mirror of
https://github.com/ansible-collections/community.general.git
synced 2024-09-14 20:13:21 +02:00
ModuleHelper guide (#8771)
* initial commit * fix initial version * add quickstart and high-level outline * MH guide progress * MH guide progress (up to params,vars,output) * adjustments * MH guide progress (up to handling changes) * MH guide progress (up to Exceptions) * typo * change section from note to important * MH guide progress (added StateModuleHelper) * minor improvement * MH guide progress (added decorators) * typo * minor adjustments * remove line * complete MH guide * adjustments * adjustments * change paragraph into seealso * rearrange sections, plus wordsmithing * adjustments * wordsmithing * fix references
This commit is contained in:
parent
e5bc38d856
commit
e3a3c6d58f
3 changed files with 543 additions and 0 deletions
2
.github/BOTMETA.yml
vendored
2
.github/BOTMETA.yml
vendored
|
@ -1485,6 +1485,8 @@ files:
|
||||||
maintainers: russoz
|
maintainers: russoz
|
||||||
docs/docsite/rst/guide_deps.rst:
|
docs/docsite/rst/guide_deps.rst:
|
||||||
maintainers: russoz
|
maintainers: russoz
|
||||||
|
docs/docsite/rst/guide_modulehelper.rst:
|
||||||
|
maintainers: russoz
|
||||||
docs/docsite/rst/guide_online.rst:
|
docs/docsite/rst/guide_online.rst:
|
||||||
maintainers: remyleone
|
maintainers: remyleone
|
||||||
docs/docsite/rst/guide_packet.rst:
|
docs/docsite/rst/guide_packet.rst:
|
||||||
|
|
|
@ -19,3 +19,4 @@ sections:
|
||||||
- guide_deps
|
- guide_deps
|
||||||
- guide_vardict
|
- guide_vardict
|
||||||
- guide_cmdrunner
|
- guide_cmdrunner
|
||||||
|
- guide_modulehelper
|
||||||
|
|
540
docs/docsite/rst/guide_modulehelper.rst
Normal file
540
docs/docsite/rst/guide_modulehelper.rst
Normal file
|
@ -0,0 +1,540 @@
|
||||||
|
..
|
||||||
|
Copyright (c) Ansible Project
|
||||||
|
GNU General Public License v3.0+ (see LICENSES/GPL-3.0-or-later.txt or https://www.gnu.org/licenses/gpl-3.0.txt)
|
||||||
|
SPDX-License-Identifier: GPL-3.0-or-later
|
||||||
|
|
||||||
|
.. _ansible_collections.community.general.docsite.guide_modulehelper:
|
||||||
|
|
||||||
|
Module Helper guide
|
||||||
|
===================
|
||||||
|
|
||||||
|
|
||||||
|
Introduction
|
||||||
|
^^^^^^^^^^^^
|
||||||
|
|
||||||
|
Writing a module for Ansible is largely described in existing documentation.
|
||||||
|
However, a good part of that is boilerplate code that needs to be repeated every single time.
|
||||||
|
That is where ``ModuleHelper`` comes to assistance: a lot of that boilerplate code is done.
|
||||||
|
|
||||||
|
.. _ansible_collections.community.general.docsite.guide_modulehelper.quickstart:
|
||||||
|
|
||||||
|
Quickstart
|
||||||
|
""""""""""
|
||||||
|
|
||||||
|
See the `example from Ansible documentation <https://docs.ansible.com/ansible/latest/dev_guide/developing_modules_general.html#creating-a-module>`_
|
||||||
|
written with ``ModuleHelper``.
