Master Puppet: Principles, Workflow, Installation, and Resource Management

1. Puppet Basics

Puppet is an open‑source configuration‑management tool licensed under GPLv2+, written in Ruby. It can run in client‑server mode or standalone, providing administrators with fast, automated system management.

2. Puppet Workflow

1. The puppet client requests authentication from the puppet master, optionally using a signed certificate.
2. The master validates the client.
3. The client runs Facter to gather facts (hostname, memory, IP, etc.) and sends them over SSL.
4. The master matches the node to a manifest, parses it, performs syntax checks, and compiles a catalog (intermediate “pseudo‑code”) which is sent back to the client.
5. The client receives the catalog and applies it.
6. If a file resource is needed, the client requests it from the fileserver.
7. If reporting is configured, the client sends the execution result to the server.
8. The server logs the result and forwards it to the reporting system.

3. Installing Puppet

1. Install the version that comes with the OS via yum.

yum install puppet -y

2. Install the latest version.

sudo rpm -ivh https://yum.puppetlabs.com/puppetlabs-release-el-6.noarch.rpm

2.1 Install puppet‑server.

sudo puppet resource package puppet-server ensure=latest

2.2 Install the agent.

sudo puppet resource package puppet ensure=latest

4. Puppet Resource Management

Resources are the smallest units that Puppet manages.

puppet describe -l               # list all resource types
puppet describe -s <resource_name>   # show a summary
puppet describe <resource_name>      # show detailed usage
# Example resource definition:
resource_name { 'title':
    attribute1 => 'value',
    attribute2 => 'value',
}

Common resource types: file, filebucket, host, group, package, service, exec, cron, notify, etc.

Public attributes:

before   => specify a resource that must run before this one
require  => specify a resource that must run after this one
notify   => actively notify other resources of state changes
subscribe=> passively receive notifications when a dependent resource changes
# Relationship operators:
->   # ordering
~>   # notification

5. Puppet Language

Variables

$webserver = "httpd"
package { "httpd":
    ensure => "present",
    name   => $webserver,
}

Data types

String, Boolean, Integer, Float, Array (e.g., $array = ['httpd','mysql','php']), Hash, undef

Operators

Comparison: ==, !=, <, >, <=, >=, =~, !~, in
Boolean: and, or, !
Arithmetic: +, -, *, /, <<, >>

Conditional statements

if ... elsif ... else
case
selector
# Example:
if $osfamily == 'CentOS' { notice('welcome to CentOS') }
elsif $osfamily == 'RedHat' { notice('Welcome to RedHat') }
else { notice('Welcome to ET') }

6. Classes and Modules

Classes group related code and must be declared before use.

class class_name [inherits] [base_class] {
    # Puppet code
}
# Example module structure:
module_name/
    manifests/
        init.pp   # declares the main class
        *.pp
    files/
    templates/
    lib/
    tests/
    spec/

Inheritance and overriding are supported.

# inheritance of resource attributes, overriding, and appending (=>, +>)

7. Example: Deploying LNMP with Puppet

Assume puppet‑server is already installed.

# Add host entries
cat >> /etc/hosts <<EOF
192.168.198.139 puppet-server
192.168.198.160 puppet-client
EOF

Create module directory and manifests

mkdir -p /etc/puppet/modules/lnmp/{manifests,files,templates,tests}
# init.pp
class lnmp {
    include lnmp::nginx
    include lnmp::mysql
    include lnmp::php
}
# nginx.pp, php.pp, mysql.pp definitions (packages, files, services)
# site.pp
node 'puppet-client' { include lnmp }

Copy configuration files

cp /root/files/{nginx.conf,www.conf,my.cnf} /etc/puppet/modules/lnmp/files/

Start puppet services

# On the master
puppet master --verbose --no-daemonize
# On the client
puppet agent --server puppet-server --verbose --no-daemonize
# Sign the certificate on the master
puppet cert sign puppet-client

8. Summary

This guide provides a concise reference for using Puppet to automate Linux system configuration, covering fundamentals, workflow, installation, resource handling, language features, class/module structure, and a practical LNMP deployment example.