An Ansible module is a standalone script or executable that performs a specific automation task within an Ansible playbook. Modules are the building blocks of Ansible's automation, responsible for everything from configuring network devices and updating packages to collecting system facts and managing users.

• Lightweight Execution: Modules are designed to execute quickly and efficiently. Each module is invoked as needed by Ansible and then removed from memory, ensuring minimal impact on target systems.
• Idempotence: Modules are typically idempotent, meaning they are designed to achieve the same result even if run multiple times. This guarantees that repeated automation does not cause unintended changes.
• Language Flexibility: While most official modules are written in Python, modules can be developed in any language that can read input from standard input (stdin) and emit JSON output.
• Arguments & Return Values: Each module accepts arguments (parameters) defined by the user and returns the outcome in a structured JSON format. This allows for clear communication between the playbook and the task being performed.
• Usage in Playbooks: Modules are called within playbooks through tasks, such as ansible.builtin.copy or ansible.builtin.user, specifying arguments relevant to the automation job at hand.
• Examples of Core Modules: Some popular core modules include:
  • copy: Uploads files to remote machines.
  • file: Manages file attributes or directories.
  • user: Manages user accounts and groups.
  • service: Controls system services.
  • yum/apt: Manages package installation for Linux distributions.

In summary, Ansible modules provide the essential task automation capabilities within Ansible, allowing IT engineers to automate operations reliably and at scale.

Creating your own Ansible module can extend automation capabilities and tailor tasks to unique network or infrastructure requirements. Follow this step-by-step approach to build a custom module using Python, Ansible’s most common language for module development.

1. Set Up Your Development Environment:
   • Install ansible-core and Python (3.x recommended).
   • Use a virtual environment for module development: python -m venv venv and activate it.
2. Create the Module Directory:
   • In your project, make a library/ directory. This is where your custom module scripts will live.
   • Place your test playbook in the same folder for easy testing.
3. Write the Module Boilerplate Code:
   • Create a new Python file (e.g., my_module.py) inside the library/ directory.
   • Start with this template:

   #!/usr/bin/python
   
   from ansible.module_utils.basic import AnsibleModule
   
   def run_module():
       module_args = dict(
           name=dict(type='str', required=True),
           new=dict(type='bool', required=False, default=False)
       )
   
       result = dict(changed=False, original_message='', message='')
   
       module = AnsibleModule(argument_spec=module_args, supports_check_mode=True)
   
       if module.check_mode:
           module.exit_json(**result)
   
       result['original_message'] = module.params['name']
       result['message'] = 'Processed in module'
   
       if module.params['new']:
           result['changed'] = True
   
       module.exit_json(**result)
   
   def main():
       run_module()
   
   if __name__ == '__main__':
       main()
   

4. Understand the Key Components:
   • Arguments: Defined as module_args. Each parameter your module will accept should be listed here.
   • AnsibleModule: This helper class handles argument parsing, check mode support, and result formatting.
   • Result Dictionary: Populate this with the data you want to return (e.g., changed, message).
   • Exit Methods: Use module.exit_json() on success or module.fail_json() for errors.
5. Add Module Documentation (Recommended):
   • At the top of your script, include YAML-formatted DOCUMENTATION, EXAMPLES, and RETURN docstrings for clarity and ansible-doc support.
6. Test Your Custom Module:
   • Create a minimal playbook to run your module. Example:

     ---
     - hosts: localhost
       tasks:
         - name: Test my custom module
           my_module:
             name: HelloWorld
             new: true
           register: module_result
         - debug: var=module_result
     

   • Run the playbook to see your module in action: ansible-playbook test_playbook.yml

By following these steps, you can create, document, and test your own Ansible modules to automate network, server, or cloud tasks unique to your environment.

Building a standalone Python module for Ansible enables you to create custom automation tasks tailored to your environment. This step-by-step guide walks you through creating your own module from scratch.

1. Organize Your Workspace:
   • Create a library/ directory in your project folder. All custom modules will reside here.
   • Place your test playbook in the same directory for easy access.
2. Initialize the Module File:
   • Create a new Python file—e.g., my_standalone_module.py—within the library/ directory.
   • This filename will be the module's name when called from your playbooks.
3. Write the Module Code:
   • Begin your script with the Ansible Python module boilerplate. Here’s an example template:

   #!/usr/bin/python
   
   from ansible.module_utils.basic import AnsibleModule
   
   def run_module():
       module_args = dict(
           param1=dict(type='str', required=True),
           param2=dict(type='int', required=False, default=0)
       )
   
       result = dict(
           changed=False,
           msg='',
           param1='',
           param2=0
       )
   
       module = AnsibleModule(
           argument_spec=module_args,
           supports_check_mode=True
       )
   
       if module.check_mode:
           module.exit_json(**result)
   
       result['param1'] = module.params['param1']
       result['param2'] = module.params['param2']
       result['msg'] = 'Module ran successfully'
   
