DevOps Day 13 — Getting Started with Ansible: Installation, Ad-hoc Commands & Playbooks

Welcome to Day 13 of the DevOps Series.

As infrastructure grows, managing servers manually becomes difficult and error-prone.

This is where Ansible plays a major role in DevOps by enabling automation, consistency, and scalability.

In Day 13, we focus on hands-on Ansible basics — from installation to running our first playbook.

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✅ What We’ll Learn Today

• How to install Ansible

• Why passwordless SSH is required

• Running Ansible ad-hoc commands

• Creating inventory files

• Writing and executing Ansible playbooks

• Understanding verbose logs

• Introduction to Ansible roles

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🔹 1. Ansible Installation

Ansible is usually installed on a control node (your laptop or EC2 instance).

On Ubuntu:

sudo apt update
sudo apt install ansible -y

Other platforms:

• Mac: Homebrew (brew install ansible)

• Windows: Chocolatey (mainly for testing)

📌 Using package managers is recommended because they handle dependencies automatically.

Verify installation:

ansible --version

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🔹 2. Passwordless Authentication (Very Important)

Ansible works using SSH, so it must connect to target servers without asking for a password.

Step 1: Generate SSH key

ssh-keygen

Press Enter for all options.

Step 2: Copy public key to target server

ssh-copy-id user@target-server-ip

After this, you should be able to login without a password:

ssh user@target-server-ip

✅ This is mandatory for Ansible automation.

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🔹 3. Ansible Inventory File

Inventory defines which servers Ansible manages.

Example:

[web]
192.168.1.10
192.168.1.11

[db]
192.168.1.20

You can group servers logically:

• web servers

• database servers

• application servers

This makes targeting easy and clean.

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🔹 4. Ansible Ad-hoc Commands

Ad-hoc commands are used for one-time tasks
(no playbook required).

Example: ping all servers

ansible all -i inventory -m ping

Create a file on all servers:

ansible all -i inventory -m shell -a "touch test.txt"

📌 Useful for:

• checking connectivity

• restarting services

• quick troubleshooting

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🔹 5. Writing Your First Ansible Playbook

Playbooks are written in YAML format.

Basic YAML structure:

---
- name: Install Nginx
  hosts: all
  become: true

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

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

Key sections:

• name → description

• hosts → target machines

• become → run as root

• tasks → automation steps

📌 Always prefer Ansible modules over shell commands.

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🔹 6. Executing the Playbook

ansible-playbook -i inventory nginx.yml

You’ll see:

• Gathering facts

• Task execution

• Success or failure status

This ensures repeatable and reliable automation.

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🔹 7. Verbose Mode (Debugging)

To understand what Ansible is doing internally:

ansible-playbook -i inventory nginx.yml -v
ansible-playbook -i inventory nginx.yml -vv
ansible-playbook -i inventory nginx.yml -vvv

More v = more details.

Very useful during troubleshooting.

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🔹 8. Introduction to Ansible Roles

When playbooks become large, managing everything in one file becomes messy.

👉 Roles help organize code

Create a role:

ansible-galaxy role init nginx

Roles separate:

• tasks

• variables

• handlers

• templates

• files

Used heavily in:

• Kubernetes setup

• Production automation

• Enterprise environments

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🚀 Why This Matters in Real DevOps

Ansible helps DevOps engineers:

• Automate server setup

• Maintain consistency

• Reduce manual errors

• Manage thousands of servers

• Work efficiently with cloud infrastructure

This is why Ansible is one of the most in-demand DevOps skills today.