Variables In Playbooks | Playbooks

Introduction

Variables in playbooks are essential for dynamic and flexible task execution. They allow us to store values that can be reused throughout the playbook, making it easier to manage and update scripts. In this tutorial, we will explore what variables are, how to define them, and how to use them in playbooks.

What are Variables?

Variables are placeholders for data that can be used in playbooks. They can store different types of data such as strings, integers, lists, and dictionaries. By using variables, you can write more modular and reusable playbooks.

Defining Variables

Variables can be defined in several ways in playbooks:

Directly in the playbook
In inventory files
As command-line arguments
From external files

Let's start with defining variables directly in a playbook:

---
- name: Example Playbook
  hosts: localhost
  vars:
    my_variable: "Hello, CrewAI!"
  tasks:
    - name: Print variable
      debug:
        msg: "{{ my_variable }}"

Using Variables

Once defined, variables can be used in tasks, templates, and handlers. Here's how you can use a variable in a task:

- name: Create a file with content from a variable
  hosts: localhost
  vars:
    file_content: "This is the content of the file."
  tasks:
    - name: Create a file
      copy:
        dest: /tmp/myfile.txt
        content: "{{ file_content }}"

Variable Types

Variables can store different types of data:

String
Integer
List
Dictionary

Here are examples of each type:

- name: Variable Types
  hosts: localhost
  vars:
    string_var: "This is a string"
    int_var: 42
    list_var:
      - "item1"
      - "item2"
    dict_var:
      key1: "value1"
      key2: "value2"
  tasks:
    - name: Print all variables
      debug:
        msg: |
          String: {{ string_var }}
          Integer: {{ int_var }}
          List: {{ list_var }}
          Dictionary: {{ dict_var }}

Using Variables in Templates

Variables can also be used in templates to dynamically generate content. Jinja2 is the templating engine used in playbooks. Here’s how you can use a variable in a Jinja2 template:

# template.j2
Hello, {{ name }}!

And here’s how you can apply the template in a playbook:

- name: Use Template
  hosts: localhost
  vars:
    name: "CrewAI"
  tasks:
    - name: Apply template
      template:
        src: template.j2
        dest: /tmp/greeting.txt

Conclusion

In this tutorial, we've covered the basics of variables in playbooks. We've explored how to define them, use them in tasks, and utilize them in templates. By leveraging variables, you can create more flexible and maintainable playbooks. Practice using variables in your playbooks to become more proficient in managing dynamic configurations.

Variables in Playbooks - CrewAI