{
  "name": "user-tomcat",
  "version": "0.1.0",
  "author": "user",
  "summary": null,
  "license": "Apache-2.0",
  "source": "",
  "project_page": null,
  "issues_url": null,
  "dependencies": [
    {"name":"puppetlabs-stdlib","version_requirement":">= 1.0.0"}
  ],
  "data_provider": null
}

DEPENDENCIES

tasks

Generate modules for java and tomcat
Create class to install java and
Create a node definition to apply the classes
Create classes to install tomcat and start the service, apply
Write classes to manage configuration files

manging files

We will need to manage configurations eg. tomcat.conf

since chef is a centralized configuration management system, we will keep the files centrally in cookbooks, which will then be copied to all managed nodes

manging files

Create tomcat.conf file in tomcat modules' files directory.

add tomcat::config class to  copy these files to the relevant locations on destination hosts

modules

tomcat

manifests

init.pp

install.pp

service.pp

config.pp

files

tomcat.conf

LAB exercise

link to tomcat.conf source

destination path in nodes: /etc/tomcat/tomcat.conf

manging files

Generate tomcat.conf using chef generate file in tomcat cookbook directory.

add tomcat::config recipe to copy these files to the relevant locations on destination hosts

cookbooks

tomcat

recipes

default.rb

install.rb

service.rb

config.rb

files

tomcat.conf

tomcat-users.xml

LAB exercise

link to tomcat.conf source

link to tomcat-users.xml source

path: /etc/tomcat/tomcat-users.xml

path: /etc/tomcat/tomcat.conf

tomcat.conf

file: cookbooks/tomcat/files/default/tomcat.conf


TOMCAT_CFG_LOADED="1"                                                                                                           
                                                                                                                                
JAVA_HOME="/usr/lib/jvm/jre"
JAVA_OPTS="-Xms64m -Xmx128m -XX:MaxPermSize=128M -Djava.security.egd=file:/dev/./urandom"
                                                                                                                                
CATALINA_BASE="/usr/share/tomcat"                                                                                               
CATALINA_HOME="/usr/share/tomcat"                                                                                               
JASPER_HOME="/usr/share/tomcat"                                                                                                 
CATALINA_TMPDIR="/var/cache/tomcat/temp"                                                                                        
                                                                                                                                
                                                                                                                                
TOMCAT_USER="tomcat"                                                                                                            
                                                                                                                                
SECURITY_MANAGER="false"                                                                                                        
                                                                                                                                
SHUTDOWN_WAIT="30"                                                                                                              
                                                                                                                                
SHUTDOWN_VERBOSE="false"                                                                                                        
                                                                                                                                
CATALINA_PID="/var/run/tomcat.pid"

Group exercise

tomcat::config

class tomcat::config {

  file { '/etc/tomcat/tomcat.conf':
    source    => 'puppet:///modules/tomcat/tomcat.conf',
    owner    => 'tomcat', 
    group    => 'tomcat', 
    mode     => '0644'
  }

}

file: modules/tomcat/manifests/config.rb

Group exercise

tomcat::config

cookbook_file '/etc/tomcat/tomcat.conf' do 
  source 'tomcat.conf'
  owner 'tomcat'
  group 'tomcat'
  mode  0644
  action :create
end 

cookbook_file '/etc/tomcat/tomcat-users.xml' do 
  source 'tomcat-users.xml'
  owner 'tomcat'
  group 'tomcat'
  mode  0644
  action :create
end

file: cookbooks/tomcat/recipes/config.rb

refreshing service

conf

service

refresh

class tomcat::config {

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

}

file: modules/tomcat/manifests/config.rb

tomcat::config


cookbook_file '/etc/tomcat/tomcat.conf' do 
  source 'tomcat.conf'
  owner 'tomcat'
  group 'tomcat'
  mode  0644
  action :create
  notifies :restart, 'service[tomcat]', :delayed
end

Update file: cookbooks/tomcat/recipes/config.rb

Note: Add config.rb recipe to default.rb

tomcat::config


cookbook_file '/etc/tomcat/tomcat.conf' do 
  source 'tomcat.conf'
  owner 'tomcat'
  group 'tomcat'
  mode  0644
  action :create
  notifies :restart, 'service[tomcat]', :delayed
end 

cookbook_file '/etc/tomcat/tomcat-users.xml' do 
  source 'tomcat-users.xml'
  owner 'tomcat'
  group 'tomcat'
  mode  0644
  action :create
  notifies :restart, 'service[tomcat]', :delayed
end

file: cookbooks/tomcat/recipes/config.rb

Puppet : Modules

By School of Devops

Puppet : Modules

PUP 04 - Creating Modular Code

2,092

School of Devops

School of Devops is a global leader in Devops Education and offers trainings on gamut of devops automation tools and practices including Cloud and Virtualization, Infrastructure as a Code, Continuous Integration/Deployment, Monitoring.

modules

TOPICS

modules

classes

ordering

node classification

notification and handlers

modules

anatomy

modulepath

Group exercise

APP server

modules

Group exercise

tasks

Group exercise

auto generating modules

generating modules Skeleton

Group exercise

writing manifests

classes

strategies

tomcat

example

Group exercise

java

module

Group exercise

java manifest

Group exercise

tasks

node definition

node definition

classifying nodes

node definition territory

node definition territory

create a node definition

Group exercise

pull and apply from node 1

Group exercise

apply on node 2

Group exercise

DEFAULT BLOCK

Group exercise

PRO TIP

pro tip

LAB exercise

discussion

ordering

ordering

ordering with

notification

sample

PARAMETERS

meta -

tasks

lab exercise

LAB exercise

Install

Service

lab

Expected Output

LAB exercise

simplify node definition

Group exercise

Group exercise

DEPENDENCIES

tasks

manging files

manging files

LAB exercise

manging files

LAB exercise

tomcat.conf

Group exercise

tomcat::config

Group exercise

tomcat::config

refreshing service

tomcat::config