What is Puppet: Components and Writing Manifests Explained

Consider a system administrator working with multiple servers. If one of the servers has an issue, they can easily fix it. The situation becomes problematic, however, when multiple servers are down. 

This is where Puppet can help. 

With Puppet, you can write simple code and deploy it to the servers that have issues. After the code runs, all servers are rolled back to their previous working states or set to the new desired states in a matter of seconds. Puppet can also be used to deploy software and add security, all through simple codes. 

This article on puppet covers the following topics:

  • What is Puppet?
  • Components of Puppet 
  • How Puppet works
  • Companies adopting Puppet
  • Writing manifests in Puppet
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Let us begin our learning about what is Puppet.

What is Puppet?

Puppet is a configuration management tool ensuring that all systems are configured to a desired and predictable state. 

You can also use Puppet as a deployment tool as it can automatically deploy software on the system. Puppet implements infrastructure as code, which means you can test the environment and ensure that it is deployed accurately.

After going through what is Puppet, let us learn the components of Puppet.

Components of Puppet

Components of Puppet

The Puppet environment can be broken down into the main server environment (shown above) and the client environment. In the main server environment, there is a Puppet master store which stores all configuration files. 

  • Manifests are the actual codes for configuring the clients
  • Templates combine code and data to render a final document 
  • Files are the static content that can be downloaded by the clients
  • Modules are a collection of manifests, templates, and files
  • Certificate authority allows the master to sign the certificates sent by the client 

The Puppet client is the machine that needs to be configured, consisting of Agent and Facter. The agent continuously interacts with the master server to ensure that the certificates are being updated appropriately. The facter collects the current state of the client that is used and communicates it back through the agent.

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Now that we have looked into the components of puppet, let us learn how Puppet works as a part of our learning about what is Puppet. 

How Puppet Works 

Puppet has a primary-secondary node architecture. 

Puppet Architecture

The clients are distributed across the network and communicate with the primary-secondary environment where Puppet modules are present. The client agent sends a certificate with its ID to the server; the server then signs that certificate and sends it back to the client. This authentication allows for secure and verifiable communication between the client and the master. 

The facter then collects the state of the clients and sends it to the master. Based on the fact sent, the master compiles the manifests into the catalogs, which are sent to the clients, and an agent executes the manifests on its machine. A report is generated by the client that describes any changes made and is sent to the master. 

This process is repeated at regular intervals, ensuring all client systems are up to date. In the next section, let us find out about the various companies adopting Puppet as a part of our learning about what is Puppet.

Companies Adopting Puppet

Your interest in understanding what is Puppet would grow if you know about the companies that have adopted it to manage their infrastructure. Some of them include:

  • Spotify 
  • Google 
  • AT&T 
  • Staples 
  • AON
  • The U.S. Air Force

The reasons why these companies adopted Puppet may vary. For example, Staples used Puppet as a configuration management tool to automate its private cloud management and IT operations to provide consistency, allowing their IT teams more time to innovate. 

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Let us know how to write manifests in the following section of What is Puppet article.

Writing Manifests in Puppet 

Files written for configuring a node are called manifests, compiled into catalogs that are executed at the client. Each of the manifests is written in Ruby language with a .pp extension.

The five key steps to write a manifest are:

  1. Create - Manifests are written by the system administrator 
  2. Compile - Manifests are compiled into catalogs
  3. Deploy - Catalogs are deployed onto the clients 
  4. Execute - Catalogs are run on the client by the agent
  5. End - Clients are configured to the desired state 

All manifests must have a common syntax:

Resourcetype { ‘title’ :

Attribute_name1 => attribute_value

Attribute_name2 => attribute_value

}

Here, the resource type can be a package, a file, or a service.

‘title’ refers to the name of the resource type.

Attribute_name1 - This is the feature whose value needs to be changed or set (for example: IP, ensure).

attribute_value - This is the new value for the attribute (for example: present, start)

A manifest can contain multiple resource types. The keyword ‘default’ applies manifest to all the clients. For example:

Node default {

file { ‘/etc/sample’ :

Content => “this is a sample manifest”

}

service { ‘httpd’ :

ensure => installed

}

}

Our first resource is a file path ‘/etc/sample’

The specified content is written into the file. The file is created first if it does not already exist. Our next resource is the Apache service, which is to be installed on the client node. The manifest is deployed on the client machine. The client now has a file named ‘sample’ under ‘etc’ folder and the Apache server will be installed.

For a better understanding, check out this video tutorial about what is Puppet and how it works -

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Learn More About Puppet

According to Grand View Research, the global DevOps market is expected to reach USD 12.85 billion by 2025, with a CAGR of 18.6 percent. The study also highlights the growing deployment of DevOps tools to address a variety of inefficiencies in the software development lifecycle. So, learning about Puppet can take you a step ahead in your DevOps journey. 

After understanding what is Puppet, you can achieve proficiency in using this tool by taking Simplilearn’s Puppet Foundation training course. This course covers a wide range of topics like Puppet architecture, its components and terminologies, and effectively managing Puppet infrastructure, modules, and environments. 

In order to extend your learning beyond Puppet and cover the other top DevOps tools, you can enroll for the DevOps Engineer Program. The course will prepare you for a career in DevOps, the fast-growing field that bridges the gap between software developers and operations. You’ll become an expert in the principles of continuous development and deployment, automation of configuration management, inter-team collaboration and IT service agility, using DevOps tools such as Git, Docker, Jenkins and more.

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