Book Image

Puppet 3 Cookbook - Second Edition

By : John Arundel
Book Image

Puppet 3 Cookbook - Second Edition

By: John Arundel

Overview of this book

A revolution is happening in web operations. Configuration management tools can build servers in seconds, and automate your entire network. Tools like Puppet are essential to taking full advantage of the power of cloud computing, and building reliable, scalable, secure, high-performance systems. More and more systems administration and IT jobs require some knowledge of configuration management, and specifically Puppet."Puppet 3 Cookbook" takes you beyond the basics to explore the full power of Puppet, showing you in detail how to tackle a variety of real-world problems and applications. At every step it shows you exactly what commands you need to type, and includes full code samples for every recipe.The book takes the reader from a basic knowledge of Puppet to a complete and expert understanding of Puppet's latest and most advanced features, community best practices, writing great manifests, scaling and performance, and extending Puppet by adding your own providers and resources. It starts with guidance on how to set up and expand your Puppet infrastructure, then progresses through detailed information on the language and features, external tools, reporting, monitoring, and troubleshooting, and concludes with many specific recipes for managing popular applications.The book includes real examples from production systems and techniques that are in use in some of the world's largest Puppet installations, including a distributed Puppet architecture based on the Git version control system. You'll be introduced to powerful tools that work with Puppet such as Hiera. The book also explains managing Ruby applications and MySQL databases, building web servers, load balancers, high-availability systems with Heartbeat, and many other state-of-the-art techniques
Table of Contents (16 chapters)
Puppet 3 Cookbook
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Writing a papply script


We'd like to make it as quick and easy as possible to apply Puppet on a machine, so I usually write a little script that wraps the puppet apply command with the parameters it needs. And to deploy the script where it's needed, what better tool than Puppet itself?

How to do it...

Follow these steps:

  1. In your Puppet repo, create the directories needed for a puppet module:

    ubuntu@cookbook:~/puppet$ mkdir modules
    ubuntu@cookbook:~/puppet$ mkdir modules/puppet
    ubuntu@cookbook:~/puppet$ mkdir modules/puppet/manifests
    ubuntu@cookbook:~/puppet$ mkdir modules/puppet/files 
    
  2. Create the file modules/puppet/files/papply.sh with the following contents (change the path /home/ubuntu/puppet to where your Puppet repo is located). The sudo puppet apply command should all be on one line:

    #!/bin/sh
    sudo puppet apply /home/ubuntu/puppet/manifests/site.pp
      --modulepath=/home/ubuntu/puppet/modules/ $*
  3. Create the file modules/puppet/manifests/init.pp with the following contents:

    class puppet {
      file { '/usr/local/bin/papply':
        source => 'puppet:///modules/puppet/papply.sh',
        mode   => '0755',
      }
    }
  4. Modify your manifests/nodes.pp file as follows:

    node 'cookbook' {
      include puppet
    }
  5. Apply your changes:

    ubuntu@cookbook:~/puppet$ sudo puppet apply manifests/site.pp
      --modulepath=/home/ubuntu/puppet/modules
    Notice: /Stage[main]/Puppet/File[/usr/local/bin/papply]
      /ensure: defined content as '{md5}
        171896840d39664c00909eb8cf47a53c'
    Notice: Finished catalog run in 0.07 seconds
    
  6. Test that the script works:

    ubuntu@cookbook:~/puppet$ papply
    Notice: Finished catalog run in 0.07 seconds
    

Now whenever you need to run Puppet, you can simply run papply. In future, when we apply Puppet changes, I'll ask you to run papply instead of the full puppet apply command.

How it works...

As you've seen, to run Puppet on a machine and apply a specified manifest file, we use the puppet apply command:

puppet apply manifests/site.pp

When you're using modules (such as the puppet module we just created) you also need to tell Puppet where to search for modules, using the modulepath argument:

puppet apply manifests/nodes.pp --
  modulepath=/home/ubuntu/puppet/modules

In order to run Puppet with the root privileges it needs, we have to put sudo before everything:

sudo puppet apply manifests/nodes.pp --
  modulepath=/home/ubuntu/puppet/modules

Finally, any additional arguments passed to papply will be passed through to Puppet itself, by adding the $* parameter:

sudo puppet apply manifests/nodes.pp --
  modulepath=/home/ubuntu/puppet/modules $*

That's a lot of typing, so putting this in a script makes sense. We've added a Puppet file resource that will deploy the script to /usr/local/bin and make it executable:

file { '/usr/local/bin/papply':
  source => 'puppet:///modules/puppet/papply.sh',
  mode   => '0755',
}

Finally, we include the puppet module in our node declaration for cookbook:

node 'cookbook' {
  include puppet
}

You can do the same for any other nodes managed by Puppet.