Скачать или смотреть Mastering Variable Usage in Ansible: How to Assign Different Values to Hosts in a Group

Learn how to effectively manage and use specific variable values across different hosts in Ansible. This post breaks down a practical example, detailing how to execute tasks in a group setup.
---
This video is based on the question https://stackoverflow.com/q/70167176/ asked by the user 'asking' ( https://stackoverflow.com/u/17504121/ ) and on the answer https://stackoverflow.com/a/70169385/ provided by the user 'Frenchy' ( https://stackoverflow.com/u/7380779/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: How to use spesific variable value in different host of the same group in Ansible Playbook?

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Mastering Variable Usage in Ansible: How to Assign Different Values to Hosts in a Group

Ansible is a powerful automation tool widely used for configuration management, application deployment, and task execution. However, when managing multiple hosts within the same group, it can become tricky to handle variable values differently across these hosts. This guide focuses on a common scenario where you need to use specific variable values in different hosts of the same group.

The Problem

Imagine you have a group called myhost consisting of two hosts, A and B. You want to execute several tasks that involve using specific values from a variable var1, which contains multiple entries: ["test1", "test2", "test3", "test4"]. Your goal is to:

Copy files with odd values (test1, test3) to host A.

Copy files with even values (test2, test4) to host B.

For instance:

On Host A, create:

file1 with the content variable: test1

file3 with the content variable: test3

On Host B, create:

file2 with the content variable: test2

file4 with the content variable: test4

This is a straightforward task in theory but requires thoughtful implementation in Ansible playbooks.

The Solution

To achieve this task, you can utilize Ansible’s loop and condition features. Here’s a detailed explanation of how to structure your playbook.

Playbook Structure

Below, you will find a structured playbook that shows how to implement the solution:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of Key Components

Hosts Declaration
You start with declaring the hosts in your group:

[[See Video to Reveal this Text or Code Snippet]]

Variable Initialization
You define the variable var1 with its values:

[[See Video to Reveal this Text or Code Snippet]]

Tasks Definition
The tasks section is where the magic happens:

Use the copy module to create and populate files.

You loop through the values in var1 using the loop directive.

File Indexing
The variable idx extracts the index of the files based on values of var1. The regex is utilized to strip any non-numeric characters, making idx a simple integer.

Conditional Logic
The when condition determines which host should receive which value:

[[See Video to Reveal this Text or Code Snippet]]

This ensures that:

Host A gets the odd indices (1 and 3)

Host B gets the even indices (2 and 4)

Conclusion

Using Ansible for managing hosts efficiently requires a solid understanding of how variables and conditional logic work together. In this case, we demonstrated a clear approach to customize file creation based on the host’s identity within a group. By applying these techniques, you can enhance your Ansible playbooks, streamline your automation processes, and effectively manage your infrastructure.



By following the provided example, you can adapt this method for even more complex scenarios, ensuring scalable and tailored configurations across your environment.