|
||||||
|
But bear in mind that it does not showcase all of MH's features:
|
||||||
|
|
||||||
|
.. code-block:: python
|
||||||
|
|
||||||
|
from ansible_collections.community.general.plugins.module_utils.module_helper import ModuleHelper
|
||||||
|
|
||||||
|
|
||||||
|
class MyTest(ModuleHelper):
|
||||||
|
module = dict(
|
||||||
|
argument_spec=dict(
|
||||||
|
name=dict(type='str', required=True),
|
||||||
|
new=dict(type='bool', required=False, default=False),
|
||||||
|
),
|
||||||
|
supports_check_mode=True,
|
||||||
|
)
|
||||||
|
use_old_vardict = False
|
||||||
|
|
||||||
|
def __run__(self):
|
||||||
|
self.vars.original_message = ''
|
||||||
|
self.vars.message = ''
|
||||||
|
if self.check_mode:
|
||||||
|
return
|
||||||
|
self.vars.original_message = self.vars.name
|
||||||
|
self.vars.message = 'goodbye'
|
||||||
|
self.changed = self.vars['new']
|
||||||
|
if self.vars.name == "fail me":
|
||||||
|
self.do_raise("You requested this to fail")
|
||||||
|
|
||||||
|
|
||||||
|
def main():
|
||||||
|
MyTest.execute()
|
||||||
|
|
||||||
|
|
||||||
|
if __name__ == '__main__':
|
||||||
|
main()
|
||||||
|
|
||||||
|
|
||||||
|
Module Helper
|
||||||
|
^^^^^^^^^^^^^
|
||||||
|
|
||||||
|
Introduction
|
||||||
|
""""""""""""
|
||||||
|
|
||||||
|
``ModuleHelper`` is a wrapper around the standard ``AnsibleModule``, providing extra features and conveniences.
|
||||||
|
The basic structure of a module using ``ModuleHelper`` is as shown in the
|
||||||
|
:ref:`ansible_collections.community.general.docsite.guide_modulehelper.quickstart`
|
||||||
|
section above, but there are more elements that will take part in it.
|
||||||
|
|
||||||
|
.. code-block:: python
|
||||||
|
|
||||||
|
from ansible_collections.community.general.plugins.module_utils.module_helper import ModuleHelper
|
||||||
|
|
||||||
|
class MyTest(ModuleHelper):
|
||||||
|
output_params = ()
|
||||||
|
change_params = ()
|
||||||
|
diff_params = ()
|
||||||
|
facts_name = None
|
||||||
|
facts_params = ()
|
||||||
|
use_old_vardict = True
|
||||||
|
mute_vardict_deprecation = False
|
||||||
|
module = dict(
|
||||||
|
argument_spec=dict(...),
|
||||||
|
# ...
|
||||||
|
)
|
||||||
|
|
||||||
|
After importing the ``ModuleHelper`` class, you need to declare your own class extending it.
|
||||||
|
|
||||||
|
.. seealso::
|
||||||
|
|
||||||
|
There is a variation called ``StateModuleHelper``, which builds on top of the features provided by MH.
|
||||||
|
See :ref:`ansible_collections.community.general.docsite.guide_modulehelper.statemh` below for more details.
|
||||||
|
|
||||||
|
The easiest way of specifying the module is to create the class variable ``module`` with a dictionary
|
||||||
|
containing the exact arguments that would be passed as parameters to ``AnsibleModule``.
|
||||||
|
If you prefer to create the ``AnsibleModule`` object yourself, just assign it to the ``module`` class variable.
|
||||||
|
MH also accepts a parameter ``module`` in its constructor, if that parameter is used used,
|
||||||
|
then it will override the class variable. The parameter can either be ``dict`` or ``AnsibleModule`` as well.
|
||||||
|
|
||||||
|
Beyond the definition of the module, there are other variables that can be used to control aspects
|
||||||
|
of MH's behavior. These variables should be set at the very beginning of the class, and their semantics are
|
||||||
|
explained through this document.
