Definitions

Here’s a complete list of Ansible concepts, components, and objects with definitions. This will cover everything an interviewer might ask.

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1. Core Concepts in Ansible

1.1. Ansible

An open-source configuration management, automation, and orchestration tool used to provision and manage infrastructure declaratively.

1.2. Agentless

Ansible does not require agents on managed nodes. It uses SSH for Linux and WinRM for Windows.

1.3. Idempotency

Ensures that running the same Ansible playbook multiple times produces the same result without unintended changes.

1.4. Push vs Pull Mode

• Push Mode (default): The Ansible control node pushes configurations to target nodes.

• Pull Mode: Managed nodes fetch configurations from a central repository (using ansible-pull).

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2. Key Components & Objects in Ansible

2.1. Inventory

A file that lists managed nodes (hosts) along with their IPs, groupings, and variables.

• Default: /etc/ansible/hosts

• Formats: INI, YAML, or Dynamic Inventory (AWS, Azure, GCP).

👉 Example (INI format)

[web]
server1 ansible_host=192.168.1.10 ansible_user=ubuntu

[db]
server2 ansible_host=192.168.1.20 ansible_user=root

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2.2. Playbook

A YAML file containing tasks that define automation steps.

• It contains plays that run sequentially on managed nodes.

👉 Example

- name: Install and start Nginx
  hosts: web
  become: yes
  tasks:
    - name: Install Nginx
      apt:
        name: nginx
        state: present

    - name: Start Nginx
      service:
        name: nginx
        state: started

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2.3. Tasks

Individual units of work inside a playbook. They execute modules to perform specific actions (e.g., install a package, restart a service).

👉 Example

- name: Ensure Apache is installed
  yum:
    name: httpd
    state: present

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2.4. Modules

Reusable Ansible plugins that execute specific actions on nodes.

📌 Types of Modules:

• System Modules: service, apt, yum, firewalld

• File Modules: copy, file, fetch, template

• Cloud Modules: ec2_instance, gcp_compute_instance

• User Modules: user, group, hostname

👉 Example (Using copy module)

- name: Copy a file
  copy:
    src: /local/path/file.txt
    dest: /remote/path/file.txt

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2.5. Roles

A structured way to organize Ansible playbooks into reusable components. Each role contains tasks, handlers, templates, and variables.

📌 Role Directory Structure

my_role/
  ├── tasks/main.yml
  ├── handlers/main.yml
  ├── templates/
  ├── files/
  ├── vars/main.yml
  ├── defaults/main.yml
  ├── meta/main.yml

👉 Run a Role in Playbook

- name: Apply Web Role
  hosts: web
  roles:
    - webserver

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2.6. Handlers

Similar to tasks but only run when notified by another task. Commonly used for restarting services after configuration changes.

👉 Example

- name: Update Nginx config
  template:
    src: nginx.conf.j2
    dest: /etc/nginx/nginx.conf
  notify: Restart Nginx

- name: Restart Nginx
  service:
    name: nginx
    state: restarted
  listen: "Restart Nginx"

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2.7. Variables

Allow parameterization in playbooks.

📌 Types of Variables:

• Defined in Playbooks

• Defined in Inventory

• Facts (Gathered from Nodes)

• External Variables (via vars_files)

👉 Example

- name: Use Variables
  hosts: web
  vars:
    package_name: nginx
  tasks:
    - name: Install package
      apt:
        name: "{{ package_name }}"
        state: present

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2.8. Templates (Jinja2)

Dynamic configuration files using Jinja2 templating.

👉 Example (nginx.conf.j2)

server {
    listen 80;
    server_name {{ server_name }};
}

👉 Apply Template in Playbook

- name: Configure Nginx
  template:
    src: nginx.conf.j2
    dest: /etc/nginx/nginx.conf

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2.9. Facts

Automatically collected system information about managed nodes.

👉 Check facts manually

ansible all -m setup

👉 Use a fact in a Playbook

- name: Display system info
  debug:
    msg: "The system is running {{ ansible_distribution }} {{ ansible_distribution_version }}"

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2.10. Conditionals

Execute tasks based on conditions.

👉 Example

- name: Install Web Server (only on Ubuntu)
  apt:
    name: apache2
    state: present
  when: ansible_distribution == "Ubuntu"

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2.11. Loops

Run a task multiple times.

👉 Example (Looping through a list)

- name: Install multiple packages
  apt:
    name: "{{ item }}"
    state: present
  loop:
    - nginx
    - curl
    - git

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2.12. Tags

Run only specific parts of a playbook.

👉 Tagging a Task

- name: Install Apache
  apt:
    name: apache2
    state: present
  tags:
    - webserver

👉 Run Playbook with a Specific Tag

ansible-playbook site.yml --tags "webserver"

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2.13. Ansible Vault

Encrypts sensitive information (passwords, keys) in playbooks.

👉 Encrypt a file

ansible-vault encrypt secrets.yml

👉 Use Vault in a Playbook

vars_files:
  - secrets.yml

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2.14. Ansible Galaxy

A community repository for Ansible roles.

👉 Install a Role from Galaxy

ansible-galaxy install geerlingguy.nginx

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2.15. Ansible Pull

Used for agent-based Ansible deployments.

👉 Example

ansible-pull -U https://github.com/myrepo/ansible.git

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Conclusion

This covers all major Ansible concepts that interviewers typically ask.

Pro Tip 💡

💬 Before the interview:

• Revise key modules (apt, yum, copy, template, service).

• Practice YAML syntax & playbooks.

• Prepare real-world use cases from your experience.

Let me know if you need mock interview questions or playbook scenarios. 🚀