       # Example: set changed if param2 > 0
       if module.params['param2'] > 0:
           result['changed'] = True
   
       module.exit_json(**result)
   
   def main():
       run_module()
   
   if __name__ == '__main__':
       main()
   

   • This template defines:
     • Module arguments (module_args), including types and required status.
     • A result dictionary for output data and status.
     • Check mode support for safe dry-runs.
     • Logic for successful completion or marking a change.
4. Test the Module:
   • Create a simple playbook to validate your new module. Example:

     ---
     - hosts: localhost
       tasks:
         - name: Run standalone Python module
           my_standalone_module:
             param1: "Hello Module"
             param2: 1
           register: custom_result
     
         - debug: var=custom_result
     

   • Run the playbook in your environment and ensure your module performs as expected.
5. Iterate and Extend:
   • Add more logic, parameters, or error handling as your infrastructure demands evolve.
   • Document module arguments and return values for clarity and maintainability.

With these steps, you can create effective, reusable custom Python modules for Ansible, enhancing your automation toolkit with powerful, purpose-built tasks.

Ansible’s “info” and “facts” modules enable you to dynamically collect system information, making playbooks more flexible and context-aware. Here’s a step-by-step walkthrough on understanding and using these modules.

1. Understanding Info and Facts Modules:
   • Facts Modules: Automatically gather data from managed hosts such as OS details, network interfaces, disk space, and hardware info. The built-in setup module is the most common facts module.
   • Info Modules: Provide details about external environments or resources (like cloud, network, or device info). Their names often end with _info or _facts but do not alter system state.
2. Gathering Built-in Facts:
   • By default, Ansible collects facts at the start of a playbook, which you can disable by setting gather_facts: no.
   • To manually gather and inspect facts:

     ansible all -m setup

   • Use fact filters to narrow down output for readability:

     ansible all -m setup -a "filter=ansible_hostname"

3. Accessing Facts in Playbooks:
   • Facts are available as variables. Example:

   - name: Show the host’s OS
     debug:
       msg: "This host runs {{ ansible_distribution }} {{ ansible_distribution_version }}"
   

4. Custom Facts with set_fact:
   • You can define your own custom facts during playbook execution:

     - name: Set a custom fact
       set_fact:
         custom_role: "database"
     

   • Reference them later in your playbook using {{ custom_role }}.
5. Host-based Custom Facts:
   • Place static or dynamic files in /etc/ansible/facts.d/ on target hosts using JSON or INI format for persistent custom facts.
   • Re-run the setup module to collect these custom facts.
6. Info Modules in Action:
   • Info modules (for example, aws_ec2_info, service_facts) gather resource data and make it accessible as variables.
   • Example:

     - name: Gather service info
       service_facts:
       - name: Print all running services
         debug:
           var: ansible_facts.services
     

7. Best Practices:
   • Use facts to write conditional and dynamic tasks.
   • Limit gathered facts to only what’s needed for efficiency.
   • Document custom facts clearly for maintainability.

By leveraging info and facts modules, your playbooks become more intelligent and adaptive, ensuring accurate automation based on real-time system data.

Module utilities in Ansible are reusable Python code components that extend the functionality of your custom modules and help you avoid code duplication. They’re particularly useful for managing shared logic across multiple modules. Follow this step-by-step guide to integrate and use module utilities effectively.

1. Create a module_utils/ Directory:
   • In your Ansible project or collection, create a directory called module_utils. This is where helper functions, common classes, and shared logic will be stored.
   • Example structure:

     my_project/
     ├── library/
     │   └── my_module.py
     ├── module_utils/
     │   └── helper.py
     

2. Write a Python Utility Module:
   • Create the file module_utils/helper.py and add your reusable functions.

   # helper.py
   
   def format_hostname(name):
       return name.lower().replace(" ", "_")
   
   def is_valid_ip(address):
       import ipaddress
       try:
           ipaddress.ip_address(address)
           return True
       except ValueError:
           return False
   

3. Import the Utility in Your Custom Module:
   • In your custom module script (e.g., library/my_module.py), import the utility:

   from ansible.module_utils.helper import format_hostname, is_valid_ip
   

   • Use the imported functions in your logic as needed.
4. Example Usage in Custom Module:

   #!/usr/bin/python
   
   from ansible.module_utils.basic import AnsibleModule
   from ansible.module_utils.helper import format_hostname, is_valid_ip
   
   def run_module():
       module_args = dict(
           hostname=dict(type='str', required=True),
           ip_address=dict(type='str', required=True)
       )
   
       module = AnsibleModule(argument_spec=module_args, supports_check_mode=True)
       hostname = module.params['hostname']
       ip = module.params['ip_address']
   
       if not is_valid_ip(ip):
           module.fail_json(msg="Invalid IP address format")
   
       transformed_name = format_hostname(hostname)
   
       result = dict(
           changed=False,
           original=hostname,
           transformed=transformed_name,
           ip=ip
       )
   
       module.exit_json(**result)
   
   def main():
       run_module()
   
   if __name__ == '__main__':
       main()
   

5. Run and Test:
   • Call the custom module from a playbook like this:

     ---
     - hosts: localhost
       tasks:
         - name: Test module utility usage
           my_module:
             hostname: "My New Host"
             ip_address: "192.168.1.1"
           register: result
     
         - debug: var=result
     

   • Ensure output reflects the use of utility functions properly.