|
||||||
|
|
||||||
|
The main logic of MH happens in the ``ModuleHelper.run()`` method, which looks like:
|
||||||
|
|
||||||
|
.. code-block:: python
|
||||||
|
|
||||||
|
@module_fails_on_exception
|
||||||
|
def run(self):
|
||||||
|
self.__init_module__()
|
||||||
|
self.__run__()
|
||||||
|
self.__quit_module__()
|
||||||
|
output = self.output
|
||||||
|
if 'failed' not in output:
|
||||||
|
output['failed'] = False
|
||||||
|
self.module.exit_json(changed=self.has_changed(), **output)
|
||||||
|
|
||||||
|
The method ``ModuleHelper.__run__()`` must be implemented by the module and most
|
||||||
|
modules will be able to perform their actions implementing only that MH method.
|
||||||
|
However, in some cases, you might want to execute actions before or after the main tasks, in which cases
|
||||||
|
you should implement ``ModuleHelper.__init_module__()`` and ``ModuleHelper.__quit_module__()`` respectively.
|
||||||
|
|
||||||
|
Note that the output comes from ``self.output``, which is a ``@property`` method.
|
||||||
|
By default, that property will collect all the variables that are marked for output and return them in a dictionary with their values.
|
||||||
|
Moreover, the default ``self.output`` will also handle Ansible ``facts`` and *diff mode*.
|
||||||
|
Also note the changed status comes from ``self.has_changed()``, which is usually calculated from variables that are marked
|
||||||
|
to track changes in their content.
|
||||||
|
|
||||||
|
.. seealso::
|
||||||
|
|
||||||
|
More details in sections
|
||||||
|
:ref:`ansible_collections.community.general.docsite.guide_modulehelper.paramvaroutput` and
|
||||||
|
:ref:`ansible_collections.community.general.docsite.guide_modulehelper.changes` below.
|
||||||
|
|
||||||
|
.. seealso::
|
||||||
|
|
||||||
|
See more about the decorator
|
||||||
|
:ref:`ansible_collections.community.general.docsite.guide_modulehelper.modulefailsdeco` below.
|
||||||
|
|
||||||
|
|
||||||
|
Another way to write the example from the
|
||||||
|
:ref:`ansible_collections.community.general.docsite.guide_modulehelper.quickstart`
|
||||||
|
would be:
|
||||||
|
|
||||||
|
.. code-block:: python
|
||||||
|
|
||||||
|
def __init_module__(self):
|
||||||
|
self.vars.original_message = ''
|
||||||
|
self.vars.message = ''
|
||||||
|
|
||||||
|
def __run__(self):
|
||||||
|
if self.check_mode:
|
||||||
|
return
|
||||||
|
self.vars.original_message = self.vars.name
|
||||||
|
self.vars.message = 'goodbye'
|
||||||
|
self.changed = self.vars['new']
|
||||||
|
|
||||||
|
def __quit_module__(self):
|
||||||
|
if self.vars.name == "fail me":
|
||||||
|
self.do_raise("You requested this to fail")
|
||||||
|
|
||||||
|
Notice that there are no calls to ``module.exit_json()`` nor ``module.fail_json()``: if the module fails, raise an exception.
|
||||||
|
You can use the convenience method ``self.do_raise()`` or raise the exception as usual in Python to do that.
|
||||||
|
If no exception is raised, then the module succeeds.
|
||||||
|
|
||||||
|
.. seealso::
|
||||||
|
|
||||||
|
See more about exceptions in section
|
||||||
|
:ref:`ansible_collections.community.general.docsite.guide_modulehelper.exceptions` below.
|
||||||
|
|
||||||
|
Ansible modules must have a ``main()`` function and the usual test for ``'__main__'``. When using MH that should look like:
|
||||||
|
|
||||||
|
.. code-block:: python
|
||||||
|
|
||||||
|
def main():
|
||||||
|
MyTest.execute()
|
||||||
|
|
||||||
|
|
||||||
|
if __name__ == '__main__':
|
||||||
|
main()
|
||||||
|
|
||||||
|
The class method ``execute()`` is nothing more than a convenience shorcut for:
|
||||||
|
|
||||||
|
.. code-block:: python
|
||||||
|
|
||||||
|
m = MyTest()
|
||||||
|
m.run()
|
||||||
|
|
||||||
|
Optionally, an ``AnsibleModule`` may be passed as parameter to ``execute()``.
