Unlike Python module development which can be run on the host that runs
Ansible, Windows modules need to be written and tested for Windows hosts.
While evaluation editions of Windows can be downloaded from
Microsoft, these images are usually not ready to be used by Ansible without
further modification. The easiest way to set up a Windows host so that it is
ready to by used by Ansible is to set up a virtual machine using Vagrant.
Vagrant can be used to download existing OS images called *boxes* that are then
deployed to a hypervisor like VirtualBox. These boxes can either be created and
stored offline or they can be downloaded from a central repository called
Vagrant Cloud.
This guide will use the Vagrant boxes created by the `packer-windoze <https://github.com/jborean93/packer-windoze>`_
repository which have also been uploaded to `Vagrant Cloud <https://app.vagrantup.com/boxes/search?utf8=%E2%9C%93&sort=downloads&provider=&q=jborean93>`_.
To find out more info on how these images are created, please go to the Github
repo and look at the ``README`` file.
Before you can get started, the following programs must be installed (please consult the Vagrant and
VirtualBox documentation for installation instructions):
When creating a new module there are a few things to keep in mind:
- Module code is in Powershell (.ps1) files while the documentation is contained in Python (.py) files of the same name
- Avoid using ``Write-Host/Debug/Verbose/Error`` in the module and add what needs to be returned to the ``$result`` variable
- When trying an exception use ``Fail-Json -obj $result -message "exception message here"`` instead
- Most new modules require check mode and integration tests before they are merged into the main Ansible codebase
- Avoid using try/catch statements over a large code block, rather use them for individual calls so the error message can be more descriptive
- Try and catch specific exceptions when using try/catch statements
- Avoid using PSCustomObjects unless necessary
- Look for common functions in ``./lib/ansible/module_utils/powershell/`` and use the code there instead of duplicating work. These can be imported by adding the line ``#Requires -Module *`` where * is the filename to import, and will be automatically included with the module code sent to the Windows target when run via Ansible
- Ensure the code runs under Powershell v3 and higher on Windows Server 2008 and higher; if higher minimum Powershell or OS versions are required, ensure the documentation reflects this clearly
- Ansible runs modules under strictmode version 2.0. Be sure to test with that enabled by putting ``Set-StrictMode -Version 2.0`` at the top of your dev script
- Favour native Powershell cmdlets over executable calls if possible
- If adding an object to ``$result``, ensure any trailing slashes are removed or escaped, as ``ConvertTo-Json`` will fail to convert it
- Use the full cmdlet name instead of aliases, e.g. ``Remove-Item`` over ``rm``
- Use named parameters with cmdlets, e.g. ``Remove-Item -Path C:\temp`` over ``Remove-Item C:\temp``
A very basic powershell module `win_environment <https://github.com/ansible/ansible/blob/devel/lib/ansible/modules/windows/win_environment.ps1>`_ is included below. It demonstrates how to implement check-mode and diff-support, and also shows a warning to the user when a specific condition is met.
A slightly more advanced module is `win_uri <https://github.com/ansible/ansible/blob/devel/lib/ansible/modules/windows/win_uri.ps1>`_ which additionally shows how to use different parameter types (bool, str, int, list, dict, path) and a selection of choices for parameters, how to fail a module and how to handle exceptions.
These are the checks that can be used within Ansible modules:
-``#Requires -Module Ansible.ModuleUtils.<module_util>``: Added in Ansible 2.4, specifies a module_util to load in for the module execution.
-``#Requires -Version x.y``: Added in Ansible 2.5, specifies the version of PowerShell that is required by the module. The module will fail if this requirement is not met.
-``#AnsibleRequires -OSVersion x.y``: Added in Ansible 2.5, specifies the OS build version that is required by the module and will fail if this requirement is not met. The actual OS version is derived from ``[Environment]::OSVersion.Version``.
-``#AnsibleRequires -Become``: Added in Ansible 2.5, forces the exec runner to run the module with ``become``, which is primarily used to bypass WinRM restrictions. If ``ansible_become_user`` is not specified then the ``SYSTEM`` account is used instead.
Windows module utilities
========================
Like Python modules, PowerShell modules also provide a number of module
utilities that provide helper functions within PowerShell. These module_utils
can be imported by adding the following line to a PowerShell module:
..code-block:: powershell
#Requires -Module Ansible.ModuleUtils.Legacy
This will import the module_util at ``./lib/ansible/module_utils/powershell/Ansible.ModuleUtils.Legacy.psm1``
- To stop the script from exiting the editor on a successful run, in ``Ansible.ModuleUtils.Legacy.psm1`` under the function ``Exit-Json``, replace the last two lines of the function with::
- To stop the script from exiting the editor on a failed run, in ``Ansible.ModuleUtils.Legacy.psm1`` under the function ``Fail-Json``, replace the last two lines of the function with::
- Prefix the Ansible command with :envvar:`ANSIBLE_KEEP_REMOTE_FILES=1<ANSIBLE_KEEP_REMOTE_FILES>` to specify that Ansible should keep the exec files on the server.
- Log onto the Windows server using the same user account that Ansible used to execute the module.
- Navigate to ``%TEMP%\..``. It should contain a folder starting with ``ansible-tmp-``.
- Inside this folder, open the PowerShell script for the module.
- In this script is a raw JSON script under ``$json_raw`` which contains the module arguments under ``module_args``. These args can be assigned manually to the ``$complex_args`` variable that is defined on your debug script.
