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Puppet 3 Cookbook

You're reading from   Puppet 3 Cookbook An essential book if you have responsibility for servers. Real-world examples and code will give you Puppet expertise, allowing more control over servers, cloud computing, and desktops. A time-saving, career-enhancing tutorial

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Product type Paperback
Published in Aug 2013
Publisher Packt
ISBN-13 9781782169765
Length 274 pages
Edition 2nd Edition
Languages
Tools
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Author (1):
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John Arundel John Arundel
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John Arundel
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Toc

Table of Contents (16) Chapters Close

Puppet 3 Cookbook
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
1. Puppet Infrastructure 2. Puppet Language and Style FREE CHAPTER 3. Writing Better Manifests 4. Working with Files and Packages 5. Users and Virtual Resources 6. Applications 7. Servers and Cloud Infrastructure 8. External Tools and the Puppet Ecosystem 9. Monitoring, Reporting, and Troubleshooting Index

Passing parameters to classes


Sometimes it's very useful to parameterize some aspect of a class. For example, you might need to manage different versions of a gem package, and rather than making separate classes for each which differ only in the version number, or using inheritance and overrides, you can pass in the version number as a parameter.

How to do it…

In this example we'll create a definition which accepts parameters:

  1. Declare the parameter as a part of the class definition:

    class eventmachine($version) {
      package { 'eventmachine':
        provider => gem,
        ensure   => $version,
      }
    }
  2. Use the following syntax to include the class on a node:

    class { 'eventmachine':
      version => '1.0.3',
    }

How it works…

The class definition

class eventmachine($version) {

is just like a normal class definition except it specifies that the class takes one parameter: $version. Inside the class, we've defined a package resource:

package { 'eventmachine':
  provider => gem,
  ensure   => $version,
...
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