# Ansible Dynamic Inventory

> Generate inventory (host and group information) dynamically rather than statically defining it in a static inventory file

- Source: https://www.itwonderlab.com/ansible-dynamic-inventory/
- Published: 2023-09-07
- Updated: 2026-10-05
- Author: Javier Ruiz Jiménez (https://www.javierruizjimenez.com/)
- Site: IT Wonder Lab (https://www.itwonderlab.com/)

---

## Generate Ansible inventory (host and groups) dynamically using AWS API

### Dynamic Inventory

Ansible dynamic inventory is a feature in Ansible that allows you to generate inventory (host and group information) dynamically rather than statically defining it in a static inventory file. This dynamic approach is particularly useful in dynamic and cloud-based environments where the number and state of hosts can change frequently.

**Inventory Sources**: Ansible dynamic inventory sources are scripts or plugins that generate inventory data dynamically. These sources can fetch information from various sources like cloud providers, databases, or external systems.

Available sources:

-   **AWS EC2**: [AWS Ansible Dynamic Inventory Plugin](https://docs.ansible.com/ansible/latest/collections/amazon/aws/docsite/aws_ec2_guide.html).
-   **OpenStack**: the `openstack.cloud.openstack` inventory plugin.
-   **Custom Plugins**: You can write custom dynamic inventory plugins to fetch inventory data from your specific environment or system.

**Dynamic Generation**: when you run Ansible commands or playbooks, Ansible executes the inventory source(s) to gather the current host and group information. This information is generated on the fly based on the current state of your infrastructure.

**Flexible Configuration**: Ansible allows you to configure dynamic inventory sources in your Ansible configuration files (ansible.cfg) or specify them on the command line using the -i option.

### Example: AWS EC2 inventory plugin

The `amazon.aws.aws_ec2` plugin reads the instances of [AWS EC2](https://www.itwonderlab.com/aws-ec2/) from the AWS API and creates groups from their tags and other attributes. Save this file as `inventory/aws_ec2.yml`:

![Ansible dynamic inventory: the aws_ec2 plugin asks the EC2 API for the instances, groups them by tag and gives the groups to ansible-playbook](https://www.itwonderlab.com/media/tutorials/Diagrams/ITWL-Ansible-Dynamic-Inventory.svg "The aws_ec2 plugin builds the groups from EC2 tags")

```yaml
plugin: amazon.aws.aws_ec2
regions:
  - us-east-1
filters:
  instance-state-name: running
keyed_groups:
  # Creates groups such as tag_environment_pro from the tag "environment"
  - key: tags.environment
    prefix: tag_environment
  - key: tags.app
    prefix: tag_app
```

Check the result with `ansible-inventory`:

```shell
$ ansible-galaxy collection install amazon.aws
$ ansible-inventory -i inventory/aws_ec2.yml --graph
```

The groups follow the mandatory tags of [AWS Tagging Best Practices](https://www.itwonderlab.com/aws-resource-tagging/), and are used as shown in [Ansible Multiple Environment Best Practices](https://www.itwonderlab.com/ansible-multiple-environment-best-practices/) and [Ansible Playbook Structure Best Practices](https://www.itwonderlab.com/ansible-playbook-structure-best-practices/). The tutorial [Terraform, AWS, and Ansible together](https://www.itwonderlab.com/terraform-aws-ansible/) uses the older `ec2.py` script, which has the same purpose.

### Benefits of using dynamic inventory in Ansible

-   **Scalability**: Easily adapt to changing infrastructure sizes and configurations.
-   **Automation**: Automate the process of updating your inventory as your infrastructure changes.
-   **Consistency**: Ensure your inventory is always up to date without manual intervention.
-   **Integration**: Seamlessly integrate with cloud providers and other external systems.

Dynamic inventory in Ansible is a powerful feature for **managing infrastructure in dynamic and cloud-native environments**, making it easier to automate configuration management and orchestration tasks.