## Dynamic Inventory

Use dynamic inventory to fetch host information at runtime:

### Example Usage

```yaml
- name: Fetch hosts from external source
  ansible.builtin.get_url:
    url: "https://api.example.com/hosts"
    dest: "hosts.json"
  register: inventory_data

- name: Display inventory hosts
  debug:
    var: inventory_data.content

# Example dynamic inventory script (hosts.py):
# import json
# print(json.dumps({"hosts": ["web1", "web2"], "groups": {"webservers": ["web1", "web2"]}}))
``` 

### Common Inventory Sources

1. **EC2 Inventory**:
   - Uses AWS API to list instances
   - Parameters: `aws_access_key_id`, `aws_secret_access_key`, `region`
   - Example:
     ```bash
     ansible-inventory --list --inventory=ec2.py
     ```

2. **OpenStack Inventory**:
   - Connects to OpenStack neutron API
   - Parameters: `auth_url`, `project_name`, `username`, `password`
   - Example:
     ```bash
     ansible-inventory --list --inventory=openstack.py
     ```

3. **Custom Scripts**:
   - Write Python scripts to generate inventory
   - Must output JSON in this format:
     ```json
     {
       "hosts": ["host1", "host2"],
       "groups": {
         "webservers": ["host1", "host2"]
       }
     }
     ```

### Best Practices

- Use `ansible-inventory --list` to verify inventory structure
- Test dynamic inventory with `--check` flag
- Store credentials securely using Ansible Vault
- Combine with `--limit` to target specific hosts/groups

### Troubleshooting

Use `--debug` flag to see inventory resolution process:
```bash
ansible-playbook site.yml --limit="webservers" --debug
```