|
||||||
|
|
||||||
|
.. _ansible_collections.community.general.docsite.guide_modulehelper.paramvaroutput:
|
||||||
|
|
||||||
|
Parameters, variables, and output
|
||||||
|
"""""""""""""""""""""""""""""""""
|
||||||
|
|
||||||
|
All the parameters automatically become variables in the ``self.vars`` attribute, which is of the ``VarDict`` type.
|
||||||
|
By using ``self.vars``, you get a central mechanism to access the parameters but also to expose variables as return values of the module.
|
||||||
|
As described in :ref:`ansible_collections.community.general.docsite.guide_vardict`, variables in ``VarDict`` have metadata associated to them.
|
||||||
|
One of the attributes in that metadata marks the variable for output, and MH makes use of that to generate the module's return values.
|
||||||
|
|
||||||
|
.. important::
|
||||||
|
|
||||||
|
The ``VarDict`` feature described was introduced in community.general 7.1.0, but there was a first
|
||||||
|
implementation of it embedded within ``ModuleHelper``.
|
||||||
|
That older implementation is now deprecated and will be removed in community.general 11.0.0.
|
||||||
|
After community.general 7.1.0, MH modules generate a deprecation message about *using the old VarDict*.
|
||||||
|
There are two ways to prevent that from happening:
|
||||||
|
|
||||||
|
#. Set ``mute_vardict_deprecation = True`` and the deprecation will be silenced. If the module still uses the old ``VarDict``,
|
||||||
|
it will not be able to update to community.general 11.0.0 (Spring 2026) upon its release.
|
||||||
|
#. Set ``use_old_vardict = False`` to make the MH module use the new ``VarDict`` immediatelly.
|
||||||
|
The new ``VarDict`` and its use is documented and this is the recommended way to handle this.
|
||||||
|
|
||||||
|
.. code-block:: python
|
||||||
|
|
||||||
|
class MyTest(ModuleHelper):
|
||||||
|
use_old_vardict = False
|
||||||
|
mute_vardict_deprecation = True
|
||||||
|
...
|
||||||
|
|
||||||
|
These two settings are mutually exclusive, but that is not enforced and the behavior when setting both is not specified.
|
||||||
|
|
||||||
|
Contrary to new variables created in ``VarDict``, module parameters are not set for output by default.
|
||||||
|
If you want to include some module parameters in the output, list them in the ``output_params`` class variable.
|
||||||
|
|
||||||
|
.. code-block:: python
|
||||||
|
|
||||||
|
class MyTest(ModuleHelper):
|
||||||
|
output_params = ('state', 'name')
|
||||||
|
...
|
||||||
|
|
||||||
|
Another neat feature provided by MH by using ``VarDict`` is the automatic tracking of changes when setting the metadata ``change=True``.
|
||||||
|
Again, to enable this feature for module parameters, you must list them in the ``change_params`` class variable.
|
||||||
|
|
||||||
|
.. code-block:: python
|
||||||
|
|
||||||
|
class MyTest(ModuleHelper):
|
||||||
|
# example from community.general.xfconf
|
||||||
|
change_params = ('value', )
|
||||||
|
...
|
||||||
|
|
||||||
|
.. seealso::
|
||||||
|
|
||||||
|
See more about this in
|
||||||
|
:ref:`ansible_collections.community.general.docsite.guide_modulehelper.changes` below.
|
||||||
|
|
||||||
|
Similarly, if you want to use Ansible's diff mode, you can set the metadata ``diff=True`` and ``diff_params`` for module parameters.
