Ansible plugins are modular pieces of code that extend and enhance Ansible’s core functionality. They allow users to customize and optimize workflows for specific requirements. This article explains what Ansible plugins are, their types, and how to use them effectively.
What Are Ansible Plugins?
Ansible plugins are Python-based extensions that modify or add capabilities to Ansible’s automation engine. They provide additional functionality without altering the core Ansible codebase, making them highly flexible and reusable.
Key Features:
- Extensibility: Add new behaviors to Ansible.
- Reusability: Share plugins across projects or teams.
- Customization: Tailor functionality to specific needs.
Types of Ansible Plugins
Ansible supports several plugin types, each serving a distinct purpose:
1. Action Plugins
Modify or enhance the behavior of modules when executed.
- Example: Add custom logic to module execution.
2. Lookup Plugins
Fetch data from external sources and pass it into playbooks.
- Example: Retrieve secrets from a vault:
``yaml
vars:
secret: "{{ lookup('aws_secretsmanager', 'my_secret') }}"
`
3. Filter Plugins
Transform data or variables in templates or playbooks.
- Example: Convert text to uppercase:
`yaml
vars:
uppercase_text: "{{ 'hello' | upper }}"
`
4. Connection Plugins
Define how Ansible connects to target nodes (e.g., SSH, WinRM).
- Example: Use a custom connection method for specialized devices.
5. Strategy Plugins
Control the execution flow of tasks in a play.
- Built-in strategies include linear, free, and debug.
6. Callback Plugins
Customize output or perform actions during playbook execution.
- Example: Send notifications to Slack after task completion.
7. Inventory Plugins
Dynamically generate inventory from external sources (e.g., AWS, GCP).
- Example:
`ini
plugin: aws_ec2
regions:
- us-east-1
`
8. Vars Plugins
Inject additional variables into playbooks dynamically.
- Example: Load variables based on host properties.
Where Are Plugins Stored?
Built-In Plugins
Ansible’s default plugins are stored in the system directory:
`
/usr/share/ansible/plugins/
`
Custom Plugins
Custom plugins can be stored in:
1. Project-Specific Directory:
`
./plugins/<plugin_type>/
`
2. Global Directory:
`
~/.ansible/plugins/<plugin_type>/
`
3. Specified Paths:
Define custom plugin paths in the ansible.cfg file:
`ini
[defaults]
plugin_paths = /path/to/custom/plugins
`
Creating Custom Plugins
Here’s an example of a custom filter plugin to reverse strings:
1. Create a directory for custom plugins:
`
./plugins/filter/
`
2. Write the plugin in Python:
``python
# plugins/filter/reverse.py
def reverse_string(va