Best Practices of Ansible Role

I have written about Ansible Roles in my career. But when I talk about the “Best Practice of writing an Ansible Role”, half of them were not following the best practices.
When I started writing this blog, I had only limited knowledge of Ansible Roles and about the practices being followed. But reading more on Ansible roles has helped in enhancing my knowledge.
Without the proper understanding of the Architecture of Ansible Role, I was incapable of enjoying all the functionality for writing an Ansible Role. Earlier, I used “command” and “shell” modules for writing an Ansible Role. Here, in this blog, I’ve discussed the best practices of Ansible Role. Let’s
read these in detail.
 

 
Advantages of Best Practices
 
  • Completing the task using Full Functionality.
  • Vandalized Architecture helps to create Ansible roles as Utilities that can be used further using different values.
  • Applying best practices helps you to learn new things every day.
  • Following “Convention Over Configuration” makes your troubleshooting much easier.
  • Helps you to grow your Automation skills.
  • You don’t have to worry about the latest version or change in values ever.
I can talk about the Advantages of best practices continuously but you should understand it after using them. Now, let’s talk about “How to apply them”.
 
First, we will understand the complete directory structure on Ansible Role:
 
  • Defaults: The default variables for the role are stored here inside this directory. These variables have the lowest priority.
  • Files: All the static files are being stored here which are used inside the role.
  • Handlers: All the handlers are being used here but not inside the Task directory. And automatically called upon from here.
  • Meta: This directory contains the metadata about your role regarding the dependencies which are being required to run this role in any system, so it will not be run until the dependencies inside it are not resolved.
  • Tasks: This directory contains the main list of the tasks which needs to be executed by the role.
  • Vars: This directory has higher precedence than the defaults directory and can only be overwritten by passing them On the command line, In the specific task, or In a block.
  • Templates: This directory contains the Jinja templates inside it. Basically, all the variablized templates which are rendered into static files during runtime are stored here.

Whitespace and Comments

Generous use of whitespace and breaking things up is really appreciated. One very important thing is the use of comments inside your roles so that someone using your role in the future can easily understand it properly.
 
YAML format
Learn YAML format properly and use of indentation properly inside the document. Sometimes, when running the role gives the error for Invalid Syntax due to bad indentation format. And writing in proper Indentation makes your role look beautiful.
 
 
Always Name Tasks
 
It is possible to leave off the ‘name’ for a given task, though it is recommended to provide a description of something being done instead. This name is shown when that particular task is being run.
 
 
Version Control
 
Use version control. Keep your roles and inventory files in git and commit when you make changes to them. This way you have an audit trail describing when and why you changed the rules that are automating your infrastructure.
 
 
Variable and Vaults
 
Since the variable contains sensitive data, so it is often easier to find variables using grep or similar tools inside the Ansible system. Since vaults obscure these variables, it is best to work with a layer of Indirection. This allows Ansible to find the variables inside the unencrypted file and all sensitive variables come from an encrypted file.
 
The best approach to perform is to start with a group_vars subdirectory containing two more subdirectories inside it naming “Vars” and “Vaults”. Inside the “Vars”  directory, define all the variables including sensitive variables also. Now, copy those sensitive variables inside the “Vault” directory while using the prefix “vault_*” for the variables. Now you should adjust the variables in the “Vars” to point the matching “vault_*” variables using jinja2 syntax and ensure that the vault file is vault encrypted.
 
Roles for multiple OS
 
Roles should be written in a way that they can run on multiple Operating systems. Try to make your roles as generic as you can. But if you have created a role for some specific kind of operating system or some specific application, then try to explicitly define that inside the role name.
 
Single role Single goal
 
Avoid tasks within a role that are not related to each other. Don’t build a common role. It’s ugly and bad for the readability of your role.
 
Other Tips:
 
  • Use a module if available
  • Try not to use command or shell module
  • Use the state parameter
  • Prefer scalar variables
  • Set default for every variable
  • If you have multiple roles related to each other than try to create a common variable file for all of them which will be called inside your playbook
  • Use “copy” or “template” module instead of “lineinfile” module
  • Make role fully variablized
  • Be explicit when writing tasks. Suppose, if you are creating a file or directory then instead of defining src and destination, try to define owner, group, mode, etc.
Summary:
 
  • Create a Role that could be used further.
  • Create it using proper modules for better understanding.
  • Do proper comments inside it so that it would be understood by someone else also.
  • Use proper Indentation for the YAML format.
  • Create your Role variables and also secure them using a vault.
  • Create a Single role for a single goal.
Opstree is an End to End DevOps solution provider
 
 

One thought on “Best Practices of Ansible Role”

  1. This is good but if you can add examples with every topic then it would be more clear to the end user. You can also describe different ansible modules here.Overall it is a good package.

    Like

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