|
||||||
|
With that, MH will automatically generate the diff output for variables that have changed.
|
||||||
|
|
||||||
|
.. code-block:: python
|
||||||
|
|
||||||
|
class MyTest(ModuleHelper):
|
||||||
|
diff_params = ('value', )
|
||||||
|
|
||||||
|
def __run__(self):
|
||||||
|
# example from community.general.gio_mime
|
||||||
|
self.vars.set_meta("handler", initial_value=gio_mime_get(self.runner, self.vars.mime_type), diff=True, change=True)
|
||||||
|
|
||||||
|
Moreover, if a module is set to return *facts* instead of return values, then again use the metadata ``fact=True`` and ``fact_params`` for module parameters.
|
||||||
|
Additionally, you must specify ``facts_name``, as in:
|
||||||
|
|
||||||
|
.. code-block:: python
|
||||||
|
|
||||||
|
class VolumeFacts(ModuleHelper):
|
||||||
|
facts_name = 'volume_facts'
|
||||||
|
|
||||||
|
def __init_module__(self):
|
||||||
|
self.vars.set("volume", 123, fact=True)
|
||||||
|
|
||||||
|
That generates an Ansible fact like:
|
||||||
|
|
||||||
|
.. code-block:: yaml+jinja
|
||||||
|
|
||||||
|
- name: Obtain volume facts
|
||||||
|
some.collection.volume_facts:
|
||||||
|
# parameters
|
||||||
|
|
||||||
|
- name: Print volume facts
|
||||||
|
debug:
|
||||||
|
msg: Volume fact is {{ ansible_facts.volume_facts.volume }}
|
||||||
|
|
||||||
|
.. important::
|
||||||
|
|
||||||
|
If ``facts_name`` is not set, the module does not generate any facts.
|
||||||
|
|
||||||
|
|
||||||
|
.. _ansible_collections.community.general.docsite.guide_modulehelper.changes:
|
||||||
|
|
||||||
|
Handling changes
|
||||||
|
""""""""""""""""
|
||||||
|
|
||||||
|
In MH there are many ways to indicate change in the module execution. Here they are:
|
||||||
|
|
||||||
|
Tracking changes in variables
|
||||||
|
-----------------------------
|
||||||
|
|
||||||
|
As explained above, you can enable change tracking in any number of variables in ``self.vars``.
|
||||||
|
By the end of the module execution, if any of those variables has a value different then the first value assigned to them,
|
||||||
|
then that will be picked up by MH and signalled as changed at the module output.
|
||||||
|
See the example below to learn how you can enabled change tracking in variables:
|
||||||
|
|
||||||
|
.. code-block:: python
|
||||||
|
|
||||||
|
# using __init_module__() as example, it works the same in __run__() and __quit_module__()
|
||||||
|
def __init_module__(self):
|
||||||
|
# example from community.general.ansible_galaxy_install
|
||||||
|
self.vars.set("new_roles", {}, change=True)
|
||||||
|
|
||||||
|
# example of "hidden" variable used only to track change in a value from community.general.gconftool2
|
||||||
|
self.vars.set('_value', self.vars.previous_value, output=False, change=True)
|
||||||
|
|
||||||
|
# enable change-tracking without assigning value
|
||||||
|
self.vars.set_meta("new_roles", change=True)
|
||||||
|
|
||||||
|
# if you must forcibly set an initial value to the variable
|
||||||
|
self.vars.set_meta("new_roles", initial_value=[])
|
||||||
|
...
|
||||||
|
|
||||||
|
If the end value of any variable marked ``change`` is different from its initial value, then MH will return ``changed=True``.
|
||||||
|
|
||||||
|
Indicating changes with ``changed``
|
||||||
|
-----------------------------------
|
||||||
|
|
||||||
|
If you want to indicate change directly in the code, then use the ``self.changed`` property in MH.
