How to Set a Variable Based on a Condition in Ansible Using set_facts

Описание: Learn how to use Ansible's `set_facts` to manage boolean values based on the contents of `register.stdout_lines`.
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Setting a Variable Based on a String Condition in Ansible

When working with Ansible, it's common to need to set variables based on certain conditions encountered during playbook executions. A common scenario arises when you want to determine if a particular service is running and set a corresponding boolean variable accordingly. In this guide, we'll explore how to achieve this using the set_facts module in Ansible.

The Problem

Suppose you have output from a service check, specifically from register.stdout_lines, and you want to set a variable called server_running to True if the output contains the string active (running). If the string isn’t found, the variable should be set to False. For example, you might have an output that looks like this:

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

The challenge lies in correctly parsing this output and extracting the information you need to set the boolean value of server_running.

The Solution

To accomplish this, we can utilize Ansible’s set_facts to check for the presence of the target string within the output. Here’s how to implement this solution step-by-step.

Step 1: Use set_facts to Define the Boolean Variable

Ansible's set_facts allows you to define variables dynamically. We will use a template condition to check if the string active (running) is present. Here’s the correct code you can use:

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

Step 2: Understanding the Code

Let’s break down what is happening in the provided code:

set_fact: This module is used to set new variables dynamically during playbook execution.

start_success: This is the name of the variable we're defining.

{% if ... %}...{% else %}...{% endif %}: This template expression checks if the string active (running) exists in the confluent_status.stdout. If it does, start_success is set to True; otherwise, it is set to False.

Step 3: Additional Considerations

In your Ansible configuration, you may notice that the output can be difficult to read. By setting stdout_callback to yaml in your ansible.cfg, you can achieve a more user-friendly format which may be beneficial for troubleshooting.

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

Conclusion

With this setup, you can effectively manage boolean variables based on service status checks in Ansible. The ability to dynamically configure your playbook based on service states opens up numerous possibilities for automation and orchestration.
Remember, by leveraging the set_facts module, combined with conditionals, you can bring powerful logic into your automation scripts.

Happy Automating!