Ansible Architecture

Architecture of Ansible

Ansible is designed with simplicity and modularity in mind. Its architecture revolves around a few key components that work together to automate tasks across systems. The two most essential concepts you'll work with are the Inventory and the Playbook.

Inventory

The Inventory tells Ansible where to apply tasks. It's a list of target machines (hosts) that can be grouped and referenced in playbooks.

Static Inventory

The most commons formats are INI and Yaml (as they are built-in), but there are many more formats and sources that are possible.

[webservers]
192.168.1.10
192.168.1.11

[dbservers]
192.168.1.20

You can group machines by role, function, or environment (it is up to you).

Dynamic Inventory

For more complex infrastructure (like cloud environments), Ansible can generate inventory dynamically via scripts or plugins (e.g., AWS EC2, Docker, Kubernetes). I will explain later how to generate an inventory using HashiCorp Vault and Ansible.

Playbook

A playbook is a YAML file that defines what tasks to perform on which hosts. It's the central part of how Ansible automates work.

Each Playbook is made of plays and has:

• hosts : the inventory group to target
• tasks : a sequence of actions to run
• modules : the tools Ansible uses to execute tasks (e.g., apt, copy, service)

Playbook Structure

Basic structure of a playbook:

---
- name: Example Play
  hosts: All
  become: true
  tasks:
    - name: Install a package
      apt:
        name:
          - git
        state: present

• name : Descibre the Play
• hosts : Targets the group from your inventory
• become : Allows you to run tasks as root
• tasks : A list of task definitions
• apt : This is a module used for Debian-based package management

Modules in Playbooks

Modules are what Ansible uses to actually perform actions. Some common modules include:

• apt, yum : package installation
• copy, template : file operations
• service : start/stop services
• shell, command : run commands (less recommended)

Create your first playbook

---
- name: Install NGINX on web servers
  hosts: webservers
  become: true
  tasks:
    - name: Update apt cache
      apt:
        update_cache: yes

    - name: Install nginx
      apt:
        name: nginx
        state: present

    - name: Ensure nginx is running
      service:
        name: nginx
        state: started
        enabled: yes

ansible-playbook -i inventory.yml install_nginx.yml

Next Steps

Now that you understand Ansible's basic architecture, you are ready to dive deeper. The upcoming sessions will cover more advanced concepts like variables, roles, templates, and Dynamic Inventory.