|
||||||
|
Beware that this is a ``@property`` method in MH, with both a *getter* and a *setter*.
|
||||||
|
By default, that hidden field is set to ``False``.
|
||||||
|
|
||||||
|
Effective change
|
||||||
|
----------------
|
||||||
|
|
||||||
|
The effective outcome for the module is determined in the ``self.has_changed()`` method, and it consists of the logical *OR* operation
|
||||||
|
between ``self.changed`` and the change calculated from ``self.vars``.
|
||||||
|
|
||||||
|
.. _ansible_collections.community.general.docsite.guide_modulehelper.exceptions:
|
||||||
|
|
||||||
|
Exceptions
|
||||||
|
""""""""""
|
||||||
|
|
||||||
|
In MH, instead of calling ``module.fail_json()`` you can just raise an exception.
|
||||||
|
The output variables are collected the same way they would be for a successful execution.
|
||||||
|
However, you can set output variables specifically for that exception, if you so choose.
|
||||||
|
|
||||||
|
.. code-block:: python
|
||||||
|
|
||||||
|
def __init_module__(self):
|
||||||
|
if not complex_validation():
|
||||||
|
self.do_raise("Validation failed!")
|
||||||
|
|
||||||
|
# Or passing output variables
|
||||||
|
awesomeness = calculate_awesomeness()
|
||||||
|
if awesomeness > 1000:
|
||||||
|
self.do_raise("Over awesome, I cannot handle it!", update_output={"awesomeness": awesomeness})
|
||||||
|
|
||||||
|
All exceptions derived from ``Exception`` are captured and translated into a ``fail_json()`` call.
|
||||||
|
However, if you do want to call ``self.module.fail_json()`` yourself it will work,
|
||||||
|
just keep in mind that there will be no automatic handling of output variables in that case.
|
||||||
|
|
||||||
|
.. _ansible_collections.community.general.docsite.guide_modulehelper.statemh:
|
||||||
|
|
||||||
|
StateModuleHelper
|
||||||
|
^^^^^^^^^^^^^^^^^
|
||||||
|
|
||||||
|
Many modules use a parameter ``state`` that effectively controls the exact action performed by the module, such as
|
||||||
|
``state=present`` or ``state=absent`` for installing or removing packages.
|
||||||
|
By using ``StateModuleHelper`` you can make your code like the excerpt from the ``gconftool2`` below:
|
||||||
|
|
||||||
|
.. code-block:: python
|
||||||
|
|
||||||
|
from ansible_collections.community.general.plugins.module_utils.module_helper import StateModuleHelper
|
||||||
|
|
||||||
|
class GConftool(StateModuleHelper):
|
||||||
|
...
|
||||||
|
module = dict(
|
||||||
|
...
|
||||||
|
)
|
||||||
|
use_old_vardict = False
|
||||||
|
|
||||||
|
def __init_module__(self):
|
||||||
|
self.runner = gconftool2_runner(self.module, check_rc=True)
|
||||||
|
...
|
||||||
|
|
||||||
|
self.vars.set('previous_value', self._get(), fact=True)
|
||||||
|
self.vars.set('value_type', self.vars.value_type)
|
||||||
|
self.vars.set('_value', self.vars.previous_value, output=False, change=True)
|
||||||
|
self.vars.set_meta('value', initial_value=self.vars.previous_value)
|
||||||
|
self.vars.set('playbook_value', self.vars.value, fact=True)
|
||||||
|
|
||||||
|
...
