ansible-training

Lab 02 - Creating a Static YAML Inventory with Group Variables in Ansible

Contents

• Objective
• Prerequisites
• Guide
  • Step 1: Create the Inventory File
  • Step 2: Test Inventory File
  • Step 3: Run a Simple Ansible Command
  • Step 4: Create Group Variables
  • Step 5: Test Group Variables
• Conclusion

Objective

Create an Ansible static inventory file in YAML format that categorizes two servers into webserver and db groups and define some example group variables for these groups.

Prerequisites

• Create a folder named lab02 inside ansible-labs
• Navigate to lab02 folder
• Finish Lab 01 to ensure you have access to managed nodes
• Copy the ansible.cfg file from lab01 folder to lab02 folder

Guide

Step 1: Create the Inventory File

Create a folder named inventory inside lab02 folder.

Inside the inventory folder, create a file named inventory.yml.

Add the following content to the file:

webserver:
  hosts:
    servidor-0:
      ansible_host: 10.0.3.100
db:
  hosts:
    servidor-1:
      ansible_host: 10.0.3.101

Step 2: Test Inventory File

Test your inventory file using the ansible-inventory command:

ansible-inventory -i inventory/inventory.yml --list

This will display your inventory in a JSON format, showing the groups, hosts, and variables.

Step 3: Run a Simple Ansible Command

To test, run a simple Ansible command like ping:

ansible -i inventory/inventory.yml all -m ping

This will ping both servers in your inventory. You should see output similar to the following:

servidor-0 | SUCCESS => {
    "changed": false,
    "ping": "pong"
}
servidor-1 | SUCCESS => {
    "changed": false,
    "ping": "pong"
}

Now let’s try to run a command on a specific group. Run the following command:

ansible -i inventory/inventory.yml webserver -m command -a "hostname"

You should see output similar to the following:

servidor-0 | CHANGED | rc=0 >>
servidor-0

Now let’s try to run a command on the other group. Run the following command:

ansible -i inventory/inventory.yml db -m command -a "hostname"

You should see output similar to the following:

servidor-1 | CHANGED | rc=0 >>
servidor-1

Finally let’s try to run on a specific host. Run the following command:

ansible -i inventory/inventory.yml servidor-0 -m command -a "hostname"

Step 4: Create Group Variables

Create one directory named group_vars inside inventory folder.

Inside the group_vars folder, create two files named webserver.yml and db.yml.

Add the following content to the webserver.yml file:

http_port: 80
max_clients: 200

Add the following content to the db.yml file:

db_port: 3306
db_name: mydatabase

Step 5: Test Group Variables

Test your inventory file using the ansible-inventory command:

ansible-inventory -i inventory/inventory.yml --list

Now run an ansible command to check the variables on webserver group:

ansible -i inventory/inventory.yml webserver -m ansible.builtin.debug -a "var=http_port"

You should see output similar to the following:

servidor-0 | SUCCESS => {
    "http_port": 80
}

Now run an ansible command to check the variables on db group:

ansible -i inventory/inventory.yml db -m ansible.builtin.debug -a "var=db_port"

Conclusion

By completing this lab, you will have created a static YAML inventory file for Ansible, categorized two servers into different groups, and defined custom variables for each group. This setup is fundamental for organizing your managed nodes and configuring them based on their roles in your infrastructure.