readme.md

Lab: Using Boolean Filters in Ansible Playbooks

Overview

In this lab, you will learn how to use boolean filters in Ansible playbooks. Specifically, you will understand how the | bool filter can evaluate human-friendly variable values like "yes" or "no" into boolean true or false, and use them to control task execution.

---

Objectives

• Learn how to use the | bool filter to evaluate variables.
• Create tasks that execute conditionally based on boolean filters.

---

Prerequisites

• Basic understanding of Ansible playbooks.
• Ansible installed on your ansible machine.
• Access to target hosts in your inventory.

---

Duration

Estimated Time: 20 minutes

---

Instructions

Step 1: Set Up the Ansible Playbook

1. Create a new YAML file named conditional_bool_playbook.yml.

2. Define the play's name, target hosts (all in this case), and whether to gather facts:

   ---
   - name: A conditional play with boolean filters
     hosts: all
     gather_facts: no

   Explanation:

   • hosts: all targets all hosts in the inventory.
   • gather_facts: no skips automatic fact gathering for simplicity.

---

Step 2: Define a Variable

1. In the vars section, define a variable named boomer and assign it the value no:

     vars:
       boomer: no # "no" translates to false, "yes" translates to true

   Explanation:

   • The variable boomer is a human-readable string that will be evaluated as a boolean.

---

Step 3: Add a Conditional Task

1. Under the tasks section, add a task that prints a message "Hello A" if the boomer variable evaluates to true:

     tasks:
       - name: Task A
         debug:
           msg: "Hello A"
         when: boomer | bool

   Explanation:

   • The when: boomer | bool clause ensures the task runs only if boomer evaluates to true (e.g., "yes").

---

Step 4: Execute the Playbook

1. Save the conditional_bool_playbook.yml file.

2. Run the playbook using the following command:

   ansible-playbook conditional_bool_playbook.yml

3. Observe the output. The task "Task A" will execute only if boomer evaluates to true.

---

Conclusion

In this lab, you've learned how to use boolean filters in Ansible playbooks to evaluate variables like "yes" or "no" into boolean values. By leveraging the | bool filter, you can make your playbooks more adaptable and intuitive. Experiment with other human-friendly values and conditions to further enhance your automation skills! 👏