|
||||||
|
|
||||||
|
def state_absent(self):
|
||||||
|
with self.runner("state key", output_process=self._make_process(False)) as ctx:
|
||||||
|
ctx.run()
|
||||||
|
self.vars.set('run_info', ctx.run_info, verbosity=4)
|
||||||
|
self.vars.set('new_value', None, fact=True)
|
||||||
|
self.vars._value = None
|
||||||
|
|
||||||
|
def state_present(self):
|
||||||
|
with self.runner("direct config_source value_type state key value", output_process=self._make_process(True)) as ctx:
|
||||||
|
ctx.run()
|
||||||
|
self.vars.set('run_info', ctx.run_info, verbosity=4)
|
||||||
|
self.vars.set('new_value', self._get(), fact=True)
|
||||||
|
self.vars._value = self.vars.new_value
|
||||||
|
|
||||||
|
Note that the method ``__run__()`` is implemented in ``StateModuleHelper``, all you need to implement are the methods ``state_<state_value>``.
|
||||||
|
In the example above, :ansplugin:`community.general.gconftool2#module` only has two states, ``present`` and ``absent``, thus, ``state_present()`` and ``state_absent()``.
|
||||||
|
|
||||||
|
If the controlling parameter is not called ``state``, like in :ansplugin:`community.general.jira#module` module, just let SMH know about it:
|
||||||
|
|
||||||
|
.. code-block:: python
|
||||||
|
|
||||||
|
class JIRA(StateModuleHelper):
|
||||||
|
state_param = 'operation'
|
||||||
|
|
||||||
|
def operation_create(self):
|
||||||
|
...
|
||||||
|
|
||||||
|
def operation_search(self):
|
||||||
|
...
|
||||||
|
|
||||||
|
Lastly, if the module is called with ``state=somevalue`` and the method ``state_somevalue``
|
||||||
|
is not implemented, SMH will resort to call a method called ``__state_fallback__()``.
|
||||||
|
By default, this method will raise a ``ValueError`` indicating the method was not found.
|
||||||
|
Naturally, you can override that method to write a default implementation, as in :ansplugin:`community.general.locale_gen#module`:
|
||||||
|
|
||||||
|
.. code-block:: python
|
||||||
|
|
||||||
|
def __state_fallback__(self):
|
||||||
|
if self.vars.state_tracking == self.vars.state:
|
||||||
|
return
|
||||||
|
if self.vars.ubuntu_mode:
|
||||||
|
self.apply_change_ubuntu(self.vars.state, self.vars.name)
|
||||||
|
else:
|
||||||
|
self.apply_change(self.vars.state, self.vars.name)
|
||||||
|
|
||||||
|
That module has only the states ``present`` and ``absent`` and the code for both is the one in the fallback method.
|
||||||
|
|
||||||
|
.. note::
|
||||||
|
|
||||||
|
The name of the fallback method **does not change** if you set a different value of ``state_param``.
|
||||||
|
|
||||||
|
|
||||||
|
Other Conveniences
|
||||||
|
^^^^^^^^^^^^^^^^^^
|
||||||
|
|
||||||
|
Delegations to AnsibleModule
|
||||||
|
""""""""""""""""""""""""""""
|
||||||
|
|
||||||
|
The MH properties and methods below are delegated as-is to the underlying ``AnsibleModule`` instance in ``self.module``:
|
||||||
|
|
||||||
|
- ``check_mode``
|
||||||
|
- ``get_bin_path()``
|
||||||
|
- ``warn()``
|
||||||
|
- ``deprecate()``
|
||||||
|
|
||||||
|
Additionally, MH will also delegate:
|
||||||
|
|
||||||
|
- ``diff_mode`` to ``self.module._diff``
|
||||||
|
- ``verbosity`` to ``self.module._verbosity``
|
||||||
|
|
||||||
|
Decorators
|
||||||
|
""""""""""
|
||||||
|
|
||||||
|
The following decorators should only be used within ``ModuleHelper`` class.
|
||||||
|
|
||||||
|
@cause_changes
|
||||||
|
--------------
|
||||||
|
|
||||||
|
This decorator will control whether the outcome of the method will cause the module to signal change in its output.
|
||||||
|
If the method completes without raising an exception it is considered to have succeeded, otherwise, it will have failed.
