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Ansible Playbook Essentials

You're reading from   Ansible Playbook Essentials Design automation blueprints to manage your multitier infrastructure

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Product type Paperback
Published in Aug 2015
Publisher
ISBN-13 9781784398293
Length 168 pages
Edition 1st Edition
Tools
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Author (1):
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Gourav Shah Gourav Shah
Author Profile Icon Gourav Shah
Gourav Shah
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Toc

Table of Contents (14) Chapters Close

Preface Setting Up the Learning Environment FREE CHAPTER 1. Blueprinting Your Infrastructure 2. Going Modular with Ansible Roles 3. Separating Code and Data – Variables, Facts, and Templates 4. Bringing In Your Code – Custom Commands and Scripts 5. Controlling Execution Flow – Conditionals 6. Iterative Control Structures – Loops 7. Node Discovery and Clustering 8. Encrypting Data with Vault 9. Managing Environments 10. Orchestrating Infrastructure with Ansible A. References
Index

Variable precedence

We specified variable defaults, used them in inventory files, and defined the same variable from different places (for example, defaults, vars, and inventory). Let's now analyze the output of the templates to understand what happened with all those variables.

The following is the figure showing the my.cnf file on Ubuntu:

Variable precedence

The following is the analysis of the screenshot:

  • The file has a notice in the comments section. This can deter admins from making manual changes to the file.
  • Most of the variables come from the defaults in a role. This is because Debian is our default family of operating systems and we already have sane defaults set for it. Similarly, for other operating system platforms, we are setting variable defaults from the vars directory in a role.
  • Even though the bind_address parameter is specified in the defaults and group_vars, it takes a value from the playbook's role parameter, which has a higher precedence over the other two levels.

The following diagram...

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