Ansible Playbooks

Ansible Playbooks provide a repeatable, reusable, simple configuration management and multimachine deployment system that is well suited to deploying complex applications. If you need to execute a task with Ansible more than once, you can write a playbook and put the playbook under source control. You can then use the playbook to push new configurations or confirm the configuration of remote systems.

Source: docs.ansible.com

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My Favorite Structure

ansible-project/
├── ansible.cfg
├── inventory
│   └── hosts.ini
├── group_vars
│   └── appservers.yml
├── plays
│   └── setup-example.yml
├── retries
└── roles
    └── example
        ├── handlers
        │   └── main.yml
        ├── tasks
        │   └── main.yml
        └── templates
            └── example.conf.j2

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Inventory and Group Variables

inventory/hosts.ini — Defines hosts and groups

Input:

[appservers]
app01 ansible_host=10.10.10.11 env=prod
app02 ansible_host=10.10.10.12 env=dev

group_vars/appservers.yml — Variables applied to whole group

Input:

app_name: "backend_service"
listen_port: 8080
log_level: "info"

env_config:
  prod:
    db_host: "10.1.1.10"
    db_port: 5432
  dev:
    db_host: "10.1.1.20"
    db_port: 5432

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Roles

Roles let you automatically load related vars, files, tasks, handlers, and other Ansible artifacts based on a known file structure. After you group your content into roles, you can easily reuse them and share them with other users.

Handlers

Sometimes you want a task to run only when a change is made on a machine. For example, you may want to restart a service if a task updates the configuration of that service, but not if the configuration is unchanged.

roles/example/handlers/main.yml

Input:

- name: Restart apache
  ansible.builtin.service:
    name: httpd
    state: restarted

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Tasks

roles/example/tasks/main.yml

Input:

- name: Render application configuration
  template:
    src: example.conf.j2
    dest: /etc/example/example.conf
    mode: "0644"
  notify:
    - Restart apache

- name: Ensure service directory exists
  file:
    path: /etc/example
    state: directory
    mode: "0755"

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Template Rendering

Templates let you build dynamic config files.

roles/example/templates/example.conf.j2

Input:

[service]
name = {{ app_name }}
port = {{ listen_port }}
log_level = {{ log_level }}

[database]
host = {{ env_config[hostvars[inventory_hostname].env].db_host }}
port = {{ env_config[hostvars[inventory_hostname].env].db_port }}

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Playbook Calling the Role

plays/setup-example.yml

Input:

- hosts: appservers
  become: yes
  gather_facts: yes
  roles:
    - example

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Ansible Configuration

Ansible reads ansible.cfg to define global behavior for inventory, roles, SSH, retries, and module paths.

Understanding ansible.cfg entries

Input:

[defaults]
host_key_checking = False
roles_path = roles
library = library
retry_files_save_path=retries

Explanation

Key	Meaning	Technical Explanation
host_key_checking = False	Disables SSH host key verification	Prevents Ansible from asking confirmation on unknown host fingerprints during SSH connection.
roles_path = roles	Sets the default directory for roles	Ansible will search for roles inside the roles/ folder relative to the project.
library = library	Custom module directory	Ansible loads any custom modules stored in the library/ path.
retry_files_save_path = retries	Where to store retry files	If a play fails, retry files are stored under retries/ for rerunning failed hosts.

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Running the Playbook

introduction about the command before input

Apply configuration to all appservers.

Input:

ansible-playbook -i inventory/hosts.ini playbook.yml

Output:

TASK [example : Render application configuration] ********************************
changed: [app01]
changed: [app02]

TASK [example : Ensure service directory exists] *********************************
ok: [app01]
ok: [app02]

This shows that the template was rendered and copied, and directory state validated.

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Resulting Configuration

Host	env	DB Host	Port
app01	prod	10.1.1.10	5432
app02	dev	10.1.1.20	5432

The config file is built from shared variables but changes per host environment.

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Get The Template

Input:

bash <(curl -s https://pndhkm.github.io/scripts/ansible_playbooks_template.sh)

Output:

Usage: ./ansible_playbooks_template [OPTIONS] <project_folder>

Creates a fully structured Ansible project scaffold.

Examples:
  ./ansible_playbooks_template my-ansible-project
  ./ansible_playbooks_template --force infra-setup

Options:
  -f, --force     Overwrite existing folder if it exists
  -h, --help      Show this help message

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