Ansible Level 01 – Day 02: Create Ansible Inventory for App Server Testing¶

This document explains how to create an Ansible inventory file from scratch using the INI format. The inventory defines the remote systems Ansible can manage and specifies the connection details required to access them.

Objective¶

Create an inventory file that allows Ansible to connect to App Server 2.

Configuration requirements:

Target Host: stapp02
Inventory Location: /home/thor/playbook/inventory
Inventory Format: INI
Execution Requirement: The command ansible-playbook -i inventory playbook.yml must work without prompting for SSH credentials.

Understanding the Role of Inventory in Ansible¶

Ansible uses an inventory file to know:

Which hosts it should manage
How to connect to those hosts
What variables are associated with each host

Without an inventory, Ansible has no information about the infrastructure it should automate.

The inventory can include hostnames, IP addresses, connection variables, authentication credentials, and grouping definitions.

Step 1: Create the Directory and Inventory File¶

Create the working directory and the inventory file.

mkdir -p /home/thor/playbook
cd /home/thor/playbook
vi inventory

Step 2: Define the Inventory Entry¶

Insert the following line in the file:

stapp02 ansible_host=stapp02 ansible_user=steve ansible_ssh_pass=Am3ric@ ansible_ssh_common_args='-o StrictHostKeyChecking=no'

Explanation of Inventory Fields¶

stapp02

This is the alias used by Ansible to refer to the host in playbooks.

ansible_host=stapp02

Defines the actual hostname or IP address used for the SSH connection.

ansible_user=steve

Specifies the remote user account used to log into the system.

ansible_ssh_pass=Am3ric@

Defines the password required for SSH authentication.

ansible_ssh_common_args='-o StrictHostKeyChecking=no'

Disables SSH host key verification so that Ansible does not pause waiting for manual confirmation during the first connection.

Step 3: Validate the Inventory¶

Before running any playbook, verify connectivity using the Ansible ping module.

ansible all -i inventory -m ping

Expected Output¶

Successful connectivity produces output similar to:

stapp02 | SUCCESS => {
    "ansible_facts": {
        "discovered_interpreter_python": "/usr/bin/python3"
    },
    "changed": false,
    "ping": "pong"
}

Receiving pong confirms that:

The inventory is valid
SSH authentication works
Ansible can communicate with the remote host

How Ansible Uses This Inventory¶

When running the command:

ansible-playbook -i inventory playbook.yml

Ansible performs the following steps:

Reads the inventory file
Resolves host connection parameters
Establishes SSH connectivity
Executes the playbook tasks on the remote system

Because credentials are embedded inside the inventory, the playbook runs without requiring interactive input.

INI Inventory Format vs YAML Inventory¶

Ansible supports multiple inventory formats.

INI Inventory

Simpler syntax
Flat structure
Suitable for small environments

Example:

stapp02 ansible_host=stapp02

YAML Inventory

Structured hierarchy
Better for large infrastructures
Supports complex grouping

Example:

all:
  hosts:
    stapp02:
      ansible_host: stapp02
      ansible_user: steve

Security Considerations¶

Storing plaintext passwords in inventory files is acceptable for lab environments but not recommended for production systems.

In real deployments, secure alternatives include:

SSH key authentication
Ansible Vault
External secrets managers

These approaches prevent exposure of sensitive credentials.

Key Outcome¶

The inventory file is successfully created at /home/thor/playbook/inventory. Ansible can now connect to stapp02 automatically and execute playbooks without requiring manual SSH authentication.