Learning Puppet

What is Puppet?

• A Configuration Management Tool
• A framework for Systems Automation
• A Declarative Domain Specific Language (DSL)
• An OpenSource software in written Ruby
• Works on Linux, Unix (Solaris, AIX, *BSD), MacOS, Windows (Supported Platforms)

Reference

• Puppet Documentation
• Example42
• Example42 in github
• hackr.io
• Puppet CookBook

Software related to Puppet

• Facter - Complementary tool to retrieve system's data
• MCollective - Infrastructure Orchestration framework
• Hiera - Key-value lookup tool where Puppet data can be placed
• PuppetDB - Stores all the data generated by Puppet
• Puppet DashBoard - A Puppet Web frontend and External Node Classifier (ENC)
• The Foreman - A well-known third party provisioning tool and Puppet ENC
• Geppetto - A Puppet IDE based on Eclipse

Installation

• Debian, Ubuntu

  wget https://apt.puppet.com/puppet7-release-focal.deb && \
  sudo dpkg -i puppet7-release-focal.deb && \
  sudo apt update

  sudo apt install puppet-agent   # On Client (Nodes)
  sudo apt install puppetserver   # On Server (Master)

• RedHat, CentOS

  # this example is for RHEL8
  sudo rpm -Uvh https://yum.puppet.com/puppet7-release-el-8.noarch.rpm

  sudo yum install puppet-agent   # On Client (Nodes)
  sudo yum install puppetserver   # On Server (Master)

Puppet Language

• A Declarative Domain Specific Language (DSL)
• It defines STATES (Not procedures)
• Puppet code is written in manifests (files with .pp extension)
• In the code we declare resources that affect elements of the system (files, packages, services ...)
• Resources are grouped in classes which may expose parameters that affect their behavior.
• Classes and configuration files are organized in modules.
• Consult the official glossary to give the correct meaning to Puppet terms

Nodes Classification

• When clients connect, the Puppet Master generates a catalog with the list of of the resources that clients have to apply locally.

• The Puppet Master has to classify nodes and define for each of them:

  • The classes to include
  • The parameters to pass
  • The Puppet environment to use

• The catalog is generated by the Master according to the logic of our Puppet code and data.

• In our code we can define our variables and use other ones that may come from different sources:

  • facts generated directly by the client.
  • parameters obtained from node's classification.
  • Puppet internal variables.

Resource Types

• Resource Types are single units of configuration composed by:
  • A type (package, service, file, user, mount, exec ...)
  • A title (how is called and referred)
  • Zero or more arguments.

    type { 'title':
      argument  => value,
      other_arg => value,
    }
    

    Example for a file resource type:

    file { 'motd':
      path     => '/etc/motd',
      content  => 'Let's learning Puppet :)'
    }

Resource Type refrence

• From the shell the command line interface:

  puppet describe file

• For the full list of available descriptions try:

  puppet describe --list

• Puppet code for the list of native resource types:

  ls $(facter rubysitedir)/puppet/type

Simple sample of resources

• Installation of OpenSSH package

  package { 'openssh':
     ensure   => present,
  }

• Creation of /etc/motd file

  file { 'motd':
     path   => '/etc/motd',
  }

• Start of http service

  service { 'httpd':
      ensure => running,
      enable => true,
  }

---

TO DO

Preview

• Complete Puppet learning in README.md file
• Vagrantfile for creating Puppet server-client environment.
• docker-compose.yml for creating puppet server instance
• Configuring puppetdb and fireman
• Creating a secanrio with this environment and Puppet. (preferably install k8s-lab through Puppet)