Ansible Playbooks

An Ansible playbook is a YAML file that defines a set of tasks to be executed on managed nodes in a structured, repeatable, and automated way.

YAML is human readable, structured and easy to write making it suitable for ansible automation playbooks

A playbook = a step-by-step automation script written in YAML that tells Ansible what to do, where to do it, and how to do it.

Compared to Ad-hoc commands, playbooks can handle reusable multiple complex tasks easily without need for running commands

Components of Ansible Playbooks

i. Play: A play is the top level unit in the playbook, defining which hosts to target and the tasks to run

ii. Host: specifies target systems from the inventory

iii. Tasks: List of actions to be executed on managed nodes

Working with Ansible

Section I: User and Group Management

The playbook creates users and group across managed nodes and adds users to assigned groups looping through variables

 name: Create users and groups, assign users to group
  hosts: servers
  become: yes

  vars:
    group_name: DevOps

    users:
      - alice
      - bob
      - charles

    group_members:
      - alice
      - charles
    tasks:

    - name: Create users
      user:
        name: "{{ username }}"
        state: present
        create_home: yes
        shell: /bin/bash
      loop: "{{ users }}"
      loop_control:
        loop_var: username

    - name: Create group
      group:
        name: "{{ group_name }}"
        state: present

    - name: Add selected users to group
      user:
        name: "{{ member }}"
        groups: "{{ group_name }}"
        append: yes
       loop: "{{ group_members }}"
      loop_control:
        loop_var: member

Section II: Backup for Control node to Managed node

This playbook automates the process of:

• creating a compressed archive of the /etc directory on the control node
• transferring that backup to all managed nodes

The variable used indicates the source of the file, the destination of the file and the name of the backup archive respectively

 name: Backup control node and distribute to managed nodes
  hosts: servers
  become: yes

  vars:
    backup_src: /etc        # what to back up on control node
    backup_dest: /tmp/backups
    backup_file: etc_backup.tar.gz

  tasks:

    - name: Create backup using tar
      command: tar -czf /tmp/{{ backup_file}} {{ backup_src }}
      delegate_to: localhost
      run_once: true

    - name: Ensure backup directory exists on managed nodes
      file:
        path: "{{ backup_dest }}"
        state: directory
        mode: '0755'

    - name: Copy backup to managed nodes
      copy:
        src: "/tmp/{{ backup_file }}"
        dest: "{{ backup_dest }}/{{ backup_file }}"

Section III: Installing Applications

This playbook automates the process of:

• Installing software packages (Git and Tree) on RHEL systems
• Verifying successful installation of each package
• Displaying installed versions for confirmation

- name: Install Git on RHEL systems
  hosts: servers
  become: yes
  tasks:
    - name: Install Git package
      package:
        name: git
        state: present
    - name: Verify Git Installation
      command: git --version
      register: git_version

- name: Install Tree on RHEL systems
  hosts: servers
  become: yes
  tasks:
    - name: Install Tree package
      package:
          name: tree
          state: present
    - name: Verify Tree Installation
      command: tree --version
      command: which tree
      register: tree_version