|
||||||
|
|
||||||
|
The decorator has a parameter ``when`` that accepts three different values: ``success``, ``failure``, and ``always``.
|
||||||
|
There are also two legacy parameters, ``on_success`` and ``on_failure``, that will be deprecated, so do not use them.
|
||||||
|
The value of ``changed`` in the module output will be set to ``True``:
|
||||||
|
|
||||||
|
- ``when="success"`` and the method completes without raising an exception.
|
||||||
|
- ``when="failure"`` and the method raises an exception.
|
||||||
|
- ``when="always"``, regardless of the method raising an exception or not.
|
||||||
|
|
||||||
|
.. code-block:: python
|
||||||
|
|
||||||
|
from ansible_collections.community.general.plugins.module_utils.module_helper import cause_changes
|
||||||
|
|
||||||
|
# adapted excerpt from the community.general.jira module
|
||||||
|
class JIRA(StateModuleHelper):
|
||||||
|
@cause_changes(when="success")
|
||||||
|
def operation_create(self):
|
||||||
|
...
|
||||||
|
|
||||||
|
If ``when`` has a different value or no parameters are specificied, the decorator will have no effect whatsoever.
|
||||||
|
|
||||||
|
.. _ansible_collections.community.general.docsite.guide_modulehelper.modulefailsdeco:
|
||||||
|
|
||||||
|
@module_fails_on_exception
|
||||||
|
--------------------------
|
||||||
|
|
||||||
|
In a method using this decorator, if an exception is raised, the text message of that exception will be captured
|
||||||
|
by the decorator and used to call ``self.module.fail_json()``.
|
||||||
|
In most of the cases there will be no need to use this decorator, because ``ModuleHelper.run()`` already uses it.
|
||||||
|
|
||||||
|
@check_mode_skip
|
||||||
|
----------------
|
||||||
|
|
||||||
|
If the module is running in check mode, this decorator will prevent the method from executing.
|
||||||
|
The return value in that case is ``None``.
|
||||||
|
|
||||||
|
.. code-block:: python
|
||||||
|
|
||||||
|
from ansible_collections.community.general.plugins.module_utils.module_helper import check_mode_skip
|
||||||
|
|
||||||
|
# adapted excerpt from the community.general.locale_gen module
|
||||||
|
class LocaleGen(StateModuleHelper):
|
||||||
|
@check_mode_skip
|
||||||
|
def __state_fallback__(self):
|
||||||
|
...
|
||||||
|
|
||||||
|
|
||||||
|
@check_mode_skip_returns
|
||||||
|
------------------------
|
||||||
|
|
||||||
|
This decorator is similar to the previous one, but the developer can control the return value for the method when running in check mode.
|
||||||
|
It is used with one of two parameters. One is ``callable`` and the return value in check mode will be ``callable(self, *args, **kwargs)``,
|
||||||
|
where ``self`` is the ``ModuleHelper`` instance and the union of ``args`` and ``kwargs`` will contain all the parameters passed to the method.
|
||||||
|
|
||||||
|
The other option is to use the parameter ``value``, in which case the method will return ``value`` when in check mode.
|
||||||
|
|
||||||
|
|
||||||
|
References
|
||||||
|
^^^^^^^^^^
|
||||||
|
|
||||||
|
- `Ansible Developer Guide <https://docs.ansible.com/ansible/latest/dev_guide/index.html>`_
|
||||||
|
- `Creating a module <https://docs.ansible.com/ansible/latest/dev_guide/developing_modules_general.html#creating-a-module>`_
|
||||||
|
- `Returning ansible facts <https://docs.ansible.com/ansible/latest/reference_appendices/common_return_values.html#ansible-facts>`_
|
||||||
|
- :ref:`ansible_collections.community.general.docsite.guide_vardict`
|
||||||
|
|
||||||
|
|
||||||
|
.. versionadded:: 3.1.0
|
Loading…
Reference in a new issue