By using module utilities, you promote clean, modular code and make it easier to maintain and scale your custom Ansible modules across large environments.

Expanding Ansible with local modules lets you incorporate custom automation quickly for your team or project. Here’s a step-by-step guide for adding local modules to your Ansible workflow.

1. Decide the Scope of Availability:
   • For all playbooks and roles: Make the module available system-wide or user-wide.
   • For selected playbooks: Limit the module's use within a particular directory or repository.
   • For a single role: Embed the module only inside a specific role's directory.
2. Choose the Appropriate Directory:
   • System-Wide:
     • /usr/share/ansible/plugins/modules/ (requires admin privileges)
   • User-Wide:
     • ~/.ansible/plugins/modules/
   • Project-Specific:
     • Create a library/ folder in your project directory (next to your playbooks).
   • Role-Specific:
     • Create a library/ subdirectory within the particular role’s folder.
   • Custom Path:
     • Add paths by setting the ANSIBLE_LIBRARY environment variable or the library option in ansible.cfg.
3. Add Your Module File:
   • Copy or write your custom module Python file, for example my_custom_module.py, into your chosen directory.
   • The module name in tasks/playbooks matches the Python filename (without the .py extension).
4. Update Configuration (If Needed):
   • To use a non-default path, update your ansible.cfg:

     [defaults]
     library = ./library
     

   • Or set the environment variable:

     export ANSIBLE_LIBRARY=./library
     

5. Verify Module Availability:
   • Run ansible-doc -t module my_custom_module to confirm Ansible recognizes your module and shows its documentation.
   • Alternatively, test with ansible localhost -m my_custom_module to execute the module.
6. Use Your Module in Playbooks and Roles:
   • Reference the module by filename (without .py), just like built-in modules:

     ---
     - hosts: localhost
       tasks:
         - name: Custom task with local module
           my_custom_module:
             option: value
     

7. Best Practices:
   • Document each custom module clearly for future users.
   • Organize modules by keeping them in dedicated library/ directories.
   • Share frequently used modules via version control for consistency across teams.

By following these steps, you can efficiently integrate and manage local modules within any Ansible project, ensuring modular, reusable, and easily testable automation workflows.

Following best practices when developing Ansible modules ensures reliability, maintainability, and seamless integration with other playbooks. Use this step-by-step approach as a checklist for developing robust custom modules.

1. Define Clear Functionality:
   • Follow the “do one thing well” philosophy by keeping your module’s scope focused and concise.
   • Avoid feature creep—don’t add unrelated tasks or logic into a single module.
2. Design Predictable Interfaces:
   • Use descriptive and consistent option names (for example, use name for addressing objects).
   • Offer aliases for parameters if an external API uses different names, but maintain internal clarity.
   • Support common Ansible option types, such as state for present/absent/started/stopped logic.
3. Support Idempotency and Check Mode:
   • Write your module to be idempotent—running it multiple times should not cause changes unless required.
   • Implement check_mode so users can perform dry runs without making changes.
4. Validate and Sanitize Input:
   • Use strict argument definitions to catch bad input early with clear error messages.
   • Convert and validate booleans, paths, or data structures robustly for predictable results.
5. Fail Fast and Clearly:
   • Detect invalid conditions quickly—exit with helpful messages using module.fail_json().
   • Return errors as soon as an issue is found to prevent unintended system changes.
6. Keep Dependencies Minimal:
   • Limit your reliance on external libraries. If dependencies are required, document them clearly at the top of your module.
   • Gracefully handle missing dependencies and provide actionable installation guidance when possible.
7. Provide Structured, Relevant Output:
   • Return only the information users need. Avoid dumping verbose logs—use structured JSON responses for easy consumption.
   • Accurately indicate whether the module made changes with the changed flag.
   • For info/facts modules, return values inside ansible_facts for consistency.
8. Document Thoroughly:
   • Include DOCUMENTATION, EXAMPLES, and RETURN docstrings at the top of each module for clarity and ansible-doc support.
   • Document all options, required parameters, default values, and typical usage.
9. Test Rigorously:
   • Test all logic paths, including error handling, check mode, and complex scenarios.
   • Leverage ansible-test or custom playbooks to validate module behavior before release.
10. Follow Naming Conventions:
    • Use underscores in module filenames and avoid spaces or hyphens to ensure compatibility and auto-discovery.
    • Maintain consistent naming for parameters and return values across modules.
11. Minimize Side Effects:
    • Avoid performing actions outside the module’s explicit purpose.
    • Use temporary files and atomic operations for any file manipulations, preventing corruption or partial changes.

Applying these best practices will make your custom Ansible modules reliable, easy to use, and maintainable in complex automation environments.