Playbook Structure Tutorial

Introduction

In this tutorial, we will explore the structure of a playbook in CrewAI. A playbook is a fundamental component that allows you to automate tasks using predefined sets of instructions. Understanding the structure of a playbook is crucial for creating efficient and effective automation scripts. Let's dive in!

Basic Structure

A playbook in CrewAI is generally composed of several key sections: hosts, tasks, and vars. Here is an example of a basic playbook structure:

---
- name: Example Playbook
  hosts: all
  vars:
    variable1: value1
  tasks:
    - name: Print a message
      command: echo "Hello, CrewAI!"
                

Hosts

The hosts section specifies the target machines on which the playbook will run. You can define a group of hosts or individual hosts:

In this example, the playbook will run on all available hosts.

Variables

The vars section is used to define variables that can be utilized throughout the playbook:

  variable1: value1
  variable2: value2
                

These variables can be referenced in tasks as {{ variable1 }} and {{ variable2 }}.

Tasks

The tasks section contains the list of actions that will be executed on the hosts. Each task is defined with a name and a specific module to perform a certain action. Here is an example of a simple task:

  - name: Print a message
    command: echo "Hello, CrewAI!"
                

This task uses the command module to print a message on the target hosts.

Handlers

Handlers are special types of tasks that are triggered by other tasks using the notify keyword. Handlers are defined similarly to regular tasks but are placed under a separate handlers section:

  - name: Restart service
    service:
      name: myservice
      state: restarted
                

In this example, a handler is defined to restart a service named myservice. This handler can be notified by other tasks.

Example Playbook

Let's compile everything we've learned into a complete playbook example:

---
- name: Complete Example Playbook
  hosts: all
  vars:
    message: "Hello, CrewAI!"
  tasks:
    - name: Print a message
      command: echo "{{ message }}"
      notify:
        - Restart service

  handlers:
    - name: Restart service
      service:
        name: myservice
        state: restarted
                

In this complete example, we define a playbook that prints a message and notifies a handler to restart a service. The message is stored in a variable for easy modification.

Conclusion

Understanding the structure of a playbook is crucial for automating tasks efficiently in CrewAI. By organizing your playbook into sections such as hosts, vars, tasks, and handlers, you can create flexible and powerful automation scripts. Practice creating your own playbooks to become proficient in CrewAI automation.