Ansible is a tool that helps automate IT tasks like configuring servers, deploying software, or managing environments. Instead of manually logging into each server to make changes you can write simple "playbooks" and Ansible will automatically apply those changes to your servers.

What is an Inventory in Ansible?

In Ansible, an inventory is a list of servers (also called hosts) that you want to manage. Normally, you'd define these servers in a text file (called a static inventory) where you manually write down their details, like IP addresses or hostnames

For example a static inventory file might look like this:

[webservers]
server1.example.com
server2.example.com

What is Dynamic Inventory?

In dynamic environments like cloud platforms (AWS, Google Cloud, Azure), servers are frequently created and terminated. Manually updating your Ansible inventory file each time a server is added or removed can be tedious and error-prone.

That’s where dynamic inventory comes in.

With dynamic inventory, Ansible automatically retrieves the list of active servers from cloud providers or other external sources in real time—eliminating the need for manual updates.

How Does Dynamic Inventory Work?

External Source Integration: Ansible connects to cloud providers, databases, or APIs to fetch a live list of hosts.
Scripts or Plugins: Ansible uses dynamic inventory scripts or plugins to query these sources.
Automated Refresh: Host lists are automatically retrieved and kept up to date—no need to edit inventory files manually.

Example Scenario

Suppose you’re running your infrastructure on AWS. Instead of manually listing EC2 instance IPs in your inventory file, Ansible can automatically pull that information. When you execute a playbook, Ansible queries AWS in real time and fetches the current list of instances. If new servers are launched or old ones are terminated, Ansible adapts automatically—no manual intervention required.

Why Use Dynamic Inventory?

No Manual Updates: Ideal for cloud or virtual environments where server counts change frequently.
Real-Time Accuracy: Ensures Ansible works with the most current server data.
Seamless Cloud Integration: Perfect for scalable, cloud-native infrastructures.

Simple Example of Using Dynamic Inventory

If you’re using AWS, Ansible provides a built-in dynamic inventory plugin for EC2. You just need to configure your AWS credentials, and Ansible will automatically fetch and manage your server list.

ansible-inventory -i aws_ec2.yml --list

This will give you a list of your EC2 instances directly from AWS. No need to manage a static file yourself.

Static vs Dynamic Inventory in Ansible:

Final Word:

Dynamic inventory streamlines the discovery and management of servers, particularly in cloud-based or dynamic environments. Instead of maintaining server lists manually, Ansible automatically generates and updates them for you.

What is Ansible?