ansible/docs/docsite/rst/dev_guide/developing_module_utilities.rst

Using and developing module utilities

Ansible provides a number of module utilities, or snippets of shared code, that provide helper functions you can use when developing your own modules. The basic.py module utility provides the main entry point for accessing the Ansible library, and all Python Ansible modules must import something from ansible.module_utils. A common option is to import AnsibleModule:

from ansible.module_utils.basic import AnsibleModule

The ansible.module_utils namespace is not a plain Python package: it is constructed dynamically for each task invocation, by extracting imports and resolving those matching the namespace against a search path <ansible_search_path> derived from the active configuration.

To reduce the maintenance burden in a collection or in local modules, you can extract duplicated code into one or more module utilities and import them into your modules. For example, if you have your own custom modules that import a my_shared_code library, you can place that into a ./module_utils/my_shared_code.py file like this:

from ansible.module_utils.my_shared_code import MySharedCodeClient

When you run ansible-playbook, Ansible will merge any files in your local module_utils directories into the ansible.module_utils namespace in the order defined by the Ansible search path <ansible_search_path>.

Naming and finding module utilities

You can generally tell what a module utility does from its name and/or its location. Generic utilities (shared code used by many different kinds of modules) live in the main ansible/ansible codebase, in the common subdirectory or in the root directory of lib/ansible/module_utils. Utilities used by a particular set of modules generally live in the same collection as those modules. For example:

• lib/ansible/module_utils/urls.py contains shared code for parsing URLs
• openstack.cloud.plugins.module_utils.openstack.py contains utilities for modules that work with OpenStack instances
• ansible.netcommon.plugins.module_utils.network.common.config.py contains utility functions for use by networking modules

Following this pattern with your own module utilities makes everything easy to find and use.

Standard module utilities

Ansible ships with an extensive library of module_utils files. You can find the module utility source code in the lib/ansible/module_utils directory under your main Ansible path. We describe the most widely used utilities below. For more details on any specific module utility, please see the source code for module_utils.

• api.py - Supports generic API modules
• basic.py - General definitions and helper utilities for Ansible modules
• common/dict_transformations.py - Helper functions for dictionary transformations
• common/file.py - Helper functions for working with files
• common/text/ - Helper functions for converting and formatting text
• common/parameters.py - Helper functions for dealing with module parameters
• common/sys_info.py - Functions for getting distribution and platform information
• common/validation.py - Helper functions for validating module parameters against a module argument spec
• facts/ - Directory of utilities for modules that return facts. See PR 23012 for more information
• json_utils.py - Utilities for filtering unrelated output around module JSON output, like leading and trailing lines
• powershell/ - Directory of definitions and helper functions for Windows PowerShell modules
• pycompat24.py - Exception workaround for Python 2.4
• service.py - Utilities to enable modules to work with Linux services (placeholder, not in use)
• six/__init__.py - Bundled copy of the Six Python library to aid in writing code compatible with both Python 2 and Python 3
• splitter.py - String splitting and manipulation utilities for working with Jinja2 templates
• urls.py - Utilities for working with http and https requests

Several commonly-used utilities migrated to collections in Ansible 2.10, including:

• ismount.py migrated to ansible.posix.plugins.module_utils.mount.py - Single helper function that fixes os.path.ismount
• known_hosts.py migrated to community.general.plugins.module_utils.known_hosts.py - utilities for working with known_hosts file

For a list of migrated content with destination collections, see https://github.com/ansible/ansible/blob/devel/lib/ansible/config/ansible_builtin_runtime.yml.