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Ansible Playbook | beginning to advance.

The playbook is the main program, all the code is written here, it is also known as a tasks file. It is written in the YAML language...

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Introduction

The playbook is the main program, all the code is written here, it is also known as a tasks file. It can contain one or multiple tasks. It is written in the YAML language. Visit www.yamllint.com/ to learn and validate your scripts.

This file is like the main() function of our program. 

It looks something like below.

PlayBook Structure

Example,

---
- name: Collect IOS Device Facts
  connection: network_cli
  gather_facts: True
  hosts: all
  tasks: 
    - name: show output
      debug: 
        var: ansible_facts
...

This playbook gathers information about all devices provided in the inventory using single task.

Our directory structure looks like below.

- It is a basic structure of files that is required every time. There are more files, which is discussed later.

Output: It contains all the information of the connected node. 

2. Write multiple tasks in a single playbook.

Eg,
---
  name: Check web servers
  hosts: webservers
  remote_user: root
  tasks:
  - name: Ensure apache is at the latest version
    yum:
      name: httpd
      state: latest
   
  - name: Ensure that postgresql is started
    service:
      name: postgresql
      state: started
...

Description:
Name: It is used for the naming convention and easy readability for the tasks, It does not affect anything if not written.
Hosts: It states the file is only executed to specific users/groups of the inventory file. Here, in our case it is webservers.
Tasks: Contain a list of plays and configurations to perform.

"There are many other different fields in the playbook which is discussed in a later part."

Playbook execution

It is also called ad-hoc commands.

ansible-playbook playbook_file.yml

By default, our inventory file is in "etc/ansible/hosts". But when we access it from a different location or change its default name we need to let it know to ansible.
There are two ways,
     1. Update the ansible.cfg file.
     2. Pass file location during execution. Example below.
 

ansible-playbook -i hosts playbook_file.yml

Include tasks in playbooks.

"Make Sure every time you write any file follow the YAML Structure"

You can separately write tasks in different files and can later include them whenever required.
E.g

Include Playbook files.

Use Variable Inside Playbook.

---
- name: Working with Variable in Ansible
  hosts: localhost
  vars:
    - name: Karan Joshi
      company: Itblizz
  tasks:
    - name: Print the Variables
      debug:
              msg: "Name :{{ name }}({{ company }})"
...

Output:



Note: We can also use a variety of variables like lists, dictionaries, etc that are covered in the later part.

Include Variable File in Playbook.

For better visibility, we use separate files. To include variables inside the playbook we use the vars_files attribute below the hosts.
Syntax,
- name: include variable File
  hosts: all
  vars_files:
    - /vars/external_vars.yml
E.g






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